Genetically modified organism

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [4]


GloFish: the first genetically modified animal to be sold as a pet.

A genetically modified organism (GMO) is an organism whose genetic material has been altered using the genetic engineering techniques generally known as recombinant DNA technology. With recombinant DNA technology, DNA molecules from different sources are combined in vitro into one molecule to create a new gene. This modified DNA is then transferred into an organism causing the expression of modified or novel traits. The product is also known as an Genetically Engineered Organism or GEO.

The term "GMO" has historically been defined as organisms whose genetic makeup has been altered by conventional cross breeding or by "mutagenesis" breeding, as these methods predate the discovery of the recombinant DNA techniques. However, this term is now interchangeable with Genetically Engineered Organism.


The general principle of producing a GMO is to add genetic material into an organism's genome to generate new traits - Genetic engineering - was made possible through a series of scientific advances including 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 a bacterium 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.[5]

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. The generation and use of GMOs has many reasons, chief among them are their use in research that addresses fundamental or applied questions in biology or medicine, for the production of pharmaceuticals and industrial enzymes, and for direct, and often controversial, 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 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.[6] Flies are often preferred over other animals for ethical reasons and ease of culture, and also because the fly genome is somewhat simpler than that of vertebrates.

Transgenic plants

Kenyans examining insect-resistant transgenic Bt corn.

Transgenic plants have been developed for various purposes: resistance to pests, herbicides or harsh environmental conditions; improved shelflife; increased nutritional value - and many more. Since the first commercial cultivation of GM plants in 1996, GM plant events tolerant to the herbicides glufosinate or glyphosate and events producing the Bt toxin, an insecticide, have dominated the market. Recently, a new generation of GM plants promising benefits for consumers and industry purposes is becoming ready to enter the markets.

Since GM plants are grown on open fields, they are often associated with environmental risks. Therefore, most countries require biosafety studies prior to the approval of a new GM plant event, usually followed by a monitoring programme 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 GM, conventional and organic plants and derived food and feed. European research programmes such as Co-Extra, Transcontainer and SIGMEA are investigating appropriate tools and rules. On the field level, these are biological containment methods, isolation distances and pollen barriers. Further down the food chain, documentation and detection methods shall ensure the coexistence.

Controversy over GMOs

Government support for and ban of GMOs

The use of GMOs has sparked significant controversy in many areas [6]. 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.

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 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. 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 [7].

Currently, there is little international consensus regarding the acceptability and effective role of modified "complete" organisms such as plants or animals. A great deal of the modern research that is illuminating complex biochemical processes and disease mechanisms makes vast use of genetic engineering.

The practice of genetic modification as a scientific technique is not restricted in the United States. Individual genetically modified crops (such as soybeans) are studied before being brought to market, but generally only by the companies providing the modification. This "test by those being tested" practice is common in the United States, where many in the FDA are ex-employees of Monsanto, the largest gene-manipulation firm. Most countries in Europe, Japan, Mexico (among others) have taken the opposite position, stating that genetic modification has not been proven safe, and therefore that they will not accept genetically modified food from the United States or any other country without assessing their safety themselves. This issue has been brought before the World Trade Organization, which determined that not allowing GMOs into the country creates an unnecessary obstacle to international trade. Consequently, genetic modification within agriculture is an issue of some strong debate in the United States, the European Union, and some other countries.

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) [8]. 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 hypothetical "Technology Protection" technology dubbed 'Terminator'[9]. This yet-to-be-commercialised 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 yearly application of a chemical to genetically-modified crops to reactivate engineered traits[10][11]. 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 selfpollinating 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.

Losses of Biodiversity

In agriculture and animal husbandry, green revolution popularized the use of conventional hybridization to increase yield many folds by creating "High yielding varieties". Often the handful of breeds of plants and animals hybridized originated in developed countries and were further hybridized with local verities, in the rest of the developing world, to create high yield strains resistant to local climate and diseases. Local governments and industry since have been pushing hybridization with such zeal that several of the wild and indigenous breeds evolved locally over thousands of years having high resistance to local extremes in climate and immunity to diseases etc. have already become extinct or are in grave danger of becoming so in the near future. Due to complete disuse because of un-profitability and uncontrolled crosspollination and crossbreeding (genetic pollution) formerly huge gene pools of various wild and indigenous breeds have collapsed causing widespread genetic erosion and genetic pollution resulting in great loss in genetic diversity and biodiversity as a whole.[7]

Concerns have been raised that Genetically Modified Organisms may contribute to genetic pollution because artificially created and genetically engineered plants and animals in laboratories, which could never have evolved in nature even with conventional hybridization, can interbreed with naturally evolved wild varieties. Genetically Modified (GM) crops today have become a common source for genetic pollution, not only of wild varieties but also of other domesticated varieties derived from conventional hybridization[8][9][10][11][12].

It is being said that genetic erosion coupled with genetic pollution is destroying that needed unique genetic base thereby creating an unforeseen hidden crisis which will result in a severe threat to our food security for the future when diverse genetic material will cease to exist to be able to further improve or hybridize weakening food crops and livestock against more resistant diseases and climatic changes[13].

See also



  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. First Transgenic Mice and Fruit Flies
  7. “Genetic Pollution: The Great Genetic Scandal”; Devinder Sharma can be contacted at: 7 Triveni Apartments, A-6 Paschim Vihar, New Delhi-110 063, India. Email: CENTRE FOR ALTERNATIVE AGRICULTURAL MEDIA (CAAM)., [1]
  8. THE YEAR IN IDEAS: A TO Z.; Genetic Pollution; By MICHAEL POLLAN, The New York Times, December 9, 2001
  9. Dangerous Liaisons? When Cultivated Plants Mate with Their Wild Relatives; by Norman C. Ellstrand; The Johns Hopkins University Press, 2003; 268 pp. hardcover , $ 65; ISBN 0-8018-7405-X. Book Reviewed in: Hybrids abounding; Nature Biotechnology 22, 29 - 30 (2004) doi:10.1038/nbt0104-29; Reviewed by: Steven H Strauss & Stephen P DiFazio; 1 Steve Strauss is in the Department of Forest Science, Oregon State University, Corvallis, Oregon 97331-5752, USA.; 2 Steve DiFazio is at Oak Ridge National Laboratory, Bldg. 1059, PO Box 2008, Oak Ridge, Tennessee 37831-6422 USA.
  10. “Genetic pollution: Uncontrolled spread of genetic information (frequently referring to transgenes) into the genomes of organisms in which such genes are not present in nature.” Zaid, A. et al. 1999. Glossary of biotechnology and genetic engineering. FAO Research and Technology Paper No. 7. ISBN 92-5-104369-8
  11. “Genetic pollution: Uncontrolled escape of genetic information (frequently refering to products of genetic engineering) into the genomes of organisms in the environment where those genes never existed before.” Searchable Biotechnology Dictionary. University of Minnesota. , [2]
  12. “Genetic pollution: Living organisms can also be defined as pollutants, when a non-indigenous species (plant or animal) enters a habitat and modifies the existing equilibrium among the organisms of the affected ecosystem (sea, lake, river). Non-indigenous, including transgenic species (GMOs), may bring about a particular version of pollution in the vegetal kingdom: so-called genetic pollution. This term refers to the uncontrolled diffusion of genes (or transgenes) into genomes of plants of the same type or even unrelated species where such genes are not present in nature. For example, a grass modified to resist herbicides could pollinate conventional grass many miles away, creating weeds immune to the most widely used weed-killer, with obvious consequences for crops. Genetic pollution is at the basis of the debate on the use of GMOs in agriculture.” The many facets of pollution; Bologna University web site for Science Communication. The Webweavers: Last modified Tue, 20 Jul 2005
  13. “Genetic Pollution: The Great Genetic Scandal”; Devinder Sharma can be contacted at: 7 Triveni Apartments, A-6 Paschim Vihar, New Delhi-110 063, India. Email: CENTRE FOR ALTERNATIVE AGRICULTURAL MEDIA (CAAM)., [3]

General references

  • Anderson, K. and Lee Ann Jackson. 2005. Some Implications of GM Food Technology Policies for Sub-Saharan Africa. Journal of African Economies 14(3):385-410; doi:10.1093/jae/eji013
  • Heong, KL, YH Chen, DE Johnson, GC Jahn, M Hossain, RS Hamilton. 2005. Debate Over a GM Rice Trial in China. Letters. Science, Vol 310, Issue 5746, 231-233 , 14 October 2005.
  • Huang, J., Ruifa Hu, Scott Rozelle, Carl Pray. 2005. Insect-Resistant GM Rice in Farmers' Fields: Assessing Productivity and Health Effects in China. Science (29 April 2005) Vol. 308. no. 5722, pp. 688 – 690. DOI: 10.1126/science.1108972
  • [5] Plague (1978) aka M3: The Gemini Strain, discussion of actors, plot, and critique of the Canadian genetically-modified organism escape thriller [12]

External links


Transgenic animals

Transgenic plants

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