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Conrad Bérubé |
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The following is an excerpt from a handout prepared for
Entomology 111: Insects and Human Affairs at the
University of California/Davis.
Transgenic organisms are artificially created plants, animals or microorganisms which have had genes from a different species spliced into their own genome. For instance, genes in the lightning bug code for the enzyme luciferase which breaks down a protein called luciferan to produce the characteristic glow in these insects; luciferase-producing genes were extracted from lightning bugs and incorporated into cells of tobacco plants. The tobacco cells were then reared into mature plants via tissue culture such that all the cells of the plant produced luciferase. When the plants were watered with a solution containing luciferin the enzyme catalyzed the reaction as it would in the insect-- and the transgenic tobacco plants glowed!The gene coding for a protein toxic to lepidopteran insects has been extracted from the bacteria Bacillus thuringiensis and spliced into the genetic blueprint of patented varieties of potatoes and tomatoes. This tactic has a distinct advantage over spraying Bt proteins on crop plants. Sprays must be applied very evenly and heavily enough that an insect will ingest enough of the toxin to receive a fatal dose before it eats very much of the plant upon which it is feeding. If incorporated into every cell of the plant fruit or foliage-feeding caterpillars would get a mouthful of poison with every bite. Some people worry, however, that this type of technology is similar to spraying a field with insecticide every day and that this would act as a constant and intense selective pressure on insect populations which may lead to rapid development of resistance in the target species. Others worry that prolonged consumption of produce containing the toxin, reportedly harmless to humans, may, in fact, pose unforeseen health risks to consumers. We can only hope that "killer tomatoes" remain the stuff of fantasy.
Copyright © 2007 Conrad Bérubé, site design, concept and scripting. All rights reserved worldwide.