GM OrganismsBy far the most common genetically modified （GM) organisms are crop plants. Bu

GM Organisms

By far the most common genetically modified (GM) organisms are crop plants. But the technology has now been applied to almost all forms of life, from pets that glow under UV light to bacteria which form. HIV-blocking "living condoms" and from pigs bearing spinach(菠菜) genes to goats that produce spider silk.

GM tomatoes ,first appeared on British supermarket shelves in 1996 (a different fresh GM tomato first appeared in the US in 1994), but the consumer furore that surrounded GM technology did not erupt until February 1999. This was because a controversial study suggested that a few strains of GM potatoes might be toxic to laboratory rats. Those experiments, subsequently criticised by other experts, were carried out in Scotland by biochemist Arpad Pustzai.

What followed was a European anti-GM food campaign of near religious fervor. Spearheaded in the UK by environmental groups and some newspapers, the campaign would have far-reaching consequences. It culminated in an unofficial moratorium(延期付款) on the growth and import of GM crops in Europe and led to a trade dispute with the US.

GM crops are today very rare in Europe, strict labeling laws and regulations are in place for food (DNV = A bar codes), and public opinion towards the technology remains largely negative. Several UK government reports have offered qualified support for GM crops and produce, though they argue that the economic benefits of the technology are currently small. Some African nations have also opposed engineered crops, even to the point of rejecting international food aid containing them.

GM produce has been taken up with far less fuss in the US (where it does not have to be labeled), India, China, Canada, Argentina, Australia and elsewhere. However controversy over a type of GM corn -- only approved for animal feed -- which turned up in taco shells and other products stirred opinion in the US.

Biotech Revolution

The human race has methodically improved crop plants through selective breeding for many thousands of years, but genetic engineering allows that time-consuming process to be accelerated and exotic traits from unrelated species to be introduced. But not everyone agrees this represents progress.

The root of genetic engineering in crops lies in the 1977 discovery that soil bug Agrobacterium Tumefaciens can be used as a tool to inject potentially useful foreign genes into plants. With the help of that microbe, and other gene-implantation technologies such as gene guns, geneticists have developed a multitude of new crop types.

Most of these are modified to pest, disease or herbicide resistant, and include: soya, wheat, corn (maize), oilseed rape (canola), cotton, sugar beet, walnuts, potatoes, peanuts, squashes, tomatoes, tobacco, peas, sweet peppers, lettuce and onions ,. among others. The bacterial gene Bt is one of the most commonly inserted. It produces an insecticidal toxin that is harmless to people.

Supporters of GM technology argue that engineered crops -- such as vitamin A -- boosted golden rice or protein-enhanced potatoes -- can improve nutrition, that drought -- or salt-resistant varieties can flourish in poor conditions and stave off world hunger, and that insect-repelling crops protect the environment by minimising pesticide use.

Other plants have been engineered to improve flavour, increase shelf life, increase hardiness and to be allergen-free (see also: hay fever-free grass). Geneticists have even created a no-tears on ion to banish culinary(厨房的) crying, and novel caffeine-free coffee plants.

"Frankenfood" Fears

Critics fear that what they call" Frankenstein foods" could have unforeseen, adverse health effects on' consumers, producing toxic proteins (and allergens ) or transferring antibiotic-resistance and other genes to human gut bacteria to damagin

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