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Genetically modified organism

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This article is about organisms which have been genetically modified. For information on the techniques of genetic modification, see transfection, gene knockout, and knock-in.
"GMO" redirects here. For other uses, see GMO (disambiguation).
File:GloFish.jpg
GloFish: the first genetically modified animal to be sold as a pet

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.

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.[1] 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 laid out from this meeting was that government oversight of recombinant DNA research should be established until the technology was deemed safe.[2][3] 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.[4]

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

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. These and other methods are useful 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.[5] 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.[6]

Genetically modified bacteria are used to produce the protein insulin to treat diabetes.[7] Similar bacteria have been used to produce clotting factors to treat haemophilia,[8] and human growth hormone to treat various forms of dwarfism.[9][10] These recombinant proteins are much safer than the products they replaced, since the older products were purified from cadavers and could transmit diseases.[11] Indeed the human-derived proteins caused many cases of AIDS and hepatitis C in haemophilliacs and Creutzfeldt-Jakob disease from human growth hormone.[12][11]

In addition to bacteria being used for producing proteins, genetically modified viruses allow gene therapy.[13] 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 engineered 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,[14] and treatments are being developed for a range of other currently incurable diseases, such as cystic fibrosis,[15] sickle cell anemia,[16] and muscular dystrophy.[17]

For instance, the bacteria found that cause tooth decay are called Streptococcus mutans. These bacteria consume left over sugars in the mouth, producing acid that corrodes tooth enamel and ultimately causes cavities. Scientists have recently modified Streptococcus mutans to produce ethanol.[citation needed] These transgenic bacteria, if properly colonized in a person's mouth, could possibly reduce the formation cavities. Transgenic microbes have also been used in recent research to kill or hinder tumors, and fight Crohn's disease.[citation needed] Genetically modified bacteria are 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. Genetic modification can also produce animals that are susceptible to certain compounds or stresses for testing in biomedical research.[18] Other applications include the production of human hormones like insulin.

In biological research, transgenic fruit flies (Drosophila melanogaster) are model organisms used to study the effects of genetic changes on development.[19] Fruit flies are often preferred over other animals due to their fast generation time, cheap maintenance, and relatively simple genome compared to many vertebrates. Transgenic mice are often used to study cellular and tissue-specific responses to disease.

Transgenic plants

Kenyans examining insect-resistant transgenic Bt corn

Transgenic plants have been engineered to possess several desirable traits, including resistance to pests, herbicides or harsh environmental conditions, improved product shelflife, 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 produce the Bt toxin, a potent insecticide.

Whenever GM plants are grown on open fields without containment, there are risks that their genetically altered seeds will escape into the general environment.[citation needed] 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 GM 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.[citation needed]

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

See also: Genetically modified food controversies

The use of GMOs has sparked significant controversy in many areas [4]. 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.

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 and 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.

Governmental support and opposition

United States

In 2004, Mendocino County, California became the first county 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.[5][dead link][citation needed]

New Zealand

In New Zealand, no genetically modified food is sold and no medicines containing live genetically-modified organisms have been approved for use.[20] However, medicines manufactured using genetically modified organisms that do not contain live organisms have been approved for sale.

Canada

In 2005, a standing committee of the government of Prince Edward Island in Canada began work to assess a proposal to ban the production of GMOs in the province. PEI has already banned GM potatoes, which account for most of its crop. Mainland Canada is one of the worlds largest producers of GM canola.

Australia

Several states of Australia have had moratoria on the planting of GM food crops dating from around 2003.[21] However, in late 2007 the states of New South Wales and Victoria lifted these bans.[22] A new government in Western Australia is to lift the states moritorium,[23] while South Australia continues its ban.[24] Tasmania has extended its moratorium until June 2008.[25] The state of Queensland has allowed the growing of GM crops since 1995 and has never had a GM ban.[26]

Currently, there is little international consensus regarding the acceptability and effective role of modified "complete" organisms such as plants or animals.

Cross-pollination concerns

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. Recent research with creeping bentgrass has lent support to the concern when modified genes were found in normal grass up to 21 km (13 miles) away from the source, and also within close relatives of the same genus (Agrostis) [6]. 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, a 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 coexistence of GM and conventional farming. This also includes research on biological containment strategies and other measures, that prevent outcrossing and enable the implementation of coexistence.

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'[7]. 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 and the United States Department of Agriculture. Delta and Pine Land was bought by Monsanto 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[8][9]. 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.

See also

References

  1. ^ Cohen, SN; et al. (1973). "Construction of Biologically Functional Bacterial Plasmids In Vitro". PNAS USA. 70 (11): 3240–3244. PMID 4594039. {{cite journal}}: Explicit use of et al. in: |first= (help)
  2. ^ Berg, P; et al. (1975). "Summary statement of the Asilomar Conference on recombinant DNA molecules". PNAS USA. 72 (6): 1981–1984. {{cite journal}}: Explicit use of et al. in: |first= (help); Unknown parameter |pmcid= ignored (|pmc= suggested) (help), also Science 188, p. 991 (1975).
  3. ^ "Guidelines for research involving recombinant DNA molecules," Federal Register 41, no. 131, pp. 27911-27943 (1976).
  4. ^ "The insulin synthesis is the first laboratory production DNA technology". Genentech. 1978. {{cite web}}: Unknown parameter |accessmonthday= ignored (help); Unknown parameter |accessyear= ignored (|access-date= suggested) (help); Unknown parameter |day= ignored (help); Unknown parameter |month= ignored (help)
  5. ^ Melo EO, Canavessi AM, Franco MM, Rumpf R (2007). "Animal transgenesis: state of the art and applications". J. Appl. Genet. 48 (1): 47–61. PMID 17272861.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  6. ^ Leader B, Baca QJ, Golan DE (2008). "Protein therapeutics: a summary and pharmacological classification". Nat Rev Drug Discov. 7 (1): 21–39. doi:10.1038/nrd2399. PMID 18097458. {{cite journal}}: Unknown parameter |month= ignored (help)CS1 maint: multiple names: authors list (link)
  7. ^ Walsh G (2005). "Therapeutic insulins and their large-scale manufacture". Appl. Microbiol. Biotechnol. 67 (2): 151–9. doi:10.1007/s00253-004-1809-x. PMID 15580495. {{cite journal}}: Unknown parameter |month= ignored (help)
  8. ^ Pipe SW (2008). "Recombinant clotting factors". Thromb. Haemost. 99 (5): 840–50. PMID 18449413. {{cite journal}}: Unknown parameter |month= ignored (help)
  9. ^ Bryant J, Baxter L, Cave CB, Milne R (2007). "Recombinant growth hormone for idiopathic short stature in children and adolescents". Cochrane Database Syst Rev (3): CD004440. doi:10.1002/14651858.CD004440.pub2. PMID 17636758.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  10. ^ Baxter L, Bryant J, Cave CB, Milne R (2007). "Recombinant growth hormone for children and adolescents with Turner syndrome". Cochrane Database Syst Rev (1): CD003887. doi:10.1002/14651858.CD003887.pub2. PMID 17253498.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  11. ^ a b Foster PR (2000). "Prions and blood products". Ann. Med. 32 (7): 501–13. PMID 11087171. {{cite journal}}: Unknown parameter |month= ignored (help)
  12. ^ Key NS, Negrier C (2007). "Coagulation factor concentrates: past, present, and future". Lancet. 370 (9585): 439–48. doi:10.1016/S0140-6736(07)61199-4. PMID 17679021. {{cite journal}}: Unknown parameter |month= ignored (help)
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  14. ^ Cavazzana-Calvo M, Fischer A (2007). "Gene therapy for severe combined immunodeficiency: are we there yet?". J. Clin. Invest. 117 (6): 1456–65. doi:10.1172/JCI30953. PMC 1878528. PMID 17549248. {{cite journal}}: Unknown parameter |month= ignored (help)
  15. ^ Rosenecker J, Huth S, Rudolph C (2006). "Gene therapy for cystic fibrosis lung disease: current status and future perspectives". Curr. Opin. Mol. Ther. 8 (5): 439–45. PMID 17078386. {{cite journal}}: Unknown parameter |month= ignored (help)CS1 maint: multiple names: authors list (link)
  16. ^ Persons DA, Nienhuis AW (2003). "Gene therapy for the hemoglobin disorders". Curr. Hematol. Rep. 2 (4): 348–55. PMID 12901333. {{cite journal}}: Unknown parameter |month= ignored (help)
  17. ^ Foster K, Foster H, Dickson JG (2006). "Gene therapy progress and prospects: Duchenne muscular dystrophy". Gene Ther. 13 (24): 1677–85. doi:10.1038/sj.gt.3302877. PMID 17066097. {{cite journal}}: Unknown parameter |month= ignored (help)CS1 maint: multiple names: authors list (link)
  18. ^ Sathasivam K, Hobbs C, Mangiarini L; et al. (1999). "Transgenic models of Huntington's disease". Philos. Trans. R. Soc. Lond., B, Biol. Sci. 354 (1386): 963–9. doi:10.1098/rstb.1999.0447. PMC 1692600. PMID 10434294. {{cite journal}}: Explicit use of et al. in: |author= (help); Unknown parameter |month= ignored (help)CS1 maint: multiple names: authors list (link)
  19. ^ First Transgenic Mice and Fruit Flies
  20. ^ Genetically modified medicines and food New Zealand Ministry for the Environment
  21. ^ www.parliament.nsw.gov.au
  22. ^ Australian Science Media Center - 27 November 2007 [1]
  23. ^ Elizabeth Finkel, Science, Vol. 321. no. 5896, p. 1629; September 19, 2008 http://www.sciencemag.org
  24. ^ Australian Science Media Center - 8 February 2008[2]
  25. ^ DPIW - GM Moratorium Extended
  26. ^ 10 Years of GM cotton - where to from here? Jeff Bidstrup, Convener, Producers’ Forum Outlook Conference, Canberra, 2006 [3]

General

Transgenic animals

Transgenic plants

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