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Genetik mühendisliğinin çeşitli teknikler kullanarak yaptığı müdahalelerle kalıtımsal değişikliğe uğrattığı organizmalar günümüzde, İngilizce'de GMO. (genetically modified organism), Türkçe'de G.D.O. (genetiği değiştirilmiş organizmalar) kısaltılmış adıyla ifade edilmektedir. Bu teknikler rekombinant DNA ya da "rekombinant DNA teknolojisi" olarak bilinirler. Rekombinant DNA teknolojisi sayesinde DNA molekülleri tüpte (In vitro), yani canlı organizmanın ya da hücrenin dışında, yeni bir tür yaratmak üzere bir molekül içinde bir araya getirilebilmektedir. Bu DNA da bir organizmaya aktarıldığında değiştirilmiş özellikleri ya da kendine özgü özellikleri olan bir canlının ortaya çıkmasını sağlamaktadır.
A genetically modified organism (GMO) or genetically engineered organism (GEO) is an organism whose genetic material has been altered using genetic engineering techniques. These techniques, generally known as recombinant DNA technology, use DNA molecules from different sources, which are combined into one molecule to create a new set of genes. This DNA is then transferred into an organism, giving it modified or novel genes. Transgenic organisms, a subset of GMOs, are organisms which have inserted DNA that originated in a different species. Some GMOs contain no DNA from other species and are therefore not transgenic but cisgenic.
Production
Further information: Horizontal Gene Transfer and Transformation (genetics)
Genetic modification involves the insertion or deletion of genes. When genes are inserted, they usually come from a different species, which is a form of horizontal gene transfer. In nature this can occur when exogenous DNA penetrates the cell membrane for any reason. To do this artificially may require attaching the genes to a virus or just physically inserting the extra DNA into the nucleus of the intended host with a very small syringe, or with very small particles fired from a gene gun. However, other methods exploit natural forms of gene transfer, such as the ability of Agrobacterium to transfer genetic material to plants, or the ability of lentiviruses to transfer genes to animal cells.
History
The general principle of producing a GMO is to add new genetic material into an organism's genome. This is called genetic engineering and was made possible through the discovery of DNA and the creation of the first recombinant bacteria in 1973, i.e., E .coli expressing a Salmonella gene. This led to concerns in the scientific community about potential risks from genetic engineering, which were thoroughly discussed at the Asilomar Conference. One of the main recommendations from this meeting was that government oversight of recombinant DNA research should be established until the technology was deemed safe. Herbert Boyer then founded the first company to use recombinant DNA technology, Genentech, and in 1978 the company announced creation of an E. coli strain producing the human protein insulin.
In 1986, field tests of bacteria genetically engineered to protect plants from frost damage (ice-minus bacteria) at a small biotechnology company called Advanced Genetic Sciences of Oakland, California, were repeatedly delayed by opponents of biotechnology. In the same year, a proposed field test of a microbe genetically engineered for a pest resistance protein by Monsanto Company was dropped.
Uses
GMOs have widespread applications. They are used in biological and medical research, production of pharmaceutical drugs, experimental medicine (e.g. gene therapy), and agriculture (e.g. golden rice). The term "genetically modified organism" does not always imply, but can include, targeted insertions of genes from one species into another. For example, a gene from a jellyfish, encoding a fluorescent protein called GFP, can be physically linked and thus co-expressed with mammalian genes to identify the location of the protein encoded by the GFP-tagged gene in the mammalian cell. Such methods are useful tools for biologists in many areas of research, including those who study the mechanisms of human and other diseases or fundamental biological processes in eukaryotic or prokaryotic cells.
To date the broadest application of GMO technology is patent-protected food crops which are resistant to commercial herbicides or are able to produce pesticidal proteins from within the plant, or stacked trait seeds, which do both. The largest share of the GMO crops planted globally are owned by Monsanto Company, according to the company. In 2007, Monsanto’s trait technologies were planted on 246 million acres (1,000,000 km2) throughout the world, a growth of 13 percent from 2006.
In the corn market, Monsanto’s triple-stack corn – which combines Roundup Ready 2 weed control technology with YieldGard Corn Borer and YieldGard Rootworm insect control – is the market leader in the United States. U.S. corn farmers planted more than 17 million acres (69,000 km2) of triple-stack corn in 2007, and it is estimated the product could be planted on 45 million to 50 million acres (200,000 km2) by 2010. In the cotton market, Bollgard II with Roundup Ready Flex was planted on nearly 3 million acres (12,000 km2) of U.S. cotton in 2007.
According to the International Service for the Acquisition of Agri-Biotech Applications (ISAAA), of the approximately 8.5 million farmers who grew biotech crops in 2005, some 90% were resource-poor farmers in developing countries. These include some 6.4 million farmers in the cotton-growing areas of China, an estimated 1 million small farmers in India, subsistence farmers in the Makhathini flats in KwaZulu Natal province in South Africa, more than 50,000 in the Philippines and in seven other developing countries where biotech crops were planted in 2005. ISAAA estimated that by 2008, 13.3 million farmers were growing GM crops, including 12.3 million in developing counties,. These comprised 7.1 million in China (Bt cotton), 5.0 million in India (Bt cotton), and 200,000 in the Philippines.
"The Global Diffusion of Plant Biotechnology: International Adoption and Research in 2004", a study by Dr. Ford Runge of the University of Minnesota, estimates the global commercial value of biotech crops grown in the 2003–2004 crop year at US$44 billion.
In the United States the United States Department of Agriculture (USDA) reports on the total area of GMO varieties planted. According to National Agricultural Statistics Service, the States published in these tables represent 81-86 percent of all corn planted area, 88-90 percent of all soybean planted area, and 81-93 percent of all upland cotton planted area (depending on the year).
USDA does not collect data for global area. Estimates are produced by the International Service for the Acquisition of Agri-biotech Applications (ISAAA) and can be found in the report, Global Status of Commercialized Transgenic Crops: 2007.
Transgenic animals are also becoming useful commercially. On 6 February 2009 the U.S. Food and Drug Administration approved the first human biological drug produced from such an animal, a goat. The drug, ATryn, is an anticoagulant which reduces the probability of blood clots during surgery or childbirth. It is extracted from the goat's milk.
Detection
Testing on GMOs in food and feed is routinely done by molecular techniques like DNA microarrays or qPCR. The test can be based on screening elements (like p35S, tNos, pat, or bar) or event-specific markers for the official GMOs (like Mon810, Bt11, or GT73). The array-based method combines multiplex PCR and array technology to screen samples for different potential GMOs, combining different approaches (screening elements, plant-specific markers, and event-specific markers). The qPCR is used to detect specific GMO events by usage of specific primers for screening elements or event-specific markers.
To avoid any kind of false positive or false negative testing outcome, comprehensive controls for every step of the process is mandatory. A CaMV check is important to avoid false positive outcomes based on virus contamination of the sample.
Transgenic microbes
Bacteria were the first organisms to be modified in the laboratory, due to their simple genetics. These organisms are now used for several purposes, and are particularly important in producing large amounts of pure human proteins for use in medicine.
Genetically modified bacteria are used to produce the protein insulin to treat diabetes. Similar bacteria have been used to produce clotting factors to treat haemophilia, and human growth hormone to treat various forms of dwarfism.
Transgenic animals
Transgenic animals are used as experimental models to perform phenotypic tests with genes whose function is unknown. Genetic modification can also produce animals that are susceptible to certain compounds or stresses for testing in biomedical research. Other applications include the production of human hormones such as insulin.
In biological research, transgenic fruit flies (Drosophila melanogaster) are model organisms used to study the effects of genetic changes on development. Fruit flies are often preferred over other animals due to their short life cycle, low maintenance requirements, and relatively simple genome compared to many vertebrates.
Transgenic mice are often used to study cellular and tissue-specific responses to disease. This is possible since mice can be created with the same mutations that occur in human genetic disorders, the production of the human disease in these mice then allows treatments to be tested. In 2009 scientists in Japan announced that they had successfully transferred a gene into a primate species (marmosets) and produced a stable line of breeding transgenic primates for the first time. It is hoped that this will aid research into human diseases that cannot be studied in mice, for example Huntington's disease and strokes.
Cnidarians such as Hydra have become attractive model organisms to study the evolution of immunity. For analytical purposes an important technical breakthrough was the development of a transgenic procedure for generation of stably transgenic hydras by embryo microinjection.
Genetically modified fish has promoters driving an over-production of "all fish" growth hormone. This resulted in dramatic growth enhancement in several species, including salmonids, carps and tilapias.
Gene therapy
Gene therapy, uses genetically modified viruses to deliver genes that can cure disease into human cells. Although gene therapy is still relatively new, it has had some successes. It has been used to treat genetic disorders such as severe combined immunodeficiency, and treatments are being developed for a range of other currently incurable diseases, such as cystic fibrosis, sickle cell anemia, and muscular dystrophy. Current gene therapy technology only targets the non-reproductive cells meaning that any changes introduced by the treatment can not be transmitted to the next generation. Gene therapy targeting the reproductive cells - so called "Germ line Gene Therapy" - is very controversial and is unlikely to be developed in the near future.
Transgenic plants
Transgenic plants have been engineered to possess several desirable traits, including resistance to pests, herbicides or harsh environmental conditions, improved product shelf life, and increased nutritional value. Since the first commercial cultivation of genetically modified plants in 1996, they have been modified to be tolerant to the herbicides glufosinate and glyphosate, to be resistant to virus damage as in Ringspot virus resistant GM papaya, grown in Hawaii, and to produce the Bt toxin, a potent insecticide.
Cisgenic plants
Genetically modified sweet potatoes have been enhanced with protein and other nutrients, while golden rice, developed by the International Rice Research Institute, has been discussed as a possible cure for Vitamin A deficiency. In reality, customers would have to eat twelve bowls of rice a day in order to meet the recommended levels of Vitamin A. In January 2008, scientists altered a carrot so that it would produce calcium and become a possible cure for osteoporosis; however, people would need to eat 1.5 kilograms of carrots per day to reach the required amount of calcium.
The coexistence of GM plants with conventional and organic crops has raised significant concern in many European countries. Since there is separate legislation for GM crops and a high demand from consumers for the freedom of choice between GM and non-GM foods, measures are required to separate foods and feed produced from GMO plants from conventional and organic foods. European research programmes such as Co-Extra, Transcontainer and SIGMEA are investigating appropriate tools and rules. At the field level, biological containment methods include isolation distances and pollen barriers.
Controversy
The examples and perspective in this article may not represent a worldwide view of the subject. Please improve this article and discuss the issue on the talk page.
Biological process
The use of GMOs has sparked significant controversy in many areas. Some groups or individuals see the generation and use of GMO as intolerable meddling with biological states or processes that have naturally evolved over long periods of time, while others are concerned about the limitations of modern science to fully comprehend all of the potential negative ramifications of genetic manipulation.
Foodchain
The safety of GMOs in the foodchain has been questioned, with concerns such as the possibilities that GMOs could introduce new allergens into foods, or contribute to the spread of antibiotic resistance. Although scientists and governments have stated that these types of crops are safe and that no adverse health effects have been seen, consumption is still being discouraged in many countries by food and environmental activist groups, who protest GM crops, claiming they are unnatural and therefore unsafe. Such concerns have led to the adoption of laws and regulations that require safety testing of any new organism produced for human consumption.
Trade with Europe and Africa
In response to negative public opinion, Monsanto announced its decision to remove their seed cereal business from Europe, and environmentalists crashed a World Trade Organization conference in Cancun that promoted GM foods and was sponsored by Committee for a Constructive Tomorrow (CFACT). Some African nations have refused emergency food aid from developed countries, fearing that the food is unsafe. During a conference in the Ethiopian capital of Addis Ababa, Kingsley Amoako, Executive Secretary of the United Nations Economic Commission for Africa (UNECA), encouraged African nations to accept genetically modified food and expressed dissatisfaction in the public’s negative opinion of biotechnology.
Agricultural surpluses
Patrick Mulvany, Chairman of the UK Food Group, accused some governments, especially the Bush administration, of using GM food aid as a way to dispose of unwanted agricultural surpluses. The UN blamed food companies and accused them of violating human rights, calling on governments to regulate these profit-driven firms. It is true that the acceptance of biotechnology and genetically modified foods will also benefit rich research companies and could possibly benefit them more than consumers in underdeveloped nations.
Labeling
While some groups advocate the complete prohibition of GMOs, others call for mandatory labeling of genetically modified food or other products. Other controversies include the definition of patent and property pertaining to products of genetic engineering.
Underdeveloped nations
Some groups believe that underdeveloped nations will not reap the benefits of biotechnology because they do not have easy access to these developments, cannot afford modern agricultural equipment, and certain aspects of the system revolving around intellectual property rights are unfair to undeveloped countries. For example, The CGIAR (Consultative Group of International Agricultural Research) is an aid and research organization that has been working to achieve sustainable food security and decrease poverty in undeveloped countries since its formation in 1971. In an evaluation of CGIAR, the World Bank praised its efforts but suggested a shift to genetics research and productivity enhancement. This plan has several obstacles such as patents, commercial licenses, and the difficulty that third world countries have in accessing the international collection of genetic resources and other intellectual property rights that would educate them about modern technology. The International Treaty on Plant Genetic Resources for Food and Agriculture has attempted to remedy this problem, but results have been inconsistent. As a result, "orphan crops", such as teff, millets, cowpeas, and indigenous plants, are important in the countries where they are grown, but receive little investment.
Private investments
The development and implementation of policies designed to encourage private investments in research and marketing biotechnology that will meet the needs of poverty-stricken nations, increased research on other problems faced by poor nations, and joint efforts by the public and private sectors to ensure the efficient use of technology developed by industrialized nations have been suggested. In addition, industrialized nations have not tested GM technology on tropical plants, focusing on those that grow in temperate climates, even though undeveloped nations and the people that need the extra food live primarily in tropical climates. Many European scientists are disturbed by the fact that political factors and ideology prevent unbiased assessment of the GM technology in some EU countries, with a negative effect on the whole community.
Transgenic organisms
Another important controversy is the possibility of unforeseen local and global effects as a result of transgenic organisms proliferating. The basic ethical issues involved in genetic research are discussed in the article on genetic engineering.
Some critics have raised the concern that conventionally-bred crop plants can be cross-pollinated (bred) from the pollen of modified plants. Pollen can be dispersed over large areas by wind, animals and insects. In 2007, the U.S. Department of Agriculture fined Scotts Miracle-Gro $500,000 when modified genetic material from creeping bentgrass, a new golf-course grass Scotts had been testing, was found within close relatives of the same genus (Agrostis) as well as in native grasses up to 21 km (13 miles) away from the test sites, released when freshly cut grass was blown by the wind.
GM proponents point out that outcrossing, as this process is known, is not new. The same thing happens with any new open-pollinated crop variety—newly introduced traits can potentially cross out into neighboring crop plants of the same species and, in some cases, to closely related wild relatives. Defenders of GM technology point out that each GM crop is assessed on a case-by-case basis to determine if there is any risk associated with the outcrossing of the GM trait into wild plant populations. The fact that a GM plant may outcross with a related wild relative is not, in itself, a risk unless such an occurrence has negative consequences. If, for example, an herbicide resistance trait was to cross into a wild relative of a crop plant it can be predicted that this would not have any consequences except in areas where herbicides are sprayed, such as a farm. In such a setting the farmer can manage this risk by rotating herbicides.
The European Union funds research programmes such as Co-Extra, that investigate options and technologies on the co-existence of GM and conventional farming. This also includes research on biological containment strategies and other measures, to prevent outcrossing and enable the implementation of co-existence.
If patented genes are outcrossed, even accidentally, to other commercial fields and a person deliberately selects the outcrossed plants for subsequent planting then the patent holder has the right to control the use of those crops. This was supported in Canadian law in the case of Monsanto Canada Inc. v. Schmeiser.
"Terminator" and "traitor"
An often cited controversy is a "Technology Protection" technology dubbed 'Terminator'. This yet-to-be-commercialized technology would allow the production of first generation crops that would not generate seeds in the second generation because the plants yield sterile seeds. The patent for this so-called "terminator" gene technology is owned by Delta and Pine Land Company and the United States Department of Agriculture. Delta and Pine Land was bought by Monsanto Company in August 2006. Similarly, the hypothetical Trait-specific Genetic Use Restriction Technology, also known as 'Traitor' or 'T-gut', requires application of a chemical to genetically modified crops to reactivate engineered traits. This technology is intended both to limit the spread of genetically engineered plants, and to require farmers to pay yearly to reactivate the genetically engineered traits of their crops. Traitor is under development by companies including Monsanto and AstraZeneca.
In addition to the commercial protection of proprietary technology in self-pollinating crops such as soybean (a generally contentious issue), another purpose of the terminator gene is to prevent the escape of genetically modified traits from cross-pollinating crops into wild-type species by sterilizing any resultant hybrids. The terminator gene technology created a backlash amongst those who felt the technology would prevent re-use of seed by farmers growing such terminator varieties in the developing world and was ostensibly a means to exercise patent claims. Use of the terminator technology would also prevent "volunteers", or crops that grow from unharvested seed, a major concern that arose during the Starlink debacle. There are technologies evolving which contain the transgene by biological means and still can provide fertile seeds using fertility restorer functions. Such methods are being developed by several EU research programmes, among them Transcontainer and Co-Extra.
Governmental support and opposition
Australia
Several states of Australia had placed bans on planting GM food crops, beginning in 2003. However, in late 2007 the states of New South Wales and Victoria lifted their bans. Western Australia lifted their state's ban in December 2008, while South Australia continues its ban. Tasmania has extended its moratorium until November 2014. The state of Queensland has allowed the growing of GM crops since 1995 and has never had a GM ban.
Canada
In 2005, a standing committee of the government of Prince Edward Island (PEI) in Canada assessed a proposal to ban the production of GMOs in the province. The ban was not passed. As of January 2008, the use of genetically modified crops on PEI was rapidly increasing. Mainland Canada is one of the world's largest producers of GM canola.
New Zealand
In New Zealand, no genetically modified food is grown and no medicines containing live genetically-modified organisms have been approved for use. However, medicines manufactured using genetically modified organisms that do not contain live organisms have been approved for sale.
United States
In 2004, Mendocino County, California became the first state in the United States to ban the production of GMOs. The measure passed with a 57% majority. In California, Trinity and Marin counties have also imposed bans on GM crops, while ordinances to do so were unsuccessful in Butte, Lake, San Luis Obispo, Humboldt, and Sonoma counties. Supervisors in the agriculturally-rich counties of Fresno, Kern, Kings, Solano, Sutter, and Tulare have passed resolutions supporting the practice.
Zambia
The Zambian government has launched a campaign to educate and increase awareness of the benefits of biotechnology, including genetically modified crops, in order to change negative public opinion.
France
The crop of Monsanto's MON810 corn was forbidden in France by the government in February 9 of 2008. It was the only GMO authorized in France. The safeguard measure is taken as far as side effects on human health will be known. |
Bu yolla ilk kez 1973’de bir bakteri yaratılmıştır. Bu olay bilimciler topluluğunda bu tür genetik uygulamaların potansiyel tehlikeleri olduğu konusunda kaygılara neden olmuş ve konu Pacific Grove’daki (Kaliforniya) Asilomar Konferansı’nda tartışmalara yol açmıştır. Rekombinant DNA teknolojisini kullanan ilk şirket Herbert Boyer tarafından kurulmuş ve şirket, 1978’de escherichia coli bakterisinin genetik manipülasyon yoluyla, insülin üreten bir türünü yarattığını açıklamıştır.
Sonraki yılllarda bu alandaki çalışmalar artan hızıyla devam etmiştir. Günümüzde bu yolla yaratılan mikroplara transjenik ( rekombinant DNA yöntemleriyle kalıtımsal olarak değiştirilmiş) mikroplar, hayvanlara transjenik hayvanlar, bitkilere ise transjenik bitkiler denmektedir.
Genetik bilgilerinin uygulamaları kısaca şöyle özetlenebilir:
Genetik sayesinde, bazı hastalıkların önceden teşhis edilerek önlenmesinde, kişiye özel ilaç ve tedavi yöntemleri geliştirilebilmesinde önemli gelişmeler sağlanmıştır.
1970’li yıllardan itibaren insülin hormonu, büyüme hormonu gibi insana özgü gen ürünleri diğer canlılarda sentezlenebilmektedir.
Koyuna bir insan geni aktarılarak, koyun sütünde bir insan proteinin bulunması sağlanmıştır.
Sazan balığı gibi bazı canlıların daha hızlı büyümesi sağlanabilmektedir.
Günümüzde, genetik mühendisliği geni bir hücreden diğerine nakledebilmektedir, gen naklinin yapıldığı hücrelerden biri bitki, diğeri bir insan veya hayvan hücresi ya da bir mikroorganizma da olsa. Yani bir böceğin, bir balığın genleri bir bitki ya da mikroorganizmaya aktarılabilmektedir. Örneğin akrebin zehirini üreten gen bir virüse nakledilebilmekte, böcek öldüren bir bakterinin geni de bitkilere nakledilebilmektedir.Böylece, tarım ürünlerine verimin arttırılması, ürünlerin zararlılardan etkilenmemesi gibi çeşitli amaçlarla genetik müdahaleler yapılmaktadır.
Böylece, doğada daha önce hiç bulunmayan gen bileşimleri de üretilebilmektedir. (Bir genin farklı bir hücreye nakliyle o hücrenin işlevi artabilir, değişebilir veya salgıladığı kimyasal maddeler farklılaşabilir.) Böylece, şimdiye dek fare,tavşan, koyun, domuz, tavuk, balık gibi birçok hayvan üzerinde embriyonları tek hücre aşamasındayken yüzlerce değişik gen denenmiş ve değişik türler elde edilmiştir. Bu yolla elde edilen yalnızca fare türlerinin sayısı bini aşmıştır.
Kısaca günümüzde, bir organizmadaki genler parçalanabilmekte, kopyalanabilmekte, üretilebilmekte ve başka bir organizmaya nakledilebilmektedir.
Genetik mühendisliği bugünkü modern biyoteknolojinin temelini oluşturmuştur. İkisi arasındaki ilişki şöyle açıklanabilir: Genetik mühendisliği bilgileri bir ürün elde etmek üzere kullanıldıklarında, ürün ancak biyoteknolojik işlemlerle günlük yaşamın bir parçası olur. İlk biyoteknoloji patenti 1980’de ham petrolü parçalamak amacıyla genetik yapısı değiştirilmiş bir mikrop geliştiren, yani yaratan Dr. Ananda Chakrabarty’ye verilmiştir. Böylece tarihte ilk kez yaratılan bir canlı için patent hakkı doğmuştur.
G.D.O. (genetik yapısı değiştirilmiş organizmalar) uygulamalarına karşı olanlar, özellikle çevrecilerin bir kısmı ve I.Asimov, J. Naisbitt, P Aburden gibi bazı araştırmacı yazarlar, bilime karşı olmamakla birlikte, genetikteki veri ve buluşların uygulanmasıyla ilgili bazı konularda huzursuz olduklarını ifade ederek, şu gelişmelere işaret etmektedirler:
Çeşitli devletlerin denetimindeki bilimciler gen aktarımı yoluyla şimdiye dek yeryüzünde ilk kez meydana gelen yüzlerce yaratık meydana getirmişlerdir. Dolayısıyla istenmeden de olsa, insan türünü yok edecek bir mikroorganizma ya da bir türün yaratılmasına yol açılabilir.
Önceleri biyoteknolojinin özellikle tarım ürünleri konusunda büyük gelişmeler sağlayarak dünyada açlığın giderilmesinde devrim yaratacağı müjdesi veriliyordu; fakat günümüzde genetik mühendisliği, özellikle biyoteknoloji üniversitelerden özel şirketlere geçmiş ve bunlar büyük maddi kazanç getirecek başka çalışmalara yönelmiş durumda bulunmaktadırlar.
1987’de A.B.D. Patent Bürosu’nun genetik yapıları değiştirilmiş hayvanların da patent altına alınabileceğini açıklamasıyla, hayvanlar alemi çokuluslu şirketler ile eczacılık ve biyoteknoloji şirketlerinin eline bırakılmıştır. Günümüzde biyoteknoloji alanında binlerce şirket bulunmaktadır.
Bu gelişmelere işaret edenler ayrıca bazı tehlikelere dikkat çekerek şu soruları yöneltmekteler:
Atomu keşfetmiş, ardından atom bombasını icat etmiş insanoğlu bilimsel buluşları her zaman insanlığın yararına kullanmadığına göre, genetik mühendisliği ve biyoteknolojideki buluşların daima insanlığın yararına kullanıldığını ve kullanılacağını, örneğin bir biyolojik savaşta asla insanlığın zararına kullanılmayacağını kim garanti edebilir?
Bazı devletlerin, diğerlerine hükmedebilmeleri için, genetikteki çalışmaları gizlice insanlar üzerinde uygulamayacağını, örneğin sıcak bir savaşa bile gerek görmeden belirli uluslara ya da toplumlara ait insanların gizlice bazı yeteneklerini köreltmek veya onlara bazı davranış biçimlerini aşılamak gibi uygulamalarda bulunmayacağını kim garanti edebilir?
Genetik çalışmaları başlangıçta açıklandığı gibi, yalnızca kalıtsal hastalıkların teşhis ve tedavisine olanak sağlamaya yönelik olarak mı devam etmektedir? Yoksa gizlice sürdürülen araştırma ve uygulamalar var mıdır?
Genetik yapısı değiştirilmiş, yoldan çıkan bir bakteri hastalığa yol açarsa, daha önce doğada hiç karşılaşılmamış olduğundan muhtemelen insan vücudunun savunmasız olacağı bu bakterinin yol açacağı hastalıktan insanlığı biyoteknoloji kurtarabilecek midir?
Genetik yapısı değiştirilmiş bir hayvan ya da organizmanın, kısa vadede insanlar için yararlı bir potansiyel taşıyor görünse de, ileride olumsuz sonuçlar yaratmayacağından, çevreyle etkileşime girmeyeceğinden veya çok hassas dengeler üzerine kurulmuş doğada ekolojik dengeyi bozmayacağından nasıl emin olabiliriz?
Mutasyona uğratılmış virüs ve bakterilerin laboratuvar dışına salınmayacağını veya kazara da olsa laboratuvar dışına hiç çıkmayacağını kim garanti edebilir?
Ülkelerin GDO'lara desteği ve engelleri
Avustralya
2003 yılının başlarından itibaren Avustralya'nın bazı eyaletleri transgenik bitkilerin yetiştirilmesini engellemekte idi. Ancak 2007'nin sonlarıda New South Wales ve Victoria eyaletleri yasakları kaldırdılar. Güney Avustralya yasakları kaldırmazken, Batı Avustralya Aralık 2008'te yasağı kaldırdı. Tazmanya Kasım 2014'e kadar yasağı uzattı. Queensland eyaleti 1995 yılından beri transgenik bitki yetiştirilmesine izin vermekte ve hiçbir zaman yasak getirmemiştir.
Kanada
2005 yılında Prince Edward Adası'nda (Prince Edward Islands - PEI) bir komite transgenik ürünlerin eyalet içinde yasaklanması için bir tasarı hazırladı. Tasarı kabul edilmedi. Ocak 2008'ten beri PEA'daki transgenik ürünlerin kullanımı hızla artmaktadır. Kanada transgenik kanolanın en fazla üretildiği ülkelerden biridir.
Yeni Zelanda
Yeni Zelanda'da GDO'lu ürünler yetiştirilmemekte ve genetiği değiştirilmiş canlı organizma içeren ilaçlar yasaktır. Ancak genetiği değiştirilmiş canlı organizma içermeyen ilaçların satışı yasak değildir.
ABD
2004 yılında Mendocino County, Kaliforniya GDO'yu yasaklayan ilk ilçe oldu. %57'lik güvenle yasak geçti. Kaliforniya'da, Trinity ve Marin ilçeleri GDO'lu bitkiler için yasaklar getirdiler, ancak Butte, Lake, San Luis Obispo, Humboldt, and Sonoma ilçelerinde ise yasaklamak başarısız oldu. Fresno, Kern, Kings, Solano, Sutter, ve Tulare gibi tarımsal açıdan zengin ilçelerin uzmanları bu kararı uygulamalarla yok saydılar.
Zambiya
Zambiya hükümeti transgenik bitkileri de içeren biyoeknolojik çalışmaların faydalarına karşı farkındalığı artırmak ve eğitim amacıyla toplumun olumsuz düşüncesini değiştirmek kapsamında bir proje başlattı.
Fransa
Monsanto'nun MON810 mısırının kullanımı Fransız hükümeti tarafından 9 Şubat 2008 tarihinde yasaklanmıştır . Bu ürün Fransa'da izin verilen tek üründü. Korunma önlemleri insan sağlığına etkileri öğrenilmesine göre alınacak.
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View Larger Map Tuz Gölü'nün hiç gölü kalmadı!
Uzaydan izleyin!
Orda bir Tuz Gölü'müz vardı uzakta! Gitmesek de... Gelmesek de... Gün batımında kıpkırmızı yanardı suları... Yanından geçerdik Kapadokya'ya, Niğde'ye, Aksaray'a, Mersin'e, Adana'ya giderken otomobille, otobüsle... Durur fotoğraf çekerdik önünde... Ama artık Tuz Gölü'müzün hiç suyu kalmadı! Kurudu! Tuz Gölü artık uzaydan bile görülen uçsuz bucaksız uzanan bembeyaz bir Tuz Çölü oldu! Haritalardaki mavi göl artık yerinde yok. İşte Tuz Çölü'müzün uzaydan görünümü... Lütfen bu sayfayı arkadaşlarınızla paylaşın! Susuzluk ve çölleşmeye dikkat çekin! Salt Lake of Turkey is the second largest lake in Turkey and is located in the Central Anatolia Region, 105 km (65 mi) northeast of Konya and 150 km (93 mi) south-southeast of Ankara. For most of the year, this very shallow (1-2 m, 3-7 ft) and saline lake has an area of 1,600 km2 (620 sq mi). It is normally 80 km (50 mi) long and 50 km (31 mi) wide at an elevation of 905 m (2,970 ft) above sea level. Its area is shared by the provinces of Ankara, Konya and Aksaray, and holds a population of over 3 million people. The lake, occupying a tectonic depression in the central plateau of Turkey, is fed by two major streams, groundwater, and surface water, but has no outlet. Brackish marshes have formed where channels and streams enter the lake. It is extremely saline and during the summer, most of the water in the lake dries up and exposes an average of 30 cm thick salt layer. During winter part of the salt is re-dissolved in the fresh water that is introduced to the lake by precipitation and surface runoff. This mechanism is used as a basis for the process of the salt mines in the lake. The three mines operating in the lake produce of the order of 70% of the salt consumed in Turkey. The salt mining generates industrial activity in the region, mainly related to salt processing and refining. Arable fields surround the lake, except in the south and southwest where extensive seasonally flooded salt-steppe occurs. In 2001, Lake Tuz was declared a specially protected area, including all of the lake surface and surrounding waterbeds and some of the important neighboring steppe areas. The main Turkish breeding colony of Greater Flamingo (Phoenicopterus roseus) is present on a group of islands in the southern part of the lake. Greater White-fronted Goose (Anser albifrons) is the second largest breeder here. Lesser Kestrel (Falco naumanni) is a common breeder in surrounding villages. [Wikipedia] |
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Dünya nüfusun giderek artan bir oranda artması, kısıtlı kaynakların ihtiyacı karşılayamaması, hatta giderek azalması gibi bir durumla karşı karşıya... Buna çevreye verdiğimiz zararı ve iklim değişikliğini de ekleyebilirsiniz... Öyle ki bazı jeologlar dünyamızın bir ateştopu halinde olduğu 4.6 milyar yıl öncesinden beri süren jeolojik hayatında 18. yüzyıldan itibaren, sanayi devrimi ile birlikte yeni bir jeolojik devre girdiğini belirtiyorlar. Buna anthropocene, yani insan devri adını veriyorlar. Kısıtlı kaynakların giderek artan insan nüfusunun ihtiyaçları karşısında yetersiz kalma sorunu bu sene enerji krizi ile kendini belli etmeye başladı. Tabii Afrika'da açlık yıllarca devam ediyordu ama modern dünya bunu hissetmedi. Ama Afrika sıcak... Oysa modern dünya modern dünya kışı daha soğuk yaşıyor. Yaşam tümüyle enerjiye dayalı, verimsiz, pahalı ve çok enerji tüketiyoruz. Isı yalıtımı yapmıyoruz. Göğü ısıtıyoruz. Hani bir reklam vardı "Göğü ısıtamazsınız!" diye... Isıttık işte... Üstelik parasını ödeyerek, ama henüz bedelini ödemedik... Aha işte gaz da bitti ! ... Ne yapacağız şimdi? Petrol zaten pahalı, o da bitiyor... Giderek daha pahalı olacak... Oysa dünyada yenilenebilir enerji, green energy, future energy diye bir şeyler söyleniyordu yıllarca... Aslında en verimli ve en ucuz enerji, ihtiyaç duyulmayan enerjidir. O da yalıtımla olur. Yalnızca konut ve büro yalıtımı değil, vücut yalıtımı ile de... Polartec, gore-tex gibi teknolojik giysiler, balık ağırlıklı beslenme gibi... Bina yalıtımı ile birlikte enerji ihtiyacınızı öyle düşürebilirsiniz ki siz de şaşırırsınız... Onlarca yıldır boş yere ödediğiniz ve ödeyeceğiniz servet ise cabası... Üstelik ne için... Küresel ısınma için... Gaz bittiğinde ne yapacaksınız? Aslında soğukta tir tir titremekle, konforlu bir yaşam sürmek arasında küçücük bir püf noktası ama sonuçları arasında büyük fark vardır. Eskimolar igloolarında gayet mutlular... Soğukta eskimo, ailesi, çocukları, bebekleri nasıl konforlu bir hayat sürmeyi başarıyor? "Aman ! Eskimo muyum ben ?!!" diyebilirsiniz. Ama dünyada insanlar lüks buz otellerde kalabilmek için kışı iple çektiklerini, dünyanın parasını ödediklerini, aylar öncesinden rezervasyon yaptırdıklarını biliyor musunuz? :)
Eskimoların igloolarını saymazsak, dünyada ilk buzdan sarayı 1739–1740 yıllarındaki soğuk kış mevsiminde Rus Çariçesi Anna Ivanovna St. Petersburg'da yaptırmıştı. Bu saraydan esinlenerek Rusya'da değişik yıllarda yapılan buzdan Çarlık Sarayları var tabii... Hatta Türkmenistan devlet başkanı Sefermurat Niyazov (Türkmenbaşı) 2004 yılında Türkmenistan'da bir buzdan başkanlık sarayı yapılmasını emretmişti...
Dünyada ise buz oteller oldukça yaygın... Norveç, İsveç, Finlandiya, Kanada gibi iklimi uygun ülkelerde büyük ilgi görüyor buzdan oteller... Hatta Romanya'da bile var... Tabii her kış taze karlardan hazırlanan buz blokları kullanılarak yeniden yapılıyor... Üstelik kar, dışarıda ne kadar soğuk olursa olsun, ısı yalıtımı da sağlıyor. İşte dünyadaki başlıca buz oteller...
Kirkenes Snow Hotel Norway
Ice Lodge Norway
Alta Igloo Hotel Norway
Icehotel in Jukkasjärvi Sweden
Mammut Snow Hotel at SnowCastle of Kemi Finland
Lainio Snow Hotel, Ylläs and Levi, Finland
Hotel & Igloo Village Kakslauttanen, Saariselkä, Finland
Duchesnay winter resort Québec City, Canada
Gelecekte ise enerji kaynakları ne olacak? Güneş enerjisi, rüzgar enerjisi, nükleer enerji... Hangisi iyi? Hangisi uygun? Biz kişisel olarak ne yapabiliriz? Güneş enerjisi, inanmayacaksınız ama, onlarca yıldan beri ülkemizin güney bölgelerinde yaygın olarak su ısıtması amacıyla kullanılıyor. Ülkemizde güneşli günlerin sayısı oldukça fazla. Bu bölgelerde, güneşin yeterli olmadığı zamanlarda elektrik ya da gaz, diğer yaygın enerji kaynalarıyla ısıtılıyor. Bu yöntem pahalı kaynakları bedava kaynakla destekliyor. Ama dünyada güneş enerjisi yalnız sıcak su değil, elektrik üretimi amacıyla kullanılır. Bir sonraki yazıda gelecekteki enerji kaynaklarımızın neler olabileceğini, bizim kişisel olarak neler yapabileceğimizi izleyeceğiz...
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 Yer CERN Nükleer Araştırma Tesisleri! İsviçre Fransa sınırı! Yerin 175 metre altında 27 kilometre uzunluğundaki çember şeklinde devasa bir tünel! Burada 2. Dünya Savaşından sonra 50 yıldan fazla süredir sessiz sedasız bir nükleer araştırma sürdürülmekte!
Önümüzdeki günlerde önemli bir deney başlıyor CERN'de... Evren, bu laboratuvarda başlangıcına geri döndürülecek, başlangıçtaki Büyük Patlama şartları yeniden yaratılacak... Böylece evreni meydana getiren nükleer şartlar laboratuvarda yeniden yaratılacak... Deneye Türkiye'den de pek çok bilim insanı katılıyor. Bilim insanları çok heyecanlı... Bu deneyle insanlığın evren hakkında bilmediklerini öğrenebileceğini, çok şeylerin değişebileceğini düşünüyorlar... Tabii akla çeşitli sorular geliyor... Bazıları bu deneyden endişeli... Bir şeyler yanlış giderse ne olacak... Büyük bir patlama olur mu? Görülmemiş derecede zararlı radyasyon meydana gelir mi? Açılan bir kapıdan gelecekler dünyayı istila ederler mi? Mikro karadelikler dünyayı yutar mı? Büyük Patlamayı tersine döndürüp Büyük Çöküş'ü yaratıp evreni tekliğe ya da hiçliğe döndürmek mümkün mü? Vahdet-i vücut nedir? gibi... Sorular uzayıp gidiyor... Bazıları "Bilmediğin şeyi ne kurcalarsın?!" diye düşünüyorlar... Bazıları bu deneyin yüzyılın deneyi olduğunu söylüyor. Bazıları ise 15 Milyar yılın deneyi olmasından endişeli... Ya siz neler düşünüyorsunuz? İşte deney hakkında bazı bilgiler. Önümüzdeki dönemde deneyi burada izleyeceğiz... 
Büyük Hadron Çarpıştırıcısı (LHC İngilizce "Large Hadron Collider" kelimelerinin başharflerinden oluşan kısaltma.) CERN'de 2008 yılında devreye girip yüksek enerjili parçacık fiziği deneyleri yapılmasına imkân verecek bir projedir. İsviçre - Fransa sınırında, daha önceden kullanılmış olan yerin 100m altındaki çevresi 27 km uzunluğunda olan LEP tünelinde kurulmuştur. Tünel İsviçre ve Fransa sınırının altında her iki ülkenin topraklarına girmektedir. Tünelin çapı 3,8 metredir. Dairesel bir hızlandırıcı - çarpıştırıcı olan LHC, öncelikli olarak protonları ilave olarak da kurşun (Pb) iyonlarını ışık hızı'na çok yakın bir hız ulaştıracak sonra da deneylerin merkezlerinde çarpıştıracaktır. LHC SPS den alacağı 450 GeV enerjilik protonları 14000 GeV enerjiye çıkaracaktır. İki proton demetinin birbirlerine çok yakın ama aksi yönde dönmelerini sağlamak için süperiletken elektromıknatıslar kullanılacaktır. Süperiletkenlik sağlamak için mıknatıslar -271 dereceye kadar soğutmaktadır ki bu mutlak soğuğun sadece 2 derece üzerindedir. Projenin yaratacağı mikro kara delikler ve gizemli cisimlerin dünyayı yok edeceği ve solucan delikleri ile zamanda yolculuğun mümkün olabileceği söylentilerine rağmen CERN mühendisleri böyle bir durumun olmayacağını belirtmişlerdir. |
The Large Hadron Collider After more than 30 years of planning, 14 years of building and $10 billion later, the Large Hadron Collider, the world's biggest atom smasher, is due to start up on September 10. Scientists predict collisions of sub-atomic particles produced by the LHC will allow them to get closer than ever before to answering questions about the origins of the universe. Lisa Schlein reports for VOA from CERN, the European Organization for Nuclear Research in Geneva. http://news.google.com/news?ned=us&ncl=1241609362&hl=en&topic=t The Large Hadron Collider (LHC) is the world's largest particle accelerator complex, intended to collide opposing beams of 7 TeV protons. Its main purpose is to explore the validity and limitations of the Standard Model, the current theoretical picture for particle physics. The LHC was built by the European Organization for Nuclear Research (CERN), and lies under the Franco-Swiss border near Geneva, Switzerland. The LHC is the world's largest and the highest-energy particle accelerator. It is funded and built in collaboration with over eight thousand physicists from over eighty-five countries as well as hundreds of universities and laboratories. The idea of the Large Hadron Collider (LHC), began in the early 1980s. The first approval of the project by the CERN Council occurred in December 1994 and the first civil engineering construction work began in April 1998. The collider is currently undergoing commissioning while being cooled down to its final operating temperature of approximately 1.9 K (-271.25 °C). Initial particle beam injections were successfully carried out on 8-11 August 2008, the first attempt to circulate a beam through the entire LHC is scheduled for 10 September 2008, and the first high-energy collisions are planned to take place after the LHC is officially unveiled, on 21 October 2008. When activated, it is theorized that the collider will produce the elusive Higgs boson, the observation of which could confirm the predictions and missing links in the Standard Model of physics and could explain how other elementary particles acquire properties such as mass. The verification of the existence of the Higgs boson would be a significant step in the search for a Grand Unified Theory, which seeks to unify three of the four known fundamental forces: electromagnetism, the strong nuclear force and the weak nuclear force, leaving out only gravity. The Higgs boson may also help to explain why gravitation is so weak compared to the other three forces. In addition to the Higgs boson, other theorized particles, models and states might be produced, and for some searches are planned, including supersymmetric particles, compositeness (technicolor), extra dimensions, strangelets, micro black holes and magnetic monopoles. Although a few individuals have questioned the safety of the planned experiments in the media and through the courts, the consensus in the scientific community is that there is no basis for any conceivable threat. http://en.wikipedia.org/wiki/Large_Hadron_Collider Concerns have been raised in the media and through the courts about the safety of the Large Hadron Collider on the grounds that high-energy particle collisions performed in the accelerator might cause disastrous events, including the production of dangerous micro black holes (mBHs) and strangelets. Two CERN-commissioned reports have reviewed the safety of the LHC particle collisions and concluded that there is no basis for any conceivable threat. The consensus in the scientific community is that experiments at the LHC present no danger and that there is no reason for concern. http://en.wikipedia.org/wiki/Safety_of_the_Large_Hadron_Collider Micro black holes, also called quantum mechanical black holes or mini black holes, are tiny black holes for which quantum mechanical effects play an important role. In theory, a black hole can have any size or mass above the Planck mass. Under some speculative theories, primordial black holes were created during the big bang at the earliest stages of the evolution of our universe. In 1974 Stephen Hawking argued that due to quantum effects, such primordial black holes could "evaporate" by a theoretical process now referred to as Hawking Radiation in which particles of matter would be emitted. Under this theory, the smaller the size of the micro black hole, the faster the evaporation rate, resulting in a sudden burst of particles as the micro black hole suddenly explodes. Searches for such evaporating micro black holes are planned for the GLAST satellite launched in June of 2008, which will search for gamma ray bursts which should be associated with such evaporation. It is believed that the Large Hadron Collider (LHC) could produce one of these micro black holes. Although the Standard Model of particle physics predicts that LHC energies are far too low to create black holes, some extensions of the Standard Model posit the existence of extra spatial dimensions, in which it would be possible to create micro black holes at the LHC at a rate on the order of one per second. According to the standard calculations these are harmless because they would quickly decay by Hawking radiation.
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Son zamanlarda bir su meselesidir gidiyor... Kafalar iyice karıştı... Bu arsenik meselesi nereden çıktı? Nasıl arıtılır? Biz ne yapabiliriz? Sulardaki arsenik kirlenmesi artan su ihtiyacı sonucu giderek daha derin seviyelerdeki yeraltı sularının kullanılması sonucunda ortaya çıkan doğal bir kirlenme. Artan nüfus sayısı ve kuraklık sonucunda tüm dünyada, özellikle Hindistan, Bangladeş, Tayland, Tayvan, Çin, gibi Asya ülkelerinin yanısıra Arjantin, Şili ve ABD gibi ülkelerde de görülüyor... Kalp damar hastalıklarının yanısıra kansere de neden oluyor. Ganj Deltasında 20-100 m. derinlikteki kuyulardan alınan sularda arsenik kirlenmesi tespit edilmiş. Sıradan arıtma tesisleri sudaki arseniği normal olarak temizlemiyor. ABD'de kullanma suyunda arsenik kirlenmesi görülen bölgelerde evlerde arseniği sudan temizleyebilecek özel arıtma filtreleri (Bayoxide E33, GFH, Titanium Dioxide, reverse osmosis) kullanılıyor. Ancak Bangladeş araştırmaları arsenikli suyun sulamada kullanıldığı yerlerdeki gıda ürünlerini tüketmenin de vücuda zararlı arsenik birikimi yapacağını öngörüyor... |
Arsenic contamination of groundwater is a natural occurring high concentration of arsenic in deeper levels of groundwater, which became a high-profile problem in recent years due to the use of deep tubewells for water supply in the Ganges Delta, causing serious arsenic poisoning to large numbers of people. A 2007 study found that over 137 million people in more than 70 countries are probably affected by arsenic poisoning of drinking water. Approximately 20 incidents of groundwater arsenic contamination have been reported from all over the world. Of these, four major incidents were in Asia, including locations in Thailand, Taiwan, and Mainland China. South American countries like Argentina and Chile have also been affected. There are also many locations in the United States where the groundwater contains arsenic concentrations in excess of the new Environmental Protection Agency standard of 10 parts per billion. Arsenic is a carcinogen which causes many cancers including skin, lung, and bladder as well as cardiovascular disease. Contamination specific nations and regions Bangladesh and West Bengal The story of the arsenic contamination of the groundwater in Bangladesh is a tragic one. Many people have died from this contamination. Diarrheal diseases have long plagued the developing world as a major cause of death, especially in children. Prior to the 1970s, Bangladesh had one of the highest infant mortality rates in the world. Ineffective water purification and sewage systems as well as periodic monsoons and flooding exacerbated these problems. As a solution, UNICEF and the World Bank advocated the use of wells to tap into deeper groundwater for a quick and inexpensive solution. Millions of wells were constructed as a result. Because of this action, infant mortality and diarrheal illness were reduced by fifty percent. However, with over 8 million wells constructed, it has been found over the last two decades that approximately one in five of these wells is now contaminated with arsenic above the government's drinking water standard. In the Ganges Delta, the affected wells are typically more than 20 m and less than 100 m deep. Groundwater closer to the surface typically has spent a shorter time in the ground, therefore likely absorbing a lower concentration of arsenic; water deeper than 100 m is exposed to much older sediments which have already been depleted of arsenic. Dipankar Chakraborti from West Bengal brought the crisis to international attention in a research paper published in The Analyst in 1995 and reported on by David Bradley (The Guardian, January 5, 1995, "Drinking the water of death"). Beginning his investigation in West Bengal in 1988, he eventually published, in 2000, the results of a study conducted in Bangladesh, which involved the analysis of thousands of water samples as well as hair, nail and urine samples. They found 900 villages with arsenic above the government limit. Chakraborti has criticized aid agencies, saying that they denied the problem during the 1990s while millions of tube wells were sunk. The aid agencies later hired foreign experts, who recommended treatment plants which were not appropriate to the conditions, were regularly breaking down, or were not removing the arsenic. Chakraborti says that the arsenic situation in Bangladesh and West Bengal is due to negligence. He also adds that in West Bengal water is mostly supplied from rivers. Groundwater comes from deep tubewells, which are few in number in the state. Because of the low quantity of deep tubewells, the risk of arsenic patients in West Bengal is comparatively less. According to the World Health Organisation, “In Bangladesh, West Bengal (India) and some other areas, most drinking-water used to be collected from open dug wells and ponds with little or no arsenic, but with contaminated water transmitting diseases such as diarrhoea, dysentery, typhoid, cholera and hepatitis. Programmes to provide ‘safe’ drinking-water over the past 30 years have helped to control these diseases, but in some areas they have had the unexpected side-effect of exposing the population to another health problem—arsenic.” WHO has defined the areas under threat: Seven of the nineteen districts of West Bengal have been reported to have ground water arsenic concentrations above 0.05 mg/L. The total population in these seven districts is over 34 million, with the number using arsenic-rich water is more than 1 million (above 0.05 mg/L). That number increases to 1.3 million when the concentration is above 0.01 mg/L. According to a British Geological Survey study in 1998 on shallow tube-wells in 61 of the 64 districts in Bangladesh, 46% of the samples were above 0.01 mg/L and 27% were above 0.050 mg/L. When combined with the estimated 1999 population, it was estimated that the number of people exposed to arsenic concentrations above 0.05 mg/L is 28-35 million and the number of those exposed to more than 0.01 mg/L is 46-57 million (BGS, 2000). The solution, according to Chakraborti, is “By using surface water and instituting effective withdrawal regulation. West Bengal and Bangladesh are flooded with surface water. We should first regulate proper watershed management. Treat and use available surface water, rain-water and others. The way we're doing at present is not advisable." United States There are many locations across the United States where the groundwater contains naturally high concentrations of arsenic. Cases of groundwater-caused acute arsenic toxicity, such as those found in Bangladesh, are unknown in the United States where the concern has focused on the role of arsenic as a carcinogen. The problem of high arsenic concentrations has been subject to greater scrutiny in recent years because of changing government standards for arsenic in drinking water. Some locations in the United States, such as Fallon, Nevada, have long been known to have groundwater with relatively high arsenic concentrations (in excess of 0.08 mg/L). Even some surface waters, such as the Verde River in Arizona, sometimes exceed 0.01 mg/L arsenic, especially during low-flow periods when the river flow is dominated by groundwater discharge. A drinking water standard of 0.05 mg/L (equal to 50 parts per billion, or ppb) arsenic was originally established in the United States by the Public Health Service in 1942. The Environmental Protection Agency (EPA) studied the pros and cons of lowering the arsenic Maximum Contaminant Level (MCL) for years in the late 1980s and 1990s. No action was taken until January 2001, when the Clinton administration in its final weeks promulgated a new standard of 0.01 mg/L (10 ppb) to take effect January 2006. The incoming Bush administration suspended the new regulation, but after some months of study, the new EPA administrator Christine Todd Whitman approved the new 10 ppb arsenic standard and its original effective date of January 2006. Many public water supply systems across the United States obtained their water supply from groundwater that had met the old 50 ppb arsenic standard but exceeded the new 10 ppb MCL. These utilities searched for either an alternative supply or an inexpensive treatment method to remove the arsenic from their water. In Arizona, an estimated 35% of water-supply wells were put out of compliance by the new regulation; in California, the percentage was 38%. The proper arsenic MCL continues to be debated. Some have argued that the 10 ppb federal standard is still too high, while others have argued that 10 ppb is needlessly strict. Individual states are able to establish lower arsenic limits; New Jersey has done so, setting a maximum of 0.005 mg/L for arsenic in drinking water. Water purification solutions Small-scale water treatment Chakraborti claims that arsenic removal plants (ARPs) installed in Bangladesh by UNDP and WHO were a colossal waste of funds due to breakdowns, inconvenient placements and lack of quality control. A simpler and less expensive form of arsenic removal is known as the Sono arsenic filter, using 3 pitchers containing cast iron turnings and sand in the first pitcher and wood activated carbon and sand in the second. Plastic buckets can also be used as filter containers. It is claimed that thousands of these systems are in use can last for years while avoiding the toxic waste disposal problem inherent to conventional arsenic removal plants. Although novel, this filter has not been certified by any sanitary standards such as NSF, ANSI, WQA and does not avoid toxic waste disposal similar to any other iron removal process. In the United States small "under the sink" units have been used to remove arsenic from drinking water. This option is called "point of use" treatment. The most common type of domestic treatment unit uses the technologies of adsorption i.e. granular media such as Bayoxide E33, GFH, Titanium Dioxide and reverse osmosis, To a less extent ion exchange and activated alumina have been considered but not commonly used. Large-scale water treatment In some places, such as the United States, all the water supplied to residences by water utilities must meet primary (health-based) drinking water standards. This may necessitate large-scale treatment systems to remove arsenic from the water supply. The effectiveness of any method depends on the chemical makeup of a particular water supply. The aqueous chemistry of arsenic is complex, and may affect the removal rate that can be achieved by a particular process. Some large utilities with multiple water supply wells could shut down those wells with high arsenic concentrations, and produce only from wells or surface water sources that meet the arsenic standard. Other utilities, however, especially small utilities with only a few wells, may have no available water supply that meets the arsenic standard. Coagulation/filtration removes arsenic by coprecipitation and adsorption using iron coagulants. Coagulation/filtration using alum is already used by some utilities to remove suspended solids and may be adjusted to remove arsenic. Iron oxide adsorption filters the water through a granular medium containing ferric oxide. Ferric oxide has a high affinity for adsorbing dissolved metals such as arsenic. The iron oxide medium eventually becomes saturated, and must be replaced. Activated alumina is another filter medium known to effectively remove dissolved arsenic. It has also been used to remove undesirably high concentrations of fluoride. Ion Exchange has long been used as a water-softening process, although usually on a single-home basis. It can also be effective in removing arsenic with a net ionic charge. (Note that arsenic oxide, As2O3, is a common form of arsenic in groundwater that is soluble, but has no net charge.) Both Reverse osmosis and electrodialysis (also called electrodialysis reversal) can remove arsenic with a net ionic charge. (Note that arsenic oxide, As2O3, is a common form of arsenic in groundwater that is soluble, but has no net charge.) Some utilities presently use one of these methods to reduce total dissolved solids and therefore improve taste. A problem with both methods is the production of high-salinity waste water, called brine, or concentrate, which then must be disposed of. Dietary intake Researchers from Bangladesh and the United Kingdom have recently claimed that dietary intake of arsenic adds a significant amount to total intake, where contaminated water is used for irrigation. Wikipedia
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Cep telefonları radyasyon yayıyor mu? Beynimize zarar veriyor mu? diye merak ediyorsanız eğer, videoyu izleyin. Bakın cep telefonlarıyla nasıl pop-corn mısır patlatılıyor. Artık cep telefonunuz beyninize ne yapıyor siz düşünün... Denemesi bedava... İsterseniz bunu evde siz de deneyebilirsiniz... Hem de çok eylenceli olur... Sonra sonuçları yorum kısmına ekleyin... Ama eminim bundan sonra telefonu kulağınıza dayarken bir daha düşüneceksiniz... Video izle...
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 ABD'de, bir intihar kurbanının kalbinin nakledildiği adam, donörünün dul karısıyla evlendi ve yıllar sonra aynı şekilde intihar etti.
İngiliz Daily Mail gazetesinin internet sitesinde verilen habere göre, Sonny Graham, 1995'te kalp yetmezliği yüzünden ölümün eşeğine geldi. Sadece 6 aylık ömrü kalan Graham'a uygun kalp bulunduğu yönündeki müjdeli haber, Güney Carolina Üniversitesinden geldi.
Graham'a, kafasına kurşun sıkarak intihar eden Terry Cottle'ın kalbi nakledildi. Graham, kalbini aldığı kişi hakkında, 33 yaşındaki bir adam olduğunun dışında bilgi sahibi değildi.
Heart transplant man dies like suicide donor
Last Updated: 8:32pm BST 07/04/2008
A heart transplant recipient who married the former wife of the heart donor, has committed suicide in the same way as the donor did.
Twelve years ago, Sonny Graham's heart was failing and he was on the verge of death, until he received a call from doctors, saying a donor heart had just become available.
That heart belonged to Terry Cottle, 33, who had committed suicide by shooting himself in the head.
The operation was a success and soon after, Mr Graham, 69, contacted the organ donor agency, saying he wanted to thank Mr Cottle's family.
He began writing to Mr Cottle's widow, Cheryl, 39, and they soon fell in love and were married in 2004, moving to the US state of Georgia.
After the wedding, Mrs Graham said: "It helped me so much. Meeting Sonny made it easier for me, knowing something so good came from something so bad."
In a newspaper article published in 2006, Mr Graham said he felt an instant and unusual attachment when he met his donor's widow.
"I felt like I had known her for years," Mr Graham said. "I couldn't keep my eyes off her. I just stared."
But now, 12 years after the operation, Mrs Graham's life has been rocked by another tragedy.
Mr Graham killed himself with a shotgun, in circumstances similar to those which claimed Mr Cottle's life.
His friends said he had shown no signs of being depressed and were at a loss to explain his sudden death.
According to scientists, there are more than 70 documented cases of transplant patients taking on some of the personality traits of the organ donors.
http://www.telegraph.co.uk/news/main.jhtml?xml=/news/2008/04/07/wheart107.xml |
Bir yıl sonra Graham organ bağışı kurumuna başvurarak kalbini veren kişinin kimliğini öğrenmek ve ailesine teşekkür etmek istedi. Graham, Terry Cottle'ın dul karısı Cheryl ile mektuplaşmaya başladı. Daha sonra görüşmeye başlayan Graham ile Cheryl, birbirine aşık oldu ve evlendi.
Kalp naklinin üzerinden 12 yıl geçtikten sonra Graham çenesinin altından kurşun sıkarak intihar etti ve eşinin aynı korkunç şeyleri tekrar yaşamasına sebep oldu.
Bilim adamları, nakil geçiren hastaların, organını aldıkları kişilerin karakter özelliklerinin bazılarını aldıklarını gösteren 70 kadar vaka olduğunu bildirdiler.
Lancashire'dan bir kadın, böbrek naklinden sonra edebiyat zevkinin değiştiğini, ünlülerin biyografilerini ve en çok satan popüler kitapları okumaktan zevk alırken, nakilden sonra klasikleri tercih etmeye başladığını anlatmıştı.
Yine de bazı uzmanlar, hastada karakter değişimi konusunda yeterli kanıt olmadığına işaret ediyor.
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 Bilgisayarınızda geleneksel silikon yapı bileşenleri yerine DNA ve moleküler biyoloji teknolojilerinden yararlanılsa ne olurdu? Hacmi sadece 1 cm³ olan 1 gram DNA, 750 terabayt bilgi barındırabilir.
DNA Bilgisayarları
Günümüzdeki en hızlı PC'den yüz bin kat daha hızlı, saniyede 330 trilyon işlem kapasiteli bir bilgisayar düşünün. En çarpıcı tarafı, bu bilgisayar, silikon değil, DNA işlemcili...
Aslında biyo-kimyasal nano-bilgisayarlar doğada, yaşayan her organizmanın bünyesinde var. Ancak bu düne kadar insanlığın hayalinde olmadığı gibi, bugün de erişiminde değil. Örneğin bir ağaca Pi sayısını henüz soramazsınız... Ancak biyo-moleküler bilgisayarlar, "hücredeki doktor" olarak görev yaparak, yaşayan organizmaların bünyesindeki anomalileri olay yerinde, anında teşhis ve tedavi edebilirler...
Hayali bile şaşırtıcı bir düşünce ama bilim adamları uzun zamandır bu konu üzerinde laboratuvarlarında sessiz sedasız çalışıyorlar. Nörofizyologlar beynin gizemli mekanizmasını keşfedebilmek için ilk önce yaşamsal fonksiyonlarını nasıl yerine getirebildiğini çözebilmeyi hedeflediler. Algıların yanı sıra, öğrenme ve fonksiyonların gerçekleştiği beynin hippocampus bölgesinin bir protezinin yapılması hedeflendi.
Computer Made from DNA and Enzymes
Israeli scientists have devised a computer that can perform 330 trillion operations per second, more than 100,000 times the speed of the fastest PC. The secret: It runs on DNA.
A year ago, researchers from the Weizmann Institute of Science in Rehovot, Israel, unveiled a programmable molecular computing machine composed of enzymes and DNA molecules instead of silicon microchips. Now the team has gone one step further. In the new device, the single DNA molecule that provides the computer with the input data also provides all the necessary fuel.
The design is considered a giant step in DNA computing. The Guinness World Records last week recognized the computer as "the smallest biological computing device" ever constructed. DNA computing is in its infancy, and its implications are only beginning to be explored. But it could transform the future of computers, especially in pharmaceutical and biomedical applications.
Following Mother Nature's Lead
Biochemical "nanocomputers" already exist in nature; they are manifest in all living things. But they're largely uncontrollable by humans. We cannot, for example, program a tree to calculate the digits of pi. The idea of using DNA to store and process information took off in 1994 when a California scientist first used DNA in a test tube to solve a simple mathematical problem.
Since then, several research groups have proposed designs for DNA computers, but those attempts have relied on an energetic molecule called ATP for fuel. "This re-designed device uses its DNA input as its source of fuel," said Ehud Shapiro, who led the Israeli research team.
Think of DNA as software, and enzymes as hardware. Put them together in a test tube. The way in which these molecules undergo chemical reactions with each other allows simple operations to be performed as a byproduct of the reactions. The scientists tell the devices what to do by controlling the composition of the DNA software molecules. It's a completely different approach to pushing electrons around a dry circuit in a conventional computer.
To the naked eye, the DNA computer looks like clear water solution in a test tube. There is no mechanical device. A trillion bio-molecular devices could fit into a single drop of water. Instead of showing up on a computer screen, results are analyzed using a technique that allows scientists to see the length of the DNA output molecule.
"Once the input, software, and hardware molecules are mixed in a solution it operates to completion without intervention," said David Hawksett, the science judge at Guinness World Records. "If you want to present the output to the naked eye, human manipulation is needed."
Don't Run to the PC Store Just Yet
As of now, the DNA computer can only perform rudimentary ********s, and it has no practical applications. "Our computer is programmable, but it's not universal," said Shapiro. "There are computing tasks it inherently can't do."
The device can check whether a list of zeros and ones has an even number of ones. The computer cannot count how many ones are in a list, since it has a finite memory and the number of ones might exceed its memory size. Also, it can only answer yes or no to a question. It can't, for example, correct a misspelled word.
In terms of speed and size, however, DNA computers surpass conventional computers. While scientists say silicon chips cannot be scaled down much further, the DNA molecule found in the nucleus of all cells can hold more information in a cubic centimeter than a trillion music CDs. A spoonful of Shapiro's "computer soup" contains 15,000 trillion computers. And its energy-efficiency is more than a million times that of a PC.
While a desktop PC is designed to perform one calculation very fast, DNA strands produce billions of potential answers simultaneously. This makes the DNA computer suitable for solving "fuzzy logic" problems that have many possible solutions rather than the either/or logic of binary computers. In the future, some speculate, there may be hybrid machines that use traditional silicon for normal processing tasks but have DNA co-processors that can take over specific tasks they would be more suitable for.
Doctors in a Cell
Perhaps most importantly, DNA computing devices could revolutionize the pharmaceutical and biomedical fields. Some scientists predict a future where our bodies are patrolled by tiny DNA computers that monitor our well-being and release the right drugs to repair damaged or unhealthy tissue.
"Autonomous bio-molecular computers may be able to work as 'doctors in a cell,' operating inside living cells and sensing anomalies in the host," said Shapiro. "Consulting their programmed medical knowledge, the computers could respond to anomalies by synthesizing and releasing drugs."
DNA computing research is going so fast that its potential is still emerging. "This is an area of research that leaves the science fiction writers struggling to keep up," said Hawksett from the Guinness World Records. |
1996’da biyomedikal mühendis Theodore W. Berger, hippocampusun aktivitesini üretebilen, özel olarak tasarlanmış bir DNA çipi üretti. Şimdi ise mikroelektrodlarla bu çipi beyin hücrelerine (neuron) bağlamayı hedefliyor. Berger, kendi kara kutusunu inşa ederek beyni kopya edebilmek ve hippocampusun her algısı karşılığında ürettiği cevabın kusursuz olarak aynısını üretebilmeye çalışıyor. Hippocampusun özel bir bölgesi olan ‘dentate gyrus’ dokusunun taklidi bu yolla yapılmış bulunuyor. Böylece beynin her bölümünün fonksiyonlarını yerine getirebilecek çiplerin yapılabileceği de kanıtlanmış oluyor. Bu yaklaşımı kullanarak gerçek nöronları ve gerçek beyin sistemlerini kurabilmeyi amaçlayan Berger’in ümidi sadece belleği ve öğrenmeyi değil, hareketi ve algıları yöneten beyin bölgelerini de çözümleyebilmek.
1997’de CALTECH’te bir araştırma grubunun sonuçlanan araştırmalarının açıklanmasıyla, geliştirilen neurochip metodunun canlı beyin hücrelerine bağlanması başarıldı. Ayrıştırılan hippocampus hücresinin, yine in vitro olarak neurochipin bulunduğu ortama yerleştirilmesiyle ve beslenmesi için gerekli ortamın sağlanmasıyla, hücre dendritler ve akson geliştirdiğinde hemen yanındaki hücrenin akson ve dendirtleriyle elektrik bağlantısı kurup bilgi iletimini kurar. Bu gelişme neural networkler üzerine yapılan araştırmalarda çok önemli bir adımı belgeliyor.
1994 yılında ortaya konulan DNAya dayanan bilgisayar kavramı kombinasyon temelli problemlerin çözümünü hedefliyor. Yaşamın temel taşı olan ve en basitten en karmaşığına bütün canlıların fonksiyonlarını kodlayan DNA molekülünün basit ve kararlı yapısı, karmaşık matematik problemlerinin çözümü olarak önerilmiş. DNA bilgisayarları ‘Hamiltonian Path Problem’ olarak adlandırılan ve DNAnın yapısını kullanarak çözüm üreten bir sistem. Kombinasyon temelli problemleri seri olarak çözmeye çalışan geleneksel bir bilgisayarın masif paralel olan DNA bilgisayarının hızına erişmesi asla mümkün olamaz. DNA bilgisayarlarının çok daha az enerji gerektirdiğini ve daha da önemlisi 1000 litre suyun, şimdiye kadar üretilmiş normal bilgisayar hafızalarından daha fazla bilgi tutabileceği ya da 1 kilogran DNA’nın bilişim kapasitesinin şimdiye kadar üretilmiş bilgisayarlardan daha fazla olduğunu göz önünde bulundurursak, bu sistemin kapasitesini anlayabiliriz.
Şaşırtıcı mı? O halde çok daha fazla şaşırmaya hazır olun... Çünkü doğadaki süper bilgisayarların sırrı henüz bitmedi... adhoc.blogcu.com'u izleyin...
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İngiltere, kök hücre araştırmalarında insan hayvan karışımı melez embriyolar üretilmesine izin verdi. Hayvan ve insan DNA'larıyla kök hücre oluşturulmasını hedefleyen çalışmalar, başta Alzheimer olmak üzere birçok hastalığın tedavisinde bir dönüm noktası olarak görülüyor.
Kök hücreler vücudumuzda bütün dokuları ve organları oluşturan ana hücrelerdir. Henüz farklılaşmamış olan bu hücreler sınırsız bölünebilme ve kendini yenileme, organ ve dokulara dönüşebilme yeteneğine sahiptir. Bu özellikleri bakımından kök hücreler kanser, sinir sistemi hastalıkları (Alzheimer) ve hasarları, metabolik hastalıklar (diyabet), organ yetmezlikleri, romatizmal hastalıklar, kalp hastalıkları, kemik hastalıkları ve daha birçok alanda kullanıma sahiptirler. Günümüzde bu hastalıkların bazılarının tedavisinde organ veya doku nakilleri yapılmaktadır. Ancak, organ veya doku nakli gerektiren hastaların çokluğu, uygun organ ve dokunun her zaman bulunamaması gibi sorunlarla sürekli karşılaşılmaktadır. Bilim ve teknolojideki son gelişmeler doğrultusunda Kök hücrelerin bu alanda kullanılması gündeme gelmiştir.
İnsan türü tek bir hücrenin çoğalmasıyla meydana gelmiştir bu hücre zigot olarak adlandırılır. Bu yapı döllenmeden hemen sonra oluşur. Zigot daha bölünmeye başlar ve bu bölünme sonucunda embriyo (cenin) meydana gelir. Embriyo bölünmeye devam eder ve embriyonun hücre sayısı katlanarak artar. Döllenmeden yaklaşık 5 gün sonra ise 150 hücre civarında içi sıvı ile dolmaya başlayan kistik bir yapı oluşur. Bu yapı blastokist olarak adlandırılır. Blastokist bir kum taneciğinden daha küçüktür ve içerisinde artık iki tür hücre gurubu barındırmaktadır. Bu yapının iç kısmında bebeği oluşturmak üzere gruplanan hücreler embryonik hücreler olarak adlandırılır. Bu hücre gurubu vücudun bütün organ ve dokularını oluşturmak üzere çoğalıp yönleneceklerdir ve tıp dilinde pluripotent hücreler olarak adlandırılırlar. Dolayısıyla embriyo bölünmeye başladığından itibaren oluşan kök hücreler embriyonik kök hücrelerdir. Pratikte embriyonik kök hücre denince blastokist içerisindeki embriyoblast denilen ve bebeği oluşturmak üzere farklılaşmış hücreler anlaşılır.
Kök hücreler aynı zamanda embriyonun bundan sonraki gelişme dönemlerinde yani fetus denen aşamada, doğumla birlikte kordon kanında ve yetişkin vücudunda da özellikle kemik iliği ve yağ dokusunda bulunurlar. Embriyonik kök hücrelere göre gelişmenin daha sonraki basamaklarında görülen bu hücreler elde edildikleri döneme göre giderek daha sınırlı bir bölünme ve farklılaşma yeteneği gösterirler. Yetişkin kök hücreler daha ziyade elde edildikleri organ ve dokuya dönüşme eğilimindedirler ve multipotent kök hücreler olarak adlandırılırlar. Yetişkinde her organ ve dokuda aynı sayı ve potansiyelde kök hücrelere rastlanmaz. Örneğin, beyinde bu hücreler oldukça az sayıda bulunmaktadır. Bu nedenle beyin hasarlarında bir kemik veya doku gibi organ yenilenmesi olmaz, hasar genellikle kalıcıdır ve ciddi sonuçlar doğurur. Günümüzde, araştırmacılar yetişkin dokulardan elde edilen kök hücrelerin diğer organ ve dokulara farklılaşması yönünde çalışmalar yapmaktadırlar.
Kök Hücre Tedavisi
Vücudumuzun önemli bir bölümünde beyin, kalp, karaciğer gibi organlara farklılaşmış hücreler ciddi hasarlar gördüklerinde doğal biçimde yenilenemez. Kök hücreler bölünebilme ve farklılaşma yetenekleri sayesinde sağlıklı ve işlev gören hücrelere farklılaşabilirler. Bu nedenle hastalık veya yaralanma nedeniyle hasar göre organ ve dokuların yenilenmesinde kullanılabilirler.
Hastalanmış hücrelerin sağlıklı hücrelerle değiştirtmesine yönelik bu tedavi biçimi "hücre tedavisi" olarak adlandırılmaktadır. Bu tedavi organ nakline benzerlik göstermektedir, ancak organ yerine hücreler kullanılmaktadır. Organ nakline göre bir diğer farkı sağlıklı hücreler kişinin kendisinde alınabilir ve bu nedenle de doku uygunluğu gibi sorunlarla karşılaşılmaz. Diğer taraftan, kordon kanı hücreleri de aynı amaçlarla kullanılabilmektedir. Ancak kordon kanı hücreleri de sanıldığının aksine kısıtlı bir kullanıma sahiptirler.
Uygun vericinin sağlanmasıyla yapılan kök hücre tedavileri kan kanseri ve diğer bazı kanser türlerinde yaygın kullanılan ve bilinen tedavi yöntemleridir. Ancak, belirgin yan etkiler ve verici bulunmasındaki zorluklar kullanımı sınırlandırmaktadır. Gelecekte kişinin kendi kök hücrelerinde yapılabilecek genetik değişimlerle birlikte yapılabilecek tedaviler daha yaygın ve etkili bir kullanım sağlayabilir.
Günümüzde araştırmacılar organ naklinin yerini alabilecek ve organ nakli olanağı olmayan hastalar için kullanılabilecek kök hücre tedavisi ile ilgili çalışmalar yapmaktadırlar. Dolayısıyla, kök hücre tedavileri henüz araştırma bazındadır. Ancak, kalp kasının yenilenmesi, diyabet, romatizma grubundaki hastalıklar, sinir sistemi hastalıları (Parkinson, Alzheimer) sinir sitemi ve omurilik yaralanmaları, karaciğer hasarları gibi birçok konuda umut vaat eden çalışmalar hızla devam etmektedir. Klinik olarak, ortopedik kusurlar, impotans gibi bazı ürolojik rahatsızlıklar ve deri hastalıklarında hücre tedavisi diğer durumlara göre daha fazla yol almıştır. Ancak, kök hücre tedavisi omurilik yaralanmalarını da içermek üzere henüz kuramsal temellidir ve pratiğe yansıyan çok az bilgi ve gelişme vardır. Vikipedi |
İngiltere, birçok ülkede etik açıdan tartışılan ve yasak olan kök hücre çalışmalarına yeni bir boyut getirdi.
İngiliz Doğurganlık ve Embriyo Kurumu'nun onayladığı çalışmalar kapsamında bilimadamları, yüzde 99.9'u insan, yüzde 0.1'i hayvan olan "melez" embriyolar üretebilecek.
İnek, tavşan ve domuz yumurtalarının kullanılmasının planlandığı çalışmalarda, insan DNA'sı hayvan yumurtasına enjekte edilerek, genetiği değiştirilmiş embriyolar oluşturulacak.
Daha sonra bu embriyolardan üretilen kök hücrelerle başta Alzheimer OLMAK üzere birçok genetik hastalığa çözüm aranacak.
Çalışmaların etik olmadığını düşünenler de var.
Vatikan, modern çağa uyarladığı yeni yedi büyük günaha genetik değişiklikler de ekledi...
Stem cells
Stem cells are cells that are able to differentiate into specialized cell types but also retain the ability to renew themselves through cell division. They were first identified in embryos. In an embryonic blastocyst, stem cells of the inner cell mass proceed to develop into all of the tissues and organs of the body. In adults, progenitor cells and possibly multipotent adult stem cells act as a repair system for the body, replenishing more specialized cells. The existence of truly pluripotent stem cells in adult human beings is still scientifically controversial.
Therapies
Since stems cells have the potential to be differentiated into basically any type of cell, they offer promise in the development of medical treatments for a wide range of conditions. These include damage to the brain, spinal cord, skeletal muscles, and the heart. Treatments that have been proposed follow either physical trauma (e.g. spinal cord injuries), degenerative conditions (e.g. Parkinson's disease), or even genetic diseases (in combination with gene therapy).
Much success and potential has been demonstrated from research using adult stem cells. There are no approved treatments or human trials using embryonic stem cells. Nevertheless, some are of the opinion that the differentiation potential of embryonic stem cells is broader than most adult stem cells. In addition, embryonic stem cells are considered more useful for nervous system therapies, as researchers have struggled to identify and isolate neural progenitors from adult tissues. Embryonic stem cells, however, might be rejected by the immune system - a problem which wouldn't occur if the patient received his or her own stem cells.
Alternative sources
Some stem cell researchers are working to develop techniques of isolating stem cells that are as potent as embryonic stem cells, but do not require a human embryo.
Some believe that human somatic cells can be coaxed to "de-differentiate" and revert to an embryonic state. Researchers at Harvard University, led by Kevin Eggan, have attempted to transfer the nucleus of a somatic cell into an existing embryonic stem cell, thus creating a new stem cell line. Another study published in August 2006 also indicates that differentiated cells can be reprogrammed to an embryonic-like state by introducing four specific factors.
Researchers at Advanced Cell Technology, led by Robert Lanza, reported the successful derivation of a stem cell line using a process similar to preimplantation genetic diagnosis, in which a single blastomere is extracted from a blastocyst. At the 2007 meeting of the International Society for Stem Cell Research (ISSCR), Lanza announced that his team had succeeded in producing three new stem cell lines without destroying the parent embryos. "These are the first human embryonic cell lines in existence that didn't result from the destruction of an embryo." Lanza is currently in discussions with the National Institutes of Health (NIH) to determine whether the new technique sidesteps U.S. restrictions on federal funding for ES cell research.
According to a January 9, 2007 Daily Telegraph (London) article reporting on a statement by Dr. Anthony Atala of Wake Forest University, there is another "ethical" source of stem cells. The fluid surrounding the fetus has been found to contain stem cells, that, when utilized correctly, "can be differentiated towards cell types such as fat, bone, muscle, blood vessel, nerve and liver cells", according to the article. The extraction of this fluid does not harm the fetus in any way as well. "Our hope is that these cells will provide a valuable resource for tissue repair and for engineered organs as well," said Dr Atala.
Patents
The patents covering a lot of work on human embryonic stem cells are owned by the Wisconsin Alumni Research Foundation (WARF). WARF does not charge academics to study human stem cells but does charge commercial users. WARF sold Geron Corp. exclusive rights to work on human stem cells but later sued Geron Corp. to recover some of the previously sold rights. The two sides agreed that Geron Corp. would keep the rights to only three cell types. In 2001 WARF came under public pressure to widen access to human stem-cell technology.
These patents are now in doubt as a request for review by the US Patent and Trademark Office has been filed by non-profit patent-watchdogs The Foundation for Taxpayer & Consumer Rights and the Public Patent Foundation as well as molecular biologist Jeanne Loring of the Burnham Institute. According to them, two of the patents granted to WARF are invalid because they cover a technique published in 1992 for which a patent had already been granted to an Australian researcher. Another part of the challenge states that these techniques, developed by James A. Thomson, are rendered obvious by a 1990 paper and two textbooks.
The outcome of this legal challenge is particularly relevant to the Geron Corp. as it can only license patents that are upheld.
Viewpoints
The status of the human embryo and human embryonic stem cell research is a controversial issue as, with the present state of technology, the creation of a human embryonic stem cell line requires the destruction of a human embryo. Stem cell debates have motivated and reinvigorated the pro-life movement, whose members are concerned with the rights and status of the embryo as an early-aged human life. They believe that embryonic stem cell research instrumentalizes and violates the sanctity of life and constitutes murder. The fundamental assertion of those who oppose embryonic stem cell research is the belief that human life is inviolable, combined with the opinion that human life begins when a sperm cell fertilizes an egg cell to form a single cell.
A portion of stem cell researchers use embryos that were created but not used in in vitro fertility treatments to derive new stem cell lines. Most of these embryos are to be destroyed, or stored for long periods of time, long past their viable storage life. In the United States alone, there have been estimates of at least 400,000 such embryos. This has led some opponents of abortion, such as Senator Orrin Hatch, to support human embryonic stem cell research.
Medical researchers widely submit that stem cell research has the potential to dramatically alter approaches to understanding and treating diseases, and to alleviate suffering. In the future, most medical researchers anticipate being able to use technologies derived from stem cell research to treat a variety of diseases and impairments. Spinal cord injuries and Parkinson's disease are two examples that have been championed by high-profile media personalities (for instance, Christopher Reeve and Michael J. Fox). The anticipated medical benefits of stem cell research add urgency to the debates, which has been appealed to by proponents of embryonic stem cell research.
Recently, researchers at Advanced Cell Technology of Worcester, Mass., succeeded in obtaining stem cells from mouse embryos without killing the embryos. If this technique and its reliability are improved, it would alleviate some of the ethical problems related to embryonic stem cell research.
Another technique announced in 2007 may also defuse the longstanding debate and controversy. Research teams in the United States and Japan have developed a simple and cost effective method of reprogramming human skin cells to functıon much like embryonic stem cells by introducing artificial viruses. While extracting and cloning stem cells is complex and extremely expensive, the newly discovered method of reprogramming cells is much cheaper. However, the technique may disrupt the DNA in the new stem cells, resulting in damaged and cancerous tissue. More research will be required before non-cancerous stem cells can be created.
Endorsement
Utilitarianism
The benefits of stem cell research outweigh the cost in terms of embryonic life
Embryonic stem cells have the capacity to grow indefinitely in a laboratory environment and can differentiate into almost all types of bodily tissue. This makes embryonic stem cells an attractive prospect for cellular therapies to treat a wide range of diseases.
The social, economic and personal costs of the diseases that embryonic stem cells have the potential to treat are far greater than the costs associated with the destruction of embryos.
Human potential and humanity
This argument often goes hand-in-hand with the utilitarian argument, and can be presented in several forms:
Embryos, while of value, are not equivalent to human life while they are still incapable of existing outside the womb (i.e. they only have the potential for life).
Approximately 18% of zygotes do not implant after conception. Thus far more embryos are lost due to chance than are proposed to be used for embryonic stem cell research or treatments.
Blastocysts are a cluster of human cells that have not differentiated into distinct organ tissue; making cells of the inner cell mass no more "human" than a skin cell .
Some parties contend that embryos are not humans, believing that the life of Homo sapiens only begins when the heartbeat develops, which is during the 5th week of pregnancy, or when the brain begins developing activity, which has been detected at 54 days after conception.
Consequentialism
The ends (i.e. new treatments and cures) justify the means (i.e. the destruction of embryos)
This can be seen as a more extreme view of the utilitarianism argument.
Efficiency
If an embryo is going to be destroyed anyway, isn't it more efficient to make practical use of it?
In vitro fertilization (IVF) generates large numbers of unused embryos (e.g. 70,000 in Australia alone). Many of these thousands of IVF embryos are slated for destruction. Using them for scientific research utilizes a resource that would otherwise be wasted.
While the destruction of human embryos is required to establish a stem cell line, no new embryos have to be destroyed to work with existing stem cell lines. It would be wasteful not to continue to make use of these cell lines as a resource.
Abortions are legal in many countries and jurisdictions. A logical argument follows that if these embryos are being destroyed anyway, why not use them for stem cell research or treatments?
Superiority
Embryonic stem cells can be considered far more useful therapeutically than adult stem cells
This is usually presented as a counter-argument to using adult stem cells as an alternative that doesn't involve embryonic destruction. The claim, however, is completely fictional.
Embryonic stem cells make up a significant proportion of a developing embryo, while adult stem cells exist as minor populations within a mature individual (e.g. in every 10,000 cells of the bone marrow, only 10 will be usable stem cells). Thus, embryonic stem cells are likely to be easier to isolate and grow ex vivo than adult stem cells.
Embryonic stem cells divide more rapidly than adult stem cells, potentially making it easier to generate large numbers of cells for therapeutic means. In contrast, adult stem cell might not divide fast enough to offer immediate treatment.
Embryonic stem cells have greater plasticity, allowing them to treat a wider range of diseases.
Adult stem cells from the patient's own body might not be effective in treatment of genetic disorders. Allogeneic embryonic stem cell transplantation (i.e. from a healthy donor) may be more practical in these cases than gene therapy of a patient's own cell.
DNA abnormalities found in adult stem cells that are caused by toxins and sunlight may make them poorly suited for treatment.
Embryonic stem cells have been shown to be effective in treating heart damage in mice.
Beginning of life
Before the primitive streak is formed when the embryo attaches to the uterus at approximately 14 days after fertilization, a single fertilized egg can split in two to form identical twins. Also, rarely, two separately fertilized eggs can, instead of resulting in fraternal twins, fuse together and develop into a single human individual (a tetragametic chimera).
Therefore before the primitive streak is formed, an individual human life does not exist at fertilization, as it can go on to split into two separate individuals. Therefore, an individual human life begins when the primitive streak is formed — beyond which the cell group cannot split to make twins — and not before. Therefore the blastocysts destroyed for embryonic stem cells do not have human life, and it is ethical to use them.
Objection
Value of life
An embryo is actually a human; it should be valued as highly as a human life.
The reasoning can be summed up by the fact that, once an egg is fertilized, unless inhibited, it will develop into a fully-developed adult. This opinion is often related to religious doctrines which assert that conception marks the beginning of human life or the presence of a soul. Based upon this reasoning, the subsequent argument against embryonic stem cell research is that human life is inherently valuable and should not be involuntarily destroyed.
It has been argued that "the line at which an embryo becomes a human life remains as arbitrary as ever".
Viability is another standard under which embryos and fetuses have been regarded as human lives. In the United States, the 1973 Supreme Court case of Roe v. Wade concluded that viability determined the permissibility of abortions performed for reasons other than the protection of the woman's health, defining viability as the point at which a fetus is "potentially able to live outside the mother's womb, albeit with artificial aid." The point of viability was 24 to 28 weeks when the case was decided and has since moved to about 22 weeks due to advancement in medical technology. If further technological advances allow a sperm and egg to be combined and fully developed completely outside of the womb, an embryo will be viable as soon as it is conceived, and under the viability standard, life will begin at conception.
Better alternatives
Embryonic stem cells should be abandoned in favor of alternatives, such as those involving adult stem cells.
This argument is used by opponents of embryonic destruction as well as researchers specializing in adult stem cell research.
It is often claimed by pro-life supporters that the use of adult stem cells from sources such as umbilical cord blood has consistently produced more promising results than the use of embryonic stem cells. Furthermore, adult stem cell research may be able to make greater advances if less money and resources were channeled into embryonic stem cell research.
Adult stem cells have already produced therapies, while embryonic stem cells have not. Moreover, there have been many advances in adult stem cell research, including a recent study where pluripotent adult stem cells were manufactured from differentiated fibroblast by the addition of specific transcrıption factors. Newly created stem cells were developed into an embryo and were integrated into newborn mouse tissues, analogous to the properties of embryonic stem cells.
This argument remains hotly debated on both sides. Those critical of embryonic stem cell research point to a current lack of practical treatments, while supporters argue that advances will come with more time and that breakthroughs cannot be predicted.
Scientific flaws
The use of embryonic stem cell in therapies may be fundamentally flawed.
For instance, one study suggests that autologous embryonic stem cells generated for therapeutic cloning may still suffer from immune rejection. The researchers note that: "Our results raise the provocative possibility that even genetically matched cells derived by therapeutic cloning may still face barriers to effective transplantation for some disorders." In other words, therapeutic cloning may not always produce matched tissues. In contrast, there are reports of adult stem cells being successfully reintegrated into an autogenic animal.
Another concern with embryonic stem cell treatments is a tendency of stem cells from embryos to create tumors. However, the tumorigenic potential of embryonic stem cells remains poorly described.
Overstatement of research potential
Scientists have long promised spectacular results from embryonic stem cell research, and this has not yet occurred.
Conspicuously, such criticism has even come from researchers themselves. For example, in November 2004, Princeton University president and geneticist Shirley Tilghman said, "Some of the public pronouncements in the field of stem-cell research come close to overpromising at best and delusional fantasizing at worst." Similarly, fertility expert and former president of the British Association for the Advancement of Science, Lord Winston has warned of a public backlash against stem cell research if it fails to deliver on some of the "hype" surrounding potential treatments. In it's defence, stem cell research has been hindered by laws against it and it's benefits have had little chance to be fully developed.
Policy debate in the United States
Origins
In 1969, the first human in vitro fertilization was accomplished and in 1973, Roe v. Wade legalized abortion nationwide. These developments prompted the federal government to create regulations barring the use of federal funds for research that experimented on human embryos. In 1995, the NIH Human Embryo Research Panel advised the Clinton administration to permit federal funding for research on embryos left over from in vitro fertility treatments and also recommended federal funding of research on embryos specifically created for experimentation. In response to the panel's recommendations, the Clinton administration, citing moral and ethical concerns, declined to fund research on embryos created solely for research purposes, but did agree to fund research on left-over embryos created by in vitro fertility treatments. At this point, the Congress intervened and passed the Dickey Amendment in 1995 (the final bill, which included the Dickey Amendment, was signed into law by Clinton) which prohibited all federal funding for research that resulted in the destruction of an embryo regardless of the source of that embryo. The Dickey Amendment remains the law to this day.
In 1998, privately funded research led to the breakthrough discovery of Human Embryonic Stem Cells (hESC). This prompted the Clinton Administration to re-examine guidelines for federal funding of embryonic research. In 1999, the president's National Bioethics Advisory Commission recommended that hESC harvested from embryos discarded after in vitro fertility treatments, but not from embryos created expressly for experimentation, be eligible for federal funding. Even though embryos are always destroyed in the process of harvesting hESC, the Clinton Administration decided that it would be permissible under the Dickey Amendment to fund hESC research as long as such research did not itself directly cause the destruction of an embryo. Therefore, HHS issued its proposed regulation concerning hESC funding in 2001. Enactment of the new guidelines was delayed by the incoming Bush administration which decided to reconsider the issue.
President Bush announced, on August 9, 2001 that federal funds, for the first time, would be made available for hESC research on currently existing stem cell lines; however, the Bush Administration chose not to permit taxpayer funding for research on hESC cell lines not currently in existence, thus limiting federal funding to research in which "the life-and-death decision has already been made". The Bush Administration's guidelines differ from the Clinton Administration guidelines which did not distinguish between currently existing and not-yet-existing hESC. Both the Bush and Clinton guidelines agree that the federal government should not fund hESC research that directly destroys embryos.
Neither Congress nor any administration has ever prohibited private funding of embryonic research. Public and private funding of research on adult and cord blood stem cells is unrestricted.
U.S. Congressional response
In April 2004, 206 members of Congress signed a letter urging President Bush to expand federal funding of embryonic stem cell research beyond what Bush had already supported.
In May 2005, the House of Representatives voted 238-194 to loosen the limitations on federally funded embryonic stem-cell research — by allowing government-funded research on surplus frozen embryos from in vitro fertilization clinics to be used for stem cell research with the permission of donors — despite Bush's promise to veto the bill if passed. On July 29, 2005, Senate Majority Leader William H. Frist (R-TN), announced that he too favored loosening restrictions on federal funding of embryonic stem cell research. On July 18, 2006, the Senate passed three different bills concerning stem cell research. The Senate passed the first bill (Stem Cell Research Enhancement Act), 63-37, which would have made it legal for the Federal government to spend Federal money on embryonic stem cell research that uses embryos left over from in vitro fertilization procedures. On July 19, 2006 President Bush vetoed this bill. The second bill makes it illegal to create, grow, and abort fetuses for research purposes. The third bill would encourage research that would isolate pluripotent, i.e., embryonic-like, stem cells without the destruction of human embryos.
In 2005 and 2007, Congressman Ron Paul introduced the Cures Can Be Found Act, with 10 cosponsors. With an income tax credit, the bill favors research upon nonembryonic stem cells obtained from placentas, umbilical cord blood, amniotic fluid, humans after birth, or unborn human offspring who died of natural causes; the bill was referred to committee. Paul argued that hESC research is outside of federal jurisdiction either to ban or to subsidize.
Bush vetoed another bill, the Stem Cell Research Enhancement Act of 2007, which would have amended the Public Health Service Act to provide for human embryonic stem cell research. The bill passed the Senate on April 11 by a vote of 63-34, then passed the House on June 7 by a vote of 247-176. President Bush vetoed the bill on June 19, 2007.
Funding
Currently, the National Institutes of Health has 399 funding opportunities for researchers interested in hESC. In 2005 the NIH funded $607 million worth of stem cell research, of which $39 million was specifically used for hESC. Of the 514 currently recruiting clinical trials that are using stem cells as treatment, the federal government is supporting 206 of them; however, none of these trials are using hESC. Sigrid Fry-Revere has argued that private organizations, not the federal government, should provide funding for stem-cell research, so that shifts in public opinion and government policy would not bring valuable scientific research to a grinding halt. Wikipedia
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