the world of biology

New Mobile Lab Allows Researchers To Study Air Quality, Health Effects

2009-10-08T21:04:00.002+07:00

A new mobile air research laboratory will help a team of researchers led by a Michigan State University professor better understand the damaging health effects of air pollution and why certain airborne particles - emitted from plants and vehicles - induce disease and illness.

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Jack Harkema, a University Distinguished Professor of pathobiology and diagnostic investigation in the College of Veterinary Medicine, will deploy the new 53-foot, 36,000-pound center - dubbed "AirCARE 2" - throughout southern Michigan, including metropolitan Detroit.

"The mobile laboratory allows us to analyze ‘real-world' pollution in communities that may be at risk," he said. "We can study why certain ailments, such as asthma, cardiovascular disease and even obesity, may be more pronounced after exposure to particulate air pollution."

With about 450 square feet of indoor laboratory space, the $400,000 center helps researchers study fine and ultrafine particles in air pollution. These small particles have been found to increase mortality and morbidity among susceptible people with pre-existing health conditions such as heart disease.

Housed in a converted semitrailer, the mobile laboratory pulls air from the surrounding atmosphere through an air-particle concentrator, allowing the scientists to selectively collect the particles and analyze for chemical components that may be responsible for damaging health effects.

Researchers can study the subtle effects of controlled particle exposure on both laboratory animals and human subjects, providing clues on why and how pollutant particles are so harmful to the heart and lungs. Harkema works closely with environmental and biomedical researchers from the University of Michigan on the projects.

"We know particles in the air can exacerbate pre-existing respiratory and cardiovascular disease in people," Harkema said. "We need to understand why. There are many different components to air pollution, and we want to determine which of these are most harmful and where there come from."

The addition of the new mobile laboratory allows Harkema and U-M collaborators Robert Brook, a cardiologist, and Gerald Keeler, an atmospheric scientist, to conduct a new study funded by the Environmental Protection Agency. As part of the project, Harkema, Brook and Keeler will deploy AirCARE 2 in rural southeastern Michigan to study the cardiovascular health effects of transported air pollution originating from distant emission sites in Michigan or adjacent states.

AirCARE 2 was partly funded through the MSU strategic partnership grant, the Michigan Agricultural Experiment Station, the College of Veterinary Medicine and the Office of the Vice President for Research and Graduate Studies. The new fine particle concentrator in the AirCARE 2 received some funds from the Electric Power Research Institute and the American Petroleum Institute.

The first MSU Mobile Air Research Laboratory, AirCARE 1, currently spends six months of the year in metro Detroit conducting air pollution studies and then six months in Los Angeles as part of a six-university partnership known as the federal Southern California Particle Center in California. The $8 million partnership, funded by the EPA and led by UCLA, is a five-year endeavor to investigate how exposure to airborne particles affects health and how the impact varies with the source, chemical composition and physical size.

New Evidence That Green Tea May Help Improve Bone Health

2009-10-08T20:57:00.002+07:00

Researchers in Hong Kong are reporting new evidence that green tea — one of the most popular beverages consumed worldwide and now available as a dietary supplement — may help improve bone health. They found that the tea contains a group of chemicals that can stimulate bone formation and help slow its breakdown.
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The beverage has the potential to help in the prevention and treatment of osteoporosis and other bone diseases that affect million worldwide, the researchers suggest.

In the new study, Ping Chung Leung and colleagues note that many scientific studies have linked tea to beneficial effects in preventing cancer, heart disease, and other conditions. Recent studies in humans and cell cultures suggest that tea may also benefit bone health. But few scientific studies have explored the exact chemicals in tea that might be responsible for this effect.

The scientists exposed a group of cultured bone-forming cells (osteoblasts) to three major green tea components — epigallocatechin (EGC), gallocatechin (GC), and gallocatechin gallate (GCG) — for several days. They found that one in particular, EGC, boosted the activity of a key enzyme that promotes bone growth by up to 79 percent. EGC also significantly boosted levels of bone mineralization in the cells, which strengthens bones. The scientists also showed that high concentrations of ECG blocked the activity of a type of cell (osteoclast) that breaks down or weakens bones. The green tea components did not cause any toxic effects to the bone cells, they note.

Nobel Prize In Chemistry: What Ribosomes Look Like And How They Functions At Atomic Level

2009-10-08T20:55:00.001+07:00

The Royal Swedish Academy of Sciences has decided to award the Nobel Prize in Chemistry for 2009 jointly to Venkatraman Ramakrishnan, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom; Thomas A. Steitz, Yale University, New Haven, CT, USA; and Ada E. Yonath, Weizmann Institute of Science, Rehovot, Israel, "for studies of the structure and function of the ribosome".
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The ribosome translates the DNA code into life

The Nobel Prize in Chemistry for 2009 awards studies of one of life's core processes: the ribosome's translation of DNA information into life. Ribosomes produce proteins, which in turn control the chemistry in all living organisms. As ribosomes are crucial to life, they are also a major target for new antibiotics.

This year's Nobel Prize in Chemistry awards Venkatraman Ramakrishnan, Thomas A. Steitz and Ada E. Yonath for having showed what the ribosome looks like and how it functions at the atomic level. All three have used a method called X-ray crystallography to map the position for each and every one of the hundreds of thousands of atoms that make up the ribosome.

Inside every cell in all organisms, there are DNA molecules. They contain the blueprints for how a human being, a plant or a bacterium, looks and functions. But the DNA molecule is passive. If there was nothing else, there would be no life.

The blueprints become transformed into living matter through the work of ribosomes. Based upon the information in DNA, ribosomes make proteins: oxygen-transporting haemoglobin, antibodies of the immune system, hormones such as insulin, the collagen of the skin, or enzymes that break down sugar. There are tens of thousands of proteins in the body and they all have different forms and functions. They build and control life at the chemical level.

An understanding of the ribosome's innermost workings is important for a scientific understanding of life. This knowledge can be put to a practical and immediate use; many of today's antibiotics cure various diseases by blocking the function of bacterial ribosomes. Without functional ribosomes, bacteria cannot survive. This is why ribosomes are such an important target for new antibiotics.

This year's three Laureates have all generated 3D models that show how different antibiotics bind to the ribosome. These models are now used by scientists in order to develop new antibiotics, directly assisting the saving of lives and decreasing humanity's suffering.

RESTORASI EKOSISTEM SUNGAI

2009-10-08T20:43:00.002+07:00

Sungai adalah suatu badan air yang mengalir ke satu arah. Air sungai dingin dan jernih serta mengandung sedikit sedimen dan makanan. Aliran air dan gelombang secara konstan memberikan oksigen pada air. Suhu air bervariasi sesuai dengan ketinggian dan garis lintang.

Komunitas yang berada di sungai berbeda dengan danau. Air sungai yang mengalir deras tidak mendukung keberadaan komunitas plankton untuk berdiam diri, karena akan terbawa arus. Sebagai gantinya terjadi fotosintesis dari ganggang yang melekat dan tanaman berakar, sehingga dapat mendukung rantai makanan.

Lingkungan perairan sungai terdiri dari komponen abiotik dan biotik (algal flora) yang saling berinteraksi melalui arus energi dan daur hara (nutrien). Bila interaksi keduanya terganggu, maka akan terjadi perubahan atau gangguan yang menyebabkan ekosistem perairan itu menjadi tidak seimbang (Soylu dan Gönülol, 2003). Seperti halnya Sungai Ciliwung yang lahan di sekitar bantaran sungainya telah dimanfaatkan untuk permukiman dan aktivitas lainnya yaitu pertanian, industri, perkantoran dan perdagangan. Kegiatan pada lahan tersebut pada umumnya mengeluarkan limbah dan menghasilkan sampah yang langsung dibuang ke dalam perairan sungai sehingga masuknya sumber-sumber pencemar tersebut menyebabkan penurunan kualitas perairan (Hendrawan dkk., 2004). Buangan tersebut pada umumnya mengandung zat-zat yang bersifat racun yang menyebabkan deoksigenasi, naiknya temperatur, serta meningkatnya padatan tersuspensi, terlarut dan partikulat bahan organik. Masuknya limbah ke dalam perairan akan mengubah kondisi ekologi perairan dan komunitas di dalamnya (Stoddard dkk., 2003; Bledsoe dkk., 2004; Tuvikene dkk., 2005).

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Salah satu biota alga yaitu fitoplankton merupakan organisme yang mempunyai peranan besar dalam ekosistem perairan dan menjadi produsen primer (Lacerda dkk., 2004). Keberadaan fitoplankton dapat dijadikan sebagai bioindikator adanya perubahan lingkungan perairan yang disebabkan ketidakseimbangan suatu ekosistem akibat pencemaran (Oxborough dan Baker, 1997; Ekwu dan Sikoki, 2006). Analisis struktur, kemelimpahan dan model distribusi kemelimpahan fitoplankton juga dapat memberikan gambaran kondisi perairan Sungai Ciliwung (Fachrul, 2003).

Sungai diibaratkan sebagai urat nadi dalam tubuh manusia, sementara air yang mengalir dalam urat nadi tersebut diumpamakan sebagai darah. Tanpa urat nadi, darah tidak mungkin mengirimkan berbagai zat makanan yang dibutuhkan oleh semua bagian tubuh manusia. Demikian juga tanpa sungai atau apabila sungai sudah tercemar maka manusia selain akan kesulitan untuk mendapatkan air yang layak, namun juga akan mahal. Sebagaimana yang sudah diketahui, DeSanto (1978) mengemukakan bahwa sekitar 70% tubuh manusia merupakan air dan setiap harinya manusia membutuhkan sekitar 1,5 L air untuk tetap survive, dan ekosistem daratan secara langsung tergantung pada air sebagai faktor yang menentukan struktur dan fungsi seluruh bioma di bumi. Sementera itu, Odum (1988) mengemukakan bahwa oleh karena air amat penting dan merupakan bagian terbesar dari protoplasma, maka dapatlah dikatakan bahwa semua kehidupan adalah ‘akuatik’.

Sungai tempat air mengalir dan membawa berbagai kebutuhan hidup manusia dan berbagai mahkluk lain yang dilaluinya, merupakan bagian dari ekosistem air tawar. Meskipun luasan sungai dan jumlah air yang mengalir di dalamnya sangat sedikit jika dibandingkan dengan luas dan jumlah air yang di laut, namun sungai memiliki peranan penting secara langsung bagi kehidupan manusia dan mahkluk di sekitarnya. Sungai, dalam sejarahnya, telah memberi manfaat besar bagi umat manusia, hingga kini. Selain sebagai sumber air, sungai juga bermanfaat sebagai sarana perhubungan, sumber tenaga (listrik dengan PLTA _Pembangkit Listrik Tenaga Air), serta juga sebagai sumber pangan, karena menyimpan keragaman plasma nutfah.

Kerusakan pada Ekosistem Sungai

Kondisi kualitas air yang terus cenderung menurun, juga disebabkan oleh masih adanya budaya di masyarakat Indonesia yang menganggap sungai dan danau sebagai tempat pembuangan sampah, limbah padat, cair, air limbah lainnya. Sehingga telah merusak lingkungan sungai di beberapa tempat dengan kondisi yang sangat mengkhawatirkan.

Musim di wilayah Indonesia merupakan faktor alam yang tidak dapat dirubah, namun kita hanya dapat berusaha untuk mengurangi efek yang merugikan. Kemungkinan efek negatif yang berpotensi untuk ditimbulkan oleh perubahan musim yaitu adanya kerusakan sumberdaya air baik pada musim kemarau maupun penghujan. Kondisi yang semakin memburuk karena hal tersebut, dapat dikurangi dengan melakukan suatu kegiatan untuk meningkatkan ketahanan. Dua faktor yang dapat dianggap sebagai pemicu terjadinya kerusakan sumberdaya air yaitu perubahan iklim dan kerusakan hutan.

Perubahan iklim

Karakteristik iklim suatu wilayah akan berpengaruh terhadap keberadaan sumberdaya air di wilayah tersebut, terutama untuk mengetahui periode kekurangan dan kelebihan pasokan air meteorologis. Unsur iklim yang perlu diperhatikan dalam kajian konservasi sumberdaya air meliputi agihan curah hujan tahunan dan agihan indeks kekeringan.

Disamping itu penyimpangan iklim global maupun regional juga berpengaruh pada rendahnya curah hujan musim kemarau pada wilayah-wilayah tertentu di Indonesia. Secara geografis, Indonesia terletak di wilayah iklim tropis dengan curah hujan rerata tahunan 2.900 mm/tahun (Suprapto, 2003). Masalah air terutama masalah banjir dan kekeringan merupakan dua hal yang selalu datang sesuai dengan datangnya musim. Hal ini terlihat dengan adanya kejadian kelangkaan atau defisit air pada musim kemarau dan terjadinya surplus air dalam bentuk banjir dan tanah longsor di musim hujan.

Kerusakan hutan

Kerusakan lahan berhutan, yang kerap terjadi di daerah dengan kelerengan curam, berpengaruh terhadap kerusakan ekosistem sungai, yang hulunya ke arah hutan. Ini terjadi karena dalam daur hidro-orologis terdapat suatu rantai perjalanan air: mulai saat hujan hingga bermuara ke laut. Kawasan hutan yang dikategorikan sebagai daerah tangkapan air hujan, merupakan bagian dari mata rantai itu. Sebab, hutan pada daerah perbukitan dan pergunungan berfungsi sebagai penyimpan cadangan air hujan, sekaligus penyarin yang bekerja secara alami. Proses penyaringan dari berbagai strata vegetasi, disertai kemampuan vegetasi menahan laju erosi lapisan atas tanah, mampu mengurangi gangguan pada ekosistem sungai secara alami pula.

Beberapa bencana seperti erosi, pendangkalan sungai di hilir, penurunan kualitas air sungai serta kepunahan spesies, terjadi karena hutan yang berada di hulu mengalami penggundulan. Jika dilakukan secara besar-besaran, akan mempengaruhi persediaan air tanah pada musim kemarau. Ini terkait dengan fungsi hutan sebagai kantung (penahan) air. Pada daerah yang gradien muka air tanahnya tinggi, daerah itu akan mudah kekurangan air di musim kemarau. Alasannya, permukaan air sungai lebih rendah dari permukaan air tanah.

Akibat penggundulan hutan (deforestasi), selain berdampak pada sungai, secara tidak langsung juga mempengaruhi pertumbuhan pohon dan tanaman. Sebab, kandungan lengas tanah yang seharusnya cukup, menjadi berkurang karena air hujan lebih sedikit yang terinfiltrasi ke dalam lapisan tanah. Pengaruh lebih luas adalah berkurangnya populasi ikan di sungai.

Beberapa jenis ikan kurang mampu beradaptasi karena terjadi perubahan habitat secara cepat. Perubahan intensitas penetrasi sinar matahari, oksigen, kandungan mineral dan tingkat keasaman (PH), adalah beberapa penyebabnya. Dengan berkurangnya populasi ikan, ini juga berdampak secara luas pada siklus rantai makanan. Populasi satwa, di antaranya, akan ikut berkurang karena kehilangan makanan.

Kerusakan hutan dan lahan pada bagian hulu merupakan penyebab utama terjadinya erosi dan sedimentasi pada alur-alur sungai alam sehingga mengurangi daya serap lahan terhadap air hujan. Hal ini menyebabkan terjadinya banjir tak terkontrol di musim penghujan dan kelangkaan air di musim kemarau. Kekeringan ini disebut sebagai kekeringan hidrologis dengan sistem penanganan yang tidak mudah dan kompleks. Data Balai Pemantapan Kawasan Hutan Jawa-Madura menggambarkan, kawasan hutan Jawa seluas 3.289.131 ha., saat ini kondisinya sangat memprihatinkan. Luas lahan di dalam kawasan hutan yang memerlukan rehabilitasi tercatat 1,714 juta ha (56,7 persen) dari luas seluruh kawsan hutan. Itu terdiri dari atas hutan lindung dan konservasi yang rusak seluas 567.315 ha serta hutan produksi tak berpohon seluas 1.147.116 ha. Kondisi ini diperparah oleh meluasnya lahan kritis di luar kawasan hutan yang telah mencapai 9,016 juta ha. Total lahan yang perlu direhabilitasi mencapai 10,731 juta ha atau 84,16 persen dari seluruh daratan Pulau Jawa.

Ekologi Restorasi

Ekosistem yang rusak dan terdegradasi merupakan suatu kesempatan bagi ahli dan praktisi biologi untuk menerapkan hasil penelitian dalam upaya pemulihan spesiaes maupun komunitas yang pernah menghuni ekosistem tersebut di masa lalu. Pemulihan ekosistem yang rusak berpotensi besar untuk memperkuat sistem kawasan konservasi yang ada. Pemulihan ekologi (ecological restoration) merupakan praktik perbaikan, yang dapat didefinisikan sebagai proses yang secara sengaja mengubah (keadaan lingkungan) suatu lokasi untuk membentuk kembali suatu ekosistem tertentu yang bersifat asli dan bernilai sejarah. Tujuan dari proses (restorasi) tersebut adalah mengembalikan struktur, fungsi, keanekaragaman serta dinamika dari ekosistem terkait (Society of Ecological Restoration, 1991). Disamping berperan menunjang strategi konservasi, proyek restorasi membuka kesempatan penyususnan kembali komunitas secara utuh, dengan mempertimbangkan fungsi ekosistem terkait (Callaway dkk., 2003).

Ekosistem dapat dirusak oleh bencana alam, misalnya oleh badai atau kebakaran yang disebabkan oleh petir. Namun, melalui proses suksesi alami pada umumnya ekosistem masih dapat memulihkan struktur komunitas asli setempat bahkan dengan komposisi spesies yang serupa dengan asalnya. Bagaimanapun, seringkali kualitas ekosistem yang dirusak oleh kegiatan manusia telah menurun sedemikian rendah sehingga sulit dipulihkan. Pemulihan alami mungkin tertunda hingga beberapa dekade atau bahkan berabad – abad. Pemulihanpun tidak dapat berjalan dengan baik bila penyebabnya masih ada dalam ekosistem.

Habitat baru umumnya dibentuk untuk menggantikan habitat yang telah rusak di tempat lain. Pembentukan habitat baru yang memiliki komposisi spesies dan fungsi ekosistem yang setara dengan lokasi acuan (references sites) seringkali menjadi tujuan utama restorasi (MacDougall dkk., 2004). Terdapat 4 macam pendekatan yang sering digunakan untuk mengembalikan ekosistem dan komunitas hayati (Whisenant, 1999):

Tanpa tindakan (no ction) : restorasi tidak dilakukan mengingat biaya pemulihan yang terlalu mahal, atau mungkin upaya restorasi sebelumnya gagal, ataupun berdasarkan pengalaman diperkirakan ekosistem dapat pulih kembali dengan sendirinya.
Rehabilitasi : ekosistem yang rusak diganti dengan ekosistem yang produktif, baik dengan menggunakan beberapa spesies maupun banyak jenis biota.
Restorasi parsial (sebagian) : yang diperbaili adalah sebagian fungsi ekosistem, dan beberapa spesies asli yang dominan mungkin dapat dikembalikan pula.
Restorasi lengkap : restorasi suatu daerah hingga mencapai struktur dan komposisi spesies semula, maupun berbagai proses ekosistem terkait.

Wilayah lahan basah seperti sungai telah menjadi sasaran upaya restorasi besar – besaran (Zedler, 1996; Rood dkk., 2003). Sungai sering dirusak karena peranan mereka dalam mengendalikan banjir, mempertahankan kualitas air, dan melestarikan komunitas hayati tidak diketahui ataupun kurang dihargai. Lebih dari setengah lahan basah asli di AS telah hilang terutama di wilayah dengan tingkat populasi tinggi seperti kalifornia, yang kehilangan lebih dari 90% lahan basahny (Cairns & Heckman, 1996). Di AS telah dilakukan kebijakan perlindungan lahan basah melalui UU Air Bersih (Clean Water Act) dan kebijakan pemerintah AS untuk tidak menghilangkan lahan basah secara efektif (no net loss of wetlands). Berbagai proyek pembangunan skala besar yang mengakibatkan kerusakan diharuskan mereparasi lahan basah tersebut, dan bila kerusakan yang ditimbulkan tidak dapat dimitigasi (kegiatan membangun lingkungan baru), pihak pengembang atau pengelola diharuskan menciptakan lahan basah baru untuk menggantikan yang telah rusak. Focus dari upaya tersebut biasanya adalah mengkonstruksi hidrologi asli wilayah setempat, dilanjutkan upaya menanam spesies asli setempat. Pengalaman menunjukkan bahwa upaya merestorasi lahan basah seringkali tidak berhasil mengembalikan komposisi spesies maupun karakteristik hidrologi dari wilayah setempat, atau tidak sesuai dengan standar yang telah ditetapkan dalam lokasi acuan. Masalahnya, komposisi spesies, pergerakan air, tanah, serta sejarah dari lokasi sulit untuk dikembalikan. Akibatnya, spesies asing seringkali mendominasi lahan basah yang direstorasi. Bagaimanapun, lahan basah yang direstorasi mungkin masih dapat mempertahankan sebagian spesies asli setempat (atau yang mirip spesies setempat), sehingga masih dapat memberikan sebagian manfaat dan fungsi mereka. Pada ekosistem sungai salah satu strategi yang dapat digunakan untuk memperbaiki keanekaragaman hayati adalah menghilangkan seluruh bendungan dan dam serta pengendalian dan pelepasan debet air dari dam (Stanley & Doyle, 2003).

Upaya untuk memulihkan sungai yang mengalami eutrofikasi (pengayaan unsure hara) ditandai dengan buruknya kualitas air, terjadi ledakan algae, menurunnya populasi ikan setempat, dan menipisnya oksigen di lapisan air dalam.upaya dilakukan dengan membangun fasilitas pengolahan limbah. Kuantitas fosfor yang masuk ke sungai dikurangi jumlahnya. Hasilnya kualitas air membaik, dan jumlah ikan predator asli mulai meningkat, dibantu pasokan oleh pemerintah daerah. Ikan predator tersebut berperan sebagai pemangsa ikan yang lebih kecil. Dengan terkendalinya jumlah ikan yang lebih kecil tersebut, maka jumlah zooplankton meningkat dan semakin banyak memangsa alga, sehingga kualitas air dapat meningkat. Dengan demikian, melalui proses pemangsaan sepanjang rantai makanan, ikan predator turut mengendalikan jumlah alga penyebab eutrofikasi.

Daftar Pustaka

Bledsoe, E., E.J. Phlips, C.E. Jett, and K.A. Donnelly. 2004. The relationships among phytoplankton biomass, nutrient loading and hydrodinamics in an inner shelf estuary. Ophelia 58 (1): 20-47.

DeSanto, R.S. 1978. Concepts of applied ecology. Springer-Verlag. New York.

Ekwu, A.O. and F.D. Sikoki. 2006. Phytoplankton diversity in the cross river estuary of Nigeria, Journal of Applied Sciences & Environmental Management 10 (1): 89-95.

Fachrul, M.F. 2003. Kajian biologi monitoring pencemaran sungai. Seminar Nasional Sistem Monitoring Pencemaran Lingkungan Sungai dan Teknologi Pengolahannya. Pusat Penelitian Elektronika dan Telekomunikasi-LIPI, Bandung, 8-9 July 2003.

Hendrawan, D., M.F. Melati, and B. Bestari. 2004. Kajian Kualitas Perairan Sungai Ciliwung, Jurnal Penelitian dan Karya Ilmiah Lemlit Usakti 3 (15): 54-66.

Lacerda, S R., M.L. Koening, S. Neumann-Leitão, and M.J. Flores-Montes. 2004. Phytoplankton Nyctemeral variation at a tropical river estuary (Itamaracá-Pernambuco-Brazil). Brazilian Journal of Biology 64 (1): 81-94.

MacDougall, A.S., B.R. Beckwith, & C.Y. Maslovat. 2004. Defining conservation strategis with historical perspectives: a case study from a degraded oak grassland system. Conservation Biology 18: 445 - 465

Odum, E.P. 1988. Dasar-dasar ekologi. (Terjemahan) Edisi 3. Gadjah Mada UNiv. Press. Yogyakarta.

Oxborough, K. and N.R. Baker. 1997. Resolving chlorophyll a fluorescence images of photosynthetic efficiency into photochemical and nonphotochemical components- calculation of qP and Fv0/Fm0 without measuring Fo-. Photosynthesis Research 54: 135- 142.

Soylu, E.N., and A. Gönülol. 2003. Phytoplankton and seasonal variations of the River Ye ilırmak, Amasya, Turkey. Turkish Journal of Fisheries and Aquatic Sciences 3: 17-24.

Stoddard, A., J.B. Harcum, J.T. Simpson, J.R. Pagenkopf, and R.K. Bastian. 2003, Municipal Wastewater Treatment: Evaluating Improvements in National Water Quality. Published by John Wiley and Sons, Inc.

Tuvikene, A., K. Piirsoo, and Pall. 2005. Effect of nutrient load on the planktonic biota in the River Narva drainage area. In Russo, R. C. (ed.), 2005. Modelling Nutrient Loads and Responses in River and Estuary Systems. Report No. 271. Brussels: Committee on the Challenges at Modern Society, NATO.

Zedler, J.B. 1996. Ecological issues in wetland mitigation : An introduction to the forum. Ecological Aplication 6:33 – 37.

Urban Myth Disproved: Fingerprints Do Not Improve Grip Friction

2009-06-19T22:07:00.005+07:00

Fingerprints mark us out as individuals and leave telltale signs of our presence on every object that we touch, but what are fingerprints really for? According to Roland Ennos, from the University of Manchester, other primates and tree-climbing koalas have fingerprints and some South American monkeys have ridged pads on their tree-gripping tails, so everyone presumed that fingerprints are there to help us hang onto objects that we grasp.

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This theory that fingerprints increase friction between the skin and whatever we grab onto has been around for over 100 years, but no one had directly tested the idea. Having already figured out why we have fingernails, Ennos was keen to find out whether fingerprints improve our grip, so he recruited Manchester undergraduate Peter Warman to test out fingerprint friction.

Because the friction between two solid materials is usually related to the force of one of the materials pressing against the other, Ennos and Warman had to find a way of pushing a piece of acrylic glass (Perspex®) against Warman's finger before pulling the Perspex® along the student's finger to measure the amount of friction between the two. Ennos designed a system that could produce forces ranging from a gentle touch to a tight grip, and then Warman strapped his index finger into the machine to begin measuring his fingerprint's friction.

But after days of dragging the Perspex® along Warman's fingers and thumbs, it was clear that something wasn't quite right. Instead of the friction between each finger and the Perspex® increasing in proportion to the amount that the Perspex® pushed against Warman's fingers, it increased by a smaller fraction than Ennos had expected. Ennos realised that instead of behaving like a normal solid, the skin was behaving like rubber, where the friction is proportional to the contact area between the two surfaces.

To check that skin behaves more like rubber than a normal solid, the duo varied the area of each fingerpad that came into contact with the surface by dragging narrow and wide strips of Perspex® along Warman's fingerpads. They found that the friction did increase as more of the fingerprint came in contact with the surface, so the skin was behaving just like rubber.

Finally, the friction issue was clinched when Warman measured his fingerprints' surface area. The area of skin in contact with the Perspex® was always 33% less than if the fingerpads were smooth resulting in the maximum contact area. Fingerprints definitely don't improve a grip's friction because they reduce our skin's contact with objects that we hold, and even seem to loosen our grip in some circumstances.

So if fingerprints don't tighten our grasp on smooth surfaces, what are they for? Ennos explains that our fingerprints may function in other ways. They might have evolved to grip onto rough surfaces, like tree bark; the ridges may allow our skin to stretch and deform more easily, protecting it from damage; or they may allow water trapped between our finger pads and the surface to drain away and improve surface contact in wet conditions. Other researchers have suggested that the ridges could increase our fingerpads' touch sensitivity. Whatever our fingerprints are for, it seems that the idea that they provide friction for grip is just another urban myth

Biology - The Study of Life

2009-06-19T21:58:00.005+07:00

What is biology? Simply put, it is the study of life -- life in all of its grandeur. From the very small algae to the very large elephant, life has a certain wonder about it. With that in mind, how do we know if something is living? Is a virus alive or dead? What are the characteristics of life? These are all very important questions with equally important answers.

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Characteristics of Life

Living things include both the visible world of animals and plants, as well as the invisible world of bacteria. On a basic level, we can say that life is ordered. Organisms have an enormously complex organization. We're all familiar with the intricate systems of the basic unit of life, the cell.

Life can also "work." No, not the daily employment variety, but living creatures can take in energy from the environment. This energy, in the form of food, is transformed to maintain metabolic processes and for survival.

Life grows and develops. This means more than just getting larger in size. Living organisms also have the ability to rebuild and repair themselves when injured.

Life can reproduce. Have you ever seen dirt reproduce? I don't think so. Life can only come from other living creatures.

Life can respond. Think about the last time you accidentally stubbed your toe. Almost instantly, you flinched back in pain. Life is characterized by this response to stimuli.

Finally, life can adapt and respond to the demands placed on it by the environment. There are three basic types of adaptations that can occur in higher organisms.

Reversible changes occur as a response to changes in the environment. Let's say you live near sea level and you travel to a mountainous area. You may begin to experience difficulty breathing and an increase in heart rate as a result of the change in altitude. These symptoms go away when you go back down to sea level.

Somatic changes occur as a result of prolonged changes in the environment. Using the previous example, if you were to stay in the mountainous area for a long time, you would notice that your heart rate would begin to slow down and you would begin to breath normally. Somatic changes are also reversible.

The final type of adaptation is called genotypic (caused by mutation). These changes take place within the genetic makeup of the organism and are not reversible. An example would be the development of resistance to pesticides by insects and spiders.

In summary, life is organized, "works," grows, reproduces, responds to stimuli and adapts. These characteristics form the basis of the study of biology.

Basic Principles of Biology

The foundation of biology as it exists today is based on five basic principles. They are the cell theory, gene theory, evolution, homeostasis, and laws of thermodynamics.

Cell Theory: all living organisms are composed of cells. The cell is the basic unit of life.
Gene Theory: traits are inherited through gene transmission. Genes are located on chromosomes and consist of DNA.
Evolution: any genetic change in a population that is inherited over several generations. These changes may be small or large, noticeable or not so noticeable.
Homeostasis: ability to maintain a constant internal environment in response to environmental changes.
Thermodynamics: energy is constant and energy transformation is not completely efficient.

Subdiciplines of Biology

The field of biology is very broad in scope and can be divided into several disciplines. In the most general sense, these disciplines are categorized based on the type of organism studied. For example, zoology deals with animal studies, botany deals with plant studies, and microbiology is the study of microorganisms. These fields of study can be broken down further into several specialized sub-disciplines. Some of which include anatomy, cell biology, genetics, and physiology.

How Proteins Find The Right DNA Sequences

2009-06-10T11:55:00.003+07:00

Illustration of how proteins find the right DNA sequences. (Credit: Image courtesy of Uppsala University)

Researchers at Uppsala University and Harvard University have collaboratively developed a new theoretical model to explain how proteins can rapidly find specific DNA sequences, even though there are many obstacles in the way on the chromosomes.

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In living cells, DNA-binding proteins regulate the activity of various genes so that different cells carry out the right tasks at the right time. For this to work, the DNA-binding proteins need to find the right DNA site sufficiently quickly. The research team behind the new study has previously succeeded in determining that it takes only a few minutes for an individual protein molecule to look through the millions of nearly identical binding alternatives and find the right place to bind. This is nevertheless slower than what is predicted by the established theoretical model for how DNA-binding proteins find their way to the proper place by alternating between diffusing in the cell cytoplasm and along DNA strands.
"By also taking into consideration the fact that there are many obstacles in the way when proteins are to diffuse along DNA strands, we can now calculate more exactly how long it takes them to find their way," says Johan Elf, associate professor of molecular biotechnology at the Center for Bioinformatics.
Besides offering a more precise prediction regarding the time needed to find the right site on DNA, the new theoretical model explains why there is an optimal total concentration of DNA-binding proteins. If there were more, it would simply be impossible for them to find a binding place in a reasonable time, since the proteins would be in each other's way. If there were fewer it would go slower as well, since not enough proteins would be searching. Finally, the new model provides an explanation why so many DNA-binding proteins also bind auxiliary binding sites close to the regulatory site, thus forming DNA loops. It turns out that this can shorten the time to find the right sites.
"This more detailed understanding of gene regulation is important, since it can ultimately provide a better understanding of diseases that occur as a result of problems in the control functions of cells, such as in cancer" says Johan Elf.
The researchers behind the study are Gene-Wei Li, Otto G. Berg, and Johan Elf. The findings are being published March 16 in the scientific journal Nature Physics.

New Antibiotics Could Come From A DNA Binding Compound That Kills Bacteria In 2 Minutes

2009-06-10T11:52:00.001+07:00

A synthetic DNA binding compound has proved surprisingly effective at binding to the DNA of bacteria and killing all the bacteria it touched within two minutes. The DNA binding properties of the compound were first discovered in the Department of Chemistry at the University of Warwick by Professor Mike Hannon and Professor Alison Rodger (Professor Mike Hannon is now at the University of Birmingham). However the strength of its antibiotic powers have now made it a compound of high interest for University of Warwick researchers working on the development of novel antibiotics.

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Dr Adair Richards from the University of Warwick said: "This research will assist the design of new compounds that can attack bacteria in a highly effective way which gets around the methods bacteria have developed to resist our current antibacterial drugs. As this antibiotic compound operates by targeting DNA, it should avoid all current resistance mechanisms of multi-resistant bacteria such as MRSA."
The compound [Fe2L3]4+ is an iron triple helicate with three organic strands wrapped around two iron centres to give a helix which looks cylindrical in shape and neatly fits within the major groove of a DNA helix. It is about the same size as the parts of a protein that recognise and bind with particular sequences of DNA. The high positive charge of the compound enhances its ability to bind to DNA which is negatively charged.
When the iron-helicate binds to the major groove of DNA it coils the DNA so that it is no longer available to bind to anything else and is not able to drive biological or chemical processes. Initially the researchers focused on the application of this useful property for targeting the DNA of cancer cells as it could bind to, coil up and shut down the cancer cell's DNA either killing the cell or stopping it replicate. However the team quickly realised that it might also be a very clever way of targeting drug-resistant bacteria.
New research at the University of Warwick, led by Dr Adair Richards and Dr Albert Bolhuis, has now found that the [Fe2L3]4+ does indeed have a powerful effect on bacteria. When introduced to two test bacteria Bacillus subtilis and E. coli they found that it quickly bound to the bacteria's DNA and killed virtually every cell within two minutes of being introduced - though the concentration required for this is high.
Professor Alison Rodger, Professor of Biophysical Chemistry at the University of Warwick, said: "We were surprised at how quickly this compound killed bacteria and these results make this compound a key lead compound for researchers working on the development of novel antibiotics to target drug resistant bacteria."
The researchers will next try and understand how and why the compound can cross the bacteria cell wall and membranes. They plan to test a wide range of compounds to look for relatives of the iron helicate that have the same mechanism for action in collaboration with researchers around the world.

Glutamate Receptor Believed Dead Comes To Life

2009-06-10T11:39:00.003+07:00

Schematic presentation of the exchange of the delta2 receptor's intrinsic ligand recognition site (red). The recognition site from another glutamate receptor (blue) enables conversion of chemical into electrical signals: the reputedly dead ion channel springs to life. (Credit: Image courtesy of Ruhr-Universitaet-Bochum)

To all intents and purposes, the delta2 receptor is an unequivocal member of the family of glutamate receptors, the most important receptors for excitatory neurotransmitters in our brain. To date, however, this receptor has been considered the “black sheep” of the family because it does not react to glutamate, which, by definition, a glutamate receptor ought to do.

This riddle fascinated the neuroscientists working with Prof. Michael Hollmann (Chair of Biochemistry I – Receptor Biochemistry) at the Ruhr University.
To unlock the secret of this receptor, they “crossed” it with another glutamate receptor that functions normally. The resulting chimera is functional and opens an ion channel. The task now at hand is to identify a transmitter that triggers this mechanism in an unchanged, physiological delta2 receptor. The scientists have published their observations in the current edition of the Proceedings of the National Academy of Sciences, USA (PNAS).

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Lively communication between brain cells

Our brain consists of a gigantic network of about 100 billion neurons. Every one of them is linked to other neurons by more than ten thousand contact sites. The universal language within this network consist of electrical impulses, the sum of which lead to the development of our world of thought in a hitherto completely unknown manner. The majority of contacts between neurons are not direct, as a few millionth of a cm separate the cells from one another. This distance must be overcome if a signal from a transmitting cell is to reach a receptor cell.
This occurs at special contact sites, so-called synapses, which conduct incoming signals with the assistance of a chemical messenger, a so-called neurotransmitter. The activated transmitting cell discharges the messenger, which then crosses the synaptic cleft and is recognized by the receiving cell. This is where the glutamate receptors come into play. Protruding from the plasma membrane into the synaptic cleft they are specialized in registering the messenger most frequently found in the brain, namely glutamate – the well-known flavor enhancer in Chinese dishes, and subsequently convert the chemical signal into an electrical signal.

Conversion of chemical into electrical signals

Key to the secret of conversion of chemical into electrical signals is the structure of the receptors. They consist of three important parts: a glutamate recognition site, a joint, and a channel. The extracellular, bipartite recognition site protruding from the plasma membrane recognizes glutamate, binds it and then snaps shut like a mouse trap. Via a sophisticated joint mechanism, this closing movement is transmitted to the channel that traverses the cell membrane and causes the channel to open. Positive ions that have accumulated outside the cell can now flow into it and thereby generate an electrical signal.

Important but mysterious role

The delta2 receptor also has the three elements discussed above. Why then is it not activated by glutamate? Prof. Hollmann summarizes the problem by stating: "We know that the delta2 receptor is located at specific sites within the cerebellum, that it plays an extremely important role for the fine coordination of motor behaviour, and that it evidently contributes to the correct circuitry of the neurons during development of the cerebellum. What we don't know is just how the receptor fulfils these functions". The scientists thus decided to pursue the principal question whether the delta2 receptor is at all capable of functioning in a manner similar to that of the other glutamate receptors, namely as a neurotransmitter-activated ion channel.

Greek mythology helps

To answer this question the scientists recalled a very old idea: they produced a chimerical receptor. In Greek mythology, the chimera is a monstrous figure with a lion’s head, the body of a goat, and a snake's tail. Within the framework of her dissertation at the IGSN (International Graduate School of Neuroscience), Sabine Schmid created a chimeric delta2 receptor with the joint and channel of the delta2 receptor, but the ligand recognition site transplanted from a normally functioning relative.
This chimeric receptor did indeed react to glutamate and opened its ion channel, which had previously been belived to be dead. Prof. Hollmann comments: "We thus have developed a tool that, for the first time, enables us to investigate of the unique properties of the joint and the ion channel of the delta2 receptor. Moreover, our results suggest that the secret of the delta2 receptor is to be found in the difference in its recognition site for neurotransmitters". To a certain degree, the scientists have thus managed to unveil the function of the “black sheep.” The next step is to determine to which signal the actual recognition site of the delta2 receptor reacts and which role this plays for its essential function in the cerebellum.

Circadian Rhythm: How Cells Tell Time

2009-06-10T11:31:00.004+07:00

The fuzzy pale mold that lines the glass tubes in Dr. Yi Liu’s lab doesn’t look much like a clock.
But this fungus has an internal, cell-based timekeeper nearly as sophisticated as a human’s, allowing UT Southwestern Medical Center physiologists to study easily the biochemistry and genetics of body clocks, or circadian rhythms.
In a new study appearing online this week in the Proceedings of the National Academy of Sciences, Dr. Liu and his co-workers have found that this mold, which uses a protein called FRQ as the main gear of its clock, marks time by a sequence of changes in the protein’s chemical structure.
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Dr. Liu said the new finding might someday help researchers develop treatments for human sleep disorders and other problems associated with a faulty biological clock.
“This timekeeping protein is really the core component of the circadian clock,” said Dr. Liu, professor of physiology at UT Southwestern and senior author of the study.
Despite the evolutionary distance from mold to man, mechanisms controlling their circadian clocks are very similar. In both, circadian rhythms control many biological processes, including cell division, hormonal release, sleep/wake cycles, body temperature and brain activity.
The researchers employed a fungus called Neurospora, an organism frequently used in studies on genetics and cell processes, especially circadian rhythms. It reproduces in the dark and rests in the light.
A decade ago, Dr. Liu discovered that FRQ controlled the cellular clock in Neurospora by chemical changes of its protein structure. As the day goes on, the cell adds chemical bits called phosphates to the protein. Each new phosphate acts like a clock’s ticking, letting the cell know that more time has passed.
When the number of phosphates added to FRQ reaches a certain threshold, the cell breaks it down, ready to start the cycle again.
The researchers, however, did not know where the phosphates attached to FRQ, how many got added throughout a day, or how they affected the protein’s ability to “tell” time.
In the current study, the researchers used purified FRQ to analyze the specific sites where phosphate groups attach. In all, the researchers found 76 phosphate docking sites.
“This is an extremely high number,” Dr. Liu said. “Most proteins are controlled by only a handful of phosphate sites.”
They also studied how these phosphates are added to FRQ daily and found that two enzymes are responsible for adding most of the phosphate groups in Neurospora. They also found that the total number of phosphates oscillates robustly day by day.
In addition, the researchers created a series of mutations in many of the phosphate docking sites, creating strains of mold that had abnormally short or long daily clocks.
In upcoming studies, the researchers plan to identify which enzymes add phosphates to specific sites and exactly how changes in a particular site affect a cell’s clock.
Other UT Southwestern physiology researchers contributing to the work were co-lead authors Dr. Chi-Tai Tang, postdoctoral researcher, and Dr. Shaojie Li, former postdoctoral researcher; Dr. Joonseok Cha, postdoctoral fellow; Dr. Guocun Huang, assistant instructor; and Dr. Lily Li, former postdoctoral researcher. Researchers from the National Institute of Biological Sciences in China and the Chinese Academy of Sciences also participated.
The study was supported by the National Institutes of Health and the Welch Foundation.

Stem Cells Cultured On Contact Lens Restore Sight In Patients With Blinding Corneal Disease

2009-06-10T11:23:00.002+07:00

In a world-first breakthrough, University of New South Wales (UNSW) medical researchers have used stem cells cultured on a simple contact lens to restore sight to sufferers of blinding corneal disease.

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Sight was significantly improved within weeks of the procedure, which is simple, inexpensive and requires a minimal hospital stay.
The research team from UNSW’s School of Medical Sciences harvested stem cells from patients’ own eyes to rehabilitate the damaged cornea. The stem cells were cultured on a common therapeutic contact lens which was then placed onto the damaged cornea for 10 days, during which the cells were able to re-colonise the damaged eye surface.
While the novel procedure was used to rehabilitate damaged corneas, the researchers say it offers hope to people with a range of blinding eye conditions and could have applications in other organs.
A paper detailing the breakthrough appears in the journal Transplantation this week.
The trial was conducted on three patients; two with extensive corneal damage resulting from multiple surgeries to remove ocular melanomas, and one with the genetic eye condition aniridia. Other causes of cornea damage can include chemical or thermal burns, bacterial infection and chemotherapy.
“The procedure is totally simple and cheap,” said lead author of the study, UNSW’s Dr Nick Di Girolamo. “Unlike other techniques, it requires no foreign human or animal products, only the patient’s own serum, and is completely non-invasive.
The surgeon who carried out the procedure and managed the patients was UNSW senior lecturer, Dr Stephanie Watson.
"The operation is relatively non-invasive. The patient merely comes into the hospital for a couple of hours to have their eye prepared and the lens put in place, and then they're able to go home," she said.
“There’s no suturing, there is no major operation: all that’s involved is harvesting a minute amount – less than a millimeter – of tissue from the ocular surface,” said Dr Di Girolamo.
“If you’re going to be treating these sorts of diseases in third world countries all you need is the surgeon and a lab for cell culture. You don’t need any fancy equipment.”
Because the procedure uses the patient’s own stem cells harvested from their eye, it is ideal for sufferers of unilateral eye disease. However, it also works in patients who have had both eyes damaged, Dr Di Girolamo said.
“One of our patients had aniridia, a congenital condition affecting both eyes. In that case, instead of taking the stem cells from the other cornea, we took them from another part of the eye altogether – the conjunctiva – which also harbours stem cells.
“The stem cells were able to change from the conjunctival phenotype to a corneal phenotype after we put them onto the cornea. That’s the beauty of stem cells,” Dr Di Girolamo said.
The therapeutic contact lens used in the trial was of a type commonly used worldwide after ocular surface surgery. However, of the several brands on the market, only one was suitable for growing the stem cells.
“We don’t know why. It’s probably to do with the components the manufacturers have used in that particular lens,” Dr Di Girolamo said.
The researchers are hopeful the technique can be adapted for use in other parts of the eye, such as the retina, and even in other organs. “If we can do this procedure in the eye, I don’t see why it wouldn’t work in other major organs such as the skin, which behaves in a very similar way to the cornea,” Dr Di Girolamo said.

Bacteria and Food Poisoning

2009-06-10T11:05:00.003+07:00

The U.S. Centers for Disease Control and Prevention (CDC) estimates that around 80 million people a year in the U.S. alone contract food poisoning or other foodborne diseases.
Foodborne illness is caused by eating or drinking food that contains disease causing agents. The most common causes of foodborne diseases are bacteria, viruses, and parasites. Foods containing toxic chemicals can cause foodborne diseases as well.
There are over two hundred types of bacteria, viruses and parasites that can cause foodborne diseases. Reactions to these germs can range from mild gastric discomfort to death. The easiest way to prevent foodborne illness is to properly handle and cook foods. This includes washing your hands and utensils carefully and cooking meat thoroughly.
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Below is a list of a few bacteria that cause foodborne diseases, along with the foods that are associated with them, as well as symptoms that are likely to develop from ingesting the contaminated foods.
Bacteria and Food Poisoning
Microbe - Aeromonas hydrophila
Affiliated Foods - Fish, Shellfish, Beef, Pork, Lamb, and Poultry
Diseases - Gastroenteritis, Septicemia
Symptoms - Diarrhea, Blood and Mucus in Stool

Microbe - Bacillus cereu
Affiliated Foods - Meats, Milk, Rice, Potato, and Cheese Products
Diseases - B. cereus Food Poisoning
Symptoms - Diarrhea, Abdominal Cramps, Nausea

Microbe - Campylobacter jejuni
Affiliated Foods - Raw Chicken, Unpasteurized Milk, Non-chlorinated Water
Diseases - B. cereus Campylobacteriosis
Symptoms - Diarrhea, Abdominal Cramps, Nausea and Fever, Headache and Muscle Pain

Microbe - Clostridium botulinum
Affiliated Foods - Canned Foods Including: Vegetables, Meats, and Soups
Diseases - Foodborne Botulism
Symptoms - Weakness, Double Vision and Vertigo, Difficulty in Speaking, Swallowing, and Breathing, Constipation

Microbe - Clostridium perfringens
Affiliated Foods - Non-refrigerated Prepared Foods: Meats and Meat Products, Gravy
Diseases - Perfringens Food Poisoning
Symptoms - Severe Abdominal Cramps, Diarrhea

Microbe - Escherichia coli O157:H7
Affiliated Foods - Undercooked Meats, Raw Ground Beef
Diseases - Hemorrhagic colitis
Symptoms - Severe Abdominal Pain, Watery and Bloody Diarrhea, Vomiting

Microbe - Listeria monocytogenes
Affiliated Foods - Dairy Products, Raw Vegetables, Raw Meats, Smoked Fish
Diseases - Listeriosis
Symptoms - Flu-like Symptoms, Persistent Fever, Nausea and Vomiting, Diarrhea

Microbe - Salmonella spp.
Affiliated Foods - Poultry and Eggs, Milk and Dairy Products, Raw Meats, Fish, Shrimp, Peanut Butter
Diseases - Salmonellosis
Symptoms - Nausea, Vomiting, Abdominal Pain, Fever, Headache, Diarrhea

Microbe - Shigella spp
Affiliated Foods - Poultry, Milk and Dairy Products, Raw Vegetables, Fecally contaminated water, Salads: Potato, Chicken, Tuna, Shrimp
Diseases - Shigellosis
Symptoms - Diarrhea, Abdominal Pain, Fever, Vomiting, Blood or Mucus in Stool

Microbe - Staphylococcus aureus
Affiliated Foods - Poultry and Egg Products, Meat Products, Dairy Products
Diseases - Staphyloenterotoxicosis, Staphyloenterotoxemia
Symptoms - Abdominal Cramping, Nausea and Vomiting, Prostration

Microbe - Vibrio cholerae
Affiliated Foods - Contaminated Water, Shellfish
Diseases - Cholera
Symptoms - Watery Diarrhea, Abdominal Pain, Dehydration, Vomiting, Shock

Melihat peluang dari 'Sarang Semut'...;)

2009-04-26T19:13:00.003+07:00

Tanaman ini berasal dari Papua, tepatnya sebelah barat hutan di daerah Wamena. Berbentuk unik layaknya kayu tua dengan tinggi tak lebih dari 1 meter, dan batang yang banyak mirip tangan seekor gurita. Bagian bonggolnya terlihat menggelembung seukuran bola volley sedangkan bagian dalam berwujud rongga-rongga serbuk berwarna cokelat kehitaman seperti bagian kayu lapuk yang menjadi tempat tinggal hewan semut atau rayap sehingga penduduk asli sekitar Wamena macam Suku Bogondini dan Suku Tolikara menamainya tumbuhan Sarang Semut.
Secara genetis, Sarang Semut termasuk dalam spesies Myrmecodia Pendans yang sanggup hidup lama di atas tanah hutan minim air dan perlakuan khusus. Permukaan batangnya dipenuhi oleh duri tajam berfungsi melindungi diri dari binatang herbivora. Jika ingin membudidayakan tanaman ini, mudah saja. Kondisikan tempat penanaman sebagaimana habitat asli Sarang Semut. Demikian keterangan Winston Moeni, pemilik Winston Nursery Sukoharjo, Jateng yang beberapa tahun belakangan mulai mengembangkan Sarang Semut di Jawa.
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“Di samping bisa dijadikan tanaman hias karena kekhasan bentuknya, Sarang Semut juga bisa dijadikan sebagai tanaman obat sebagaimana yang dilakukan masyarakat Suku Bogondini dan Suku Tolikara sejak ratusan tahun silam. Sering mereka mencampur sarang semut dengan bubur sagu atau makanan pokok lainnya untuk menyembuhkan rematik, asam urat dan pegal-pegal. Ketika hewan ternak mereka sakit, mereka mengobatinya juga dengan rebusan Sarang Semut”.
Hanya itukah khasiat Sarang Semut? Ternyata tidak. Berbagai penelitian menunjukkan bahwa kandungan zat-zat yang terdapat pada Sarang Semut berguna untuk meningkatkan imunitas atau kekebalan tubuh serta mampu memberikan energi bagi manusia. Kandungan zat-zat itu meliputi beberapa senyawa aktif antioksidan (Tokoferol dan Fenolik), Kalsium (Ce), Natrium (Na), Kalium (K), Seng (Zn), Besi (Fe), Fosfor (P) dan Magnesium (Mg), dan dimungkinkan ada kandungan-kandungan lainnya yang sampai sekarang masih terus dibuktikan secara klinis.
Jadi Sarang Semut mampu menanggulangi multi ragam penyakit dari yang ringan sampai penyakit berat dan kronis. Adapun manual pembuatan obat Sarang Semut cukup simpel yaitu dengan mengambil lima sendok serbuk bagian dalam tanaman ini kemudian dilarutkan, diaduk-aduk ke dalam segelas air putih atau sekitar 200 cc. setelah itu diminum sedikitnya 3 kali sehari

AYAM KLONING KEBAL FLU BURUNG

2009-04-26T19:10:00.001+07:00

Wabah flu burung pernah menyerang di Spanyol dengan korban 40-50 jiwa pada tahun 1918, di Asia 1 juta jiwa tahun 1957, di Hong Kong juga 1 juta jiwa. Serangan flu burung hingga saat ini mencapai ratusan saja.
Sebuah tim ahli yang dipimpin oleh Dr. Laurence Tiley melalui Multi-institute British Research Project, bekerjasama dengan Dr. Helen Sang dari Roslin Institute Edinburg, Scotland melakukan eksplorasi potensi penciptaan ternak unggas yang memiliki sifat resisten terhadap virus flu burung dengan menggunakan teknologi modifikasi genetik.
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Strategi untuk memperoleh ayam kebal flu burung dilakukan dengan mempertimbangkan mekanisme kekebalan alamiah dan memadukan dengan metode pembaharuan yang inkonvensional. Pekerjaan ini bertujuan memproduksi ayam yang memiliki kekebalan terhadap semua strain (galur) virus flu burung baik yang bersifat HPAI (Hight Pathogenic AI) maupun LPAI (Low Pathogenic AI).
Itulah kesulitan dan tantangan proyek tersebut. Seperti kita ketahui strain virus flu ditentukan oleh Haemaglutinin dengan kode H dan Neuraminidase dengan kode N yang terdapat pada selubung protein luar. Hingga saat ini terdapat H 1 sampai 15 dan N 1 sampai 9. Profesor Rangga Tabu dari UGM menambahkan hingga H 16. Virus yang mewabah saat ini adalah H5N1 yang bersifat HPAI.
Apabila ayam kebal flu burung tersebut telah diproduksi secara massal dan diperdagangkan secara komersial, maka terjadi efisiensi dalam memproduksi vaksin. Artinya tidak diperlukan lagi sama sekali vaksin flu burung yang jika kita hitung kombinasi strainnya dapat mencapai 135 jenis. Itu secara teknis maupun ekonomis.
Sebenarnya terdapat beberapa alasan mengapa penelitian itu dilakukan. Pertama, flu burung telah menjadi persoalan global saat ini. Seluruh dunia berada pada posisi pertengahan wabah terbesar internasional yang pernah tercatat dari jenis virus HPAI. Ratusan juta ternak telah dibantai dalam rangka pengendalian penyakit. Hal ini telah menyebabkan penderitaan tersendiri bagi para peternak.
Kedua, adanya kekhawatiran kemampuan virus untuk menular dan berkembang antar spsies yakni kemungkinan besar terjadinya penularan dari hewan ke manusia. Lebih lanjut dari manusia ke manusia. Ayam merupakan jembatan spesies yang potensial bagi penularan virus barbahaya ini dan dapat memfasilitasi penularan dari unggas liar ke manusia.

JELLY JAMBU BIJI MERAH DAN JELLY DURIAN MINUMAN SEHAT TANPA PENGAWET

2009-04-26T19:02:00.001+07:00

Durian dan jambu biji merah merupakan komoditas yang banyak dijumpai di beberapa daerah di Sumatera Barat. Durian banyak dikembangkan pada hampir semua Kabupaten dan Kota di Sumatera Barat, mencakup luasan 1.668,75 hektar yang mampu memproduksi sekitar 36.801,90 ton. Sementara itu, produksi jambu biji merah sering dijumpai dalam jumlah yang cukup banyak di Kota Padang.
Pengolahan berbagai komoditas tanaman buah-buahan menjadi berbagai produk olahan, merupakan salah satu cara yang umum dilakukan untuk mengantisipasi limpahan produksi yang tidak laku terjual atau afkiran yang masih baik, yang seringkali terjadi pada saat musim panen raya. Pengolahan produk pertanian salah satunya juga bertujuan untuk meningkatkan nilai tambah maupun nilai jual. Salah satu bentuk olahan yang saat ini dapat dikembangkan adalah pembuatan minuman jelly.

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Minuman jelly dibuat dengan cara mengekstrak buah dan menambahkan tepung jelly sebagai pengental, gula tebu sebagai pemanis, garam dan asam sitrat. Jelly buah-buahan mengandung nutrisi yang berguna bagi kesehatan. Jelly ini dapat dikatakan sebagai minuman fungsional, yaitu minuman yang berkhasiat menjaga kesehatan.
BPTP Sumatera Barat menangkap peluang pengembangan usaha tersebut dan telah mengkaji teknologi inovasi pengolahan jambu biji merah dan durian menjadi minuman jelly. Teknologi pembuatannya tidaklah sulit, hanya dengan peralatan sederhana dan biaya murah. Produksinya dapat dilakukan dalam skala rumah tangga, baik secara perorangan ataupun berkelompok. Sesuai dengan tuntutan pasar saat ini, maka produk jelly yang dihasilkan tanpa menggunakan bahan pengawet dan pewarna buatan, menarik untuk disuguhkan.

Pembuatan Jelly Jambu Biji Merah dan Jelly Durian

Bahan-bahan yang diperlukan untuk pembuatan jelly jambu biji merah adalah buah jambu biji merah, tepung jelly, gula pasir, garam dan asam sitrat. Peralatan yang digunakan adalah baskom, pisau, blender, panci, kompor, cup plastik, dan lemari pendingin untuk mempercepat proses pengentalan.
Prosedur pembuatan jelly jambu biji merah diawali dengan mencuci, mengupas dan menghancurkannya dengan blender sampai menjadi bubur. Bubur dimasukkan ke dalam panci besar, lalu ditambahkan air sebanyak 2,5 liter untuk setiap 0,5 kg jambu biji merah, kemudian disaring. Hasil saringan atau filtrat ditambah gula pasir, tepung jelly, garam dan asam sitrat. Penambahan bahan-bahan tersebut disesuaikan dengan selera. Selanjutnya, campuran filtrat jambu biji merah tersebut dipanaskan sampai mendidih sambil terus diaduk-aduk.
Terakhir, jelly jambu biji merah dikemas dalam cup plastik dan didinginkan dalam lemari pendingin. Setelah mengental, jelly jambu biji merah dapat langsung diminum atau dipasarkan dan tahan disimpan dalam lemari pendingin selama 4 hari, jika disimpan di ruang terbuka hanya tahan 2 hari. Agar tahan lebih lama lagi, sebelum dimasukkan ke dalam lemari pendingin, terlebih dahulu dipasteurisasi dalam air panas dengan suhu 80oC selama 5 menit.

Lalat Buah ( Bactrocera sp.)

2009-04-26T18:53:00.004+07:00

Salah satu hama penting tanaman hortikultura yang saat ini menjadi isu nasional juga menjadi faktor pembatas perdagangan (trade barrier). Adalah lalat buah. Komoditas ekspor suatu negara dapat ditolak oleh negara lain dengan alasan terdapatnya lalat buah.
Jenis Lalat Buah di IndonesiaLalat buah yang banyak terdapat di Indonesia adalah dari genus Bactrocera dan salah satu jenis yang sangat penting dan ganas adalah Bactrocera dorsalis Hendel complex. B. dorsalis Hendel complex merupakan lalat buah yang bersifat polifag, mempunyai sekitar 26 jenis inang seperti belimbing, jambu biji, tomat, cabai merah, melon, apel, nangka kuning, mangga, dan jambu air.
Selain merusak buah-buahan seperti jatuhnya buah muda yang terserang, serangan hama ini juga menyebabkan buah menjadi busuk dan dihinggapi belatung lalat buah juga merupakan vektor bakteri Escherichia coli, penyebab penyakit pada manusia sehingga dapat dijadikan alasan untuk menghambat perdagangan. Untuk mencegah masuknya spesies baru lalat buah ke Indonesia, pemerintah mengeluarkan Permentan No.37/ KPTS/HK. 060/172006 yang menetapkan hanya tujuh pintu masuk buah segar ke Indonesia, yaitu Batu Ampar, Batam; Ngurah Rai, Bali; Makassar; Belawan, Medan; Tj. Priok, Jakarta; Tj. Perak, Surabaya, dan Cengkareng, Jakarta.
Intensitas serangan lalat buah di beberapa daerah di Jawa Timur dan Bali menunjukkan variasi yang cukup besar, berkisar antara 6,4-70% Intensitas serangan lalat buah pada mangga berkisar antara 14,8-23%. Namun tidak jarang kerusakan yang diakibatkan lalat buah, khususnya pada belimbing dan jambu biji, dapat mencapai 100% .
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Gejala

Pada buah yang terserang biasanya terdapat lubang kecil di bagian tengah kulitnya. Serangan lalat buah ditemukan terutama pada buah yang hampir masak. Gejala awal ditandai dengan noda/titik bekas tusukan ovipositor (alat peletak telur) lalat betina saat meletakkan telur ke dalam buah. Selanjutnya karena aktivitas hama di dalam buah, noda tersebut berkembang menjadi meluas. Larva makan daging buah sehingga menyebabkan buah busuk sebelum masak. Apabila dibelah pada daging buah terdapat belatung-belatung kecil dengan ukuran antara 4-10 mm yang biasanya meloncat apabila tersentuh. Kerugian yang disebabkan oleh hama ini mencapai 30-60%. Kerusakan yang ditimbulkan oleh larvanya akan menyebabkan gugurnya buah sebelum mencapai kematangan yang diinginkan.
Bioekologi

Dalam siklus hidupnya lalat buah mempunyai 4 stadium hidup yaitu telur, larva, pupa dan dewasa. Lalat buah betina memasukkan telur kedalam kulit buah jeruk atau di dalam luka atau cacat buah secara berkelompok. Lalat buah betina bertelur sekitar 15 butir. Telur berwarna putih transparan berbentuk bulat panjang dengan salah satu ujungnya runcing. Larva lalat buah hidup dan berkembang di dalam daging buah selama 6-9 hari. Larva mengorek daging buah sambil mengeluarkan enzim perusak atau pencerna yang berfungsi melunakkan daging buah sehingga mudah diisap dan dicerna. Enzim tersebut diketahui yang mempercepat pembusukan, selain bakteri pembusuk yang mempercepat aktivitas pembusukan buah. Jika aktivitas pembusukan sudah mencapai tahap lanjut, buah akan jatuh ke tanah, bersamaan dengan masaknya buah, larva lalat buah siap memasuki tahap pupa, larva masuk dalam tanah dan menjadi pupa. Pupa berwarna kecoklatan berbentuk oval dengan panjang 5 mm. Lalat dewasa berwarna merah kecoklatan, dada berwarna gelap dengan 2 garis kuning membujur dan pada bagian perut terdapat garis melintang. Lalat betina ujung perutnya lebih runcing dibandingkan lalat jantan. Siklus hidup dari telur menjadi dewasa berlangsung selama 16 hari. Fase kritis tanaman yaitu pada saat tanaman mulai berbuah terutama pada saat buah menjelang masak. Lalat buah yang mempunyai ukuran tubuh relatif kecil dan siklus hidup yang pendek peka terhadap lingkungan yang kurang baik. Suhu optimal untuk perkembangan lalat buah ? 26?C, sedangkan kelembaban relatif sekitar 70%. Kelembaban tanah sangat berpengaruh terhadap perkembangan pupa. Kelembaban tanah yang sesuai untuk stadia pupa adalah 0-9%. Cahaya mempunyai pengaruh langsung terhadap perkembangan lalat buah. Lalat buah betina akan meletakkan telur lebih cepat dalam kondisi yang terang, sebaliknya pupa lalat buah tidak akan menetas apabila terkena sinar. Lalat buah paling banyak menyerang pada pamelo (Citrus grandis) dan sedikit yang menyerang jeruk manis (C. sinensis) maupun keprok (C. reticulata). Pada pamelo diidentifikasi sebagai B. carambolae dan B. papayae. Pada pamelo serangan lalat buah kadang-kadang bersamaan dengan serangan penggerek buah Citripestis sagitiferella, sehingga agak sulit membedakan serangga tersebut. Hama ini banyak ditemukan di sentra-sentra produksi jeruk seperti di Sumatera Utara dan Jawa Timur.

Pengendalian Lalat Buah

Di Hawaii, pengendalian lalat buah memadukan beberapa teknik pengendalian, di antaranya dengan atraktan dalam perangkap, yang dapat menekan penggunaan pestisida kimia sintetis hingga 75-95%. Beberapa teknik pengendalian telah banyak dikembangkan, di antaranya penggunaan GA (Gibberellic Acid), yaitu membuat penampilan buah-buahan tidak matang, sehingga lalat buah enggan meletakkan telur pada buah. Selain itu, pelepasan serangga mandul, khususnya jantan mandul, telah dikembangkan pula dan memberikan hasil yang memuaskan. Teknik lain yang sudah berhasil dikembangkan di Australia adalah foliage baiting (penggunaan umpan beracun), coversprayng (penyemprotan tanaman beserta buahnya dengan insektisida), dan trapping (perangkap dengan atraktan di dalamnya), selain menjaga sanitasi kebun (Broghton etal., 2004).
Pengendalian dengan Atraktan (Zat Pemikat)

Penggunaan atraktan metil eugenol merupakan cara pengendalian yang ramah lingkungan dan telah terbukti efektif. Atraktan dapat digunakan untuk mengendalikan hama lalat buah dalam tiga cara, yaitu: (a) mendeteksi atau memonitor populasi lalat buah, (b) menarik lalat buah untuk kemudian dibunuh dengan perangkap, dan (c) mengacaukan lalat buah dalam perkawinan, berkumpul, dan cara makan.

membuat bioethanol dari singkong....

2009-04-26T18:33:00.003+07:00

Singkong diolah menjadi bioetanol, pengganti premium. Singkong salah satu sumber pati. Pati senyawa karbohidrat kompleks. Sebelum difermentasi, pati diubah menjadi glukosa, karbohidrat yang lebih sederhana. Untuk mengurai pati, perlu bantuan cendawan Aspergillus sp. Cendawan itu menghasilkan enzim alfamilase dan gliikoamilase yang berperan mengurai pati menjadi glukosa alias gula sederhana. Setelah menjadi gula, bam difermentasi menjadi etanol.
Lalu bagaimana cara mengolah singkong menjadi etanol? Berikut Langkah-langkah pembuatan bioetanol berbahan singkong. Pengolahan berikut ini berkapasitas 10 liter per hari.

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1. Kupas 125 kg singkong segar, semua jenis dapal dimanfaatkan. Bersihkan dan cacah berukuran kecil-kecil.
2. Keringkan singkong yang telah dicacah hingga kadar air maksimal 16%. Persis singkong yang dikeringkan menjadi gaplek. Tujuannya agar lebih awet sehingga produsen dapat menyimpan sebagai cadangan bahan baku
3. Masukkan 25 kg gaplek ke dalam tangki stainless si eel berkapasitas 120 liter, lalu tambahkan air hingga mencapai volume 100 liter. Panaskan gaplek hingga 100"C selama 0,5 jam. Aduk rebusan gaplek sampai menjadi bubur dan mengental.
4. Dinginkan bubur gaplek, lalu masukkan ke dalam langki sakarifikasi. Sakarifikasi adalah proses penguraian pati menjadi glukosa. Setelah dingin, masukkan cendawan Aspergillus yang akan memecah pati menjadi glukosa. Untuk menguraikan 100 liter bubur pati singkong. perlu 10 liter larutan cendawan Aspergillus atau 10% dari total bubur. Konsentrasi cendawan mencapai 100-juta sel/ml. Sebclum digunakan, Aspergilhis dikuhurkan pada bubur gaplek yang telah dimasak tadi agar adaptif dengan sifat kimia bubur gaplek. Cendawan berkembang biak dan bekerja mengurai pati
5. Dua jam kemudian, bubur gaplek berubah menjadi 2 lapisan: air dan endapan gula. Aduk kembali pati yang sudah menjadi gula itu, lalu masukkan ke dalam tangki fermentasi. Namun, sebelum difermentasi pastikan kadar gula larutan pati maksimal 17—18%. Itu adalah kadar gula maksimum yang disukai bakteri Saccharomyces unluk hidup dan bekerja mengurai gula menjadi alkohol. Jika kadar gula lebth tinggi, tambahkan air hingga mencapai kadar yang diinginkan. Bila sebaliknya, tambahkan larutan gula pasir agar mencapai kadar gula maksimum.
6 Tutup rapat tangki fermentasi untuk mencegah kontaminasi dan Saccharomyces bekerja mengurai glukosa lebih optimal. Fermentasi berlangsung anaerob alias tidak membutuhkan oksigen. Agar fermentasi optimal, jaga suhu pada 28—32"C dan pH 4,5—5,5.
7. Setelah 2—3 hari, larutan pati berubah menjadi 3 lapisan. Lapisan terbawah berupa endapan protein. Di atasnya air, dan etanol. Hasil fermentasi itu disebut bir yang mengandung 6—12% etanol
8.Sedot larutan etanol dengan selang plastik melalui kertas saring berukuran 1 mikron untuk menyaring endapan protein.
9. Meski telah disaring, etanol masih bercampurair. Untuk memisahkannya, lakukan destilasi atau penyulingan. Panaskan campuran air dan etanol pada suhu 78"C atau setara titik didih etanol. Pada suhu itu etanol lebih dulu menguap ketimbang air yang bertitik didih 100°C. Uap etanol dialirkan melalui pipa yang terendam air sehingga terkondensasi dan kembali menjadi etanol cair.
10. Hasil penyulingan berupa 95% etanol dan tidak dapat larut dalam bensin. Agar larul, diperlukan etanol berkadar 99% atau disebut etanol kering. Oleh sebab itu, perlu destilasi absorbent. Etanol 95% itu dipanaskan 100"C. Pada suhu ilu, etanol dan air menguap. Uap keduanya kemudian dilewatkan ke dalam pipa yang dindingnya berlapis zeolit atau pati. Zeolit akan menyerap kadar air tersisa hingga diperoleh etanol 99% yang siap dieampur denganbensin. Sepuluh liter etanol 99%, membutuhkan 120— 130 lifer bir yang dihasilkan dari 25 kg gaplek

Teknik Pembuatan Nata De Coco neh......:)

2009-04-26T18:03:00.006+07:00

Buah kelapa merupakan bagian paling penting dari tanaman kelapa karena mempunyai nilai ekonomis dan gizi yang tinggi. Air kelapa salah satu bagian buah kelapa yang mengandung sejumlah zat gizi yaitu protein, lemak, gula, sejumlah vitamin, asam amino, clan hormon pertumbuhan.
Air kelapa dapat dimanfaatkan sebagai media untuk produksi nata de coco. Nata de coco merupakan hasil fermentasi air kelapa dengan bantuan mikroba Acetobacter xylinum, yang berbentuk padat, berwarna putih, transparan, berasa manis clan bertekstur kenyal. Selain banyak diminati karena rasanya yang enak dan kaya serat, pembuatan nata de coco pun tidak sulit dan biaya yang dibutuhkan tidak banyak sehingga dapat sebagai alternatif usaha yang dapat memberikan keuntungan.
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TAHAPAN PEMBUATANNATA DE COCO

1. Persiapan media starter
Starter atau biakan mikroba merupakan suatu bahan yang paling penting dalam pembentukan nata. Sebagai starter, digunakan biakan murni dari Acetobacter xylinum. Bakteri ini dapat dihasilkan dari ampas nenas yang telah diinkubasi ( diperam) selama 2-3 minggu. Starter yang digunakan dalam pembuatan nata sebanyak 170 ml.
2. Penyaringan dan pendidihan
Untuk menghilangkan kotoran yang bercampur pada air kelapa dilakukan penyaringan air kelapa dengan menggunakan kain saring. Kemudian campurkan gula pasir ( 100 g/l air kelapa ), dengan air kelapa lalu didihkan dan dinginkan.
4. Inokulasi (Pencampuran dengan starter)
Setelah dingin, pH -nya diatur dengan menambahkan asam asetat atau asam cuka sekitar 20 ml hingga diperoleh kisaran keasaman (pH) 3-4. Kemudian diinokulasi dengan menambahkan starter (Acetobacter xylinum) 170 ml.
5. Fermentasi (Pemeraman)
Masukkan campuran tersebut ke dalam wadah fermentasi ( baskom berukuran 34 x 25 x 5 cm ). Wadah ditutup dengan kain saring dan diletakkan ditempat yang bersih dan aman. Dilakukan pemeraman selama 8-14 hari hingga lapisan mencapai ketebalan kurang lebih 1.5 cm.
6. Pemanenan
Setelah pemeraman selesai dengan terbentuk lapisan nata, lapisan nata diangkat secara hati-hati dengan menggunakan garpu atau penjepit yang bersih supaya cairan dibawah lapisan tidak tercemar. Cairan dibawah nata dapat digunakan sebagai cairan bibit pada pengolahan berikutnya.
Buang selaput yang menempel pada bagian bawah nata, dicuci lalu dipotong dalam bentuk kubus dan dicuci. Tuang dan rendam potongan nata de coco dalam ember plastik selama 2 - 3 hari dan setiap hari air rendaman diganti. Sesudah itu direbus selama 10 menit. Tujuan perendaman dan perebusan untuk menghilangkan rasa asam.7. Pembuatan sirup nata Pembuatan sirup nata dengan perbandingan untuk 3 kg produk nata potongan diperlukan 2 kg gula dan 4,5 liter air. Gula dituangkan ke dalam air, panaskan sampai larut, lalu disaring. Selanjutnya nata dicampur dalam larutan sirup gula, bila perlu tambahkan essence kemudian biarkan satu malam agar terjadi penyerapan gula ke dalam potonganpotongan nata, lalu didihkan selama 15 menit.
8. Pengemasan
Selanjutnya nata dikemas dalam kantong plastik atau botol selai dengan perbandingan antara padatan dan cairan 3:1, botol ditutup rapat, kemudian direbus dalam air mendidih selama 30 menit. Angkat dan dinginkan di udara dengan tutup terletak pada bagian bawah, selanjutnya botol diberi label dan siap untuk dipasarkan.

Viruses Can Turn Harmless E. Coli Dangerous....^_^

2009-04-26T17:26:00.006+07:00

Viruses attacking E. coli, (electron microscopy picture). (Credit: Image courtesy of Norwegian School of Veterinary Science)

Bacteriophage Structure© Gary E. Kaiser

For her doctorate, Camilla Sekse studied how viral DNA can be transmitted from pathogenic to non-pathogenic E. coli. Viruses that infect bacteria in this way are called bacteriophages. Her findings reveal that such transmission of bateriophage between bacteria can occur, and that in the case of E. coli it can transform a harmless bacterium into one capable of causing disease in man.

Escherichia coli is a complex group of gut bacteria that are found in all warm-blooded animals and are for the most part harmless. A few, however, cause disease in man and animals. The E. coli bacteria that produce a poison called Shiga toxin can produce a range of effects in man. One common effect is bloody diarrhoea followed by complications such as kidney failure (haemolytic uraemic syndrome). The bacteria may be spread through contaminated food or water, or from contact with animals.

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A combination of qualities necessary to produce disease
A sequence of favourable circumstances needs to exist before E. coli can produce disease. The most important of these is the ability to produce Shiga toxin. The gene that codes for Shiga toxin is not innate, but is contained within bacteriophages. In other words, the bacterium needs first to be infected by a bacteriophage coding for Shiga toxin in order to produce the toxin itself.
In her work, Camilla Sekse studied E. coli O103:H25 bacteria isolated both from foodstuffs and patients from the E. coli outbreak of 2006. She and her colleagues discovered special features of these E. coli bacteria that separate them from ordinary, benign forms. This discovery lead to it being easier to demonstrate E. coli O103:H25 in suspect food products.

Dangerous bacteria in our environment
It seems that E. coli O103:H25 has existed in Norway for some time, since this bacterium was also found to be a cause of the kidney failure outbreaks both in 2003 and 2005. Studies of the entire genome of this bacterium have shown that it more closely resembles the enteropathogenic E. coli (bacteria that cause diarrhoea) than the more common, Shiga toxin-producing E. coli, namely E. coli O157:H7.
Escherichia coli bacteria that are not disease-causing can absorb and lose bacteriophages coding for Shiga toxin, and can be important in the spread of these bacteriophages in the environment, even though they don't themselves cause disease. It appears that some E. coli bacteria can both more easily absorb and lose bacteriophages that contain the gene for Shiga toxin, and this may well be the case for E. coli O103:H25.
The work was primarily carried out at the Department Food Safety & Environment of the Norwegian School of Veterinary Science. Parts of the study were done in close collaboration with scientists of the University of Barcelona and at the Technical University of Denmark in Copenhagen, and in co-operation with the Norwegian Institute of Public Health in Oslo. The project was financed by the Research Council of Norway and the Norwegian School of Veterinary Science.

Minimizing The Spread Of Deadly Hendra Virus

2009-04-22T02:09:00.003+07:00

This artificially coloured electron micrograph of Hendra virus is from the first identified case in Brisbane in 1994. (Credit: CSIRO)

CSIRO Livestock Industries' scientists working at the Australian Animal Health Laboratory (AAHL), in Geelong Victoria, have made a major breakthrough in better understanding how Hendra spreads from infected horses to other horses and humans.

Funded by the Australian Biosecurity CRC for Emerging Infectious Diseases, Dr Deb Middleton and her team at AAHL have defined the period following the first signs of disease when horses are most likely to shed Hendra virus and therefore infect other horses and people.
First identified in Brisbane in 1994, Hendra virus, which spreads from flying foxes, has regularly infected horses in Australia. Of the 11 equine outbreaks, four have led to human infection, with three of the six known human cases being fatal, the most recent of these in August 2008.
Dr Deb Middleton and her team at AAHL have defined the period following the first signs of disease when horses are most likely to shed Hendra virus and therefore infect other horses and people.

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Dr Middleton says limited information in the past, on when the disease can transmit, has made it difficult to manage infected horses to stop Hendra spreading further to people and other susceptible horses.
"Our research has also determined the best biological samples required for rapid diagnosis of the virus in horses and identified the important relationship between the period of highest transmission risk and the time with which the disease can easily be detected," Dr Middleton says.
As a result of these findings, veterinarians and horse owners are likely to consider the possibility of Hendra virus infection sooner when dealing with sick horses. This will mean appropriate management strategies can be put in place immediately, reducing the risk of spread while testing is being carried out.
"Unlike in horse flu, where apparently healthy horses can transmit the virus, horses in the early stages of Hendra infection generally appear to be at lower risk compared to animals with more advanced signs of illness."
These research findings will be used to update the guidelines that horse owners and vets use to handle potential Hendra virus infections.
Dr Middleton says her research also indicates there is an opportunity to diagnose Hendra virus in horses early, prior to advanced clinical signs and the highest risk of transmission.
"Developing a sensitive and specific stall-side test, which vets could use out in the field to diagnose the disease, has become even more important. However there are still key challenges to developing this type of advanced technology."
Although it is still not known how Hendra spreads from flying foxes to horses, Dr Middleton says the key to preventing human exposure and the exposure of additional horses is first understanding the disease in horses and secondly controlling the viral spread from diseased horses.
All research for the project was undertaken within AAHL's high-biocontainment facility.

Climate Change Makes Migrations Longer For Birds

2009-04-22T01:59:00.004+07:00

A team of scientists, led by Durham University, have published findings that show that the marathon flights undertaken by birds to spring breeding grounds in Europe, are going to turn into even more epic journeys; the length of some migrations could increase by as much as 250 miles.

The research team looked at the current migration patterns of European Sylvia warblers, a group of birds that are common residents and visitors to Europe, like the Blackcap. Published in the Journal of Biogeography, the scientists demonstrate evidence of potential breeding ranges shifting northwards in the future, while the wintering ranges remain stationary for many species.

The team used simulation models to see how climate change might affect warblers and found that climate change will have significant impacts, particularly on the projected migration distances for some of the long distance fliers.

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Some 500 million birds are estimated to migrate to Europe and Asia from Africa; birds as small as 9 grams undertake the annual migration of 1,000s of miles between the two continents to find food and suitable climate. Birds have to put on a large amount of weight as fat before migrating long distances; they even shrink the size of some of their internal organs to become more fuel efficient. Some species must double their weight to have enough energy to undertake the huge journeys. The first of these migrants are now starting to reappear once again in the UK countryside.
Team leader, Dr Stephen Willis of Durham University, said birds face an increasing fight to survive: “Most warblers come here in spring and summer time to take advantage of the surplus of insects, and leave for warmer climes in the autumn. From 2071 to 2100, nine out of the 17 species we looked at are projected to face longer migrations, particularly birds that cross the Sahara desert.
“Our findings show that marathon migrations for some birds are set to become even longer journeys. This is bad news for birds like the Whitethroat, a common farmland bird. The added distance is a considerable threat.”
Co-author of the research paper, Professor Rhys Green of Cambridge University and RSPB said: "These tiny birds make amazing journeys, pushing themselves to the limits of endurance. Anything that makes those journeys longer or more dependent on rare and vulnerable pit-stop habitats used for refuelling on migration could mean the difference between life and death.”
In terms of EU policy, the predicted effects of climate change on birds indicate a need for an appraisal of the designation of protected areas for migrant species, including key areas used for stopovers on long-distance migrations. The protection of bird species within the European Union is covered by legal directives that require member states to designate and protect Special Areas of Conservation (SACs) for habitats and Special Protection Areas (SPAs), the latter specifically designated to protect birds.
The research predicts that some species that fly long distances (on average 2,800 miles to 3,700 miles), are likely to face significantly longer flights, up to 250 miles longer, and shorter distance fliers may face journeys of up to 125 miles longer. Some birds cross the Mediterranean Sea and the Sahara in one go, whilst others pause to refuel in North Africa before crossing the desert. Night flying when the temperature is cooler is a technique that is also used by some of the long distance fliers.
Northern parts of the species’ ranges are expected to become of increasing importance and in some cases, species of northern populations are already thought to be exhibiting increases. Some birds might also be able to find new short distance routes. One common migrant, the Blackcap has already started spending winters in the UK.
Professor Rhys Green said: "These findings come as many people in the UK are enjoying the sights and sounds of their favourite birds returning after a winter in Africa. The challenges are large if we are to continue to see and hear these harbingers of the spring in anything like the numbers we are used to witnessing.
"We have already seen evidence that birds' ranges are moving north to track suitable climate conditions in the way predicted by past modelling. This latest research suggests they will face an increase in the length of an already arduous journey.”
Assuming increases in the fuel requirements for longer migrations can be physiologically accommodated by birds, they are likely to require more time for feeding prior to migration and/or additional stopovers to feed.
Nathalie Doswald, a student on the Durham team, said: “The projected distances for migrations would require long and short distance fliers to increase their fuel loads by 9 per cent and 5 per cent of lean body mass respectively. The predicted future temperature changes and the associated changes in habitat could have serious consequences for many species.”
Dr Willis said: “Some species may be able to adapt and change, for example by adopting shorter migration routes, if they can find enough food at the right time. Bird migrations are incredible feats of stamina and endurance but, as temperatures rise and habitats change, birds will face their biggest challenge since the Pleistocene era.”
Average migration distances – now and (in brackets) predicted for the future.
The four species with the largest predicted migration increases:
Subalpine Warbler – 1,615 miles (1,895-2,081miles) - Southern Europe to sub-Saharan Africa
Orphean Warbler – 1,679 miles (1,926-2,019 miles) - Southern Europe to sub-Saharan Africa
Barred Warbler – 2982 miles (3480-3,573 miles) - Central Europe to sub-Saharan Africa
Whitethroat – 3,417 miles (3,541-3,759 miles) – All Europe to sub-Saharan Africa
This research was funded by the Natural Environment Research Council and the RSPB.

All Octopuses Are Venomous: Could Lead To Drug Discovery

2009-04-21T10:00:00.002+07:00

Once thought to be only the realm of the blue-ringed octopus, researchers have now shown that all octopuses and cuttlefish, and some squid are venomous. The work indicates that they all share a common, ancient venomous ancestor and highlights new avenues for drug discovery.

Conducted by scientists from the University of Melbourne, University of Brussels and Museum Victoria, the study was published in the Journal of Molecular Evolution.
Dr Bryan Fry from the Department of Biochemistry at the Bio21 Institute, University of Melbourne said that while the blue-ringed octopus species remain the only group that aredangerous to humans, the other species have been quietly using their venom for predation, such as paralysing a clam into opening its shell.

...

“Venoms are toxic proteins with specialised functions such as paralysing the nervous system” he said.
“We hope that by understanding the structure and mode of action of venom proteins we can benefit drug design for a range of conditions such as pain management, allergies and cancer.”
While many creatures have been examined as a basis for drug development, cephalopods (octopuses, cuttlefish and squid) remain an untapped resource and their venom may represent a unique class of compounds.
Dr Fry obtained tissue samples from cephalopods ranging from Hong Kong, the Coral Sea, the Great Barrier Reef and Antarctica.
The team then analysed the genes for venom production from the different species and found that a venomous ancestor produced one set of venom proteins, but over time additional proteins were added to the chemical arsenal.
The origin of these genes also sheds light on the fundamentals of evolution, presenting a prime example of convergent evolution where species independently develop similar traits.
The team will now work on understanding why very different types of venomous animals seem to consistently settle on the similar venom protein composition, and which physical or chemical properties make them predisposed to be useful as toxin.
“Not only will this allow us to understand how these animals have assembled their arsenals, but it will also allow us to better exploit them in the development of new drugs from venoms,” said Dr Fry.
“It does not seem a coincidence that some of the same protein types have been recruited for use as toxins across the animal kingdom.”

New Orangutan Population Found in Indonesia

2009-04-14T23:57:00.002+07:00

Conservationists discovered a new population of orangutans in a remote, mountainous corner of Indonesia — perhaps as many as 2,000 — giving a rare boost to one of the world's most endangered great apes.
A team surveying forests nestled between jagged, limestone cliffs on the eastern edge of Borneo island counted 219 orangutan nests, indicating a "substantial" number of the animals, said Erik Meijaard, a senior ecologist at the U.S.-based The Nature Conservancy.
"We can't say for sure how many," he said, but even the most cautious estimate would indicate "several hundred at least, maybe 1,000 or 2,000 even."

...

The team also encountered an adult male, which angrily threw branches as they tried to take photos, and a mother and child.
There are an estimated 50,000 to 60,000 orangutans left in the wild, 90 percent of them in Indonesia and the rest in neighboring Malaysia.
The countries are the world's top producers of palm oil, used in food, cosmetics and to meet growing demands for "clean-burning" fuels in the U.S. and Europe. Rain forests, where the solitary animals spend almost all of their time, have been clear-cut and burned at alarming rates to make way for lucrative palm oil plantations.

The steep topography, poor soil and general inaccessibility of the rugged limestone mountains appear to have shielded the area from development, at least for now, said Meijaard. Its trees include those highly sought after for commercial timber.
Birute Mary Galdikas, a Canadian scientist who has spent nearly four decades studying orangutans in the wild, said most of the remaining populations are small and scattered, which make them especially vulnerable to extinction.
"So yes, finding a population that science did not know about is significant, especially one of this size," she said, noting that those found on the eastern part of the island represent a rare subspecies, the black Borneon orangutan, or Pongo pygmaeus morio.
The 700-square mile (2,500-square kilometer) jungle escaped the massive fires that devastated almost all of the surrounding forests in the late 1990s. The blazes were set by plantation owners and small-scale farmers and exacerbated by the El Nino droughts.
Nardiyono, who headed The Nature Conservancy's weeklong survey in December, said "it could be the density is very high because after the fires, the orangutans all flocked to one small area."
It was unusual to come face-to-face with even one of the elusive creatures in the wild and to encounter three was extraordinary, he said, adding that before this expedition, he had seen just five in as many years.
Conservationists say the most immediate next step will be working with local authorities to protect the area and others that fall outside of national parks. A previously undiscovered population of several hundred also was found recently on Sumatra island, home to around 7,000.
"That we are still finding new populations indicates that we still have a chance to save this animal," said Paul Hartman, who heads the U.S.-funded Orangutan Conservation Service Program, adding it's not all "gloom and doom."
Noviar Andayani, head of the Indonesian Primate Association and Orangutan Forum, said the new discoveries point to how much work still needs to be done to come up with accurate population assessments, considered vital to determining a species' vulnerability to extinction.
"There are many areas that still have not been surveyed," she said, adding that 18 private conservation groups have just started work on an in-depth census based on interviews with people who spend time in the forests.
They include villagers and those working on plantations or within logging concessions.
"We hope this will help fill in a few more gaps," said Andayani, adding that preliminary tests in areas where populations are known indicate that the new interview-based technique could provide a clearer picture than nest tallies.
"Right now the information and data we have about orangutans is still pretty rudimentary," she said.
Some experts say at the current rate of habitat destruction, the animals could be wiped out within the next two decades.

Scientists Milk Animals For Malaria Vaccine

2009-04-14T23:54:00.002+07:00

In their quest to mass-produce an effective malaria vaccine, scientists might one day replace expensive manufacturing facilities with a goat. In a study reported December 18 in the Proceedings of the National Academy of Sciences online, researchers developed mice that could secrete an experimental malaria vaccine into their milk. When the purified candidate vaccine was injected into monkeys, it protected four out of five animals from a lethal dose of the malaria parasite. If the process can be scaled up to larger animals such as goats -- and early experiments indicate it can -- livestock might prove to be inexpensive, high-yield malaria vaccine factories. “A vaccine must not only be effective, it must be cheap to manufacture if it is to be used in those countries hit hardest by malaria,” says lead author Anthony Stowers, Ph.D., a malaria researcher at the National Institute of Allergy and Infectious Diseases (NIAID). “Using transgenic animals to achieve both ends is an exciting possibility. If it works, a herd of several goats could conceivably produce enough vaccine for all of Africa.”

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Transgenic animals are so named because they contain a gene, called a transgene, from another individual or organism. For years transgenic animals, particularly mice, have been used to help scientists understand how genes work and interact with one another. More recently, researchers have introduced genes encoding specific proteins into animals to produce large quantities of those proteins for medical use. Dr. Stowers and his colleagues investigated whether transgenic animals could produce proteins for use in malaria vaccines.
Dr. Stowers and Louis Miller, M.D., chief of NIAID’s Laboratory of Parasitic Diseases and the director of its Malaria Vaccine Development Unit, joined other investigators from NIAID and Genzyme Transgenics Corporation, Framingham, Mass., to produce two transgenic mouse strains. Each strain carried a form of the gene for a surface protein from the deadliest malaria parasite, Plasmodium falciparum. The researchers designed the transgenes to be switched on by the cells that line the mammary glands, such that the resulting proteins would be secreted into the animals’ milk.
Both mouse strains produced large quantities of the desired vaccine protein, which was used to vaccinate monkeys against malaria. Only one of the five immunized animals contracted the disease. By comparison, six out of seven unvaccinated animals had to be treated for virulent malaria.
The high yield of the protein and its ability to stimulate protective immunity in mice offers promising evidence that the technique could also be used in goats or even cows. The researchers had anticipated future studies in goats by designing the transgenes’ on/off switch using regulatory elements from goat DNA. Preliminary experiments, which have not yet been published, suggest the procedure works well in the larger animals. That possibility offers a far more practical option for large-scale vaccine production.
Anthony S. Fauci, M.D., who as NIAID director guides an extensive research program on global infectious diseases, believes this approach is promising. “Malaria causes untold suffering in the poorest regions of the world, so we cannot restrict our focus simply to finding a vaccine that works,” he says. “Rather, we must look for innovative strategies that will bring effective vaccines to regions where economic conditions preclude the use of costly alternatives. Transgenic animals could be one way to accomplish that goal.”
The study involved many researchers from the two participating institutions. Among these, Drs. Li-How Chen and Harry Meade directed the studies conducted at Genzyme Transgenics. B. Fenton Hall, M.D., from NIAID’s Parasitology and International Programs Branch, also helped initiate the project and played an active role in its development.
NIAID is a component of the National Institutes of Health (NIH). NIAID supports basic and applied research to prevent, diagnose, and treat infectious and immune-mediated illnesses, including HIV/AIDS and other sexually transmitted diseases, tuberculosis, malaria, autoimmune disorders, asthma and allergies.

Chimps beat college students in memory test

2009-04-14T23:49:00.003+07:00

When chimpanzees and university students went head-to-head in a short-term memory test, the chimps scored higher. The study was led by a Kyoto, Japan scientist who has studied the cognitive abilities of primates for 30 years.
In a recent study a Japanese researcher used short-term memory tests to compare the cognitive abilities between chimps and college students. The chimps won. Tetsuro Matsuzawa, director of the Primate Research Institute at Japan’s Kyoto University, has been studying chimpanzees and chimpanzee communities for 30 years.
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In his official bio at the university he compares the genomic difference between humans as comparable to the difference between horses and zebras and suggests humans are “98.77% chimpanzee.” He has long made the case that humans and chimpanzees are close genetic relatives and that they should co-exist peacefully.

To demonstrate their cognitive strengths, Matsuzawa taught three chimps, ages one through five, to recognize numbers one through nine. The test involved random flashing numbers on a touch screen computer. After a fraction of a second, the numbers were masked by white squares. The chimps were able to remember the location of up to eight of the numbers, and touch the spot where they had appeared in the correct order. But the college undergrads who volunteered for the study could only accurately recall the location of up to five numbers.

Matsuzawa opposes the use of primates in biomedical research and helped launch SAGA (Support for African/Asian Great Apes) in 1998. SAGA promotes conservation of chimpanzee, gorilla and orangutan natural habitats and supports non-invasive scientific inquiry.

World's First Cloned Transgenic Goats Born

2009-04-14T23:46:00.001+07:00

The world's first cloned transgenic goats have been born as part of a research program conducted by LSU Agricultural Center and Genzyme Transgenic Corp. While much of the research was done at LSU in Baton Rouge, the goats made their appearance last fall at the Genzyme farm in Massachusetts.
LSU's resident transgenic goat is Millie. Though she's a million-dollar goat, she doesn't look any different from the other goats she hangs out with. She is different, though, because her milk contains a therapeutic protein that could be extracted to make a drug for patients undergoing coronary bypass surgery. The drug works in conjunction with heparin, which prevents blood from clotting.
The protein, anti-thrombin III (AT III), is now in the third phase of human clinical trials. Pending FDA approval during the next 12 months, the product could be on the market in the next couple of years.

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"The technology used to clone the three Genzyme goats is one of the first applications of the nuclear transfer (cloning) procedure to produce transgenic goats for the pharmaceutical industry, said Richard Denniston, a researcher with the LSU Agricultural Center. An article in the May issue of Nature Biotechnology will announce the breakthrough. Researchers at Tufts University School of Veterinary Medicine also participated in the research.
LSU researchers have for the past six years carried a collaborative research program with Genzyme, which may become the first company to have a transgenic product on the market. "The FDA is being very careful because there's no precedent," Denniston said. Transgenics is the process of taking DNA from one species and implanting it into the genetic structure of another.
"Genzyme takes the gene for anti-thrombin III. The DNA is like a computer code. Once researchers identify the code, they can punch it into a DNA sequencer. Four different molecular building blocks of the DNA material are put in a vial, and a gene is built synthetically. Then you can make millions of copies of that," he explained.
The AT III gene is attached to a promoter gene, usually the gene for casein, a milk protein, and then microinjected into the male pronucleus of the newly fertilized egg. During the first cell divisions, the gene may become attached to the genetic material of the embryo. If this happens, the new gene, or transgene, will be incorporated into every cell of the developing goat embryo. The embryo is cultured and then transfered to the goat surrogate mother, and researchers wait for normal fetal development. If a female is produced, she will produce milk with the AT III protein, which can be extracted from the milk for pharmaceutical use.
"When you breed the AT III female offspring, 50 percent of her offspring will have this gene. Now you've got an animal that is very valuable. How do you produce these animals as quickly as possible? Genzyme does the molecular work. We are trying to develop technologies to reproduce these transgenic animals as quickly as possible," Denniston said.
"The idea of cloning arose in the past two years. Cloning is desirable because it would increase the efficiency rate. When you insert the AT III protein into 1,000 fertilized eggs and transfer 100 embryos, you can expect one transgenic offspring. There's a 50 percent chance of its being female," he said.
Denniston explained that there are three possible sources of genetic material for cloning. One source is the adult animal; this is how Dolly the sheep was produced. "That's what really made big news, taking a cell from an adult animal," he said. "Another source is the 16-32 cell-stage embryo, which was first done about 15 years ago. A third source is a developing fetus. In each case, the donor cell containing all the genetic material is fused with an enucleated egg (an egg that has had its genetic material removed). The resulting cloned embryo is then transferred into a recipient female that carries the clone to term."
The transgenic goat clones born from the joint LSU/Genzyme project were produced by taking fibroblast cells from a 30-day female goat fetus. These cells were grown in an incubator in media containing the gene for AT III. The growing cells then underwent a procedure called electroporation, which allows the gene to cross the cell membrane and enter the host cell's nucleus.
The resulting transgenic fibroblast cells were then fused with an enucleated egg. These cloned embryos were then transferred into a recipient goat. The result was three genetically identical transgenic female goats that can produce the valuable AT III protein in their milk. Using the cloning process in conjunction with transgenics improves the overall efficiency of producing transgenic animals, Denniston said.
Not all pregnancies are successful, but 100 percent of the births will be females with the gene for AT III," Denniston said.
The agricultural applications of this technique are widespread. For example, researchers could insert a gene for bruccilosis resistance and clone a herd of bruccilosis-resistant cattle.
"What we are doing for Genzyme is to test procedures or techniques and develop in vitro fertilization. Six years ago, nobody was doing in vitro fertilizationin goats. They asked us to, and we did," he said.
"The Massachusetts farm has more than 1,500 goats under the watchful eye of the FDA. They produce the gene in a lab in Framingham. They get a 30-day fetus, culture fiborblast cells, insert the gene for AT III into fiborblast cells, do nuclear transfer, send embryos to us, and we transfer them into recipients."
"The market for AT III is $200 million. That amount of protein can be produced by fewer than 100 goats. Even with the cost being a half to $1 millon per animal, the potential earnings from the pharmaceutical product are enormous," the LSU researcher said. Genzyme has received a patent on the protein.
It is cheaper to produce transgenic goats than cows; the goat's gestation period is shorter (5 months to a cow's 9 months), and the protein is not required in huge quantities, Denniston said.
LSU's contract with Genzyme has brought LSU approximately $850,000 in research funds, and LSU's reproductive physiology laboratory will continue working with the nuclear transfer process as a tool for pharmaceuticals, agricultural applications and propagation of endangered species.

Medicine From Milk: Gene Therapy Could Transform Goats Into Pharmaceutical Factories

2009-04-14T23:28:00.003+07:00

Researchers have used gene therapy to reduce the time it takes to breed goats capable of producing therapeutic proteins in their milk, such as insulin or those that fight cancer. (Credit: iStockphoto)

University of Pennsylvania researchers have used gene therapy to reduce the time it takes to breed large animals capable of producing therapeutic proteins in their milk, such as insulin or those that fight cancer. This represents a significant milestone in drug development, as current methods involve cloning, which takes more time and generally costs more.

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"Having an easier way to harness nature's power to produce large quantities of specific proteins in milk could increase the availability of drugs for people who could otherwise not afford these treatments," said Ina Dobrinski, one of the researchers on the study.
The study also is significant because it may also be a new way to eliminate diseases in future generations of animals, such as those used for livestock. Here's why: To get the goats to produce specific proteins, the researchers used radiation to kill a portion of a male goat's germ cells (the cells that produce sperm). Then they used a modified adeno-associated virus (a well studied and tolerated gene therapy vector) to insert a gene in the remaining cells. Once the new gene took hold in the germ cells, a predictable number of offspring carried the gene necessary to produce the desired protein in their milk.
The advance is immediately valuable for pharmaceutical development and biology research, but a similar approach could be used to bolster the food supply by eliminating genetic disorders in animals over several generations. It is also possible that once perfected, this technique could eliminate disease genes in humans over several generations, assuming ethical concerns can be resolved adequately.
This study is published in the February 2008 print edition of The FASEB Journal.
"For thousands of years, people have domesticated cows and goats to make milk, butter and cheese. And for thousands of years dairy products have been used as folk remedies for practically every human illness. Most have been completely ineffective." said Gerald Weissmann, MD, editor-in-chief of The FASEB Journal. "So it is reassuring that modern science would find a way to use the milk we drink to yield of drugs that actually work."

wetz...Tidur Telentang Bisa Menyebabkan Kematian...

2009-04-11T18:22:00.003+07:00

Teman-teman ini ada hasil penelitian terbaru dari Jepang masalah kesehatan yang dikutip dari hidupsehat.com, semoga bermanfaat bagi kita semua.

Menurut penelitian yg di lakukan oleh para Profesor ahli dari jepangselama hampir 20 tahun akhirnya mereka mengumumkan keputusan yg sangatmengejutkan kita semua tentang cara kita tidur selama ini.Ternyata tidur telentang sangat tidak dianjurkan sama sekali oleh para peneliti dari jepang.

...

Berikut kutipan dari Prof. Dr. Yosihiro :
"Kalo tidur jangan sekali kali dengan posisi TELENTANG!!…Karena tidur TELENTANG itu bisa mengganggu kesehatan anda.
Beberapa survei telah dilakukan dan menghasilkan bukti yg akurat."Orang2 yg tidur TELENTANG akan mengalami gejala2 sbb:
1. Susah bernafas
2. Tersedak
3. Pencernaan terganggu
4. Yg paling fatal,dapat menyebabkan KEMATIAN!!…

Oleh karena itu, disarankan agar anda menghindari tidur TELENTANG,Sebab jangankan tidur TELEN TANG, TELEN BAUT saja susahnya setengah modar……
Jadi disarankan cukup tidur TELEN LIUR aja ya..
hehehe.. .

Terapi Hormon Memperbaiki Seks dan Tidur Wanita Menopause

2009-04-11T18:16:00.003+07:00

Wanita menopause yang menjalani terapi penggantian hormon dapat meningkatkan fungsi seksual, mengurangi insomnia dan mengurangi gejolak panas, menurut penelitian yang diliris hari ini.

Riset yang dilakukan terhadap 2.130 wanita menopause dari Australia, Selandia Baru dan Inggris itu menemukan bahwa penggunaan terapi hormon kombinasi oestrogen dan progestogen dapat meningkatkan beberapa indikator kualitas hidup.

Hasil ini muncul di tengah debat tentang risiko dan manfaat terapi hormon bagi wanita menopause yang juga dikaitkan dengan risiko lebih tinggi akan serangan stroke, pembekuan darah dan kanker payudara.

Sebagian besar wanita yang diteliti berusia pertengahan 60-an, yang telah menjalani menopause rata-rata 13 tahun, dan sebagian besar mereka tidak memiliki gejala perubahan hidup.

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"Hasil penelitian kami menunjukkan gejolak panas, keringat di malam hari, susah tidur dan rasa sakit lainnya sangat kecil bagi wanita yang melakukan terapi hormon di kelompok usia ini," ujar Professor Alastair MacLennan, kepala studi independen Australia.

"Seksualitas juga meningkat," tambahnya.Penelitian itu menemukan bahwa persentase wanita yang menjalani terapi hormon mengalami gejolak panas menurun dari 30 persen menjadi 9 persen selama setahun, sementara mereka yang menderita insomnia menurun dari 45 persen menjadi 35 persen.

Sementara 63 persen wanita yang menjalani terapi mengatakan mereka mengalami sakit tulang sendi dan otot di awal terapi, kemudian turun 57 persen setelah 12 bulan.

MacLennan mengatakan bahkan bagi wanita yang tidak mempunyai gejala panas dan baik-baik saja saat menopause, ada "peningkatan meskipun kecil dalam kualitas hidup dan dalam masalah tidur, seksualitas dan penyakit gabungan.

"Hasil ini dipublikasikan di situs Jurnal Kedokteran Inggris berasal dari percobaan terapi hormon terlama dan terbesar di dunia-- Women's International Study of long Duration Oestrogen after Menopause (WISDOM).MacLennan, yang menjadi kepala kebidanan dan kandungan di Universitas Adelaide mengatakan studi WISDOM akan membantu mengurangi risiko pengobatan.

"Untuk sebagian besar wanita dengan gejala menopause signifikan manfaat terapi hormon mengalahkan risikonya," ujarnya.Kepala cabang WISDOM Selandia Baru, Beverley Lawton, mengatakan kualitas dari manfaat terapi hormon kemungkinan lebih besar pada wanita dengan gejala berat mendekati menopause.
"Riset baru menyatakan bahwa terapi homon yang dilakukan mendekati menopause menghindarkan risiko serangan jantung yang terlihat ketika terapi hormon dilakukan beberapa tahun setelah menopause," ujarnya.

Hmmm....Nasi Berbahay Bagi Kesehatan???!!!!...

2009-04-11T18:02:00.004+07:00

Hasil research yang baru saja dilakukan oleh para ilmuwan membuktikan bahwa makan nasi ternyata tidak baik bagi kita.

Buktinya :

1. Nasi MENYEBABKAN KECANDUAN.Responden kami yang tidak makan nasi selama sehari saja akan kelaparan dan merasa sangat ingin makan nasi lagi.

2. SETENGAH dari seluruh siswaIndonesia yang makan nasi nilainya ada di bawah rata-rata kelas.

3. HAMPIR 99% KEJAHATAN terjadi dalamwaktu kurang dari 24-jam setelah pelakunya mengkonsumsi nasi.

4. Suku-suku pada zaman batu yang tidakpernah makan nasi terbukti TIDAK PERNAH mengidap tumor, Alzheimer,osteoporosis, ataupun Parkinson.

5. Dokter melarang bayi yang baru lahir untuk makan nasi. Hal ini menjadi bukti bahwa nasi punya dampak berbahaya yang sudah dibuktikan oleh ilmu kedokteran.

...

6. Nasi yang kering biasa dimakan oleh ayam. Nah, sekarang anda perlu curiga dari mana flu burung berasal.

7. Jumlah pemakan nasi di Indonesiajauh lebih banyak dibandingkan dengan jumlah pemakan nasi di negara maju. Ini mungkin salah satu penyebab keterbelakangan pada negara ini.

8. Di warung-warung, biasanya KULI makan nasi dalam jumlah lebih banyak daripada kaum eksekutif. Hal ini membuktikan jika makan nasi MENURUNKAN kemampuan ekonomi seseorang.

9. Makan nasi dapat menyebabkan rasahaus alias MENYERAP air. Padahal tubuh kita sebagian besar terdiri dari air.

10. Dalam kondisi tertentu, makan nasi MENINGKATKAN resiko kematian. Misalnya makan nasi sambil menyetir mobil.

11. Pengidap DIABETES lebih dianjurkan makan kentang daripada nasi. Berarti nasi kurang baik bagi kesehatan.

12. Makan nasi menyebabkan keinginan mengkonsumsi sayur dan lauk. Misalnya nasi bandeng (nasi + bandeng goreng), nasi kucing (nasi + kucing goreng), dsb. Hal ini bisa menyebabkan obesitas.

13. Nasi mengandung ZAT BESI yangkonfigurasi elektron terluarnya 4s2. Zat lain yang elektron terluarnya 4adalah Racun ARSENIK (4p3), Batu batere TITANIUM (4s2), dan racun yangmenyerang Superman yaitu KRIPTON (4p6). Ini mengindikasikan bahwa nasi punya kesamaan dengan zat-zat berbahaya lainnya. (hahaha, jarang2 gini q ngerti KIMIA, padahal dulu kimia SMA q cuman 8, Pak!)

14. Dalam Alkitab tidak pernah menyebut-nyebut soal nasi. Para Nabi juga tidak makan nasi. Lagipula nasi bukan sesuatu yang dianjurkan agama sehingga keabsahan penggunaannya pun belum dapat dipastikan.

15. Nasi DIMASAK dalam suhu lebih dari100 derajat Celsius. Itu panas yang cukup untuk bunuh orang.

serius amat bacanya !!!!!!!!!!!!!!

huaauhuahuahuaua......

Mauw tauw rahasia kentut..???^_^

2009-04-11T17:54:00.005+07:00

Buang angin, kentut, atau yang dalam istilah ilmiahnya disebutflatulence, flatulency, flatus, adalah ciptaan Allah, yang sudah pasti bukanlah peristiwa biasa. Anda dapat membuktikannya dengan mencari tulisan ilmiah seputar kentut di mesin pencari pustaka ilmiah di internet, misalnya di scholar.google. com dengan mengetikkan kata kunci flatulence intestine. Yang akan Anda dapatkan adalah tidak kurang dari 4800 rujukan ilmiah yang membahas atau mengandung rujukan tentangkentut dari tahun 2000 hingga sekarang!
Tidak sampai di situ saja. Rujukan ilmiah tersebut diterbitkan olehberagam jurnal ilmiah dari berbagai disiplin, dari ilmu gizi, kedokteran, hingga kesehatan dan pengobatan. Sudah pasti ini bermakna pula peneliti dan para ilmuwan yang berkecimpung di bidang penelitian kentut juga berasal dari beragam disiplin ilmu.
...

Fisika di balik kentut
Keluarnya angin dari anus itu sendiri juga merupakan peristiwa yang memperlihatkan kebesaran Sang Pencipta. Di dalam saluran pencernaan makanan, terutama di dalam usus, terdapat berbagai zat berwujud padat, cair, gas, serta dengan tingkat kepadatan dan keenceran beragam. Hebatnya, angin kentut yang berbentuk gas bisa mengalir ke arah bawah, dan menerobos cairan dan padatan di dalam usus, untuk kemudian keluarmeninggalkan dubur.
Ini bukan peristiwa yang tidak aneh. Mengapa? Anda bisa mencoba mencampur zat padat, zat cair dan gas di dalam tabung atau gelas yang memiliki katup pengeluaran di bagian dasarnya. Lalu Anda berikan tekanan pada campuran tersebut, bisakah Anda memastikan bahwa gas tersebut bergerak ke arah bawah dan bahwa yang keluar dari katup pengeluaran tersebut hanya gas saja?
Biasanya gas atau gelembung udara bergerak menuju ke atas karena lebih ringan, dan sulit mengeluarkan gas tanpa mencegah keluarnya cairan atau padatannya melalui katup tersebut. Tapi peristiwa kentut terjadi melalui cara di luar kebiasaan itu berkat sempurnanya ciptaan Allah pada otot cincin yang membuka dan menutup lubang anus itu.
Otot lingkar pada dubur ini mampu merasakan keberadaan gas kentut dan mengatur pengeluarannya sedemikian rupa sehingga hanya gas saja, dan bukan padatan dan cairan, yang keluar dari anus. Bayangkan seandainya otot ini tidak mampu memilah dan mencegah keluarnya cairan dan padatan dari usus besar kita di saat kita buang angin di tempat terbuka.
Sangat diragukan jika ada alat buatan manusia yang mampu melakukan kerja seperti lubang anus yang luar biasa itu. Otot-otot dan jaringan terkait di seputar anus adalah organ ciptaan Allah yang Mahahebat, yang mampu melakukan kerja pelepasan gas kentut sekitar 10 kali per hari dengan sempurna, selama puluhan tahun usia manusia.
Kimia gas kentut
Di dalam usus besar, sekitar 70% gas berasal dari udara yang tertelan melalui mulut kita. Ketika makan, orang pada saat yang sama menelan ke dalam perutnya sekitar 2-3 cc udara. Misalnya, jika kita makan apel, udara tambahan yang ikut tertelan ke dalam tubuh kita adalah sekitar 20 cc. Begitu pula dengan minum. Kurang lebih 17 cc udara memasuki saluran pencernaan makanan saat seseorang meminum 10 cc air.
Gas selebihnya yang terdapat pada usus adalah gas asli buatan “dalam negeri”, alias muncul dari dalam usus itu sendiri dan bukan dari luar tubuh. Gas ini dihasilkan melalui aktifitas penguraian oleh mikroba di dalam saluran pencernaan kita.
Bagaimana gas-gas itu terbentuk? Tidak semua makanan yang kita telan dicerna sempurna dan diserap keseluruhannya di dalam usus halus. Sebagian makanan berserat atau zat tepung yang tak tercerna sempurna ini, misalnya kacang-kacangan, kemudian dirombak atau diuraikan oleh mikroba yang menghuni saluran pencernaan kita. Penguraian ini di antaranya menghasilkan zat-zat berwujud gas seperti metana dan hidrogen sulfida, serta gas-gas yang mengandung unsur belerang lainnya.
Gas kentut adalah campuran beragam gas. Kentut sebagian besarnya terdiri atas gas oksigen, nitrogen, karbon dioksida dan metana yang kesemuanya ini bukan penyebab bau tidak sedap. Yang memunculkan aroma tidak sedap pada kentut adalah gas-gas yang mengandung belerang. Di antaranya adalah hidrogen sulfida (bau telur busuk), methanethiol (bau sayur membusuk). Namun ada pula dimetil sulfida yang memiliki bau manis.
Kreatif karena kentut
Ternyata kentut memiliki nilai komersial. Sebut saja Josef Pujol,warga Prancis kelahiran Marseilles tahun 1857. Ia memiliki kelebihan mampu dengan sengaja mengendalikan otot-otot perutnya. Dengannya, ia dapat dengan mudah menyedot 2 liter udara ke dalam usus besarnya melalui anus, dan meniupkan kembali ke luar anus. Dengan kata lain, ia mampu membuat “kentut buatan”.
Berbekal bakat ini, ia memasuki dunia pentas hiburan. Sebelum pentas, ia “mencuci usus besarnya” agar tidak menimbulkan bau tak sedap. Suara buang anginnya hanya memiliki 4 tangga nada: do, mi, sol dan do lagi.
Pentas profesionalnya berawal di tahun1887. Karirnya mulai menanjak ketika ia naik panggung di gedung musik Moulin Rouge di Paris pada tahun1892. Dalam pentasnya, terkadang ia memasang selang pada anusnya yang kemudian disambungkan ke berbagai alat musik tiup untuk bermain musik.
Selain sangat terkenal, ia juga mendapatkan penghasilan 20.000 frank per minggu, dua setengah kali lebih banyak dibandingkan artis kondang kala itu, Sarah Bernhardt. Ketenarannya ini bahkan sempat mendorong Raja Belgia datang diam-diam untuk melihat Josef Pujol.
Penyaring kentut
Kini telah tersedia produk di pasaran yang berfungsi menghilangkan bau kentut yang tidak sedap. FLAT-D adalah salah satu nama produk berbentuk kain persegi panjang, yang mudah dilipat dan dibawa. Kain ini digunakan dengan cara menghamparkan di atas kursi kerja, atau kursi kantor. Selain dapat dicuci dan digunakan ulang, kain ini mengandung karbon teraktifasi.
Ketika seseorang buang angin dalam keadaan duduk di atas kursi kerja yang tertutup kain FLAT-D, kain ajaib ini menyerap aroma tidak sedap kentut tersebut. Penyaring kentut ini diproduksi pula dalam bentuk pembalut yang dapat direkatkan pada celana dalam, sehingga lebih praktis.
Selain FLAT-D, ada pula produk serupa bernama Under-Ease yangdikeluarkan oleh perusahaan Under-Tec Corp. Pakaian dalam yang sudah mendapatkan hak paten ini adalah hasil kerja keras penelitian pasangan suami istri Buck and Arlene Weimer. Produk mereka sempat menjadi buah bibir di media massa AS di awal tahun 2000-an.
Demikianlah, tulisan singkat ini tidak mungkin dapat menampung seluruh hasil-hasil temuan ilmiah dan inovasi teknologi seputar kentut, gas yang seringkali dicemooh orang. Namun, sebagai salah satu ciptaan Allah, ternyata kentut membuktikan bahwa tiada sesuatu yang Allah ciptakan, melainkan menjadi bukti keagungan dan keluasan ilmu Allah, Pencipta tanpa tara. Dialah yang menciptakan segala sesuatu dengan tujuan yang benar, sebagaimana firman-Nya, yang artinya:
(yaitu) orang-orang yang mengingat ALLAH sambil berdiri atau duduk atau dalam keadaan berbaring dan mereka memikirkan tentang penCIPTAAN langit dan bumi (seraya berkata): Ya Rabb kami, tiadalah Engkau menciptakan ini dengan SIA-SIA Maha Suci Engkau, maka peliharalah kami dari siksa neraka. (QS. Ali `Imran, 3:191)
(Penulis: Abdul Halim – Februari 2008)
Sumber: www.mitrafm. com

Bahaya Radiasi Ponsel..!!!!

2009-04-11T17:51:00.002+07:00

Tengoklah iklan tarif telepon seluler dari berbagai perusahaan. Tawaran mereka benar-benar menggiurkan: gratis bicara sepanjang hari, bebas menelepon semaumu atau ngobrol sampai dower, dan banyak iming-iming lainnya. Gara-gara tarif murah, orang dengan mudah berhalo-halo tanpa batas. Pulsa mungkin saja "aman", namun kesehatan bisa terancam.
Pembantu rumah tangga atau buruh bangunan pun mengantongi telepon. Di Indonesia, menurut Budi Putra, pengamat dan pengelola blog teknologi komunikasi, pengguna telepon seluler kini mencapai 115 juta orang, sekitar separuh dari jumlah penduduk Indonesia. Menurut data Organisasi Kesehatan Dunia (WHO), pengguna handphone di seluruh jagat mencapai tiga miliar orang. Dua kali lipat dibandingkan data 2005.Di balik semua kemudahan berkomunikasi, telepon genggam memunculkan kekhawatiran, terutama bagi kesehatan. Pemicunya, penelitian Vini Gautam Khurana, ahli bedah saraf dari Universitas Nasional Australia, Canberra, yang dipublikasikan pada akhir Maret lalu. Selama 15 bulan, Khurana menelaah lebih dari 100 penelitian yang telah dilakukan berbagai lembaga, tentang keselamatan penggunaan telepon seluler. Hasil penelitian itulah yang menimbulkan gelombang reaksi besar hingga sekarang, karena Khurana menyatakan penggunaan telepon seluler akan memicu epidemi tumor otak, yang akan membunuh lebih banyak orang ketimbang rokok. Menurut riset profesor peraih 14 penghargaan medis ini, penggunaan telepon seluler--langsung dari handset--lebih dari 10 tahun akan menggandakan risiko terkena kanker otak.

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Tidak hanya Khurana yang punya perhatian besar terhadap dampak buruk penggunaan telepon seluler, lembaga penelitian bergengsi lain juga demikian. Pada Juni lalu Mobile Telecommunications and Health Research di Inggris, bekerja sama dengan Imperial College, London, mengadakan penelitian besar-besaran tentang apakah telepon genggam bisa memicu gejala kanker otak, alzheimer, dan parkinson. Penelitian yang didanai pemerintah Inggris dan sejumlah perusahaan seluler ini akan "membuntuti" 90 ribu orang responden selama setahun. Lalu mengevaluasi dampak kesehatannya. Menjawab kekhawatiran dunia akan bahaya telepon genggam, Organisasi Kesehatan Dunia juga telah meluncurkan Health Evidence Network. Ini merupakan layanan informasi Organisasi Kesehatan Dunia Kantor Regional Eropa, sebagai referensi bagi pengambil keputusan di bidang medis. Ternyata, menurut organisasi kesehatan di bawah Perserikatan Bangsa-Bangsa ini, bukti bahwa radiasi telepon seluler dapat memicu tumor otak, tumor pada sel saraf pendengaran, tumor kelenjar saliva, leukemia dan limfoma, masih "lemah dan tak bisa disimpulkan". Alasannya, orang hanya memakai telepon dalam waktu terbatas--bukan sepanjang hari secara terus-menerus. Meski begitu, lembar fakta Organisasi Kesehatan Dunia menyebutkan, tidak ada bukti bukan berarti tidak ada efek. Harus ada penelitian lanjutan yang lebih spesifik untuk tiap-tiap kasus. Untuk itu, pada Oktober 2009, organisasi ini akan mengeluarkan rekomendasi resmi tentang aturan menggunakan telepon genggam, tentu saja berdasar penelitian yang lebih kredibel. Khurana sendiri menyarankan untuk membuat penelitian dampak penggunaan telepon seluler dalam jangka 10-15 tahun, agar menghasilkan "kajian ilmiah yang solid".Belum adanya kepastian tentang tingkat bahaya penggunaan telepon seluler itulah yang menjadi masalah. Para dokter di Indonesia menyatakan, meski pemakaian telepon seluler meningkat belakangan ini, belum ada penelitian di Tanah Air tentang bahayanya bagi kesehatan. Menurut Silvia F. Lumempouw, dari berbagai kasus penyakit saraf yang ia tangani--termasuk alzheimer dan neuroma akustik--belum pernah ada yang terkait langsung dengan penggunaan telepon genggam. Spesialis saraf dari Rumah Sakit Cipto Mangunkusumo dan Rumah Sakit Dharma Nugraha ini menyatakan, radiasi dari seluler sebetulnya tak terlalu berbahaya jika dibandingkan dengan sumber radiasi lain seperti rontgen atau CT-scan. Para pekerja medis yang setiap hari berurusan dengan radiasi pun aman, apalagi "cuma" telepon. Silvia juga mengingatkan, sebetulnya kita juga dikelilingi radiasi dari televisi, radio, komputer, dan berbagai peranti lain. Karena itu, ia menyarankan, kita juga wajib mewaspadai gejala akibat penggunaan handphone yang berlebihan. "Teknologi kan diciptakan untuk memudahkan, bukan untuk membuat sakit," katanya.Pengurus Perhimpunan Dokter Spesialis Saraf Indonesia (Perdossi) ini membandingkan telepon genggam dengan obat. Jika sebelum dipasarkan, obat harus sukses melalui serangkaian proses (dicoba di hewan, lalu di manusia, kemudian di orang sakit), alat-alat teknologi pun seharusnya begitu. "Mesti ada aturan dari sisi kesehatan, sebelum produk itu dipasarkan," kata Silvia. Jangan hanya berorientasi pada kecanggihan tapi tak mementingkan sisi medis. Himawan W.H. juga menyatakan hal senada. Dokter spesialis telinga, hidung, dan tenggorokan di jaringan Rumah Sakit Mitra Internasional ini menyebut semua radiasi pada dasarnya berbahaya. Namun radiasi dari telepon genggam relatif kecil.Selain dari telepon genggam, potensi radiasi di sekitar kita yang patut diwaspadai adalah penggunaan microwave, telepon tanpa kabel, paparan sinar matahari langsung, dan penerbangan. Laporan United States Federal Aviation Administration menyatakan, mereka yang terbang secara rutin terekspos radiasi setara dengan 170 kali dipindai sinar X. Karena selalu mengarungi udara itulah, pramugari dan pilot lebih rentan terkena kanker. (Majalah Tempo)

Wow...Kulit Semangka Bisa Jadi Obat...Keyen g tuh??!!

2009-04-11T17:45:00.004+07:00

Hasil penelitian terbaru, seperti dikutip kantor berita Arab Saudi (SPA) Minggu (22/7), menyebutkan bahwa kulit semangka juga dapat menyembuhkan sedikitnya lima macam penyakit.
Penyakit-penyakit yang bisa disembuhkan oleh kulit semangka adalah darah tinggi kronis, radang ginjal, sulit buang air kecil, sulit buang air besar kronis dan penyakit dropsy (sakit gembur-gembur).

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Hasil penelitian yang dilakukan Lembaga Medis Biologi yang disiarkan oleh Majalah Riset Medis Yordania itu juga memberikan jaminan bagi pasien dapat sembuh setelah melakukan pengobatan selama sebulan dengan teratur.
Untuk darah tinggi disarankan untuk mengeringkan kulit semangka lalu ditumbuk halus. Setiap hari diambil 20 gram dari kulit yang telah ditumbuk itu dan dimasak dengan air secukupnya. Pasien yang meminumnya secara teratur selama sebulan, penyakit darah tingginya bisa tersembuhkan secara total.Sedangkan empat penyakit lainnya disarankan untuk memotong kecil kulit semangka tersebut lalu dimasak sehingga menjadi adonan lalu disimpan di dalam botol kaca yang ditutup rapi.
Pasien penderita radang ginjal, sulit buang air kecil, sulit buang air besar kronis dan penyakit gembur-gembur, dianjurkan memakan adonan tersebut satu sendok makan sehari sebelum sarapan selama sebulan.“Apabila pasien mengikuti petunjuk tersebut dengan teratur paling sedikit selama sebulan penuh, maka penyakit-penyakit tersebut akan sembuh total dengan izin Allah,” demikian hasil penelitian tersebut.
Dengan adanya hasil penelitian terbaru tersebut, warga Arab yang dikenal memang doyan makan buah semangka, kemungkinan tidak akan membuang kulitnya ke sampah, tapi akan disimpan menjadi bahan obat.(*) @Antara

Virus Kills Cancer Stem Cells

2009-04-11T17:36:00.003+07:00

Breast Cancer Cell

National Cancer Institute

Who would have thought that a common virus could become a potent weapon in the fight against breast cancer. Researchers have discovered that the human reovirus, a virus that does not cause disease in humans, effectively destroys breast cancer cells and cancer stem cells. This is a key discovery as cancer stem cells are very difficult to kill.

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Cancer researcher Dr. Patrick Lee explains, "Cancer stem cells are essentially mother cells. They continuously produce new cancer cells, aggressively forming tumours even when there are only a few of them. You can kill all the regular cancer cells in a tumour, but as long as there are cancer stem cells present, disease will recur.

"An added benefit that human reovirus brings to the battle against cancer is that it also stimulates the immune system to attack cancer cells. Because the human immune system also attacks the reovirus however, the researchers are now focusing on a method to rein in the immune system so that it will attack the cancer cells while leaving the reovirus unharmed.

Sleep May Help Clear Brain For New Learning

2009-04-09T01:38:00.004+07:00

Washington University scientists used genetically modified fruit flies to track the creation of new brain synapses, junctures where two brain cells communicate. They found that two scenarios that give the fruit fly's brain a workout caused new synapses to arise. To their surprise, all of the new synapses originated from a group of 16 cells in the fly brain's internal timekeeping mechanism. The cells are highlighted in the encircled area above. (Credit: Image courtesy of Washington University School of Medicine)

A new theory about sleep's benefits for the brain gets a boost from fruit flies in the journal Science. Researchers at Washington University School of Medicine in St. Louis found evidence that sleep, already recognized as a promoter of long-term memories, also helps clear room in the brain for new learning.
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The critical question: How many synapses, or junctures where nerve cells communicate with each other, are modified by sleep? Neurologists believe creation of new synapses is one key way the brain encodes memories and learning, but this cannot continue unabated and may be where sleep comes in.
"There are a number of reasons why the brain can't indefinitely add synapses, including the finite spatial constraints of the skull," says senior author Paul Shaw, Ph.D., assistant professor of neurobiology at Washington University School of Medicine in St. Louis. "We were able to track the creation of new synapses in fruit flies during learning experiences, and to show that sleep pushed that number back down."
Scientists don't yet know how the synapses are eliminated. According to theory, only the less important connections are trimmed back, while connections encoding important memories are maintained.
Many aspects of fly sleep are similar to human sleep; for example, flies and humans deprived of sleep one day will try to make up for the loss by sleeping more the next day. Because the human brain is much more complex, Shaw uses the flies as models for answering questions about sleep and memory.
Sleep is a recognized promoter of learning, but three years ago Shaw turned that association around and revealed that learning increases the need for sleep in the fruit fly. In a 2006 paper in Science, he and his colleagues found that two separate scenarios, each of which gave the fruit fly's brain a workout, increased the need for sleep.
The first scenario was inspired by human research linking an enriched environment to improved memory and other brain functions. Scientists found that flies raised in an enhanced social environment—a test tube full of other flies—slept approximately 2-3 hours longer than flies raised in isolation.
Researchers also gave male fruit flies their first exposure to female fruit flies, but with a catch—the females were either already mated or were actually male flies altered to emit female pheromones. Either fly rebuffed the test fly's attempts to mate. The test flies were then kept in isolation for two days and exposed to receptive female flies. Test flies that remembered their prior failures didn't try to mate again; they also slept more. Researchers concluded that these flies had encoded memories of their prior experience, more directly proving the connection between sleep and new memories.

Scientists repeated these tests for the new study, but this time they used flies genetically altered to make it possible to track the development of new synapses, the junctures at which brain cells communicate.
"The biggest surprise was that out of 200,000 fly brain cells, only 16 were required for the formation of new memories, " says first author Jeffrey Donlea, a graduate student. "These sixteen are lateral ventral neurons, which are part of the circadian circuitry that let the fly brain perform certain behaviors at particular times of day."
When flies slept, the number of new synapses formed during social enrichment decreased. When researchers deprived them of their sleep, the decline did not occur.
Donlea identified three genes essential to the links between learning and increased need for sleep: rutabaga, period and blistered. Flies lacking any of those genes did not have increased need for sleep after social enrichment or the mating test.
Blistered is the fruit fly equivalent to a human gene known as serum response factor (SRF). Scientists have previously linked SRF to plasticity, a term for brain change that includes both learning and memory and the general ability of the brain to rewire itself to adapt to injury or changing needs.
The new study shows that SRF could offer an important advantage for scientists hoping to study plasticity: unlike other genes connected to plasticity, it's not also associated with cell survival.
"That's going to be very helpful to our efforts to study plasticity, because it removes a large confounding factor," says co-author Naren Ramanan, Ph.D., assistant professor of neurobiology. "We can alter SRF activity and not have to worry about whether the resulting changes in brain function come from changes in plasticity or from dying cells."
Shaw plans further investigations of the connections between memory and sleep, including the question of how increased synapses induce the need for sleep.
"Right now a lot of people are worried about their jobs and the economy, and some are no doubt losing sleep over these concerns," Shaw says. "But these data suggest the best thing you can do to make sure you stay sharp and increase your chances of keeping your job is to make getting enough sleep a top priority."

New Use for Tobacco

2009-04-09T01:28:00.002+07:00

We all know how harmful tobacco products can be, so it seems a little strange to think that tobacco could possibly have medicinal benefits. Researchers are creating genetically modified tobacco plants that are able to produce anti-inflammatory proteins. These proteins could then be used to treat several diseases including diabetes.
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Lead scientist Mario Pezzotti states, "Transgenic plants are attractive systems for the production of therapeutic proteins because they offer the possibility of large scale production at low cost, and they have low maintenance requirements. The fact that they can be eaten, which delivers the drug where it is needed, thus avoiding lengthy purification procedures, is another plus compared with traditional drug synthesis." The next step in the study is to see how effective the plants are by feeding them to mice with auto-immune diseases.

New Use for Tobacco

2009-04-09T01:28:00.000+07:00

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Lead scientist Mario Pezzotti states, "Transgenic plants are attractive systems for the production of therapeutic proteins because they offer the possibility of large scale production at low cost, and they have low maintenance requirements. The fact that they can be eaten, which delivers the drug where it is needed, thus avoiding lengthy purification procedures, is another plus compared with traditional drug synthesis." The next step in the study is to see how effective the plants are by feeding them to mice with auto-immune diseases.

Why Lizards Shed Their Tail

2009-04-09T01:24:00.004+07:00

Aegean wall lizardCredit: Johannes Foufopoulos

Did you know that some lizards have the ability to quickly shed their tail when under attack from a predator? Researchers had assumed that predator-prey relationships were a key factor in determining this ability in lizards. A deeper look however has given insight into why some lizards have this ability while others don't. The answer lies in the type of predator, specifically those that kill their prey with venom.
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In a study of lizards in Greece and the Aegean islands, researchers noticed that lizards with the quick tail-shedding ability were located in areas that were also populated by vipers. This ability is advantageous. If the lizard is bitten on its tail, it can shed the tail before the deadly venom is able to reach any vital organs. The lizard can then regrow its tail over time. Lizards that are located in areas where venomous snakes are not around do not have this same ability to quickly shed their tails.

Cholesterol Crystals and Heart Attacks

2009-04-09T01:20:00.003+07:00

Researchers from Michigan State University have discovered that heart attacks can be caused by cholesterol crystals in the blood stream that disrupt plaque found in arteries. Plaque consists of cholesterol, fat, calcium, and other substances that build-up and reduce blood flow. As cholesterol builds on artery walls, it crystallizes and expands. The sharp crystals eventually move into the blood causing damage to arterial they move along. As the body tries to repair itself through the prwalls as ocess of clotting, it can lead to the development of blood clots that completely block blood flow. When this happens, a heart attack occurs.
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Cholesterol CrystalsImage courtesy of Michigan State University

The image to the right shows cholesterol crystals. The protruding elements seen in the different slides are the crystals. Those elements are arising from within the artery wall, causing tearing and damage to the artery. The colors have been added for enhancement and imagery.

How To Extract DNA From a Banana

2009-04-09T01:04:00.003+07:00

Extracting DNA from a banana may sound like a difficult task, but it is not very difficult at all. The process involves a few general steps which include mashing, filtration, precipitation, and extraction. Mashing exposes a greater surface area from which to extract the DNA. Substances are also added that will help break-down cell membranes to release the DNA. The filtration step allows for the collection of the DNA and other cellular substances. The precipitation step allows the DNA to separate from other cellular substances. Finally, the DNA is removed from the solution.
Renee Comet/National Cancer Institute

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All living organisms contain DNA. That includes you, me, and even a banana. DNA stands for deoxyribonucleic acid. It is housed within the nucleus of our cells and contains the genetic information for cellular function and the reproduction of life.

Mashing exposes a greater surface area from which to extract the DNA. Substances are also added that will help break-down cell membranes to release the DNA. The filtration step allows for the collection of the DNA and other cellular substances. The precipitation step allows the DNA to separate from other cellular substances. Finally, the DNA is removed from the solution.

Here's How:

Using your knife, cut your banana into tiny pieces to expose more of the cells.
Place your banana pieces in the blender, add a teaspoon of salt and slightly cover the mixture with warm water. The salt will help the DNA stay together during the mashing process.
Mix in the blender for 5 to 10 seconds making sure the mixture is not too runny.
Pour the mixture into the glass jar through the strainer. You want the jar to be about half full.
Add about 2 teaspoons of liquid soap and gently stir the mixture. You should try not to create bubbles when stirring. The soap helps to break-down cell membranes to release the DNA.
Carefully pour very cold rubbing alcohol down the side of the glass stopping near the top.
Wait for 5 minutes to allow the DNA to separate from the solution.
Use the toothpicks to extract the DNA that floats to the surface. It will be long and stringy.
Tips:

when pouring the alcohol, make sure that two separate layers are being formed (The bottom layer being the banana mixture and the top layer being the alcohol).
When extracting the DNA, twist the toothpick slowly. Be sure to only remove the DNA from the top layer.
Try repeating this experiment again using other foods such as an onion or chicken liver.
What You Need:
Banana
Salt
Warm water
Liquid soap
Blender
Toothpicks
Strainer
Glass jar
Rubbing alcohol
Knife

Psst! Coffee Drinkers: Fruit Flies Have Something To Tell You About Caffeine

2009-03-26T03:34:00.002+07:00

In their hunt for genes and proteins that explain how animals discern bitter from sweet, a team of Johns Hopkins researchers began by testing whether mutant fruit flies prefer eating sugar over sugar laced with caffeine. Using a simple behavioral test, the researchers discovered that a single protein missing from the fly-equivalent of our taste buds caused them to ignore caffeine's taste and consume the caffeine as if it were not there.

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"No, you won't see jittery Drosophila flitting past your bananas to slurp your morning java anytime soon," says Craig Montell, Ph.D., a professor of biological chemistry in the Institute of Basic Biomedical Sciences at Hopkins. "The bottom line is that our mutant flies willingly drink caffeine-laced liquids and foods because they can't taste its bitterness -- their taste receptor cells don't detect it."
The Hopkins flies, genetically mutated to lack a certain taste receptor protein, have been the focus of studies to sort out how animals taste and why we like the taste of some things but are turned off by the taste of others.
By color-coding sweet and bitter substances eaten by fruit flies and examining the coloring that shows up in their translucent bellies, the Hopkins team hoped to learn whether flies missing a specific "taste-receptor" protein changed their taste preferences.
"Normally," Montell explains, "when given the choice between sweet and bitter substances, flies avoid caffeine and other bitter-tasting chemicals. But flies missing this particular taste-receptor protein, called Gr66a, consume caffeine because their taste-receptor cells don't fire in response to it."
The discovery, which is the first ever example of a protein required for both caffeine tasting and caffeine-induced behavior, will be published Sept. 19 in Current Biology.
For the study, Montell and his colleagues kept 50 fruit flies away from food overnight and for breakfast gave the starved flies 90 minutes to eat as much as they wanted of either or both of two concoctions: a blue-colored mixture of sugar and agar and a red-colored mixture of caffeine, sugar and agar. The researchers then flipped the flies onto their backs and looked at the color of their bellies to see what they ate - blue indicating a preference for eating sugar, red indicating a preference for bitter caffeine, and purple indicating no preference.
Flies missing the critical taste receptor protein Gr66a consumed the bitter caffeine solution to the same extent as the sugar-only solution. Montell and colleagues conclude that Gr66a is crucial for the normal caffeine avoidance behavior and without it, flies are seemingly indifferent to the bitter taste.
The researchers went on to examine whether this indifference to bitter was due to the taste nerves on the fly's "tongue" or some malfunction in the fly's brain. Chemical stimulants trigger taste receptor cells to send an electrical current to the brain where the information is processed and often leads to a change in behavior, such as the decision to eat or avoid.
With fine tools, the research team recorded electrical currents in those cells known to contain the Gr66a caffeine taste receptor in the fly's equivalent of the taste buds - dubbed the taste bristles.
Applying sugar to the taste bristles of normal flies, or to mutant flies missing the Gr66a protein, causes the neurons to produce electrical current "spikes" at a frequency of about 20 spikes per second. Other bitter compounds like quinine generated electrical current spikes at about the same frequency in the mutants.
Only flies missing the Gr66a taste receptor protein were unable to generate any current spikes when given caffeine. "This is a clear demonstration that Gr66a is functioning in the taste receptor cells and is not a 'general sensor' for bitter compounds, but is required more specifically for the caffeine response," says Montell.
"This indicates that flies have different receptors for the response to other types of bitter compounds," he says.
"We also tested whether the flies avoided the related bitter compounds found in tea and cocoa -- chocolate -- and found that Gr66a also is required for the response to the compound in tea, but not for the one in chocolate," he says.
Fruit flies often are used as experimental organisms because they grow quickly and are easy to manipulate genetically. Now that Montell and his colleagues have a mutant fly that is unable to taste caffeine, they hope to further examine the other genes and molecules involved in the caffeine response and better understand the biochemistry behind caffeine-induced behavior in other organisms, namely humans.
The researchers were funded by the Polycystic Kidney Disease Foundation and the National Institute of Deafness and Communicative Disorders of the National Institutes of Health.

Like Sweets? You're More Like A Fruit Fly Than You Think

2009-03-26T03:27:00.003+07:00

A fruit fly extends its proboscis to 'taste' a drop of sucrose. (Credit: Beth Gordesky-Gold)

According to researchers at the Monell Center, fruit flies are more like humans in their responses to many sweet tastes than are almost any other species.
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The diverse range of molecules that humans experience as sweet do not necessarily taste sweet to other species. For example, aspartame, a sweetener used by humans, does not taste sweet to rats and mice.
However, fruit flies respond positively to most sweeteners preferred by humans, including sweeteners not perceived as sweet by some species of monkeys.
The findings, published in a recent issue of the journal Chemical Senses, demonstrate the critical role of environment in shaping the genetic basis of taste preferences and feeding behavior.
"Humans and flies have similar taste responses because they share similar environments and ecological niches, not because their sweet receptors are similar genetically," notes senior author Paul A.S. Breslin, PhD, a Monell sensory geneticist. "Both are African species, both are omnivorous, and both historically are primarily fruit eaters."
To compare how molecular structure is related to sweet taste perception in humans and flies, the Monell researchers evaluated how fruit flies respond to 21 nutritive and nonnutritive compounds of varying molecular structure, all of which taste sweet to humans.
Breslin and lead author Beth Gordesky-Gold, PhD, used two behavioral tests to evaluate the flies' responses to the various sweeteners.
The taste reactivity test measures whether a fly extends its feeding tube, or 'proboscis,' to consume a given sweetener. In addition, a two-choice preference test evaluates the flies' responses to a sweetener by measuring whether they consume it in preference to a control solution (usually water).
The Monell researchers found that fruit flies and humans both respond positively to the same broad range of sweet-tasting molecules.
"The similarity between human and fly responses to sweeteners is astounding, especially in light of the differences in their taste receptors," notes Gordesky-Gold, a Drosophila (fruit fly) geneticist at Monell.
Sweet receptors belong to a large family of receptors known as G-protein coupled receptors (GPCRs), which are involved in biological processes throughout the body. Human and fly sweet taste GPCRs are presumed to have markedly different structures, an assumption that is based on differences in the genes that code for them.
Since substances will only taste sweet if they are able to bind to and activate a receptor, these two structurally different types of sweet receptors must have similar 'binding regions' that fit the same range of molecular shapes.
"That genes could be so divergent in sequence and so similar in physiology and function is truly striking," says Breslin. "This is a wonderful example of convergent evolution in perceptual behavior, where evolution has taken two different routes to address pressures imposed by shared environment and nutrition."
Future work will be directed towards modeling how these two structurally different sweet receptors could have highly overlapping sweetener affinities. Such knowledge will increase understanding of how molecules bind to GPCRs, which are targets for many pharmaceutical drugs.
The research was supported by the National Institute on Deafness and Other Communication Disorders.

Liking Sweets Makes Sense For Kids

2009-03-26T03:21:00.004+07:00

As any parent knows, children love sweet-tasting foods. Now, new research from the University of Washington and the Monell Center indicates that this heightened liking for sweetness has a biological basis and is related to children's high growth rate.

New research indicates that this heightened liking for sweetness has a biological basis and is related to children's high growth rate. (Credit: Copyright Joan Vicent Cantó Roig)

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"The relationship between sweet preference and growth makes intuitive sense because when growth is rapid, caloric demands increase. Children are programmed to like sweet taste because it fills a biological need by pushing them towards energy sources," said Monell geneticist Danielle Reed, PhD, one of the study authors.
Across cultures, children prefer higher levels of sweetness in their foods as compared to adults, a pattern that declines during adolescence. To explore the biological underpinnings of this shift, Reed and University of Washington researcher Susan Coldwell, PhD, looked at sweet preference and biological measures of growth and physical maturation in 143 children between the ages of 11 and 15.
The findings, reported in the journal Physiology & Behavior, suggest that children's heightened liking for sweet taste is related to their high growth rate and that sweet preferences decline as children's physical growth slows and eventually stops.
Based on the results of sensory taste tests, children were classified according to their sweet taste preference into a 'high preference' or 'low preference' group. Children in the 'low preference' group also had lower levels of a biomarker (type I collagen cross-linked N-teleopeptides; NTx) associated with bone growth in children and adolescents.
"This gives us the first link between sweet preference and biological need," said Reed. "When markers of bone growth decline as children age, so does their preference for highly sweet solutions."
Other biological factors associated with adolescence, such as puberty or sex hormone levels, were not associated with sweet preference.
"We now know that sweet preference is related to physical growth. The next step is to identify the growth-related factor that is signaling the brain to influence sweet preference," said study lead author Coldwell, Washington Dental Service Endowed Professor and Associate Professor of Dental Public Health Sciences at the University of Washington School of Dentistry.
The research was funded by a grant to the University of Washington from the National Institute of Dental and Craniofacial Research (National Institutes of Health).

Biological Evolution

2009-03-16T21:25:00.003+07:00

What is Evolution?

Biological evolution is defined as any genetic change in a population that is inherited over several generations. These changes may be small or large, noticeable or not so noticeable. In order for an event to be considered an instance of evolution, changes have to occur on the genetic level of a population and be passed on from one generation to the next. This means that the genes, or more specifically, the alleles in the population change and are passed on. These changes are noticed in the phenotypes (expressed physical traits that can be seen) of the population. A change on the genetic level of a population is defined as a small-scale change and is called microevolution. Biological evolution also includes the idea that all of life is connected and can be traced back to one common ancestor. This is called macroevolution.

What is not Evolution?

Biological evolution is not defined as simply change over time. Many organisms experience changes over time, such as weight loss or gain. These changes are not considered instances of evolution because they are not genetic changes that can be passed on to the next generation.

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Is Evolution a Theory?

Evolution is a scientific theory that was proposed by Charles Darwin. A scientific theory gives explanations and predictions for naturally occurring phenomena based on observations and experimentations. This type of theory attempts to explain how events seen in the natural world work.The definition of a scientific theory differs from the common meaning of theory, which is defined as a guess or a supposition about a particular process. In contrast, a good scientific theory must be testable, falsifiable, and substantiated by factual evidence. When it comes to a scientific theory, there is no absolute proof. It's more a case of confirming the reasonability of accepting a theory as a viable explanation for a particular event.

What is Natural Selection?

Natural selection is the process by which biological evolutionary changes take place. Natural selection acts on populations and not individuals. It is based on the following concepts:

Individuals in a population have different traits which can be inherited.
These individuals produce more young than the environment can support.

The individuals in a population that are best suited to their environment will leave more offspring, resulting in a change in the genetic makeup of a population.The genetic variations that arise in a population happen by chance, but the process of natural selection does not. Natural selection is the result of the interactions between genetic variations in a population and the environment.The environment determines which variations are more favorable. Individuals that possess traits that are better suited to their environment will survive to produce more offspring than other individuals. More favorable traits are thereby passed on to the population as a whole.

How Does Genetic Variation Occur in a Population?

Genetic variation occurs through sexual reproduction. Due to the fact that environments are unstable, populations that are genetically variable will be able to adapt to changing situations better than those that do not contain genetic variations.Sexual reproduction allows for genetic variations to occur through genetic recombination. Recombination occurs during meiosis and provides a way for producing new combinations of alleles on a single chromosome. Independent assortment during meiosis allows for an indefinite number of combinations of genes. (Example of recombination) Sexual reproduction makes it possible to assemble favorable gene combinations in a population or to remove unfavorable gene combinations from a population. Populations with more favorable genetic combinations will survive in their environment and reproduce more offspring than those with less favorable genetic combinations.

Biological Evolution Versus Creation

The theory of evolution has caused controversy from the time of its introduction until today. The controversy stems from the perception that biological evolution is at odds with religion concerning the need for a divine creator. Evolutionists contend that evolution does not address the issue of whether or not God exists, but attempts to explain how natural processes work.In doing so however, there is no escaping the fact that evolution contradicts certain aspects of some religious beliefs. For example, the evolutionary account for the existence of life and the biblical account of creation are quite different.Evolution suggests that all life is connected and can be traced back to one common ancestor. A literal interpretation of biblical creation suggests that life was created by an all powerful, supernatural being (God). Still others have tried to merge these two concepts by contending that evolution does not exclude the possibility of the existence of God, but merely explains the process by which God created life. This view however, still contradicts a literal interpretation of creation as presented in the bible.In paring down the issue, a major bone of contention between the two views is the concept of macroevolution. For the most part, evolutionists and creationists agree that microevolution does occur and is visible in nature.Macroevolution however, refers to the process of evolution that takes place on the level of species, in which one species evolves from another species. This is in stark contrast to the biblical view that God was personally involved in the formation and creation of living organisms.For now, the evolution/creation debate continues on and it appears that the differences between these two views are not likely to be settled any time soon.

Archaea

2009-03-16T21:09:00.005+07:00

Clusters of halobacterium strain NRC-1.NASA

Archaea:

Archaea are a group of microscopic organisms that were discovered in the early 1970s. Like bacteria, they are single-celled prokaryotes. Archaeans were originally thought to be bacteria until DNA analysis showed that they are different. In fact, they are so different that the discovery prompted scientists to come up with a new system for classifying life.

There is still much about archaeans that is not known. What we do know is that they can exist under some of the most extreme conditions, such as extremely hot, acidic, or alkaline environments.

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Three Domains:

Organisms are now classified into three Domains. The Domains are Eukaryota, Eubacteria, and Archaea.There are three main divisions of archaeans. These divisions are: Crenarchaeota, Euryarchaeota, and Korarchaeota.
Crenarchaeota:

Crenarchaeota consist mostly of hyperthermophiles and thermoacidophiles.Hyperthermophilic microorganisms live in extremely hot or cold environments.Thermoacidophiles are microscopic organisms that live in extremely hot and acidic environments. Their habitats have a pH between 5 and 1. You would find these organisms in hydrothermal vents and hot springs.

Crenarchaeota Species:

Examples of Crenarchaeotans include:

Sulfolobus acidocaldarius - found near volcanic environments in hot, acidic springs containing sulfur.
Pyrolobus fumarii - live in temperatures between 90 and 113 degrees Celsius.

Euryarchaeota:

Euryarchaeota organisms consist mostly of extreme halophiles and methanogens.Extreme halophilic organisms live in salty habitats. They need salty environments to survive. You would find these organisms in salt lakes or areas where sea water has evaporated.Methanogens require oxygen free (anaerobic) conditions in order to survive. They produce methane gas as a byproduct of metabolism. You would find these organisms in environments such as swamps, wetlands, the guts of animals (cow, deer, humans), and in sewage.

Euryarchaeota Species:

Examples of Euryarchaeotans include:

Halobacterium - include several species of halophilic organisms that are found in salt lakes and high saline ocean environments.
Methanococcus - Methanococcus jannaschii was the first genetically sequenced Archaean. This methanogen lives near hydrothermal vents.

Korarchaeota:

Korarchaeota organisms are thought to be very primitive life forms. Little is currently known about the major characteristics of these organisms. We do know that they are thermophilic and have been found in hot springs and obsidian pools.

Phylogeny:

Archaea are interesting organisms in that they have genes that are similar to both bacteria and eukaryotes. Phylogenetically speaking, archaea and bacteria are thought to have developed separately from a common ancestor.Eukaryotes are believed to have branched off from archaeans millions of years later. This suggests that archaeans are more closely related to eukayotes than bacteria.

Drink Green Tea For Healthy Teeth And Gums

2009-03-16T21:00:00.004+07:00

With origins dating back over 4,000 years, green tea has long been a popular beverage in Asian culture, and is increasingly gaining popularity in the United States. And while ancient Chinese and Japanese medicine believed green tea consumption could cure disease and heal wounds, recent scientific studies are beginning to establish the potential health benefits of drinking green tea, especially in weight loss, heart health, and cancer prevention.

Recent study suggests that antioxidants in green tea may help reduce periodontal disease. (Credit: iStockphoto/Ron Hohenhaus)

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A study recently published in the Journal of Periodontology, uncovered yet another benefit of green tea consumption. Researchers found that routine intake of green tea may also help promote healthy teeth and gums. The study analyzed the periodontal health of 940 men, and found that those who regularly drank green tea had superior periodontal health than subjects that consumed less green tea.

"It has been long speculated that green tea possesses a host of health benefits," said study author Dr. Yoshihiro Shimazaki of Kyushu University in Fukuoka, Japan. "And since many of us enjoy green tea on a regular basis, my colleagues and I were eager to investigate the impact of green tea consumption on periodontal health, especially considering the escalating emphasis on the connection between periodontal health and overall health."

Male participants aged 49 through 59 were examined on three indicators of periodontal disease: periodontal pocket depth (PD), clinical attachment loss (CAL) of gum tissue, and bleeding on probing (BOP) of the gum tissue. Researchers observed that for every one cup of green tea consumed per day, there was a decrease in all three indicators, therefore signifying a lower instance of periodontal disease in those subjects who regularly drank green tea.

Green tea's ability to help reduce symptoms of periodontal disease may be due to the presence of the antioxidant catechin. Previous research has demonstrated antioxidants' ability to reduce inflammation in the body, and the indicators of periodontal disease measured in this study, PD, CAL and BOP, suggest the existence of an inflammatory response to periodontal bacteria in the mouth. By interfering with the body's inflammatory response to periodontal bacteria, green tea may actually help promote periodontal health, and ward off further disease. Periodontal disease is a chronic inflammatory disease that affects the gums and bone supporting the teeth, and has been associated with the progression of other diseases such as cardiovascular disease and diabetes.

"Periodontists believe that maintaining healthy gums is absolutely critical to maintaining a healthy body," says Dr. David Cochran, DDS, PhD, President of the AAP and Chair of the Department of Periodontics at the University of Texas Health Science Center at San Antonio. "That is why it is so important to find simple ways to boost periodontal health, such as regularly drinking green tea – something already known to possess certain health-related benefits."

Bioteknologi Tanaman

2009-03-08T17:50:00.004+07:00

Dewasa ini, teknik-teknik bioteknologi tanaman telah dimanfaatkan terutama untuk memberikan karakter baru pada berbagai jenis tanaman. Penekanan pemberian karakter tersebut dapat dibagi kedalam beberapa tujuan utama yaitu peningkatan hasil, kandungan nutrisi, kelestarian lingkungan, dan nilai tambah tanaman-tanaman tertentu. Sebagai contoh, beberapa tanaman transgenik yang dikembangkan adalah:

Peningkatan kandungan nutrisi: Pisang, cabe, raspberries, stroberi, ubi jalar
Peningkatan rasa: tomat dengan pelunakan yang lebih lama, cabe, buncis, kedelai
Peningkatan kualitas: pisang, cabe, stroberi dengan tingkat kesegaran dan tekstur yang meningkat
Mengurangi alergen: polong-polongan dengan kandungan protein allergenik yang lebih rendah
Kandungan bahan berkhasiat obat: tomat dengan kandungan lycopene yang tinggi (antioksidan untuk mengurangi kanker), bawang dengan kandungan allicin untuk menurunkan kolesterol, padi dengan kandungan vitamin A dan besi untuk mengatasi anemia dan kebutaan,
Tanaman untuk produksi vaksin dan obat-obatan untuk mengobati penyakit manusia
Tanaman dengan kandungan nutrisi yang lebih baik untuk pakan ternak
dan lain-lain .

Selain itu, pemanfaatan bioteknologi tanaman seperti rekayasa genetika juga dapat memudahkan petani dalam budidaya tanaman. Misalkan dalam pengendalian gulma yaitu dengan menghasilkan tanaman yang memiliki ketahanan terhadap jenis herbisida tertentu. Sebagai contoh adalah Roundup Ready yang terdiri dari kedelai, canola dan jagung yang tahan terhadap herbisida Roundup. Di dunia saat ini telah banyak dilepas berbagai tanaman transgenik. Sebagai contoh, di Asia yaitu di China pada tahun 2006 saja, telah telah ada sekitar 30 spesies tanaman transgenik, antara lain padi, jagung, kapas, rapeseed, kentang, kedelai, poplar, tomat (delay ripening dan ketahanan virus), petunia (warna bunga), paprika (virus resistance), kapas (ketahanan hama) yang telah dilepas untuk produksi.

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Kemajuan dan penerapan bioteknologi tanaman pada tanaman pangan

Kemajuan dan penerapan bioteknologi tanaman tidak terlepas dari tanaman pangan. Untuk memenuhi kebutuhan pangan dunia termasuk kebutuhan nutrisi, kemajuan bioteknologi telah mewarnai trend produksi pangan dunia. Padi saat ini masih merupakan tanaman pangan utama dunia. Dengan demikian prioritas utama untuk teknik biologi molekuler dan transgenik saat ini masih diutamakan pada padi. Selain karena merupakan tanaman pangan utama, padi memiliki genom dengan ukuran sehingga dapat digunakan sebagai tanaman model utama. Selain padi tanaman pangan yang telah banyak mendapat sentuhan bioteknologi adalah kentang.

Golden Rice

Penerapan bioteknologi pada tanaman padi sebenarnya telah lama dilakukan namun menjadi sangat terdengar ketika muncul golden rice pada tahun 2001 yang diharapkan dapat membantu jutaan orang yang mengalami kebutaan dan kematian dikarenakan kekurangan vitamin A dan besi. Vitamin A sangat penting untuk penglihatan, respon kekebalan, perbaikan sel, pertumbuhan tulang, reproduksi, hingga penting untuk pertumbuhan embrionik dan regulasi gen-gen pendewasaan.
Luasan lahan pertanian yang semakin sempit mengakibatkan produksi perlahan harus ditingkatkan. Peningkatan ini tidak hanya berupa peningkatan bobot panen namun juga nutrisi atau nilai tambah. Oleh sebab itu dari suatu luasan yang sebelumnya hanya menghasilkan karbohidrat diharapkan dapat ditambah dengan vitamin dan mineral. Hal inilah yang mendorong para peneliti padi mengembangkan Golden Rice. Pada awalnya penelitian dilakukan untuk meningkatkan kandungan provitamin A berupa beta karoten, dan saat ini fokus penelitian tetap dilakukan.
Nama Golden Rice diberikan karena butiran yang dihasilkan berwarna kuning menyerupai emas. Rekayasa genetika merupakan metode yang digunakan untuk produksi Golden Rice. Hal ini disebabkan karena tidak ada plasma nutfah padi yang mampu untuk mensintesis karotenoid. Pendekatan transgenik dapat dilakukan karena adanya perkembangan teknologi transformasi dengan Agrobacterium dan ketersediaan informasi molekuler biosintesis karotenoid yang lengkap pada bakteri dan tanaman. Dengan adanya informasi tersebut terdapat berbagai pilihan cDNA. Produksi prototype Golden Rice menggunakan galur padi japonica (Taipe 309), teknik transformasi menggunakan agrobacterium dan beberapa gen penghasil beta karoten tanaman daffodil hingga bakteri.

Bioteknologi Tanaman Kentang

Tanaman pangan dunia yang tidak kalah penting adalah kentang. Seperti halnya padi, kentang juga menjadi komoditas utama yang menjadi obyek penerapan bioteknologi tanaman. Teknik bioteknologi saat ini telah banyak digunakan dalam produksi kentang. Baik dalam teknik penyediaan bibit, pemuliaan kentang, hingga rekayasa genetika untuk meningkatkan sifat-sifat unggul kentang. Dalam hal penyediaan bibit, saat ini teknik kultur jaringan telah banyak digunakan. Teknik kultur jaringan memungkinkan petani mendapatkan bibit dalam jumlah besar yang identik dengan induknya.
Teknik kultur jaringan juga dapat digunakan untuk menghasilkan umbi mikro (microtuber). Produksi kentang dari umbi mikro dan umbi konvensional menurut penelitian tidak berbeda nyata. Gambar 2. Skema produksi bibit kentang melalui teknik kultur jaringan. Umbi mikro kentang Selain itu teknik kultur jaringan pada tanaman kentang juga bermanfaat terutama untuk preservasi in vitro, fusi protoplas dan membantu dalam seleksi pada skema pemuliaan tanaman. Pemuliaan kentang dilakukan untuk meningkatkan sifat-sifat unggul dan menambah sifat baru sesuai kondisi yang diharapkan. Salah satu kendala utama produksi kentang adalah serangan penyakit yang tinggi sehingga pemuliaan kentang sering diarahkan untuk meningkatkan tingkat ketahanan tanaman terhadap penyakit. Jika dilakukan secara konvensional diperlukan sedikitnya 15 tahun untuk menghasilkan kultivar baru. Hal ini terjadi karena kentang komersial pada umumnya adalah tetraploid sehingga persilangan kentang akan menghasilkan keragaman yang sangat tinggi. Untuk mengatasi permasalahan ini teknik seleksi awal dengan teknik in vitro telah dilakukan serta dapat juga dilakukan melalui marker assisted breeding (MAS). Untuk meningkatkan sifat ketahanan dan sifat lain pendekatan rekayasa genetika juga telah dilakukan melalui fusi protoplast dan tranformasi genetik.
Contoh pemanfaatan teknik transformasi agrobacterium pada tanaman kentang adalah dengan menyisipkan gen dari spesies liar yaitu Rpi-blb, Rpi-blb2 yang dapat meningkatkan ketahanan terhadap Phytopthora infestans. Kentang tersebut dinamakan dengan kultivar Kathadin. Contoh lain adalah kentang dengan kandungan pati yang tinggi yang dapat menghasilkan kentang goreng dan kripik kentang dengan kualitas yang lebih baik karena menyerap lebih sedikit minyak ketika digoreng. Kentang ini dirakit dengan rekayasa genetika dengan menginsert gen dari bakteri ke kentang Russet Burbank. Gen tersebut dapat meningkatkan kandungan pati umbi yang dihasilkan dan menurunkan penyerapan minyak sewaktu digoreng. Hal ini dianggap menguntungkan karena dapat menurunkan biaya produksi sekaligus lebih sehat bagi konsumen. Uji lapangan kultivar Katahdin terhadap serangan Phytopthora infestans. Tampak Kathadin lebih tahan dibandingkan dengan kentang kontrol

Kemajuan dan penerapan bioteknologi tanaman pada tanaman hortikultura

Dengan semakin meningkatnya pendapatan dan kesadaran masyarakat akan arti penting kesehatan, kebutuhan akan produk-produk hortikultura sebagai sumber vitamin meningkat. Selain itu dari sisi kesehatan mental, kebutuhan produk hortikultura yang lain yaitu berbagai tanaman hias turut meningkat. Teknik kultur jaringan telah dimanfaatkan secara luas pada tahaman hortikultura, seperti perbanyakan klonal yang dikombinasikan dengan teknik bebas virus pada kentang, pisang, anggur, apel, pear dan berbagai jenis tanaman hias, serta penyelamatan embrio untuk mendapatkan tanaman hibrida dari hasil persilangan interspecies. Teknologi rekayasa genetika juga telah diaplikasikan pada tanaman hortiklutura. Sebagai contoh yang cukup terkenal adalah Tomat FlavrSavr. Tomat merupakan salah satu produk hortikultura utama. Seperti produk hortikultura pada umumnya, tomat memiliki shelf-life yang pendek.
Shelf-life yang pendek ini disebabkan dengan aktifnya beberapa gen seperti pectinase saat tomat mengalami kematangan. Dengan kondisi seperti ini, tomat sulit sekali untuk dipasarkan ke tempat yang jauh terlebih untuk ekspor. Biaya pengemasan sangat mahal seperti menyediakan box yang dilengkapi pendingin. Untuk mengatasi hal ini para peneliti di Amerika mencoba merekayasa kerja gen polygalacturonase (PG) yang berasosiasi dengan shelf-life tomat yaitu dengan menginsert antisense dari gen PG.
Dengan demikian shelf-life tomat menjadi lebih lama. Tomat ini dinamakan dengan FlavrSavr. Pada industri tanaman hias, teknik kultur jaringan telah digunakan secara meluas pada berbagai tanaman hias. Teknik kultur jaringan yang diaplikasikan mencakup kultur meristem, organogenesis dan somatic embryogenesis, konservasi, eliminasi patogen.
Sementara itu untuk meningkatkan keragaman dapat memanfaatkan adanya variasi somaklonal. Hal ini sangat penting dilakukan mengingat tanaman hias kebanyakan dinilai dari segi estetika dan kelangkaannya, serta bentuk-bentuk baru seperti bentuk serta warna daun dan bunga, arsitektur tanaman, serta sifat-sifat unik tanaman tertentu. Teknik lain untuk keperluan ini adalah mutasi. Pada industri tanaman hias dalam pot sering digunakan Zat Pengatur Tumbuh untuk mengatur pola pertumbuhan dan perkembangan tanaman. Contohnya adalah penggunaan retardan untuk membuat pertumbuhan menjadi pendek dan meroset.
Pemanfaatan rekayasa genetika pada tanaman hias berpotensi untuk menambahkan sifat-sifat baru yang unik. Contoh tanaman yang telah direkayasa antara lain krisan dan mawar dengan tingkat ketahanan dan vase life yang lebih tinggi.

Kemajuan dan penerapan bioteknologi tanaman pada tanaman perkebunan

Bioteknologi juga diterapkan pada beberapa tanaman perkebunan seperti tebu, tembakau, kelapa sawit dan lain-lain. Hingga saat ini kapas merpuakan komoditas yang paling banyak mendapat sentuhan bioteknologi. Di Amerika, hingga saat ini tanaman transgenik yang paling banyak dilepas adalah kapas.
Kapas transgenik yang terkenal adalah kapas Bt (Bacillus thuringiensis). Dengan introduksi gen Bt ke tanaman kapas, tanaman kapas menjadi tahan terhadap hama yang disebabkan tanaman dapat memproduksi protein Bt-toxin. Bt pertama ditemukan tahun 1911 dan terdaftar sebagai biopestisida di Amerika Serikat tahun 1961.
Salah satu dari sekian banyak kerugian merokok adalah gangguan kesehatan karena kadar nikotin yang tinggi. Pendekatan bioteknologi dilakukan untuk mengatasi permasalahan ini yaitu dengan merakit tanaman tembakau yang bebas kandungan nikotin. Dengan cara ini perokok dapat terkurangi resiko gangguan kesehatannya.
Pada tahun 2001 jenis tembakau ini diklaim dapat mengurangi resiko serangan kanker akibat merokok. Selain bebas nikotin, sentuhan bioteknologi lain juga dilakukan untuk tanaman tembakau misalnya dengan meningkatkan aroma menggunakan gen aroma dari tanaman lain. Salah satu yang telah berhasil adalah menggunakan monoterpene synthase dari lemon.

Defense Mechanisms

2009-03-08T16:45:00.004+07:00

Defense mechanisms are very important to all animal life. Animals must eat to survive. With predators always on the lookout for a meal, prey must constantly avoid being eaten. Any adaptation the prey uses adds to the chances of survival for the species. Some adaptations are defense mechanisms which can give the prey an advantage against enemies.

Leopard camouflaged in the grass.U.S. Fish and Wildlife Service/Gary Stolz

Defense Mechanisms

There are several ways animals avoid falling prey to a predator. One way is very direct and comes naturally. Imagine you are a rabbit and you have just noticed a fox preparing to attack. What would be your initial response? Right, you'd run. Animals can use speed as a very effective means of escaping predators. Remember, you can't eat what you can't catch!

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Another defense mechanism is camouflage or protective coloration. One form, cryptic coloration, allows the animal to blend in with its environment to avoid being detected. It is important to note that predators also use cryptic coloration to avoid detection by unsuspecting prey.

Trickery can also be used as a formidable defense. False features that appear to be enormous eyes or appendages can serve to dissuade potential predators. Mimicking an animal that is dangerous to a predator is another effective means of avoiding being eaten.

Physical or chemical combat are other types of defense mechanisms. Some animals' physical features make them a very undesirable meal. Porcupines, for example, make it very difficult for predators with their extremely sharp quills. Similarly, predators would have a tough time trying to get to a turtle through its protective shell.

Chemical features can be just as effective. We all know the hazards of scaring a skunk! The chemicals released result in a not so pleasant aroma that an attacker will never forget. The dart frog also uses chemicals (poisons secreted from its skin) to deter attackers. Any animals that eat these small frogs are likely to get very sick or die.

Predator-Prey Relationship

To sum it all up, the predator-prey relationship is important to maintaining balance among different animal species. Adaptations that are beneficial to prey, such as chemical and physical defenses, ensure that the species will survive. At the same time, predators must undergo certain adaptive changes to make finding and capturing prey less difficult.

Without predators, certain species of prey would drive other species to extinction through competition. Without prey, there would be no predators. Thus, this relationship is vital to the existence of life as we know it.

Trust Your Heart: Emotions May Be More Reliable When Making Choices

2009-03-08T15:52:00.003+07:00

When choosing a flavor of ice cream, an item of clothing, or even a home, you might be better off letting your emotions guide you, according to a new study in the Journal of Consumer Research.

"Our current research supports theories in evolutionary psychology that propose that our emotions can be conceived as a set of 'programs' that have evolved over time to help us solve important recurrent problems with speed and accuracy, whether it is to fall in love or to escape from a predator," write authors Leonard Lee (Columbia Business School), On Amir (University of California, San Diego), and Dan Ariely (Duke University).

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"We investigated the following question: To what extent does relying on one's feelings versus deliberative thinking affect the consistency of one's preferences?" write the authors. To get at the question, the authors designed experiments where participants studied and chose among 8-10 products, sometimes relying upon their emotional reactions and sometimes calling upon cognitive skills. Their conclusion: "Emotional processing leads to greater preference consistency than cognitive processing."

The researchers made some additional discoveries about eliciting consistent choices from participants. The study participants tended to make more consistent choices when products were represented by pictures instead of names; when pictures were in color (rather than black and white); when participants were encouraged to trust their feelings when making their choices; when the participants had greater cognitive constraints (i.e., when they were asked to memorize a ten-digit number as opposed to a two-digit one); and when the products tended to be more exciting (a pen with a built-in FM radio receiver) rather than functional (an LED book light).

It seems the old adage "trust your heart" is true for consumers. "If one buys a house and relies on very cognitive attributes such as resale value, one may not be as happy actually purchasing it," write the authors. "Indeed, our results suggest that the heart can very well serve as a more reliable compass to greater long-term happiness than pure reason."

How We Make Decisions

2009-03-08T15:16:00.003+07:00

The frontal lobe is a region of the cerebral cortex of the brain that is responsible for decision-making, problem solving, and planning. Researchers have now discovered the specific areas of the frontal lobe that control abstract and concrete decision-making. The front portion of the frontal lobe handles abstract decisions and the back portion handles concrete decisions.

Photo credit: Gray's Anatomy

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For example, if you had an idea that you wanted to bake some cookies, the decision process would start at the front portion of the frontal lobe. As you begin to determine the actions involved in making the cookies, a more concrete decision, the back portion of the frontal lobe would be involved. Understanding exactly how this part of the brain works could be very important to finding new treatments for strokes and other brain disorders.

Bacterial Reproduction

2009-03-08T15:08:00.005+07:00

Bacteria are prokaryotic organisms that reproduce asexually. Bacterial reproduction most commonly occurs by a kind of cell division called binary fission. Binary fission results in the formation of two bacterial cells that are genetically identical.

Bacterial Cell Structure

Bacterial cells typically contain the following structures: a cell wall, cell membrane, cytoplasm, ribosomes, plasmids, flagella, and a nucleiod region.

Cell Wall - Outer covering of the cell that protects the bacterial cell and gives it shape.
Cytoplasm - A gel-like substance composed mainly of water that also contains enzymes, salts, cell components, and various organic molecules.

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Cell Membrane or Plasma Membrane - Surrounds the cell's cytoplasm and regulates the flow of substances in and out of the cell.
Flagella - Long, whip-like protrusion that aids in cellular locomotion.
Ribosomes - Cell structures responsible for protein production.
Plasmids - Gene carrying, circular DNA structures that are not involved in reproduction.
Nucleiod Region - Area of the cytoplasm that contains the single bacterial DNA molecule.

Bacterial Reproduction:

AsexualMost bacteria reproduce by binary fission. During binary fission, the single DNA molecule replicates and both copies attach to the cell membrane.The cell membrane begins to grow between the two DNA molecules. Once the bacterium just about doubles its original size, the cell membrane begins to pinch inward.A cell wall then forms between the two DNA molecules dividing the original cell into two identical daughter cells.

Bacterial Recombination:

Binary fission is an effective way for bacteria to reproduce, however it does produce problems. Since the cells produced through this type of reproduction are identical, they are all susceptible to the same types of antibiotics. In order to incorporate some genetic variation, bacteria use a process called recombination. Bacterial recombination can be accomplished through conjugation, transformation, or transduction.

Conjugation

Some bacteria are capable of transferring pieces of their genes to other bacteria that they come in contact with. During conjugation, one bacterium connects itself to another through a protein tube structure called a pilus. Genes are transferred from one bacterium to the other through this tube.

Transformation

Some bacteria are capable of taking up DNA from their environment. These DNA remnants most commonly come from dead bacterial cells. During transformation, the bacterium binds the DNA and transports it across the bacterial cell membrane. The new DNA is then incorporated into the bacterial cell's DNA.

Transduction

Transduction is a type of recombination that involves the exchanging of bacterial DNA through bacteriophages. Bacteriophages are viruses that infect bacteria. There are two types of transduction: generalized and specialized transduction.Once a bacteriophage attaches to a bacterium, it inserts its genome into the bacterium. The viral genome, enzymes, and viral components are then replicated and assembled within the host bacterium. The newly formed bacteriophages then lyse or split open the bacterium, releasing the replicated viruses.During the assembling process however, some of the host's bacterial DNA may become encased in the viral capsid instead of the viral genome. When this bacteriophage infects another bacterium, it injects the DNA fragment from the previous bacterium. This DNA fragment then becomes inserted into the DNA of the new bacterium. This type of transduction is called generalized transduction.In specialized transduction, fragments of the host bacterium's DNA become incorporated into the viral genomes of the new bacteriophages. The DNA fragments can then be transfered to any new bacteria that these bacteriophages infect.
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DNA (DEOKSIRIBO NUCLEIC ACID)

2009-02-06T00:59:00.003+07:00

Asam deoksiribonukleat atau DNA merupakan persenyawaan kimia yang paling penting pada makhluk hidup, yang membawa keterangan genetik dari sel khususnya atau dari makhluk hidup dalam keseluruhannya dari satu generasi ke generasi berikutnya. Semua makhluk hidup kecuali beberapa virus memiliki DNA. Di dalam sel , bagian terbesar dari DNA terdapat di dalam nukleus, terutama dalam kromosom. Molekul DNA juga ditemukan dalam mitokondria, plastida dan sentriol. Molekul DNA dari sel – sel dengan nukleus sejati mempunyai bentuk sebagai benang lurus dan tak bercabang, sedangkan pada sel – sel tanduk nukleus sejati, mitokondria dan plastida molekul DNA berbentuk lingkaran ( Suryo, 1988 ).

DNA tersusun atas basa purin dan pirimidin, fosfor dan gula deoksiribosa yang membentuk polipepetida. Setiap DNA tersusun dari 2 polipeptida yang saling berpillin. Urutan basa dan polinukleotida setiap species DNA identik dan mentranskripsi diri membentuk DNA, RNA dibentuk oleh DNA dan memiliki struktur hampir sama dengan DNA. DNA adalah singkatan dari deoksiribonucleocid acid atau asam deoksiribonukleat. DNA terdiri dari atas 2 utas benang polinukleotida yang saling berpilin (double helix = ganda berpilin). Seutas polinukleotida tersusun atas rangkaian nukleotida. Setiap nukleotida tersusun atas :

Gugusan gula deoksiribosa (gula pentosa yang kehilangan satu asam oksigen)
Gugusan asam fosfat yang terikat pada atom C nomor 5 dari gula
gugusan basa nitrogen yang tereikat pada atom 1 dari gula

Basa nitrogen penyusun DNA terdiri dari basa purin, yaitu adenine (A) dan guanine (G), serta basa pirimidin yaitu sitosin (S), dan timin (T). ikatan gula-basa disebut nukleosida, yaitu :

Ikatan A-gula disebut adenosin deoksiribonukleosida (deoksiadenosin)
Ikatan G-gula disebut guanosin, deoksiribonukleosida (deoksiguanosin)
Ikatan S-gula disebut sitidin deoksiribonukleosida (deoksisitidin)
Ikatan T-gula disebut timidin deoksinukleosida (deoksitimidin)
(Syamsuri,2000)

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DNA umumnya terdapat didalam kromosom dan kromosom terdapat didalam inti sel. Berartti kromosom itu membelah, demikian pula molekul DNA. Proses kelipatan molekul DNA dinamakan replikasi DNA (Suryo,1988).

Bagian terbesar dari DNA terdapat didalam kromosom. Sedikit DNA tedapat juga didalam organel seperti mitokondria dari tumbuhan dan hewan, dan dalam kloroplas dari ganggang dan tumbuhan tingkat tinggi. DNA didalam mitokondria dan kloroplast tidak ada hubunganya dengan protein histon dan bentuk molekulnya bulat seperti yang terdapat pada bakteri dan ganggang biru. Asam nukleat tersusun atas nukleotida yang bila terurai terdiri dari gula, phosfat dan basa yang mengandung nitrogen. Karena banyaknya nukleotida yang menyusun molekul DNA, maka molekul DNA merupakan suatu polinukleotida.

Gula, molekul gula yang menyusun molekul DNA adalah sebuah pentosa yaitu deoksitil.
Phospat, molekul phosfatnnya berupa PO4
Basa, basa nitrogen menyusun molekul DNA dibedakan atas :

kelompok pirimidin, kelompok ini dibedakan atas basa :

sitosin (S)
Timin (T)

kelompok purin, kelompok ini dibedakan atas basa :
Adenin (A)
Guanin (G)

Dalam tahun 1953 watson crick mengemukakan bahwa kebanyakan molekul DNA mempunyai bentuk sebagai pita yang spiral dobel yang saling berpilin (‘double helix’)
Pada isolasi tumbuhan kita menggunakan EDTA, SDS yang berfungsi:
EDTA : melisiskan membran sel
SDS : melisiskan dinding sel
(Sumarjito, 1996)

Pada isolasi DNA bakteri digunakan EDTA (efien Diamin Tetra Adsetat) yang berfungsi : melisiskan selubung sel dengan menghilangkan ion Mg dan menghambat Enzim seluler yang dapat merusak DNA. SDS digunakan yang berfungsi sebagai pelisis membran dengan senyawa lipid. Nacl yang dipakai berfungsi untuk Na+ yang akan berikatan dengan gugus asam nukleat. Yang terakhir kita tambahkan lisosim yang berfungsi mendigesti senyawa polimer yang menyebabkan kelakuan dinding Sel (Brown, 1991).

Perbedaan DNA dan RNA antara lain :

Bagian pentosa RNA adalah ribosa, sedangkan pentosa DNA adalah deoksiribosa.
Bentuk molekul DNA adalah helix ganda. Bentuk molekul RNA bukan helix ganda, tetapi berupa rantai tunggal yang terlipat sehingga menyerupai rantai ganda.
RNA mengandung basa adenine, guanine dan sitosin seperti DNA, tetapi tidak mengandung timin. Sebagai gantinya RNA sebagai urasil.dengan demikian bagian basa pirimidin RNA berbeda dengan basa pirimidin DNA.
Jumlah guanin dalam molekul RNA tidak perlu sama dengan sitosin, demikian pula jumlah adenin tidak harus sama dengan urasil.
Pentosa RNA yaitu ribosa dan DNA yaitu deoksiribosa mempuyai perbedaan yaitu bahwa deoksiribosa tidak memiliki satu atom oksigen pada karbon nomor-nomornya yang membuat namanya disebut reaksi.
Pada umumnya molekul RNA lebih pendek dari pada DNA (Anna,1994).

Manfaat teknik isolasi antara lain :

Dapat dilakukan cloning terhadap tumbuhan atau hewan yang mempunyai sifat unggul
Meningkatkan produksi dan mengembangkan kualitas produk dari berbagai usaha pertanian, kehutanan, usaha perikanan, dan peternakan.
Membuka peluang perubahan make-up genetik suatu organisme melalui pertukaran genetik.
Untuk memanipulasi gen-gen genetiknya
Untuk menyimpan informasi genetik
Usaha untuk mengatur struktur polipeptida yang terbentuk agar sesuai dengan yang dikehendaki
Untuk mengetahui DNA dapat melaksanakan fungsinya yaitu menyimpan dan menggandakan informasi
Untuk menerangkan satu sifat utama dari informasi genetik yaitu kemampuan untuk duplikasi diri sendiri (Brown,1991).

Spektrofotometer

2009-02-06T00:40:00.004+07:00

Metode spektrofotometri adalah metode analisis berdasarkan pengukuran absorbsi cahaya oleh senyawa yang mengalami transisi elektron saat terkena sinar dengan panjang gelombang tertentu. Spektrofotometri merupakan salah satu cabang analisis instrumental yang mempelajari interaksi antara atom atau molekul dengan radiasi elektromagnetik. Salah satu penggunaan spektrofotometri adalah dapat menentukan kandungan kimiawi dari suatu bahan. Sumber cahaya ultraviolet dan cahaya tampak apabila dilewatkan pada sampel akan memberikan informasi nilai absorbansi dengan variasi panjang gelombang.

Alat yang digunakan untuk mengukur daya serapan dinamakan spektrofotometer. Alat ini mengeluarkan cahaya pada jarak gelombang yang dipilih terlebih dahulu, lalu dipancarkan melalui sampel (selalu dilarutkan didalan satu pelarut dan diletakkan didalam kuvet), dan kecepatan cahaya yang ditransmisikan/diserap sampel tersebut diukur.

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Terdapat dua jenis spektrofotometer, yaitu spektrofotometer beralur tunggal (single beam) dan spektrofotometer beralur ganda (double beam). Secara umum, sesebuah spektrofotometer terdiri dari komponen utama yaitu sumber cahaya, monokromator (termasuk beberapa penapis, celah (slits) dan cermin), kotak sampel, alat pengesan, dan sebuah meter atau perekam.

Sumber Cahaya

Bergantung kepada panjang cahaya, maka sesebuah spektrofotometer itu dapat mengukur daya serap pada kawasan ultraviolet, dimana lampu hidrogen atau deutrium tekanan tinggi digunakan; atau dikawasan tampak yang menggunakan lampu tungsten-halogen. Yang pertama itu mengeluarkan cahaya pada panjang gelombang 200 - 340 nm, manakala yang kedua itu pada panjang gelombang 340 - 800 nm. Alat yang mempunyai kedua-dua jenis lampu mempunyai kelenturan yang lebih baik dan boleh digunakan untuk kajian kebanyakan molekul yang mempunyai kepentingan biologi.

Monokromator

Kedua lampu diatas mengeluarkan cahayan pada keseluruhan panjang gelombang. Sehingga, sebuah spektrofotometer perlulah mempunyai sebuah sistem optik yang dapat memilih cahaya monokromatik (cahaya yang mempunyai panjang gelombang tertentu). Alat modern menggunakan prisma, atau selalu menggunakan diffraction grating untuk menghasilkan cahaya pada panjang gelombang tertentu. Perlu juga diingatkan disini bahwa cahaya yang keluar dari monokromator tidaklah terdiri dari hanya satu panjang gelombang, tetapi sebaliknya diperkaya dengan panjang gelombang tersebut. Ini bermakna, kebanyakan cahaya adalah dari panjang gelombang yang tunggal, tetapi yang pada panjang gelombang lebih pendek atau lebih panjang dari itu juga ada.

Sebelum cahaya monokromatik itu sampai kepada sampel, ia akan melalui satu siri celah (slits), kanta, penapis dan cermin. Sistem optik ini memekatkan cahaya, meningkatkan kelenturan spektra dan menumpukan ia kearah sampel. Cahaya yang melintasi dari monokromator ke sampel akan menemui satu pintu atau celah. Lebarnya celah ini menentukan kecepatan cahaya yang mengenai sampel dan kelenturan spektra cahaya tersebut. Dengan menyempitkan celah, kelenturan spektra akan meningkat, tetapi banyaknya cahaya yang mengenai sampel akan berkurang. Dalam hal ini kecekapan atau kepekaan alat pengesan akan menjadi faktor penting. Sehingga lebarnya celah perlu ditentukan untuk mendapatkan keseimbangan diantara kelenturan spektra dengan kepekaan pengesan.

Kotak Sampel

Cahaya monokromatik yang telah diproses itu kemudiannya diarahkan pada kotak sampel yang boleh menempatkan beberapa jenis pemegang sel. Sampel selalu dalam bentuk larutan. Sampel diisikan kedalam kuvet yang diperbuat dari kaca, kuarza, atau lain-lain bahan lutsinar. Kuvet kaca agak murah, tetapi disebabkan ia menyerap cahaya UV, ia hanya boleh digunakan untuk panjang gelombang melebihi 340 nm. Kuvet kuarza atau silika boleh digunakan disepanjang kawasan cahaya UV dan tampak (~200 - 800 nm). Kuvet sekarang ini banyak terdapat dipasaran dibuat dari polimetakrilat (280 - 800nm) dan polistiren (350 - 800nm).

Spektrofotometer yang kurang mahal terdiri dari alat beralur-tunggal (single-beam) yang membolehkan satu kuvet dimasukkan kedalam pemegang sel pada satu masa. Alat yang lebih canggih adalah beralur-dua (double-beam) yang boleh memuatkan dua kuvet, yang satu mengandungi sampek terlarut didalam suatu pelarut (kedudukan sampel) dan yang satu lagi mengandung pelarut tulin (kedudukan rujukan/control).

Pengesan

Kecepatan cahaya yang melintasi sampel kajian bergantung kepada banyaknya cahaya yang diserap oleh sampel tersebut. Kecepatan diukur oleh pengesan peka-cahaya, selalu merupakan sebuah tabung fotogandaan (photomultiplier tube, PMT). PMT mengesan jumlah tenaga cahaya yang kecil, menguatkannya melalui lata elektron (cascade of electrons) yang dipercepat oleh dinod (dynode), dan menukarkannya menjadi isyarat elektrik yang boleh dimasukkan kedalam sebuah meter atau perekam.

Meter dan Perakam

Alat dapat memberikan bacaan daya serapan dan /atau transmitans secara terus dalam bentuk analog atau digital. Alat ini sesuai untuk pengukuran pada panjang gelombang tunggal. Sekiranga pengimbasan (scanning) daya serapan lwn. panjang gelombang (A lwn. l) diperlukan, maka sebuah perakam (recorder) perlulah dipasang.

Pada masa ini kebanyakan spektrofotometer telah dilengkapi dengan komputer berserta perisian yang canggih bagi memudahkan pengaturan acara, parameter pengukuran, terutama untuk tujuan kajian kinetika.

Protein

2009-02-06T00:30:00.003+07:00

Protein (akar kata proteus dari bahasa Yunani yang berarti "yang paling utama") adalah senyawa organik kompleks berbobot molekul tinggi yang merupakan polimer dari monomer-monomer asam amino yang dihubungkan satu sama lain dengan ikatan peptida. Molekul protein mengandung karbon, hidrogen, oksigen, nitrogen dan kadang kala sulfur serta fosfor. Protein berperan penting dalam struktur dan fungsi semua sel makhluk hidup dan virus. Kebanyakan protein merupakan enzim atau subunit enzim. Jenis protein lain berperan dalam fungsi struktural atau mekanis, seperti misalnya protein yang membentuk batang dan sendi sitoskeleton. Protein terlibat dalam sistem kekebalan (imun) sebagai antibodi, sistem kendali dalam bentuk hormon, sebagai komponen penyimpanan (dalam biji) dan juga dalam transportasi hara. Sebagai salah satu sumber gizi, protein berperan sebagai sumber asam amino bagi organisme yang tidak mampu membentuk asam amino tersebut (heterotrof). Protein merupakan salah satu dari biomolekul raksasa, selain polisakarida, lipid, dan polinukleotida, yang merupakan penyusun utama makhluk hidup. Selain itu, protein merupakan salah satu molekul yang paling banyak diteliti dalam biokimia. Protein ditemukan oleh Jöns Jakob Berzelius pada tahun 1838. Biosintesis protein alami sama dengan ekspresi genetik. Kode genetik yang dibawa DNA ditranskripsi menjadi RNA, yang berperan sebagai cetakan bagi translasi yang dilakukan ribosoma. Sampai tahap ini, protein masih "mentah", hanya tersusun dari asam amino protein ogenik. Melalui mekanisme pascatranslasi, terbentuklah protein yang memiliki fungsi penuh secara biologi ( "http://id.wikipedia.org/wiki/Protein" ).

Protein membentuk sebagian besar struktur di dalam sel termasuk sebagai enzim dan pigment respiratori. Protein dibentuk dari percantuman unit asas yang dikenal sebagai asam amino. Protein dapat dibagi menjadi dua jenis yaitu protein fibrous yang banyak bergantung kepada struktur sekunder dimana bentuk protein ini boleh diulang. Bentuk kedua ialah protein globular (enzim dan antibodi) yang banyak bergantung kepada interaksi struktur tertiar. Terdapat 20 jenis asam amino yang digunakan untuk membentuk rantaian polipeptida (protein) Fungsi, bentuk, ukuran dan jenis protein akan ditentukan oleh jenis, bilangan dan taburan asam amino yang terdapat di dalam struktur tersebut. Percantuman beberapa asam amino disebut tindak balas kondensasi yang ditandai dengan terjadinya pembentukan ikatan peptida dan pembentukan molekul air. Percantuman ini akan menghasilkan rantaian peptida yang lebih dikenal sebagai polipeptida yang memiliki dua ujung rantaian yang berbeda sifatnya. Di ujung yang mempunyai kumpulan amino dikenali sebagai terminal N (amino) dan ujung yang mempunyai kumpulan karboksil dikenali sebagai terminal N. Penyambungan rantai asam amino ini memerlukan tenaga yang tinggi dan ketepatan urutan asam amino dalam rantaian ini pula bergantung kepada koordinasi di antara mRNA dan tRNA. Protein yang dibentuk dengan hanya menggunakan satu polipeptida dinamakan sebagai protein monomerik dan yang dibentuk oleh beberapa polipeptida contohnya hemoglobin dikenal sebagai protein multimerik ( "http://ms.wikipedia.org/wiki/Protein" ).

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Sumber protein :

Yang diketahui dan dikomsumsi banyak orang selama ini adalah sumber protein hewani yaitu daging, ikan, ayam, telur dan susu. Protein yang berasal dari hewan ini memiliki semua asam amino esensial, hingga disebut protein lengkap. Sumber protein lainnya adalah padi-padian, biji-bijian,dan kacang-kacangan. Namun sumber protein jenis ini yang disebut protein nabati atau protein tidak lengkap, senantiasa mempunyai kekurangan satu atau lebih asam amino esensial. Sebab itu cara mengkonsumsinya harus dikombinasikan agar saling melengkapi. Perbedaan kelengkapan itu mengakibatkan ia hanya mampu memelihara jaringan tubuh, sedangkan protein hewani mampu memelihara jaringan tubuh dan menjamin pertumbuhannya. Agar asam aminonya layak disebut sebagai protein lengkap, protein nabati bisa dikomsumsi dengan sesamanya. Misalnya padi-padian (kaya dengan methionin) dengan biji-bijian (kaya dengan lisin dan triptofan). Dalam hal ini terdapat pada nasi dengan tahu atau perkedel jagung. Namun toh protein hewani tetap penting bagi tubuh dan tak dapat digantikan seratus persen oleh protein nabati. Jika dianggap terlalu mahal, cukup mengkonsumsi sehari sekali, misalnya ikan dan telur. Kelebihan protein tidak baik, karena dapat mengganggu metabolisme protein yang berada di hati. Ginjal pun akan terganggu tugasnya, karena bertugas membuang hasil metabolisme protein yang tidak terpakai. Kekurangan protein akan membuat Anda mudah merasa lelah, tekanan darah turun, dan daya tahan terhadap infeksi menurun. Pada anak-anak, selain mudah terserang penyakit kwasiorkor, juga pertumbuhan dan tingkat kecerdasannya akan terganggu( Ahreus,1970 ).

Protein merupakan molekulmakro yang mengandung nitrogen dengan bobot molekul berkisar antara 5.000 hingga 1.000.000 lebih. Protein merupakan suatu unsure selular utama, meliputi kira – kira 50% berat kering dari sel. Fungsi [rotein berkisar dari katalik, dalam hal enzim, hingga toksik dalam hal racun bakteri dan ular (Page,1985).

Protein merupakan polimer yang terdiri dari satuan asam amino yang terikat secara kovalen. Hubungan kovalen dasarnya adalah suatu ikatan amida, sederhana yang terbentuk oleh kondensasi gugus amino dari suatu asam amino dengan gugus asam karboksilat dari yang lain. Ikatan amida ini diber nama khusus : ikatan peptide (Page,1985).

Struktur susunan molekul protein :

Protein Fibriler / skleroprotein : protein yang berbentukl serabut, tidak larut dalam pelarut “encer , baik garam, asam, basa ataupun alkohol. Susunan molekulnya terdiri dari Rantai molekul yang panjang, sejajar Rantai utama , tidak membentuk kristal dan bila rantai ditarik memanjang dapat kembali seperti keadaan semula. Contoh : kolagen pada tulang rawan
Protein globular : protein yang berbentuk bola ( sferoprotein ), banyak terdapat dibahan pangan ( susu, telur, dan daging ). Protein ini larut dalam larutan garam dan asam encer, juga lebih mudah berubah dibawah pengaruh suhu, konsentrasi garam, pelarut asam dan basa.

Sifat-sifat protein yang penting :

Ionisasi : apabila larut dalam air akan membentuk ion ( + dan - )
Denaturasi : perubahan konformasi serta posisi protein sehingga aktivitasnya berkurang atau kemampuannya menunjang aktivitas organ tertentu dalam tubuh hilang → tubuh mengalami keracunan.
Viskositas : tahanan yang timbul adanya gesekan antara molekul didalam zat cair yang mengalir.
Kristalisasi : proses yang sering dilakukan dengan jalan penambahan garam amonium sulfat atau NaCl pada larutan dengan pengaturan pH pada titik isolistriknya.
Sistim Koloid : sistem yang heterogen terdiri atas dua fase yaitu partikel kecil yang terdispersi dari medium atau pelarutnya ( Poedjiadi ,1994).

Fungsi protein :

Sebagai katalis reaksi enzimatis, yaitu reaksi-raksi kimia yang terjadi dalam sisitim biologi. Contoh : pepsin, isomerase, β – galaktosidase
Sebagai sarana transportasi, sejumlah protein spesifik berperan sebagai proses transport ion dan molekul-molekul kecil. Contoh : hemoglobin
Sebagai koordinasi dalam pergerakan, yaitu sebagai pembantu sel dalam berkontraksi. Contoh : aktin dan miosin, tubulin dan protofilamen
Sebagai pendukung mekanik / kerangka : sebagai pertahanan kekuatan kulit dan tulang. Contoh : kolagen, keratin, fibroin.
Sebagai sistim kekebalan atau perlindungan yaitu pertahanan sel dalam serangan benda asing, contoh : Imuniglobin atau antibodi
Penghasil dan penerus rangsangan sistim saraf . Contoh : rhodopsin
Sebagai kontrol pertumbuhan dan diferensiasi. Contoh : protein hormon
(Page,1985)

Protein konjugasi : protein yang mengandung senyawa lain non protein.
Protein sederhana : protein yang tidak mengandung senyawa non protein.

Mutu protein :

Mutu tinggi yaitu protein yang mampu menyediakan asam amino esensial dalam suatu perbandingan yang menyamai kebutuhan manusia
Mutu rendah yaitu protein yang kekurangan satu atau lebih asam amino esensial
( winarmo,1992 )

PROTEIN

2009-02-06T00:25:00.001+07:00

New Insights Into A Leading Poultry Disease And Its Risks To Human Health

2009-02-01T16:56:00.003+07:00

When bacteria contain the DNA plasmid pAPEC-1, they produce a powerful toxin that kills other bacteria. The top spot and bottom spot both contain pAPEC-1, creating a lysis zone where no other bacteria can grow within the area. The spot in the middle of the plate contains no pAPEC-1, allowing bacteria to grow and surround the spot. (Credit: The Biodesign Institute, Arizona State University)

Biodesign Institute at Arizona State University associate research scientist Melha Mellata, a member of professor Roy Curtiss' team, is leading a USDA funded project to develop a vaccine against a leading poultry disease called avian pathogenic E. coli (APEC).

APEC is part of a large, diverse group of microbes called extra-intestinal pathogenic E. coli (ExPEC). They cause a number of complex brain, lung and urinary tract diseases in human, animals, and birds. There is also considerable concern in the scientific community that APEC strains are becoming an emergent food pathogen. The poultry products are a suspected source of a suite of ExPEC infections, including those causing human disease.

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The U.S. is the leading poultry industry in the world at an annual value of more than $50 billion, and E. coli infections are a big threat, causing millions in losses for the industry. According to the USDA, the two most common types of poultry infections are from the bacteria E. coli and Salmonella.

Antibiotics have long been the first line of defense to prevent APEC, but have lost their potency, as the bacteria have grown increasingly resistant to treatment. How these microbes cause disease is poorly understood. Mellata and colleagues in the institute's Center for Infectious Diseases and Vaccinology, led by Roy Curtiss, have been hard at work to understand the molecular tricks these bacteria use to evade a host's immune system.

Now, in a paper published in the journal PLoS One, Mellata's team has analyzed the DNA sequence of a critical genetic element of APEC that contains several genes responsible for triggering its harmful effects. In addition, by comparing these genes to a collection of human ExPEC strains, they have shown that human and avian E. coli can carry the same disease-causing elements, which may increase the human risk of infection from poultry.

"The best way to prevent this infection is to develop a vaccine," said Mellata. "Our idea is to ultimately protect both poultry and humans by finding a group of genes common against all extra-intestinal E. coli." With this new knowledge of APEC, the group hopes to pursue the development of several new vaccine candidates.

Their latest research results help narrow the genetic search for the cause of APEC infections. Previously, she had shown that a circular, 100,000 base pair long DNA segment, called a plasmid, was responsible for causing disease. Without the plasmid, APEC becomes docile, losing its disease-causing strength.

Plasmids, in an evolutionary game of high-stakes poker, are swapped freely among bacteria in order to gain the upper hand---or in the case of pathogenic E. coli, to outwit its competitors by colonizing animals and causing disease. Over time, each plasmid becomes a patchwork quilt of DNA information, containing DNA parts exchanged among billions of bacterial encounters.

Her team took advantage of the latest advances in DNA sequencing to analyze the complete 103,275 DNA chemical letters that make up the plasmid, called pAPEC-1.

The multidisciplinary effort involved expertise from several ASU researchers, including Jeff Touchman, a School of Life Science Professor specializing in bioinformatics. It also utilized MEGA4, a software program developed by the Biodesign colleague Sudhir Kumar's lab that is used by more than 50,000 scientists worldwide to trace back and compare the evolutionary history of any DNA segment.

"DNA sequencing and bioinformatics analysis are very powerful tools that contribute in fully understanding the virulence of APEC, and provide new avenues of research," said Mellata.

The ABCs of APEC

In all, the group found 31 genes important for bacterial virulence, with more than one quarter (26 percent) conserved in other species. Almost half of the proteins made by these genes (46 percent) had no similarity to proteins that have been deposited into a public gene database.

Among the disease causing parts of the plasmid pAPEC-1 are a series of genes that make up proteins responsible for trafficking nutrients in and out of bacteria, called ABC transporters, which may be used to develop vaccine candidates. In addition to nutrition, many other ABC transporters help the bacteria elude toxins a host uses to fight off the infection.

Most of the genes that cause APEC's harmful effects are responsible for iron acquisition. Iron is a key element necessary for bacterial health, and the pAPEC-1 portion uses redundant systems to acquire and then hold onto iron at all costs. Mellata speculates that only bacteria that have strategies to acquire iron sequestered by the host can survive in specific niches and consequently cause blood-borne infections, and the bacteria may need these multiple iron acquisition systems to adapt to environment changes.

To look for the presence of these APEC genes in humans, Mellata worked with a collection of one hundred human clinical samples of ExPEC strains isolated from urinary and non-urinary tract infections by Dr. James R. Johnson of the VA Medical Center at the University of Minnesota. Her team found that human and avian E. coli can carry the same disease-causing plasmids, indicating there is a risk that APEC can be transmitted, or its genetic material transmitted from poultry to humans.

These common genes could be considered as potential candidates for a vaccine.

During the course of their research, the team also discovered a finding that could have broad implications for understanding the strategies that bacteria use to trade genetic material. Plasmids are able to acquire more virulence genes or turn benign bacteria into harmful pathogens by their ability to transfer from their own host bacteria into new recipient bacteria. By analyzing the DNA sequence of plasmid pAPEC-1 and testing the mechanism of transfer of pAPEC-1, Mellata and her team have discovered a new way that plasmids use to move from one bacteria to another. This system consists of hijacking the transfer machinery of other helper plasmids present in the same bacteria.

To create a vaccine for the USDA project, the APEC genes would be shuttled into the Salmonella bacteria in the hopes of triggering a protective immune response against both Salmonella and E. coli. This double duty vaccine could protect people not only against the increased risk of APEC causing human illness, but also against the most common food-borne illness, Salmonella.

Mellata feels that now that her team has identified many of the APEC gene targets they will use, it represents the end of the beginning of their research journey to develop a vaccine that will provide improved poultry health, an economic benefit to producers and enhanced food safety.

"The problem right now is understanding the virulence of APEC as well as Salmonella to find a way that will protect against all types of the bacteria," said Mellata.

New Disease, Comparable To BSE, Created In Laboratory Mice

2009-02-01T16:47:00.004+07:00

Folding of the prion proteins of moose (a), mouse (b), and the moose/mouse hybrid prion protein expressed in the transgenic RL mice (c). The loop mentioned in the text is highlighted in colour. (Credit: Image courtesy of ETH Zurich)

A team composed of researchers from across the globe and including scientists from ETH Zurich and the University of Zurich has created a new disease, comparable to BSE, in laboratory mice. The team showed that exchanging just two amino acids in the structure of the prion protein is enough to trigger a disease.

The starting point of the project was the discovery by the team led by ETH Zurich Nobel prize-winner Kurt Wüthrich of a structural peculiarity in the prion protein of moose and deer.

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Kurt Wüthrich says that it all began with the resolving of the structure of the prion protein in mammals: "A small region of this protein, the region between the 166th and 175th amino acids, forms a loop close to the surface of the protein." The ETH Zurich Professor of Biophysics was awarded the Nobel Prize for Chemistry in 2002 for his fundamental discoveries in the field of protein structural analysis. "Our analyses using nuclear magnetic resonance spectroscopy (NMR) showed that this loop has an irregular shape in the prion proteins of humans, cattle, sheep and other mammals, but, astonishingly, it is precisely defined in moose and deer."

Prion disease in deer and moose not under control

The fact that up to 20 percent of all the deer and moose living wild in the USA and Canada suffer from Chronic Wasting Disease (CWD), an infectious prion disease comparable to mad cow disease (BSE), is not well known in Europe. In this disease, as in BSE and in Creutzfeldt-Jakob Disease in humans, misfolded versions of one of the body’s own proteins lead to deposits and finally to the death of nerve cells. It is assumed that heredity also plays a part in the transmission of the disease. The shape of the prion protein characteristic of moose could now give new impetus to efforts to explain CWD and other prion diseases.

Up to 100 percent of the mice with the new gene become ill

Using the conspicuous moose prion protein for further studies of prion diseases seemed the obvious thing to do. First of all, Kurt Wüthrich’s team showed that the type of amino acids at positions 170 and 174 has a decisive influence on whether the suspect loop in the prion protein adopts a rigid or a flexible shape. The researchers now took advantage of this to test the possible effects of the rigid loop in animal experiments.

The results of this study were published in the scientific journal PNAS on 6 January 2009.

In Adriano Aguzzi’s laboratory at the University Hospital Zurich, Christina Sigurdson created a prion gene in mice with two so-called point mutations which, in the living animal, manufactures the mutant form of the mouse prion protein being studied by Wüthrich’s team and containing the rigid loop of the moose prion protein instead of a flexible loop. The researchers were astonished by the fact that, over time, all the transgenic mice carrying this artificial prion protein developed a new, transmissible and fatal prion disease. The deposits which are typical of this disease and which successively damage the organ and finally destroy it accumulated in their brains, with the mice displaying the corresponding symptoms of neurological defects.

Insights still unimaginable at the start of the research

Christina Sigurdson told Science Daily that, "We also discovered that the transfer of brain tissue from mice with the altered protein into normal mice also triggers the prion disease." She says that the fact that an infectious disease can be generated by two mutations in the prion gene deliberately introduced into the mouse prion protein is of particular scientific interest. According to Sigurdson, "This new mouse model of the disease may help us to understand how the incorrectly folded protein causes nerve cell degeneration – and it helps in the search for effective treatments for prion diseases."

Kurt Wüthrich adds, "For us, it’s a marvellous story." He says it emphasizes once again the outstanding importance of basic research undertaken without any motive for short-term profit.

According to Wüthrich, "We determined the NMR structure of a prion protein, that of the mouse, for the first time twelve years ago. We introduced the NMR method to resolve protein structures 25 years ago, with the Swiss physicist Felix Bloch and the American Edward Purcell having carried out the first NMR experiments more than 60 years ago. At none of these milestones could the researchers have dreamt that subtle NMR observations on a protein molecule would lead us directly to a new form of a hitherto incompletely characterised, infectious and fatal disease."

BSE: Sounding the all clear would be out of place

Using meat and bone meal as animal feed played a central role in the BSE crisis in Switzerland. A ban on feeding meat and bone meal to ruminants had already been imposed after the first cases of "bovine spongiform encephalopathy" (BSE; "mad cow disease") in 1990. This ban was extended to cover all livestock in 2001. However, no further cases of mad cow disease have occurred for two years. For a few producers of slaughterhouse by-products (which includes meat and bone meal) this is sufficient justification to demand at least a partial relaxation of the ban on feeding meat and bone meal to animals. However, as the Swiss Federal Veterinary Office insists, sounding the all clear would be out of place. To keep BSE under control, it will probably be necessary to maintain the meat and bone meal ban for years to come.

How Ebola Virus Avoids The Immune System

2009-02-01T16:41:00.003+07:00

Scanning electron microscope image of Ebola virions (spaghetti-like filaments) on the surface of a tetherin-expressing cell (center). (Credit: Paul Bates, PhD, University of Pennsylvania School of Medicine)

Researchers at the University of Pennsylvania School of Medicine have likely found one reason why the Ebola virus is such a powerful, deadly, and effective virus. Using a cell culture model for Ebola virus infection, they have discovered that the virus disables a cellular protein called tetherin that normally can block the spread of virus from cell to cell.

“Tetherin represents a new class of cellular factors that possess a very different means of inhibiting viral replication,” says study author Paul Bates, PhD, Associate Professor of Microbiology at the University of Pennsylvania School of Medicine. “Tetherin is the first example of a protein that affects the virus replication cycle after the virus is fully made and prevents the virus from being able to go off and infect the next cell.” These findings appear online this week in the Proceedings of the National Academy of Sciences.

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When a cell is infected with a virus like Ebola, which is deadly to 90 percent of people infected, the cell is pirated by the virus and turned into a production factory that makes massive quantities on new virions. These virions are then released from that cell to infect other cells and promote the spreading infection.

Tetherin is one of the immune system's responses to a viral infection. If working properly, tetherin stops the infected cell from releasing the newly made virus, thus shutting down spread to other cells. However, this study shows that the Ebola virus has developed a way to disable tetherin, thus blocking the body's response and allowing the virus to spread.

“This information gives us a new way to study how tetherin works,” says Bates. "Binding of a protein produced by Ebola to tetherin apparently inactivates this cellular factor. Understanding how the Ebola protein blocks the activity of tetherin may facilitate the design of therapeutics to inhibit this interaction, allowing the cell's natural defense systems to slow down viral replication and give the animal or person a chance to mount an effective antiviral response and recover.”

Previous research had found that tetherin plays a role in the immune system's response to HIV-1, a retrovirus, and that tetherin is also disabled by HIV. These new studies reveal that human cells also use this defense against other types of viruses, such as Ebola, that are not closely related to HIV-1. “Because we see such broad classes of viruses that are affected by tetherin, it's possible that all enveloped viruses are targets of this antiviral system,” says Bates. “If so, then understanding how tetherin works and how viruses escape from the effect of tetherin will be very important.”

Rachel L. Kaletsky, Joseph R. Francica and Caroline Agrawal-Gamse of the University of Pennsylvania School of Medicine are co-authors of this study. This work was funded by the Public Health Service Grants and the Philip Morris External Research Foundation.

How A Brain Chemical Changes Locusts From Harmless Grasshoppers To Swarming Pests

2009-02-01T16:29:00.004+07:00

Scientists have uncovered the underlying biological reason why locusts form migrating swarms. Their findings, reported in today's edition of Science, could be used in the future to prevent the plagues which devastate crops (notably in developing countries), affecting the livelihood of one in ten people across the globe.

This is a portrait shot of an adult solitarious phase locust. (Credit: Image copyright Tom Fayle)

A collaboration between a team of scientists in Cambridge and Oxford, UK and Sydney, Australia has identified an increase in the chemical serotonin in specific parts of the insects' nervous system as initiating the key changes in behaviour that cause them to swarm.

Desert Locusts are one of the most devastating insect pests, affecting 20% of the world's land surface. Vast swarms containing billions of locusts stretching over many square kilometres periodically devastated parts of the USA at the time of the settlement of the West, and continue to inflict severe economic hardship on parts of Africa and China. In November 2008 swarms six kilometres (3.7 miles) long plagued Australia.

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Locusts belong to the grasshopper family but unlike their harmless relatives they have the unusual ability to live in either a solitary or a gregarious state, with the genetic instructions for both packaged within a single genome.

Locusts originate from barren regions that see only occasional transient rainfalls. While unforgiving conditions prevail, locusts eke out a living as solitary individuals with a strong aversion to mingling with other locusts. When the rains come, the amount and quality of vegetation expands and the locusts can breed in large numbers.

In deserts, however, the rains are not sustained and food soon becomes more and more sparse. Thus large numbers of locusts are funnelled into dwindling patches of remaining vegetation where they are forced into close contact with each other. This crowding triggers a dramatic and rapid change in the locusts' behaviour: they become very mobile and they actively seek the company of other locusts. This new behaviour keeps the crowd together while the insects acquire distinctly different colours and large muscles that equip them for prolonged flights in swarms.

As Steve Rogers from Cambridge University emphasises: "The gregarious phase is a strategy born of desperation and driven by hunger, and swarming is a response to find pastures new".

Solitary and gregarious locusts are so different in looks and behaviour that they were thought to be separate species until 1921. But the realisation that crowding triggers swarming posed a new problem: how can the mere presence of other locusts have such a dramatic effect? The new research, which was funded by the Biotechnology and Biological Sciences Research Council, the Natural Sciences and Engineering Research Council of Canada and the Royal Society, solved this 90 year old question by identifying an increase in the chemical serotonin in specific parts of the locust's nervous system as launching the fundamental changes in behaviour that lead to the gregarious phase.

In the laboratory, solitary locusts can be turned into gregarious ones in just two hours simply by tickling their hind legs to simulate the jostling that locusts experience in a crowd. This period coincides with a threefold but transient (less than 24 hours) increase in the amount of serotonin in the thoracic region of the nervous system. Experiments were then designed to show that serotonin is indeed the causal link between the experience of being in a crowd and the change in behaviour.

First, locusts were injected with specific chemicals that block the action of serotonin on its receptors: when these locusts were exposed to the same gregarizing stimuli, they did not become gregarious. Second, chemicals that block the production of serotonin had the same effect. Third, when injected with serotonin or chemicals that mimic serotonin, locusts turned gregarious even in the absence of other locusts. Finally, chemicals that increased the natural synthesis of serotonin enhanced gregarization when locusts were exposed to the tickling stimuli. This indicates that it is the synthesis of serotonin that is driven by these specific stimuli and in turn changes the behaviour.

Dr Michael Anstey, an author of the paper from the University of Oxford, said: "Up until now, whilst we knew the stimuli that cause locusts' amazing 'Jekyll and Hyde'-style transformation, nobody had been able to identify the changes in the nervous system that turn antisocial locusts into monstrous swarms. The question of how locusts transform their behaviour in this way has puzzled scientists for almost 90 years, now we finally have the evidence to provide an answer."

Dr Swidbert Ott, from Cambridge University, one of the co-authors of the article, said: "Serotonin profoundly influences how we humans behave and interact, so to find that the same chemical in the brain is what causes a normally shy antisocial insect to gang up in huge groups is amazing."

Professor Malcolm Burrows, also from Cambridge University: "We hope that this greater understanding of the mechanisms causing such a big change in behaviour will help in the control of this pest, and more broadly help in understanding the widespread changes in behavioural traits of animals."

Professor Steve Simpson of Oxford and Sydney Universities said: "No other biological system is understood from nerve cells to populations in such detail or to such effect: locusts offer an exemplar of the how to span molecules to ecosystems – one of the greatest challenges in modern science."

Locust Facts:

Locusts are grasshoppers that swarm. Of the 8,000 known species of grasshoppers throughout the world only about 12 are swarm-forming locusts.
An adult Desert Locust is 2-2.5 inches long and weighs 0.05-0.07 oz.
A Desert Locust adult can consume roughly its own weight in fresh food per day.
They are prodigious fliers, covering 60 miles in 5-8 hours.
The two phases are so different in appearance and behavior that they were thought to be separate species until 1921.

Chemists Shed Light On Health Benefits Of Garlic

2009-02-01T16:15:00.003+07:00

A Queen's-led team has discovered the reason why garlic is so good for us.

Garlic. Chemists have discovered the reason why garlic is so good for us. (Credit: iStockphoto/Jorge Farres Sanchez)

Researchers have widely believed that the organic compound, allicin – which gives garlic its aroma and flavour – acts as the world's most powerful antioxidant. But until now it hasn't been clear how allicin works, or how it stacks up compared to more common antioxidants such as Vitamin E and coenzyme Q10, which stop the damaging effects of radicals.

"We didn't understand how garlic could contain such an efficient antioxidant, since it didn't have a substantial amount of the types of compounds usually responsible for high antioxidant activity in plants, such as the flavanoids found in green tea or grapes," says Chemistry professor Derek Pratt, who led the study. "If allicin was indeed responsible for this activity in garlic, we wanted to find out how it worked."

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The research team questioned the ability of allicin to trap damaging radicals so effectively, and considered the possibility that a decomposition product of allicin may instead be responsible. Through experiments with synthetically-produced allicin, they found that an acid produced when the compound decomposes rapidly reacts with radicals.

Their findings are published in the January 2009 issue of the international chemistry journal Angewandte Chemie.

"Basically the allicin compound has to decompose in order to generate a potent antioxidant," explains Dr. Pratt, who is Canada Research Chair in Free Radical Chemistry. "The reaction between the sulfenic acid and radicals is as fast as it can get, limited only by the time it takes for the two molecules to come into contact. No one has ever seen compounds, natural or synthetic, react this quickly as antioxidants."

The researcher is confident that a link exists between the reactivity of the sulfenic acid and the medicinal benefits of garlic. "While garlic has been used as a herbal medicine for centuries and there are many garlic supplements on the market, until now there has been no convincing explanation as to why garlic is beneficial," says Dr. Pratt. "I think we have taken the first step in uncovering a fundamental chemical mechanism which may explain garlic's medicinal benefits."

Along with onions, leeks and shallots, garlic is a species in the family Alliaceae. All of these other plants contain a compound that is very similar to allicin, but they do not have the same medicinal properties. Dr. Pratt and his colleagues believe that this is due to a slower rate of decomposition of the allicin analogs in the onions, leaks and shallots, which leads to a lower level of sulfenic acid available to react as antioxidants with radicals.

The study was funded by the Natural Sciences and Engineering Research Council of Canada (NSERC) and the Ontario Ministry of Innovation. Other members of the research team are Queen's Chemistry post-doctoral researcher Vipraja Vaidya and Keith Ingold, from the National Research Council of Canada.

How Safe is the Air Indoors?

2009-01-27T08:13:00.004+07:00

What is in the air in your home, where you work, or in public buildings? There may be bioaerosols — airborne biological contaminants. Aerobiological health hazards affect everyone on a daily basis and include allergens, mold spores, bacteria, and viruses that cause infectious diseases. How can these hazards be controlled indoors?

Aspergillus fumigatus is a fungus whose spores are common inhalation pollutants that pose a health hazard. Photo: Centers for Disease Control and Prevention.

Aerobiological engineering is a field of study that combines elements of engineering and microbiology that focus on reducing the risk of airborne disease by controlling the aerobiology of our indoor environments. It offers some solutions to the hazards of bioaerosols:

Existing technologies can collectively control these bioaerosols if we retrofit old buildings or specifically design new buildings to control airborne microbes.
By re-engineering our buildings on city-wide scales, the population can be broadly protected and potentially immunized against epidemics.
Developing standards for indoor environments and educating the public are critical steps to transforming our disease-prone society.

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Aerobiological health threats

Contagious diseases are the most dangerous and costly threats posed to building occupants today, including influenza, SARS, tuberculosis, pneumonia, and meningitis. Emerging pathogens such as avian flu and the resurgence of old diseases like plague, scarlet fever, whooping cough, and measles highlight the increasing vulnerability of populations to epidemic disease.

Evolving drug resistance, especially among hospital-acquired infections, complicates treatment of microbial agents, and physicians see their once abundant arsenal of antibiotics shrinking faster than new miracle drugs can be developed. Vaccines, once thought to be magic bullets, seem insufficient by themselves to combat airborne pathogens that can be transmitted freely in our unprotected buildings and have the potential to spread globally and cause pandemics.

Relatively mundane health threats like mold, dander, and allergens burden homes, schools, and offices, while the threat of bioterrorism leaves our buildings vulnerable to manmade epidemics that could decimate cities. Such formidable challenges can be placed into a manageable context if we recognize that protecting our buildings against the most common microbes simultaneously protects against the most dangerous threats as well.

Air- and surface-cleaning technologies

The technologies needed to create healthy buildings already exist, but they are not implemented widely enough to interdict epidemics. Optimized combinations of filtration and ultraviolet germicidal irradiation (UVGI) can be used to remove airborne microbes with high efficiencies. Combining and optimizing these technologies is the most cost effective means of disinfecting indoor air.

Filtration removes airborne particles including mold spores, many bacteria, and allergens.
UVGI eliminates many harmful bacteria and viruses.

Existing buildings can be retrofitted with air disinfection systems, but the most economic long-term solution is to construct new buildings that maintain aerobiological cleanliness by design. Air circulation is often poor in older buildings, and there are limits to what retrofitted air-cleaning systems can do for them. New buildings can be built in which the airflow is more evenly distributed and in which effectiveness of air cleaning can be maximized.2 A variety of other technologies, including photocatalytic oxidation (PCO), ozone, pulsed light, and antimicrobial materials, are also available options for air and surface biocontamination problems.

Criteria for rating healthy buildings

Modern air disinfection systems can achieve high levels of air cleaning, but limited budgets often require us to ask exactly how much air cleaning is needed to protect health. This question ultimately hinges on how buildings rate:

aerobiologically — the indoor levels of airborne microbes
epidemiologically — the infection risk of the building

Airborne levels of microbes

Indoor air contains a great variety of bioaerosols, most of which are relatively harmless to healthy humans. The concentration of airborne microbes in indoor environments, treated collectively without regard to species, provides a reasonable indication of overall aerobiological air quality. Levels of bacteria and fungi vary by season, with lows in winter, and increase with occupancy, as people are the primary source of contagious pathogens. Airborne levels are measured in terms of colony-forming units (cfu) of bacteria or fungi per cubic meter. Some hospital operating rooms are designed to maintain levels as low as 10 cfu/m3, although this level often proves difficult to achieve. Levels in homes and offices need not be this low, making solutions there less cost-prohibitive.

Infection risk

The infection risk (IR) of any building might be estimated by collecting data on infection rates and symptoms or through methods of risk analysis.3 Another approach is to estimate the risk using computer models of building airflow to calculate daily doses of inhaled contaminants. Airborne levels can be easily, if not always accurately, assessed with air samplers. The IR to an occupant in a particular building can be evaluated from epidemiological data. The IR can also be inversely viewed as the percentage of occupants protected from infection, a parameter called the building protection factor (BPF).

The BPF is the complement of the IR— a low IR implies a high BPF— and it can be used to rate and compare buildings under a common design basis. The BPF is primarily a function of the volume, airflow, outside air fraction, and removal efficiency of the air disinfection system. Being an intrinsic property of the building, it applies generically to all microbial species.4
Buildings differ according to their operating parameters. A completely unprotected building may have a BPF of 0% to 1%, whereas a building that maximizes protection of occupants may have a BPF of up to 99%. BPF can be considerably improved in existing buildings through the addition of air cleaning or other ventilation system improvements.

At least four general categories of buildings have been suggested:

Problem buildings foster aerobiological problems or act as amplifiers. Their airborne levels may exceed 10,000 cfu/m3. IR can approach 99% or more and BPF 1% or less.
Normal buildings have average airborne levels, about 500 to 5000 cfu/m3. Typically, IR is about 50% to 75% and BPF about 25% to 50%.
Healthy buildings promote good air quality and health or are above average. Airborne levels are 100 to 1000 cfu/m3. Typically, IR is less than 50% and BPF 50% or higher.
Immune buildings are designed to actively prevent airborne disease transmission. Airborne levels are as low as 10 cfu/m3. IR is less than 10% and BPF 90% or higher.

Disease-free buildings

Buildings concentrate allergens due mainly to the protective effects of shade, warmth, substrate materials, and moisture. For the same basic reasons, they act as vectors (carriers) for contagious airborne diseases. Humans have been building enclosed habitats for perhaps half a million years, and in this course of time airborne pathogens evolved the ability to survive indoors just long enough to transmit to new hosts. They have adapted to our enclosed habitats so completely that they cannot survive outdoors. This evolutionary process accelerated when man began husbanding animals, from which almost all human pathogens seem to have jumped species. The evolutionary process continues today as emerging pathogens adapt to indoor transmission, and the number of new disease species has increased exponentially over time, in concert with the size and density of the human population.

By designing our habitats strictly for human comfort, we have unwittingly fostered the adaptation and proliferation of dangerous pathogens. It is only by re-engineering our buildings to eliminate, rather than foster, airborne disease transmission that we can reverse this evolutionary trend. By immunizing enough buildings against disease, it is theoretically possible to develop herd immunity in a community or city. The percentage of buildings that would need to be immunized to block an airborne epidemic is similar to the percentage of a population vaccinated to achieve herd immunity, and depending on the contagiousness of the species, this may be as low as 30%.

In addition to air disinfection and improved delivery of clean air, there are other factors that can aid in the development of healthy buildings. Rugs, carpets, furniture, draperies, and the like can absorb mold spores and regenerate new ones if they become wet. Material selectivity can be one beneficial approach, and other alternatives include the use of self-disinfecting materials, pressurization, and isolation of zones within buildings, including the provision of buffer zones between the inside and outdoor air and the creation of clean inner zones safe from airborne health threats.

Regulating healthy buildings

Implementing changes to building construction on a vast enough scale to control epidemics would require governmental programs. As yet there are virtually no existing standards or laws regarding the aerobiological healthiness of buildings. It is curious to note that airborne chemical contaminants are regulated in many states while airborne pathogens, which cause far more fatalities, are not.

The key to regulation is the development of aerobiological air quality standards. Several organizations and government agencies are involved in the control of disease epidemics, including the Centers for Disease Control and Prevention (CDC), National Institute of Occupational Safety and Health (NIOSH), and World Health Organization (WHO), but none of them is responsible for regulating the living environments in which these diseases are transmitted.

The task of improving air quality in homes, schools, and offices has mostly fallen to independent professional societies. The American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) has had a long and active interest in air quality, healthy buildings, and green buildings, and it is currently developing new programs in these directions. The International Ultraviolet Association (IUVA) is currently drafting a set of guidelines to assist in the design, development, implementation, and testing of UVGI and other air- and surface-cleaning systems.

Aerobiologically green buildings

Green building design is a field geared toward constructing sustainable indoor environments without damaging the environment. Green is clean, as they say, and healthy. The concept of human health is intrinsic to both this field and to aerobiological engineering, and common ground can be found through the exploration of aerobiologically green buildings that implement sustainable technologies for air and surface cleaning.

An example of where these fields overlap is the selection of building materials and furnishings that are both ecofriendly and less likely to contribute to health problems. Solar exposure can provide benefits, since sunlight can destroy mold spores, bacteria, and viruses. Radiant floor heating is an energy-efficient alternative to covering floors with carpets, as are dedicated outside air systems that efficiently control humidity. Although forced air is generally considered a necessity for air cleaning, buildings can also be naturally ventilated using wind energy.

Hygienic protocols

Engineering may go a long way toward the control of airborne diseases, but it may not be sufficient to eradicate them if other transmission routes remain unattenuated. Direct contact may be the dominant route of infection for many pathogens considered airborne, and engineering alone cannot control unhygienic human behavior. People must be educated to protect themselves, and for this purpose we need to define a set of protocols for human hygiene. These might include hand-washing procedures, quarantining contagious individuals, and other commonsense practices that can be taught in elementary school.

Many office workers today are so motivated they come to work during the contagious phase of their infection, placing other workers at risk. Economic losses from lost work and diminished productivity can be staggering. Working at home and in-office quarantine are two options for employers.

What can the individual do?

The most important thing individuals can do to protect themselves against airborne disease is to become educated about sources and transmission routes of airborne pathogens. Proximity to a contagious individual for as little as one hour can cause a secondary infection. Families with children must be especially careful since the youngest children tend to bring home diseases from schools, which are then transmitted to the rest of the family. Frequent hand washing and isolating sick children in bedrooms is one approach to protecting the rest of the family.

In regard to allergens, the home environment can be improved in some simple ways even without air cleaning. Old rugs and carpets that absorb spores can be cleaned, removed, or replaced with alternatives such as linoleum or other growth-resistant materials, and the amount of sunlight entering a home can be increased in various ways.

Misconceptions about disease must be dispelled. For example:

The myth that colds and flus come from outdoor air has persisted since the ancient world and is kept alive every time children are told to “bundle up or you’ll catch a cold.”
Another popular misconception is that some disease is beneficial, or that disease makes you stronger, but such fuzzy ideas are not grounded in science. Acquired immunity from pathogenic disease is always specific, never providing any general protection, and is often temporary at best. It is true our bodies are filled with friendly bacteria that were once parasites, but if selection for antibiotic resistance is allowed to continue, millions could become victims of unnecessary plagues.

Conclusion

Humanity stepped beyond the hardships of living in the elements by building habitats, but modern human culture and technology have created new contingencies and unexpected problems. It is well within human capabilities to redesign buildings and cities to be resistant to epidemic airborne disease, which is arguably the most serious threat we face today. Human health is a global concern, and achieving it begins with education, redesign of living environments, and large-scale implementation of aerobiological standards. The ultimate goal of these efforts must be disease eradication; all other remedies are merely triage and half-measures that fail to deal directly with the environments that are the root of the airborne disease problem today.

Newly Discovered Protein Kills Anthrax Bacteria By Exploding Their Cell Walls

2009-01-27T01:45:00.003+07:00

Not all biological weapons are created equal. They are separated into categories A through C, category A biological agents being the scariest: They are easy to spread, kill effectively and call for special actions by the pubic health system. One of these worrisome organisms is anthrax, which has already received its fair share of media attention. But work in Vince Fischetti’s laboratory at Rockefeller University suggests that a newly discovered protein could be used to fight anthrax infections and even decontaminate areas in which anthrax spores have been released.

“Anthrax is the most efficient biowarfare agent. Its spores are stable and easy to produce, and once someone inhales them, there is only a 48-hour window when antibiotics can be used,” says Fischetti. “We’ve found a new protein that could both potentially expand that treatment window and be used as a large-scale decontaminant of anthrax spores.” Because anthrax spores are resistant to most of the chemicals that emergency workers rely on to sterilize contaminated areas, a solution based on the protein would be a powerful tool for cleaning up after an anthrax attack.

A bacillus bacterium, a close relative of anthrax, begins to explode after being treated with PlyPH. The PlyPH protein, discovered by Rockefeller scientists, offers several advantages over existing anthrax treatments. (Image courtesy of Rockefeller University)

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All bacteria, anthrax included, have natural predators called bacteriophage. Just as viruses infect people, bacteriophage infect bacteria, reproduce, and then kill their host cell by bursting out to find their next target. The bacteriophage use special proteins, called lysins, to bore holes in the bacteria, causing them to literally explode. Fischetti and colleagues identified one of these lysins, called PlyG, in 2004, and showed that it could be used to help treat animals and humans infected by anthrax. Now, they have identified a second lysin, which they have named PlyPH, with special properties that make it not only a good therapeutic agent, but also useful for large-scale decontamination of areas like buildings and military equipment.

The new protein has several advantages. Most lysins, including PlyG, are only active in a very specific pH range of six to seven, so that they work very effectively in our bloodstream, but may not useful in many environmental conditions. “PlyPH works in an extremely wide pH range, from as low as four to as high as eight,” says Fischetti. “I don’t know of any other lytic enzyme that has such a broad range of activity.”

In addition, PlyPH, like PlyG, is highly specific in terms of the types of bacteria it affects. When Fischetti and colleagues added PlyPH to different bacterial species, only the anthrax bacteria were killed. This is a great benefit over antibiotics, which kill many different kinds of bacteria, including many helpful species. Because it is so specific, the chances of anthrax becoming resistant to PlyPH, as it is to many of the antibiotics currently available to treat it, are extremely low.

“We have never seen bacterial resistance to a lysin,” says Fischetti. “PlyPH and PlyG are probably the most specific lysins we, or anyone, has ever identified — they only kill anthrax and its very close relatives. This feature, and the wide pH range offered by PlyPH, is why we think it could be used as an environmental decontaminant.”

Fischetti hopes to combine PlyPH with a non-toxic aqueous substance developed by a group in California that will germinate any anthrax spores it comes in contact with. As the spores germinate, the PlyPH protein will kill them, usually in a matter of minutes. The combined solution could be used in buildings, on transportation equipment, on clothing, even on skin, providing a safe, easy way to fight the spread of anthrax in the event of a mass release.

Cilia and Flagella

2009-01-27T01:18:00.005+07:00

Cilia and flagella are motile cellular appendages found in most microorganisms and animals, but not in higher plants. In multicellular organisms, cilia function to move a cell or group of cells or to help transport fluid or materials past them. The respiratory tract in humans is lined with cilia that keep inhaled dust, smog, and potentially harmful microorganisms from entering the lungs. Among other tasks, cilia also generate water currents to carry food and oxygen past the gills of clams and transport food through the digestive systems of snails. Flagella are found primarily on gametes, but create the water currents necessary for respiration and circulation in sponges and coelenterates as well. For single-celled eukaryotes, cilia and flagella are essential for the locomotion of individual organisms. Protozoans belonging to the phylum Ciliophora are covered with cilia, while flagella are a characteristic of the protozoan group Mastigophora.

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In eukaryotic cells, cilia and flagella contain the motor protein dynein and microtubules, which are composed of linear polymers of globular proteins called tubulin. The core of each of the structures is termed the axoneme and contains two central microtubules that are surrounded by an outer ring of nine doublet microtubules. One full microtubule and one partial microtubule, the latter of which shares a tubule wall with the other microtubule, comprise each doublet microtubule (see Figure 1). Dynein molecules are located around the circumference of the axoneme at regular intervals along its length where they bridge the gaps between adjacent microtubule doublets.

A plasma membrane surrounds the entire axoneme complex, which is attached to the cell at a structure termed the basal body (also known as a kinetosome). Basal bodies maintain the basic outer ring structure of the axoneme, but each of the nine sets of circumferential filaments is composed of three microtubules, rather than a doublet of microtubules. Thus, the basal body is structurally identical to the centrioles that are found in the centrosome located near the nucleus of the cell. In some organisms, such as the unicellular Chlamydomonas, basal bodies are locationally and functionally altered into centrioles and their flagella resorbed before cell division.

Eukaryotic cilia and flagella are generally differentiated based on size and number: cilia are usually shorter and occur together in much greater numbers than flagella, which are often solitary. The structures also exhibit somewhat different types of motion, though in both cases movement is generated by the activation of dynein and the resultant bending of the axoneme. The movement of cilia is often described as whip-like, or compared to the breast stroke in swimming. Adjacent cilia move almost simultaneously (but not quite), so that in groups of cilia, wave-like patterns of motion occur. Flagella, however, exhibit a smooth, independent undulatory type of movement in eukaryotes. Prokaryotic flagella, which have a completely different structure built from the protein flagellin, move in a rotating fashion powered by the basal motor.

Defects in the cilia and flagella of human cells are associated with some notable medical problems. For example, a hereditary condition known as Kartagener's syndrome is caused by problems with the dynein arms that extend between the microtubules present in the axoneme, and is characterized by recurrent respiratory infections related to the inability of cilia in the respiratory tract to clear away bacteria or other materials. The disease also results in male sterility due to the inability of sperm cells to propel themselves via flagella. Damage to respiratory cilia may also be acquired rather than inherited and is most commonly linked to smoking cigarettes. Bronchitis, for instance, is often triggered by a build-up of mucus and tar in the lungs that cannot be properly removed due to smoking-related impairment of cilia.

Peroxisomes

2009-01-27T01:05:00.008+07:00

Microbodies are a diverse group of organelles that are found in the cytoplasm of almost all cells, roughly spherical, and bound by a single membrane. There are several types of microbodies, including lysosomes, but peroxisomes are the most common. All eukaryotes are comprised of one or more cells that contain peroxisomes. The organelles were first discovered by the Belgian scientist Christian de Duve, who also discovered lysosomes.

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Peroxisomes contain a variety of enzymes, which primarily function together to rid the cell of toxic substances, and in particular, hydrogen peroxide (a common byproduct of cellular metabolism). These organelles contain enzymes that convert the hydrogen peroxide to water, rendering the potentially toxic substance safe for release back into the cell. Some types of peroxisomes, such as those in liver cells, detoxify alcohol and other harmful compounds by transferring hydrogen from the poisons to molecules of oxygen (a process termed oxidation). Others are more important for their ability to initiate the production of phospholipids, which are typically used in the formation of membranes.

In order to carry out their activities, peroxisomes use significant amounts of oxygen. This characteristic of the organelles would have been extremely important millions of years ago, before cells contained mitochondria, when the Earth's atmosphere first began to amass large amounts of oxygen due to the actions of photosynthetic bacteria. Peroxisomes would have been primarily responsible at that time for detoxifying cells by decreasing their levels of oxygen, which was then poisonous to most forms of life. The organelles would have provided the cellular benefit of carrying out a number of advantageous reactions as well. Later, when mitochondria eventually evolved, peroxisomes became less important (in some ways) to the cell since mitochondria also utilize oxygen to carry out many of the same reactions, but with the additional benefit of generating energy in the form of adenosine triphosphate (ATP) at the same time.

Peroxisomes are similar in appearance to lysosomes, another type of microbody, but the two have very different origins. Lysosomes are generally formed in the Golgi complex, whereas peroxisomes self-replicate. Unlike self-replicating mitochondria, however, peroxisomes do not have their own internal DNA molecules. Consequently, the organelles must import the proteins they need to make copies of themselves from the surrounding cytosol. The importation process of peroxisomes is not yet well understood, but it appears to be heavily dependent upon peroxisomal targeting signals composed of specific amino acid sequences. These signals are thought to interact with receptor proteins present in the cytosol and docking proteins present in the peroxisomal membrane. As more and more proteins are imported into lumen of a peroxisome or are inserted into its membrane, the organelle gets larger and eventually reaches a point where fission takes place, resulting in two daughter peroxisomes. Illustrated in Figure 2 is a fluorescence digital image of an African water mongoose skin fibroblast cell stained with fluorescent probes targeting the nucleus (red), actin cytoskeletal network (blue), and peroxisomes (green).

Since the early 1980s, a number of metabolic disorders have been discovered to be caused by molecular defects in peroxisomes. Two major categories have been described so far. The first category consists of disorders of peroxisome biogenesis in which the organelle fails to develop normally, causing defects in numerous peroxisomal proteins. The second category involves defects of single peroxisomal enzymes. Studies indicate that approximately one in every 20,000 people has some type of a peroxisomal disorder. The most serious of these disorders is Zellweger syndrome, which is characterized by an absence or reduced number of peroxisomes in the cells. Present in patients at birth (congenital), Zellweger syndrome has no cure or effective treatment and usually causes death within the first year of life.

Lysosomes

2009-01-27T01:02:00.004+07:00

The main function of these microscopic organelles is to serve as digestion compartments for cellular materials that have exceeded their lifetime or are otherwise no longer useful. In this regard, the lysosomes recycle the cell's organic material in a process known as autophagy. Lysosomes break down cellular waste products, fats, carbohydrates, proteins, and other macromolecules into simple compounds, which are then transferred back into the cytoplasm as new cell-building materials. To accomplish the tasks associated with digestion, the lysosomes utilize about 40 different types of hydrolytic enzymes, all of which are manufactured in the endoplasmic reticulum and modified in the Golgi apparatus. Lysosomes are often budded from the membrane of the Golgi apparatus, but in some cases they develop gradually from late endosomes, which are vesicles that carry materials brought into the cell by a process known as endocytosis.

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Like other microbodies, lysosomes are spherical organelles contained by a single layer membrane, though their size and shape varies to some extent. This membrane protects the rest of the cell from the harsh digestive enzymes contained in the lysosomes, which would otherwise cause significant damage. The cell is further safeguarded from exposure to the biochemical catalysts present in lysosomes by their dependency on an acidic environment. With an average pH of about 4.8, the lysosomal matrix is favorable for enzymatic activity, but the neutral environment of the cytosol renders most of the digestive enzymes inoperative, so even if a lysosome is ruptured, the cell as a whole may remain uninjured. The acidity of the lysosome is maintained with the help of hydrogen ion pumps, and the organelle avoids self-digestion by glucosylation of inner membrane proteins to prevent their degradation.

The discovery of lysosomes involved the use of a centrifuge to separate the various components of cells. In the mid-twentieth century, the Belgian scientist Christian Ren� de Duve was investigating carbohydrate metabolism of liver cells and observed that that the cells released an enzyme called acid phosphatase in larger amounts when they received proportionally greater damage in the centrifuge. To explain this phenomenon, de Duve suggested that the digestive enzyme was encased in some sort of membrane-bound organelle within the cell, which he dubbed the lysosome. After estimating the probable size of the lysosome, he was able to identify the organelle in images produced with an electron microscope.

Lysosomes are found in all animal cells, but are most numerous in disease-fighting cells, such as white blood cells. This is because white blood cells must digest more material than most other types of cells in their quest to battle bacteria, viruses, and other foreign intruders. Several human diseases are caused by lysosome enzyme disorders that interfere with cellular digestion. Tay-Sachs disease, for example, is caused by a genetic defect that prevents the formation of an essential enzyme that breaks down complex lipids called gangliosides. An accumulation of these lipids damages the nervous system, causes mental retardation, and death in early childhood. Also, arthritis inflammation and pain are related to the escape of lysosome enzymes.

The Cytoskeleton

2009-01-27T00:51:00.004+07:00

What is the cytoskeleton?

The cytoskeleton is a network of fibers throughout the cell's cytoplasm that helps the cell maintain its shape and gives support to the cell.

A variety of cellular organelles are held in place by the cytoskeleton.

Fibroblast cells. Fluorescent light micrograph of two fibroblast cells, showing their nuclei (purple) and cytoskeleton. The cytoskeleton is made up of microtubules of the protein tubulin (yellow) and filaments of the protein actin (blue). The cytoskeleton supports the cell's structure, allows the cell to move and assists in the transport of organelles and vesicles within the cell. Fibroblasts are cells forming connective tissue, and are responsible for secreting connective tissue proteins such as collagen.

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What are some distinguishing characteristics?

The cytoskeleton is composed of at least three different types of fibers: microtubules, microfilaments and intermediate filaments.

These types are distinguished by their size with microtubules being the thickest and microfilaments being the thinnest.

Microtubules are hollow rods functioning primarily to help support and shape the cell and as "routes" along which organelles can move. Microtubules are typically found in all eukaryotic cells.
Microfilaments or actin filaments are solid rods and are active in muscle contraction. Microfilaments are particularly prevalent in muscle cells but similar to microtubules, they are also typically found in all eukaryotic cells.
Intermediate filaments can be abundant in many cells and provide support for microfilaments and microtubules by holding them in place.In addition to providing support for the cell, the cytoskeleton is also involved in cellular motility and in moving vesicles within a cell, as well as assisting in the formation of food vacuoles in the cell.

The Golgi Apparatus

2009-01-27T00:40:00.006+07:00

The Golgi apparatus (GA), also called Golgi body or Golgi complex and found universally in both plant and animal cells, is typically comprised of a series of five to eight cup-shaped, membrane-covered sacs called cisternae that look something like a stack of deflated balloons. In some unicellular flagellates, however, as many as 60 cisternae may combine to make up the Golgi apparatus. Similarly, the number of Golgi bodies in a cell varies according to its function. Animal cells generally contain between ten and twenty Golgi stacks per cell, which are linked into a single complex by tubular connections between cisternae. This complex is usually located close to the cell nucleus.

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Due to its relatively large size, the Golgi apparatus was one of the first organelles ever observed. In 1897, an Italian physician named Camillo Golgi, who was investigating the nervous system by using a new staining technique he developed (and which is still sometimes used today; known as Golgi staining or Golgi impregnation), observed in a sample under his light microscope a cellular structure that he termed the internal reticular apparatus. Soon after he publicly announced his discovery in 1898, the structure was named after him, becoming universally known as the Golgi apparatus. Yet, many scientists did not believe that what Golgi observed was a real organelle present in the cell and instead argued that the apparent body was a visual distortion caused by staining. The invention of the electron microscope in the twentieth century finally confirmed that the Golgi apparatus is a cellular organelle.

The Golgi apparatus is often considered the distribution and shipping department for the cell's chemical products. It modifies proteins and lipids (fats) that have been built in the endoplasmic reticulum and prepares them for export outside of the cell or for transport to other locations in the cell. Proteins and lipids built in the smooth and rough endoplasmic reticulum bud off in tiny bubble-like vesicles that move through the cytoplasm until they reach the Golgi complex. The vesicles fuse with the Golgi membranes and release their internally stored molecules into the organelle. Once inside, the compounds are further processed by the Golgi apparatus, which adds molecules or chops tiny pieces off the ends. When completed, the product is extruded from the GA in a vesicle and directed to its final destination inside or outside the cell. The exported products are secretions of proteins or glycoproteins that are part of the cell's function in the organism. Other products are returned to the endoplasmic reticulum or may undergo maturation to become lysosomes.

The modifications to molecules that take place in the Golgi apparatus occur in an orderly fashion. Each Golgi stack has two distinct ends, or faces. The cis face of a Golgi stack is the end of the organelle where substances enter from the endoplasmic reticulum for processing, while the trans face is where they exit in the form of smaller detached vesicles. Consequently, the cis face is found near the endoplasmic reticulum, from whence most of the material it receives comes, and the trans face is positioned near the plasma membrane of the cell, to where many of the substances it modifies are shipped. The chemical make-up of each face is different and the enzymes contained in the lumens (inner open spaces) of the cisternae between the faces are distinctive. Illustrated in Figure 2 is a fluorescence digital image taken through a microscope of the Golgi apparatus (pseudocolored red) in a typical animal cell. Note the close proximity of the Golgi membranes to the cell nucleus.

Proteins, carbohydrates, phospholipids, and other molecules formed in the endoplasmic reticulum are transported to the Golgi apparatus to be biochemically modified during their transition from the cis to the trans poles of the complex. Enzymes present in the Golgi lumen modify the carbohydrate (or sugar) portion of glycoproteins by adding or subtracting individual sugar monomers. In addition, the Golgi apparatus manufactures a variety of macromolecules on its own, including a variety of polysaccharides. The Golgi complex in plant cells produces pectins and other polysaccharides specifically needed by for plant structure and metabolism. The products exported by the Golgi apparatus through the trans face eventually fuse with the plasma membrane of the cell. Among the most important duties of the Golgi apparatus is to sort the wide variety of macromolecules produced by the cell and target them for distribution to their proper location. Specialized molecular identification labels or tags, such as phosphate groups, are added by the Golgi enzymes to aid in this sorting effort.

The Endoplasmic Reticulum

2009-01-27T00:31:00.005+07:00

What is the endoplasmic reticulum?

The endoplasmic reticulum (ER) is a network of flattened sacs and branching tubules that extends throughout the cytoplasm in plant and animal cells. These sacs and tubules are all interconnected by a single continuous membrane so that the organelle has only one large, highly convoluted and complexly arranged lumen (internal space). Usually referred to as the endoplasmic reticulum cisternal space, the lumen of the organelle often takes up more than 10 percent of the total volume of a cell. The endoplasmic reticulum membrane allows molecules to be selectively transferred between the lumen and the cytoplasm, and since it is connected to the double-layered nuclear envelope, it further provides a pipeline between the nucleus and the cytoplasm.

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The endoplasmic reticulum manufactures, processes, and transports a wide variety of biochemical compounds for use inside and outside of the cell. Consequently, many of the proteins found in the cisternal space of the endoplasmic reticulum lumen are there only transiently as they pass on their way to other locations. Other proteins, however, are targeted to constantly remain in the lumen and are known as endoplasmic reticulum resident proteins. These special proteins, which are necessary for the endoplasmic reticulum to carry out its normal functions, contain a specialized retention signal consisting of a specific sequence of amino acids that enables them to be retained by the organelle. An example of an important endoplasmic reticulum resident protein is the chaperone protein known as BiP (formally: the chaperone immunoglobulin-binding protein), which identifies other proteins that have been improperly built or processed and keeps them from being sent to their final destinations.

There are two basic kinds of endoplasmic reticulum morphologies: rough and smooth. The surface of rough endoplasmic reticulum is covered with ribosomes, giving it a bumpy appearance when viewed through the microscope. This type of endoplasmic reticulum is involved mainly with the production and processing of proteins that will be exported, or secreted, from the cell. The ribosomes assemble amino acids into protein units, which are transported into the rough endoplasmic reticulum for further processing. These proteins may be either transmembrane proteins, which become embedded in the membrane of the endoplasmic reticulum, or water-soluble proteins, which are able to pass completely through the membrane into the lumen. Those that reach the inside of the endoplasmic reticulum are folded into the correct three-dimensional conformation, as a flattened cardboard box might be opened up and folded into its proper shape in order to become a useful container. Chemicals, such as carbohydrates or sugars, are added, then the endoplasmic reticulum either transports the completed proteins to areas of the cell where they are needed, or they are sent to the Golgi apparatus for further processing and modification.

Most proteins exported from the endoplasmic reticulum exit the organelle in vesicles budded from the smooth portion, which has a more even appearance than rough endoplasmic reticulum when viewed through the electron microscope because of the lack of ribosomes. The smooth endoplasmic reticulum in most cells is much less extensive than the rough endoplasmic reticulum and is sometimes alternatively termed transitional. Smooth endoplasmic reticulum is chiefly involved, however, with the production of lipids (fats), building blocks for carbohydrate metabolism, and the detoxification of drugs and poisons. Therefore, in some specialized cells, such as those that are occupied chiefly in lipid and carbohydrate metabolism (brain and muscle) or detoxification (liver), the smooth endoplasmic reticulum is much more extensive and is crucial to cellular function. Smooth endoplasmic reticulum also plays a role in various cellular activities through its storage of calcium and involvement in calcium metabolism. In muscle cells, smooth endoplasmic reticulum releases calcium to trigger muscle contractions. Presented in Figure 2 is a fluorescence digital image taken through the microscope of the endoplasmic reticulum network in a bovine (cow) pulmonary artery endothelial cell grown in culture.

It is the rough endoplasmic reticulum that is directly continuous with the nuclear envelope (as illustrated in Figure 1), which is also studded with ribosomes, and the two organelles are thought to have evolved simultaneously in ancient cells. Due to their physical membranous connection, the lumen of the endoplasmic reticulum and the space between the layers of the nuclear envelope comprise a single compartment. Accordingly, the nucleus has direct access to proteins (many of which are produced by the ribosomes upon its surface) and other materials present in the endoplasmic reticulum lumen, so that transport vesicles are not needed to obtain them. The close association between the endoplasmic reticulum and the nucleus also enables the organelles to share information in a very efficient manner. For instance, if the endoplasmic reticulum begins to undergo functional problems and unfolded proteins accumulate within the organelle, which can be extremely hazardous to the cell, the organelle quickly sends a signal to the nucleus (as well as to the cytoplasm). The nucleus responds by slowing ribosomal translation through a several-step process, thereby giving the endoplasmic reticulum extra time to catch up on its protein folding, thus maintaining cellular health.