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Thursday, December 11, 2008

Genetically modified organism, Uses of GMOs, Transgenic microbes

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 are generally known as recombinant DNA technology. With this technology, DNA molecules from different sources 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.


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 have been thoroughly discussed at the Asilomar Conference in Pacific Grove, California. The recommendations laid out from this meeting were 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 the 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 was dropped.

Uses of GMOs

Examples of GMOs are highly diverse, and include transgenic (genetically modified by recombinant DNA methods) animals such as mice, fish, transgenic plants, or various microbes, such as fungi and bacteria. GMOs are used for many reasons, chief among them are their use in research that addresses questions in biology or medicine, for the production of pharmaceuticals, and for direct applications aimed at improving human health (e.g., gene therapy) or agriculture (e.g., golden rice). The term "genetically modified organism" does not always imply, but can include, targeted insertions of genes from one into another species. 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. These and other methods are useful and indispensable tools for biologists in many areas of research, including those that study the mechanisms of human and other diseases or fundamental biological processes in eukaryotic or prokaryotic cells.

Transgenic microbes

Bacteria were the first organisms to be modified in the laboratory, due to their simple genetics. These organisms are now used in a variety of tasks, 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. These recombinant proteins are much safer than the products they replaced, since the older products were purified from cadavers and could transmit diseases. Indeed the human-derived proteins caused many cases of AIDS and hepatitis C in haemophilliacs and Creutzfeldt-Jakob disease from human growth hormone.

In addition to bacteria being used for producing proteins, genetically modified viruses allow gene therapy. Gene therapy is a relatively new idea in medicine. A virus reproduces by injecting its own genetic material into an existing cell. That cell then follows the instructions in this genetic material and produces more viruses. In medicine this process is adapted to deliver a gene that could 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 incurable diseases, such as cystic fibrosis, sickle cell anemia, and muscular dystrophy.

For instance, the bacteria in your mouth which causes tooth decay is called Streptococcus mutans. This bacteria eats left over sugars in your mouth and produces acid that eats away tooth enamel and causes cavities. Scientists have recently modified Streptococcus mutans to produce ethanol. This transgenic bacterium, if properly colonized in a person's mouth, could possibly eliminate cavities and other tooth related issues. Transgenic microbes have also been used in recent research to kill or hinder tumors, and fight Crohn's disease. Genetically modified bacteria is also used in some soils to facilitate crop growth, and can also produce chemicals which are toxic to crop pests.

Transgenic animals

Transgenic animals are used as experimental models to perform phenotypic tests with genes whose function is unknown or to generate 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.

Frequently used in genetic research are transgenic fruit flies (Drosophila melanogaster) as genetic models to study the effects of genetic changes on development. Flies are often preferred over other animals for ease of culture, and also because the fly genome is somewhat simpler than that of vertebrates. Transgenic mice are often used to study cellular and tissue-specific responses to disease.

* Enviropig

[Transgenic plants

Transgenic plants have been developed for various purposes. Among many, these include 1) resistance to pests, herbicides or harsh environmental conditions, 2) improved product shelflife, and 3) increased nutritional value. Since the first commercial cultivation of GM plants in 1996, GM plants tolerant to the herbicides glufosinate or glyphosate, and producing the Bt toxin, an insecticide, have dominated the agriculutral seed market for corn and other crops. Recently, a new generation of GM plants promising benefits for consumers and industry purposes is entering the market.

Whenever GM plants are grown on open fields without containment there are risks that the modification will escape into the general environment. This occurred on Canadian farmer Percy Schmeiser's farm in Bruno, Sakatchewan, Canada and led to a controversial court ruling regarding seed patents of the multinational corporation Monsanto. 75% of all farmers on earth depend on saved seeds to plant their farms each season and cross pollination or any other natural process that may bring a GMO organism to a farmer's land put's the farmer under infringement of patents. Most countries require biosafety studies prior to the approval of a new GM plant release, usually followed by a monitoring program to detect environmental impacts.

Especially in Europe, the coexistence of GM plants with conventional and organic crops has raised many concerns. 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, these are biological containment methods, isolation distances and pollen barriers.

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