单项选择题

A Mystery in the Lunchbox Hungry Sit down. We’’re having catfish, corn on the cob, baked potatoes and fresh tomatoes. This might turn out to be the most nutritious meal of your life. It might even be the best-tasting dinner you ever had. On the other hand, it might induce an allergic (过敏性的) reaction — even though you are not allergic to any of these foods. Different Opinions about Biotechnology (生物工程) Products Last week’’s announcement that the U.S. federal government would impose no special regulations on bioengineered foods, in effect permitting them to be marketed exactly like nature’’s own, proclaims a potentially vast change in our food supply. "We will not compromise safety one bit," Vice President Dan Quayle told the press. "And consumers will enjoy better, healthier food products at lower prices." Many specialists in biotechnology agree — in fact, they see consumers around the world benefiting from a new, genetically-engineered green revolution — but critics are urging the government to move ahead more cautiously. "We should have learned from the history of regulating pesticides (杀虫剂) that we never knew the long-term consequences until it was too late," says Ellen Haas, executive director of Public Voice for Food and Healthy Policy, a Washington D.C.-based advocacy group. The Food and Drug Administration maintains that most bioengineered foods present no special safety issues. "We’’re saying this is just another plant-breeding technique," says Eric Flamm, deputy director of the FDA’’s Office of Biotechnology. How Does Recombination of DNA Work Here’’s how bioengineering works: all cells contain DNA, the long molecule (分子) shaped like a double helix (螺旋). A gene is a swatch (样本) of DNA that controls a certain characteristic of the organism. In the 1970s scientists discovered they could clip off a gene-length swatch from a DNA molecule, and later they learned to affix (固定) it to a different DNA molecule — a cut-and-paste job that became known as gene splicing and results in what’’s called recombinant DNA. Immediately, visions of carrots with the flavor of peanut butter began dancing in the imaginations of scientists and food writers alike. But most current experiments are less exotic (异乎寻常的). In many ways the new technology differs little from traditional crossbreeding. One Product of Bioengineered Technology The first example of recombinant DNA in a form suitable for lunch makes its debut (首次露面) next summer: the Flavr Savr tomato. Scientists at Calgene, Inc., a biotech company based in Davis, California, isolated the gene in the tomato that triggers the enzyme (酶) responsible for rotting and rendered it inactive. Rather man having to be picked hard and green for easy shipping, the tomatoes stay on the vine about five days longer than usual. They can be shipped* without refrigeration, which also helps retain flavor, and they’’ll resist rotting for more man three weeks, twice as long as their conventionally grown cousins. They aren’’t perfect: like other supermarket tomatoes they’’re grown with pesticides, they may be waxed, and they still lack the last three to five days of vine-ripening that homegrown tomatoes enjoy. Sampled at Calgene’’s headquarters, the Flavr Savr tasted fine; whether consumers still find it worth a dollar more per pound remains to be seen. Developing Pest Resistant Plant Several companies are hard at work on plants that will repel (抵制) pests (害虫). Monsanto, a St. Louis, Missouri, chemical company, expects to put many such products on the market before the end of the decade. The weapon of choice is Bacillus thuringiensis, or BT, a soil-dwelling bacterium (细菌) that creates a protein crystal that is toxic to certain insects but harmless digested by humans. BT has been used for 30 years as an organic pesticide. Scientists can transfer the gene for the toxin into plant cells, and the new plants will produce their own insecticides. Like traditional insecticides, however, these may simply spur the creation of new, more resistant pests. According to Belknap, the solution will be to splice several toxins into a given plant, thus lessening the potential for insects to develop resistance (or inviting the birth of some pretty amazing insects). One Member of the Herbicide (除草剂) Family, and Its Problems Monsanto is also developing herbicide-resistant plants, specifically Roundup-resistant plants. Roundup is one of Monsanto’’s most lucrative (获利的) products, a herbicide with sales of a billion dollars a year. It has been recognized as noncarcinogenic (非致癌的) by the Environmental Protection Agency, though it’’s toxic to fish. Roundup is used as a weed-killer, but it will kill everything else it touches in the field, so farmers have had to apply it carefully. Now, however, Monsanto can isolate the enzyme in, say, corn, that is fatally vulnerable to Roundup. A corn plant engineered to have twice as much of that enzyme can lose a chunk of it to Roundup and still survive. Critics charge that this technology simply invites fanners to use more Roundup. Good News for the Business but Consumers Are Entitled to Know What They Are Eating It’’s not surprising that biotechnology companies were delighted by the FDA’’s green light. Environmentalists and other consumer advocates don’’t claim the new foods are unsafe by definition, but they do call for tougher scrutiny (监督) than the FDA believes is necessary. "The regulations do a lot more to protect the industry than they do to protect the American consumers, "says Rebecca Goldburg, a senior scientist at the Environmental Defense Fund, an advocacy group. "The public has a right to know what’’s in its food." It’’s Up to the Biotechnology Industry, not FDA Goldbury and other critics are especially concerned about potential allergens that may be hiding in new products — an orange touched up with a gene from a cherry, for instance. The FDA requires no special testing or labeling unless the new food is substantially different from its traditional version. A new food containing a "common allergen" would also have to be labeled, but as examples of common allergens the FDA suggests only eggs, milk, fish, shellfish, tree nuts, wheat and other legumes. The truth is, almost any food is an allergen (过敏源) to someone. According to the FDA, it’’s up to the biotechnology industry to police itself on potential allergens. "If you move a gene, you have to prove it not allergenic or you will have to label it," says Flamm. There Are Better Ways to Produce Food than Using Biotechnological Methods Other critics are uneasy about making such dramatic changes with such speed. "We ought to be testing these changes in large populations over large periods of time," says Greg Drescher, a director of Old-ways Preservation & Exchange Trust, a Boston-based think-tank for food issues. He also questions how useful the new foods really are. "We don’’t need to play sorcerer’’s (魔法师) apprentice (学徒) with agriculture," he says. "We know how to produce good-tasting food in this country. There are much better ways to eat healthfully than a food supply based on techno-foods." Jeremy Rifkin, the activist who has been fighting biotechnology for years, promises lawsuits and a massive publicity campaigns, and he thinks the public will be on his side. "If people don’’t want foods pumped full of hormones (激素) and antibiotics (抗生素), they are never going to go along with genetically-engineered foods," he says. At the very least, these critics may persuade the FDA to require more labeling of the new foods. Biotechnology methods are used to produce tomatoes that soften later than usual.