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| Sunday, 28 April 2002 |
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Features |  |
| News Business Features Editorial
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Genetically modified foods Genetically modified foods have recently become a subject of intense discussion. The following article should help our readers to understand what EMF is all about...... The genetic engineering technology has made possible the insertion of desired foreign gene (s) to overcome problems of sexual incompatibility and species barriers between organisms. This technology helps the breeders and molecular biologists to introduce only the gene of interest with more selective modification and represents significant scientific advancement. The primary aim of modern biotechnology is to make a living cell perform a specific useful task in a predictable and controllable way. The outcome of genetic engineering technology is a transgenic/genetically modified (GM) product. Genetically modified foods (GMF) are those produced through the use of this gene technology. Such recombination of genes would not occur in nature and even if it was artificially attempted using conventional methods, it would not take place. Therefore, to achieve this gene transfer, the alien gene will have to be 'smuggled' into the host organism using genetic engineering methods. Therefore, according to this definition it is clear that 'cross breeding', and 'hybridization' etc. do not fall into the 'genetically modified' or GM category, where gene transfer is between organisms of the same species and not forced upon. Presently, there are over 20 plants, that have been produced by plant biotechnology (some by genetic engineering and others by techniques such as tissue culture), undergoing field trials. They have been modified for improved agronomic properties such as resistance to pests and diseases, produce greater yields, less requirement of agrochemicals etc. and for new qualities like improved nutritional status, better keeping quality and less processing. Wheat, soybean and tomatoes and their products are few of the GMF's that are known to be in the market shelves at present [1] The creation of GM foods The first transgenic plant - a tobacco plant resistant to an antibiotic - was created in 1983 [5]. It was another 10 years before the first commercialization of a GM plant in the United States - a delayed-ripening tomato - and yet another two years (1996) before a GM product - tomato paste - hit UK supermarket shelves. 1996 was also the year the European Union approved the importation and use of Monsanto's Roundup Ready soybean in human food and animal feed. These beans have been modified to survive being sprayed with the Roundup herbicide that is applied to a field to kill weeds. This soybean, together with GM maize, is now used in a variety of processed foods on sale in the UK. The products range from crisps to pasta. A genetically engineered version of the milk-clotting enzyme Chymosin is also used in cheese-making. In 1988, Chymosin was the first enzyme from a genetically modified source to gain approval for use in food (6). Three such enzymes are now approved in several European countries and the USA. These proteins behave in exactly the same way as calf Chymosin, but their activity is more predictable and they have fewer impurities. Chymosin obtained from recombinant organisms has been subjected to rigorous tests to ensure its purity. Today about 90% of the hard cheese in the UK is made using Chymosin from genetically-modified microbes. This cheese is not made using a GMO, but rather the product of a GMO (the enzyme). Consequently, all cheeses on sale are in fact 'GMO free'. Another important point is that the enzyme does not remain in the finished cheese. Like all enzymes it is required only in very small quantities and because it is a relatively unstable protein, breaks down as the cheese matures. The World's first genetically engineered whole food, the Calgene Flavr Savr tomato, went on sale on 21 May, 1994 in two grocery stores in the USA. Calgene had engineered the tomatoes to ripen on the vine and still be hard enough to withstand the process of picking, packing and transport. However, contrary to company's expectations the Flavr Savr gene could not keep the vine-ripned fruit firm enough to be packed and transported like green tomatoes. By 1997, the Calgene Flavr Savr tomato had been withdrawn from the market. Advantages and benefits of GMOs/GM foods What are the main benefits of plant biotechnology including genetic engineering? Supporters of plant biotechnology say that it will lead to the introduction of new and improved agronomic practices and the production of crops with new qualities and higher yields. The consumers are expected to benefit by improved flavour, improved nutritional status, better keeping quality and easier processing. Consistency in quality and safety and environmental friendliness are also considered to be further benefits brought about by biotechnology. GM crops that produce extra nutrients and grow well in poor conditions could provide much needed help to people in developing nations who suffer from malnutrition. Eg. Golden rice, a genetically modified rice produced in the Philippines. Golden rice is being developed to contain high levels of beta-carotene to help fight rampant Vitamin A deficiency and resulting blindness. According to reports, one million children die each year worldwide, and half-million develop blindness, due to Vitamin A deficiency (7). Of some 3 billion people who depend on rice as their major staple, around 10% risk some degree of Vitamin A deficiency and associated health problems. According to rough estimates, golden rice should supply 50% of the daily requirement of Vitamin A. Some GM crops are designed to have tolerance to insects thereby limiting the need for toxic pesticides and can potentially benefit health indirectly. Concerns related to health and food safety All foods including the transgenic foods created through genetic engineering are potential sources of allergens. That is because the transferred genes contain instructions for making proteins, and some proteins cause allergic reactions in humans. The anti-GM lobby is critical of the use of DNA from plant viruses and bacteria in the modification of crops - they fear this may also somehow trigger disease. The 'marker' genes that are used in genetic engineering could permit their recipient to make a new protein, which could have unwanted effects. Such genes could also be transferred to other organisms such as microbes in the intestine of the consumer. The recent introduction of maize with a bacterial marker conveying resistance to the antibiotic ampicillin has raised questions especially in the European Union countries. Proteins made from foreign genes can be toxic to humans even in minor quantities. New genes may alter the functions of the plant in ways that make its food component less nutritious or more prone to carrying elevated levels of natural poisons that many plants contain in small amounts. Environmental safety The question of 'genetic pollution' has also been highlighted. Pollen grains from wind pollinated plants such as corn, are carried far and wide. Since such plants may contain genes of natural insecticides (e.g. Bt com and Bt cotton), ecologists are concerned that widespread planting of such crops will spur resistance amongst crop pests. Allergic reactions There are many people who are allergic to one or more foods such as eggs, dairy products, nuts, wheat etc, especially foods containing high levels of protein. For people who are unable to tolerate certain proteins, eating even trace amounts of foods containing them will cause allergic reactions, ranging from minor discomforts to serious illnesses and even death. In genetic engineering when genes are transferred from one organism to another they produce new proteins. If such a new protein happens to cause an allergic reaction then the food previously safe for a person may become a dangerous one. Critics argue that there aren't enough facts/evidence about the way genes operate and interact to be sure of what the outcome of any modification will be. They worry that the alteration could accidentally lead to substances that are poisonous or trigger allergies. This view is aggravated by the fact that most genes being introduced into GE plants come from sources which have never been part of a human diet and therefore there is no way of knowing whether or not the products of these genes will cause allergic reactions. (National Science and Technology Commission) |
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