What is GMO?

Definition:

A genetically modified organism (GMO) is any organism whose genetic material has been altered using genetic engineering techniques. According to the Human Genome Project, GMOs are created when scientists select specific genes within one organism and insert them into a different species.
Introduction:

Scientists generally design GMOs to convey some sort of improvement or benefit to the organism. GMOs are the source of genetically modified foods and are also widely used in scientific research and to produce goods other than food.
Genetically modified foods are altered in some way, usually for the purpose of increasing yield or efficiency. This is common in agricultural crops, especially in corn, grains, and various fruits and vegetables. Common reasons for genetic modification include improving flavor, increasing resistance to insects, and increasing the yield. Though agricultural crops are the most commonly modified foods, animal products are sometimes altered as well. For example, synthetic growth hormones are used to make beef cows bigger, yielding more meat, and to increase the amount of milk that dairy cows can produce. Some of these practices are criticized by various groups as being unsafe or unnatural. Despite this, an estimated 75% of all foods purchased in America contain at least some genetically modified ingredients.
In genetic modification (or engineering) of food plants, scientists remove one or more genes from the DNA of another organism, such as a bacterium, virus, animal, or plant and “recombine” them into the DNA of the plant they want to alter. By adding these new genes, genetic engineers hope the plant will express the traits associated with the genes. For example, genetic engineers have transferred genes from a bacterium known as Bacillus thuringiensis or Bt into the DNA of corn. Bt genes express a protein that kills insects, and transferring the genes allows the corn to produce its own pesticide.

Background

People have been altering the genomes of plants and animals for many years using traditional breeding techniques. Artificial selection for specific, desired traits has resulted in a variety of different organisms, ranging from sweet corn to hairless cats. But this artificial selection, in which organisms that exhibit specific traits are chosen to breed subsequent generations, has been limited to naturally occurring variations. In recent decades, however, advances in the field of genetic engineering have allowed for precise control over the genetic changes introduced into an organism. Today, we can incorporate newgenes from one species into a completely unrelated species through genetic engineering, optimizing agricultural performance or facilitating the production of valuable pharmaceutical substances. Crop plants, farm animals, and soil bacteria are some of the more prominent examples of organisms that have been subject to genetic engineering.

Production


Genetic modification involves the mutation, insertion, or deletion of genes. Inserted genes usually come from a different species in a form of horizontal gene-transfer (the transfer of genes between organisms in a manner other than traditional reproduction). 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 (here virus acts as a vector)
· physically inserting the extra DNA into the nucleus of the intended host with a very small syringe
· with the use of electroporation (introducing DNA from one organism into the cell of another by use of an electric pulse)
· with very small particles fired from a gene gun.
Other methods exploit natural forms of gene transfer, such as the ability of Agrobacterium (naturally occurring soil bacterium that has the ability to introduce new genetic material into the plant cell) to transfer genetic material to plants, or the ability of lentiviruses to transfer genes to animal cells.

Current Uses of Genetically Modified Organisms

Agriculture:

Agricultural plants are one of the most frequently cited examples of genetically modified organisms (GMOs). Some benefits of genetic engineering in agriculture are increased crop yields, reduced costs for food or drug production, reduced need for pesticides, enhanced nutrient composition and food quality, resistance to pests and disease, greater food security, and medical benefits to the world's growing population. Advances have also been made in developing crops that mature faster and tolerate aluminum, boron, salt, drought, frost, and other environmental stressors, allowing plants to grow in conditions where they might not otherwise flourish. Other applications include the production of nonprotein (bioplastic) or nonindustrial (ornamental plant) products.

A number of animals have also been genetically engineered to increase yield and decrease susceptibility to disease. For example, cattle have been enhanced to exhibit resistance to mad cow disease.

Aquaculture:

The transgenic fish enjoy growth rates markedly superior to those in comparable (in some cases sibling) non-transgenics. Studies have revealed enhancement of growth particularly in salmonids to an average of 3 to5 times the size of non-transgenic controls with some individuals reaching as much as 10?30 times the size of controls. The economic gains to be made from use of such GMOs are obvious and transgenics must therefore be considered as a route for providing superior strains along with selective breeding.

Table 1: Examples of GMOs Resulting from Agricultural Biotechnology

Genetically Conferred Trait Example Organism Genetic Change
APPROVED COMMERCIAL PRODUCTS
Herbicide tolerance Soybean Glyphosate herbicide (Roundup) tolerance conferred by expression of a glyphosate-tolerant form of the plant enzyme 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) isolated from the soil bacterium Agrobacterium tumefaciens, strain CP4
Insect resistance Corn Resistance to insect pests, specifically the European corn borer, through expression of the insecticidal protein Cry1Ab from Bacillus thuringiensis
Altered fatty acid composition Canola High laurate levels achieved by inserting thegene for ACP thioesterase from the California bay tree Umbellularia californica
Virus resistance Plum Resistance to plum pox virus conferred by insertion of a coat protein (CP) gene from the virus
PRODUCTS STILL IN DEVELOPMENT
Vitamin enrichment Rice Three genes for the manufacture of beta-carotene, a precursor to vitamin A, in the endosperm of the rice prevent its removal (from husks) during milling
Vaccines Tobacco Hepatitis B virus surface antigen (HBsAg) produced in transgenic tobacco induces immune response when injected into mice
Oral vaccines Maize Fusion protein (F) from Newcastle disease virus (NDV) expressed in corn seeds induces an immune response when fed to chickens
Faster maturation Coho salmon A type 1 growth hormone gene injected into fertilized fish eggs results in 6.2% retention of thevector at one year of age, as well as significantly increased growth rates

Genetically modified crops approved to be grown in the US?


  • Corn
  • Soybeans
  • Cotton
  • Canola
  • Sugar beets
  • Alfalfa
  • Papaya
  • Yellow “crook neck” squash
  • Zucchini
  • “Arctic” apple
  • “Innate” potato


Medicine

GMOs have emerged as one of the mainstays of biomedical research since the 1980s. The pharmaceutical industry is a major frontier for the use of GMOs. In 1986, human growth hormone was the first protein pharmaceutical made in plants, and in 1989, the first antibody was produced. For these purposes, researchers used tobacco, which has since dominated the industry as the most intensively studied and utilized plant species, for the expression of foreign genes. As of 2003, several types of antibodies produced in plants had made it to clinical trials. The use of genetically modified animals has also been indispensible in medical research. Transgenic animals are routinely bred to carry human genes or mutations in specific genes, thus allowing the study of the progression and genetic determinants of various diseases.

Environmental Management:

Another application of GMOs is in the management of environmental issues. For example, some bacteria can produce biodegradable plastics, and the transfer of this ability to microbes that can be easily grown in the laboratory may enable the wide-scale “greening” of the plastics industry. Zeneca, a British company, developed a microbially produced biodegradable plastic called Biopol. This plastic is made using a GM bacterium, Ralstonia eutropha, to convert glucose and a variety of organic acids into a flexible polymer. GMOs endowed with the bacterially encoded ability to metabolize oil and heavy metals may provide efficient bioremediation strategies.

Endangered Species

Genetic modification of animals so that they can deal with changing climate and habitats may be a very helpful way to save some of the most endangered species from becoming extinct. Biologists suggest that genes might be introduced even from other species to help endangered species survive in changing climatic conditions
Genetic modification technologies may help save the giant panda, whose genome is being sequenced in an international effort led by the Beijing Genomics Institute at Shenzhen.


Potential GMO Applications

Many industries stand to benefit from additional GMO research. For instance, a number of microorganisms are being considered as future clean fuel producers and bio-degraders.
In addition, genetically modified plants may someday be used to produce recombinant vaccines. In fact, the concept of an oral vaccine expressed in plants (fruits and vegetables) for direct consumption by individuals is being examined as a possible solution to the spread of disease in underdeveloped countries, one that would greatly reduce the costs associated with conducting large-scale vaccination campaigns. Work is currently underway to develop plant-derived vaccine candidates in potatoes and lettuce for hepatitis B virus (HBV), enterotoxigenic Escherichia coli (ETEC), and Norwalk virus.
Scientists are also looking into the production of other commercially valuable proteins in plants, such as spider silk protein and polymers that are used in surgery or tissue replacement.
Genetically modified animals have even been used to grow transplant tissues and human transplant organs, a concept called xenotransplantation.
GMOs provide a number of valuable benefits to humans, but many people also worry about potential risks.

Risks and Controversies Surrounding the Use of GMOs

Despite the fact that the genes being transferred occur naturally in other species, there are unknown consequences to altering the natural state of an organism through foreign gene expression. After all, such alterations can change the organism's metabolism, growth rate, and/or response to external environmental factors. These consequences influence not only the GMO itself, but also the natural environment in which that organism is allowed to proliferate. Potential health risks to humans include the possibility of exposure to new allergens in genetically modified foods, as well as the transfer of antibiotic-resistant genes to gut flora.
Horizontal gene transfer of pesticide, herbicide, or antibiotic resistance to other organisms would not only put humans at risk, but it would also cause ecological imbalances, allowing previously innocuous plants to grow uncontrolled, thus promoting the spread of disease among both plants and animals. Although the possibility of horizontal gene transfer between GMOs and other organisms cannot be denied, in reality, this risk is considered to be quite low. Horizontal gene transfer occurs naturally at a very low rate and, in most cases, cannot be simulated in an optimized laboratory environment without active modification of the target genome to increase susceptibility.

In contrast, the alarming consequences of vertical gene transfer between GMOs and their wild-type counterparts have been highlighted by studying transgenic fish released into wild populations of the same species (Muir & Howard, 1999). The enhanced mating advantages of the genetically modified fish led to a reduction in the viability of their offspring. Thus, when a new transgene is introduced into a wild fish population, it propagates and may eventually threaten the viability of both the wild-type and the genetically modified organisms.

Unintended Impacts on Other Species: The Bt Corn Controversy

One example of public debate over the use of a genetically modified plant involves the case of Bt corn. Bt corn expresses a protein from the bacterium Bacillus thuringiensis. Prior to construction of the recombinant corn, the protein had long been known to be toxic to a number of pestiferous insects, including the monarch caterpillar, and it had been successfully used as an environmentally friendly insecticide for several years. The benefit of the expression of this protein by corn plants is a reduction in the amount of insecticide that farmers must apply to their crops. Unfortunately, seeds containing genes for recombinant proteins can cause unintentional spread of recombinant genes or exposure of non-target organisms to new toxic compounds in the environment.

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Unintended Economic Consequences

Another concern associated with GMOs is that private companies will claim ownership of the organisms they create and not share them at a reasonable cost with the public. If these claims are correct, it is argued that use of genetically modified crops will hurt the economy and environment, because monoculture practices by large-scale farm production centers (who can afford the costly seeds) will dominate over the diversity contributed by small farmers who can't afford the technology. However, a recent meta-analysis of 15 studies reveals that, on average, two-thirds of the benefits of first-generation genetically modified crops are shared downstream, whereas only one-third accrues upstream. These benefit shares are exhibited in both industrial and developing countries. Therefore, the argument that private companies will not share ownership of GMOs is not supported by evidence from first-generation genetically modified crops.

GMOs and the General Public: Philosophical and Religious Concerns

In a 2007 survey of 1,000 American adults conducted by the International Food Information Council (IFIC), 33% of respondents believed that biotech food products would benefit them or their families, but 23% of respondents did not know biotech foods had already reached the market. In addition, only 5% of those polled said they would take action by altering their purchasing habits as a result of concerns associated with using biotech products.
According to the Food and Agriculture Organization of the United Nations, public acceptance trends in Europe and Asia are mixed depending on the country and current mood at the time of the survey in 2004. Attitudes toward cloning, biotechnology, and genetically modified products differ depending upon people's level of education and interpretations of what each of these terms mean. Support varies for different types of biotechnology; however, it is consistently lower when animals are mentioned.
The ethical issues surrounding GMOs include debate over the introduction of foreign material into foods that are abstained from for religious reasons. Some people believe that tampering with nature is intrinsically wrong, and others maintain that inserting plant genes in animals, or vice versa, is immoral. When it comes to genetically modified foods, those who feel strongly that the development of GMOs is against nature or religion have called for clear labeling rules so they can make informed selections when choosing which items to purchase.
Respect for consumer choice and assumed risk is as important as having safeguards to prevent mixing of genetically modified products with non-genetically modified foods.
These issues are increasingly important to consider as the number of GMOs continues to increase due to improved laboratory techniques and tools for sequencing whole genomes, better processes for cloning and transferring genes, and improved understanding of gene expression systems. Thus, legislative practices that regulate this research have to keep pace.
It should be noted that prior to permitting commercial use of GMOs, governments perform risk assessments to determine the possible consequences of their use. But difficulties in estimating the impact of commercial GMO use makes regulation of these organisms a challenge.

Increased Research and Improved Safety Go Hand in Hand

Proponents of the use of GMOs believe that, with adequate research, these organisms can be safely commercialized. There are many experimental variations for expression and control of engineered genes that can be applied to minimize potential risks. Some of these practices are already necessary as a result of new legislation, such as avoiding superfluous DNA transfer (vector sequences) and replacing selectable marker genes commonly used in the lab (antibiotic resistance) with innocuous plant-derived markers. Issues such as the risk of vaccine-expressing plants being mixed in with normal foodstuffs might be overcome by having built-in identification factors, such as pigmentation, that facilitate monitoring and separation of genetically modified products from non-GMOs. Other built-in control techniques include having inducible promoters (e.g., induced by stress, chemicals, etc.), geographic isolation, using male-sterile plants, and separate growing seasons.


Conclusion

GMOs benefit mankind when used for purposes such as increasing the availability and quality of food and medical care, and contributing to a cleaner environment. If used wisely, they could result in an improved economy without doing more harm than good, and they could also make the most of their potential to alleviate hunger and disease worldwide. However, the full potential of GMOs cannot be realized without due diligence and thorough attention to the risks associated with each new GMO on a case-by-case basis.