Genetically modified organism

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.
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.

Contents

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 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.[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.[4]

Uses of GMOs

Examples of GMOs are highly diverse, and include transgenic (genetically modified by recombinant DNA methods) animals such as mice,[5] 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.[6] 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.[7]

Genetically modified bacteria are used to produce the protein insulin, to treat diabetes.[8] Similar bacteria have been used to produce clotting factors to treat haemophilia,[9] and human growth hormone to treat various forms of dwarfism.[10][11] These recombinant proteins are much safer than the products they replaced, since the older products were purified from cadavers and could transmit diseases.[12] Indeed the human-derived proteins caused many cases of AIDS and hepatitis C in haemophilliacs and Creutzfeldt-Jakob disease from human growth hormone.[13][12]

In addition to bacteria being used for producing proteins, genetically modified viruses allow gene therapy.[14] 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,[15] and treatments are being developed for a range of other incurable diseases, such as cystic fibrosis,[16] sickle cell anemia,[17] and muscular dystrophy.[18]

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.[19] 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.[20] 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.

Transgenic plants

Kenyans examining insect-resistant transgenic Bt corn.

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.

Controversy over GMOs

See also: Genetically modified food controversies

Government support for and ban of GMOs

The use of GMOs has sparked significant controversy in many areas [5]. 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.

USA

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, 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 [6].

New Zealand

In New Zealand no genetically-modified food is sold and no medicines containing live genetically-modified organisms have been approved for use.[21] 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 [22]. However, in late 2007 the states of New South Wales and Victoria lifted these bans [23]. A new government in Western Australia is to lift the states moritorium [24] while South Australia continues its ban [25]. Tasmania has extended their moritorium to June 2008 which[26] The state of Queensland has allowed the growing of GM crops since 1995 [27] and has never had a GM ban.

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

Crosspollination 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) [7]. 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 neighbouring 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 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'[8]. 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[9][10]. 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 crosspollinating 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, S., Chang, A., Boyer, H. & Helling, R. (1973) Construction of Biologically Functional Bacterial Plasmids In Vitro. Proc. Natl. Acad. Sci. USA 70, 3240-3244
  2. ↑ Berg, P., Baltimore, D., Brenner, S., Roblin, R.O. III, Singer, M.F., "Summary statement of the Asilomar Conference on recombinant DNA molecules," Proc. Nat. Acad. Sci. USA 72, pp. 1981-1984 (1975), also Science 188, p. 991 (1975).
  3. ↑ "Guidelines for research involving recombinant DNA molecules," Federal Register 41, no. 131, pp. 27911-27943 (1976).
  4. ↑ Genentech: Press Releases - News Release September 6, 1978 The insulin synthesis is the first laboratory production DNA technology.
  5. ↑ Transgenic Animals, Dr. John W. Kimball, Harvard University
  6. ↑ 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. http://jag.igr.poznan.pl/2007-Volume-48/1/abstracts/373.html. 
  7. ↑ Leader B, Baca QJ, Golan DE (January 2008). "Protein therapeutics: a summary and pharmacological classification". Nat Rev Drug Discov 7 (1): 21–39. doi:10.1038/nrd2399. PMID 18097458. 
  8. ↑ Walsh G (April 2005). "Therapeutic insulins and their large-scale manufacture". Appl. Microbiol. Biotechnol. 67 (2): 151–9. doi:10.1007/s00253-004-1809-x. PMID 15580495. 
  9. ↑ Pipe SW (May 2008). "Recombinant clotting factors". Thromb. Haemost. 99 (5): 840–50. PMID 18449413. 
  10. ↑ 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. 
  11. ↑ 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. 
  12. ↑ 12.0 12.1 Foster PR (October 2000). "Prions and blood products". Ann. Med. 32 (7): 501–13. PMID 11087171. 
  13. ↑ Key NS, Negrier C (August 2007). "Coagulation factor concentrates: past, present, and future". Lancet 370 (9585): 439–48. doi:10.1016/S0140-6736(07)61199-4. PMID 17679021. 
  14. ↑ Selkirk SM (October 2004). "Gene therapy in clinical medicine". Postgrad Med J 80 (948): 560–70. doi:10.1136/pgmj.2003.017764. PMID 15466989. http://pmj.bmj.com/cgi/pmidlookup?view=long&pmid=15466989. 
  15. ↑ Cavazzana-Calvo M, Fischer A (June 2007). "Gene therapy for severe combined immunodeficiency: are we there yet?". J. Clin. Invest. 117 (6): 1456–65. doi:10.1172/JCI30953. PMID 17549248. 
  16. ↑ Rosenecker J, Huth S, Rudolph C (October 2006). "Gene therapy for cystic fibrosis lung disease: current status and future perspectives". Curr. Opin. Mol. Ther. 8 (5): 439–45. PMID 17078386. 
  17. ↑ Persons DA, Nienhuis AW (July 2003). "Gene therapy for the hemoglobin disorders". Curr. Hematol. Rep. 2 (4): 348–55. PMID 12901333. 
  18. ↑ Foster K, Foster H, Dickson JG (December 2006). "Gene therapy progress and prospects: Duchenne muscular dystrophy". Gene Ther. 13 (24): 1677–85. doi:10.1038/sj.gt.3302877. PMID 17066097. 
  19. ↑ Sathasivam K, Hobbs C, Mangiarini L, et al (June 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. PMID 10434294. PMC: 1692600. http://journals.royalsociety.org/openurl.asp?genre=article&issn=0962-8436&volume=354&issue=1386&spage=963. 
  20. ↑ First Transgenic Mice and Fruit Flies
  21. ↑ Genetically modified medicines and food New Zealand Ministry for the Environment
  22. ↑ www.parliament.nsw.gov.au
  23. ↑ Australian Science Media Center - 27 November 2007 [1]
  24. ↑ Elizabeth Finkel, Science, Vol. 321. no. 5896, p. 1629; September 19, 2008 http://www.sciencemag.org
  25. ↑ Australian Science Media Center - 8 February 2008[2]
  26. ↑ DPIW - GM Moratorium Extended
  27. ↑ 10 Years of GM cotton - where to from here? Jeff Bidstrup, Convener, Producers’ Forum Outlook Conference, Canberra, 2006 [3]

External links

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Transgenic animals

Transgenic plants