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DNA Structure
Source: National Institue of Health
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Genetic engineering, or genetically modified organisms (GMO): are they good or bad? It depends on who you ask.
History of Genetic Engineering
Genetic Engineering dates back to 1953, when James Watson (American), Francis Crick (British), and Maurice Wilkins (New Zealand/ British) first developed a 3D model of DNA. This opened the door to understanding what we know today about genes and gene traits in organisms such as plants, animals, humans and microorganisms. The discovery of the DNA structure changed many areas of science, particularly in the agriculture industry. The three shared the 1962 Nobel Prize for physiology/medicine.
With the growing worldwide population and the demand for more food, scientists have tried to improve crop yields by modifying specific genes to induce specific desirable traits and produce better yields by improving resistance to insects, disease, herbicides and harsh weather conditions such as drought, flood, and freezing weather. Some scientists are also trying to add more nutritional value to food products.
Gene modifications were accomplished by inserting a single desired gene from one species into another non-related species, in hopes that the host would acquire the desired trait, resulting in transgenic organisms (plants, animals and microorganisms). Bacillus thuringiensis (Bt), a soil bacterium, its gene is used in plants to produce a toxin that would kill certain insects when the insect eats the plant in building insect resistance. Another bacterium was used to build herbicide resistance and viruses were used for disease resistance.
Repercussions
Crop yields have prospered, but many consumers were not in favor of GMO foods when they discovered that foods contained a gene from a bacterium called Bt that produced a toxin. One anti-GMO advocate describes the Bt as producing "a protein that ruptures the stomach when ingested by pests," implying that this may occur when humans ingest the food that contains this bacteria and toxin.
However, Bt has been used as a microbial spray pesticide to control caterpillars, certain types of beetles, as well as mosquitoes and black flies for years. In 1995, the EPA registered the first Bt plant-incorporated protectants for use in the United States and 11 more since then. According to the Environmental Protection Agency (EPA), the use of conventional pesticides for control of the European corn borer has dropped by about one-third since Bt corn was introduced.
Bt may also have been confused with DDT, organochlorine insecticide, the first insecticide on the market that did create a lot of health problems, most notably reproductive problems and cancer in animals. The use of DDT as an insecticide was cancelled in 1972 by the EPA.
Organic food advocates were certainly not in favor of GMO foods and organic farmers feared that GMO grains could potentially cross - contaminate fields located nearby to a GMO farm.
More negative publicity for GMO foods occurred when Monsanto's GMO corn did not kill the rootworm and the rootworm formed resistance in four mid-west states. Additionally, there was fear of the potential to create "super weeds" that might be born due to cross - resistance that could occur over time.
Environmentalists were concerned that Bt corn was responsible for the death of the Monarch Butterfly. University scientists found that Bt corn pollen, like natural corn pollen, can blow onto milkweed leaves, which are the exclusive diet of Monarch caterpillars. Steps were recommended to avoid cross - contamination of crops.
Another issue was the introduction of StarLink, a GMO corn derived from Bt that produces a protein, Cry9C, that acts as a pesticide, protecting the plant from pests such as the European Corn Borer. StarLink corn was registered for use in animal feed only and not for human consumption due to unresolved questions concerning StarLink's potential allergenicity.
In 2000, taco shells were tested to find traces of StarLink corn DNA. Confirmed by the FDA, a number of food companies implemented a voluntary recall of taco shells and other products manufactured with yellow corn meal.
The USDA, FDA, and EPA worked to test corn grain for the presence of StarLink and remove any potentially contaminated corn seeds from the market. Since then, the EPA will no longer issue split registrations (animal feed only and not for human consumption) for pesticide products.
The EPA has incorporated regulation of biopesticides to address gene transfer and outcrossing (transfer from one field to another) to ensure the safety of plants crops. Currently the EPA has found no gene flow or outcrossing for corn and potato due to differences in chromosome number, phenology and habitat. There is a possibility, however, of gene transfer from Bt cotton to wild or feral cotton relatives in Hawaii, Florida, Puerto Rico and the U.S. Virgin Islands.
Overall, the EPA encourages the use of biopesticides vs. synthetic pesticides, which fall into 3 major classes:
1) Microbial pesticides consist of a microorganism (e.g., a bacterium, fungus, virus, or protozoan) as the active ingredient which includes Bt.
2) Plant pesticides are pesticidal substances that plants produce from genetic material that has been added to the plant or GMO plants such as corn, cotton, and potato.
3) Biochemical pesticides are naturally occurring substances that control pests by non-toxic mechanisms such as insect sex pheromones, that interfere with mating, as well as various scented plant extracts that attract insect pests to traps. This excludes conventional pesticides that are synthetic chemicals.
The goal of producing GMO foods was to yield better crops, resulting in lower food prices, greater benefit (longer shelf life or nutritional value), or both. But according to the World Health Organization (WHO), when the first GMO foods were introduced onto the European market, the products were not perceived by the consumer as having any direct benefit (not significantly cheaper, no increased shelf life, no better taste).
The three main health concerns regarding GMO foods according to the WHO are:
- Allergenicity - "...the transfer of genes from commonly allergenic organisms to non-allergic organisms is discouraged unless it can be demonstrated that the protein product of the transferred gene is not allergenic."
- Gene transfer - "Gene transfer from GMO foods to cells of the body or to bacteria in the gastrointestinal tract would cause concern if the transferred genetic material adversely affects human health. This would be particularly relevant if antibiotic resistance genes, used as markers when creating GMOs, were to be transferred."
- Outcrossing - "The migration of genes from GMO plants into conventional crops or related species in the wild (outcrossing), as well as the mixing of crops derived from conventional seeds with GM crops, may have an indirect effect on food safety and food security. Cases have been reported where GMO crops approved for animal feed or industrial use were detected at low levels in the products intended for human consumption."
On May 29, 1992, The Food and Drug Administration (FDA) published its "Statement of Policy: Foods Derived from New Plant Varieties" in The Federal Registry (57 FR 22984) which includes GMO foods.
What about GMO wheat?
Wheat is used in numerous foods for human consumption such as cereal, bread, pasta, and desserts (cookies, cakes, pies, bread, etc.). Is there GMO wheat? Scientists have been working on GMO wheat for a long time but they've been unsuccessful, because wheat has a very complex DNA structure. Agriculture companies such as Monsanto have actually spent nearly a decade-and-a-half researching GMO wheat. The company began field testing a variety starting in 1998, but suspended operations in 2005, after determining that a super-wheat strain wasn't quite ready to be launched.
Here is the reason why. A human cell (diploid) has two copies of 23 chromosomes for a total of 46 chromosomes, but a wheat cell (hexaploid) has six copies of its seven chromosomes (42 chromosomes total). Corn has 20 chromosomes total, and rice has 24. While wheat has fewer pairs of chromosomes than humans it has a greater number of genes, with an estimated 164,000 to 334,000 genes, compared to 20,000 to 25,000 genes for a human.
While there is no commercially approved GM wheat on the market, there has been an incident where GMO wheat was found in a farmer's unmodified wheat in Oregon. It was found that the GMO wheat came from Monsanto. Outcrossing can happen whether it's through nature (seeds blowing into another field) or through seeds clinging to someone's clothes and accidently transferring to another crop as that person travels.
In fact, due to the controversy about GMO products and the incident of GMO wheat being found in an unmodified wheat field where there is no commercially approved GMO, a ban of GMO products is in effect in 26 countries.
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