餐桌上的麻烦 Trouble on the Table


餐桌上的麻烦 Trouble on the Table

What do you get when you cross a chicken with an apple? A daffodil with rice? A flounder with a tomato? These aren't jokes waiting for a punch line. Believe it or not, combinations like these may make their way to your dinner table. There's a brave new world of agriculture that has some people excited about new superfoods. Others are very nervous.


For thousands of years, farmers improved their crops by patiently crossbreeding plants that have good traits. They would take pollen from the sweetest melon plants and add it to the flowers of plants that produced the biggest melons to create new plants with melons that are both sweet and big. But crossbreeding doesn't always work. Even when it does, it can take decades to get good results.


Now, thanks to advances in gene science, there are amazing shortcuts. Genes are the instructions inside cells that help determine what a living thing looks like: its size,its shape and countless other traits. Using the new tools of genetic engineering, scientists can take a gene from one living thing and put it directly into another plant or animal. That way, says John Mount, professor of agriculture at the University of Tennessee, “you can make changes more precisely in a much shorter period of time.”


Here's how it works. First, scientists identify a gene that controls a desirable trait — for example, a protein in an Arctic flounder that helps the fish thrive in frigid waters. The scientists then use chemicals to cut and paste the flounder gene into the genes of tomato cells in a test tube. The cells grow into a tomato plant. Then the plant is tested to see if the fish gene still works. Do its tomatoes resist the cold? Yes, they do!


Scientists believe the new techniques can create crops that are pest-proof, disease resistant and more nutritious. Researchers are working on rice that has an extra boost of vitamin A from a daffodil gene. The rice could help prevent blindness, even death, for millions of kids who don't get enough vitamin A in their diet.


Are we making monster food?


Not everybody is convinced that pumping up our food with foreign genes is a good idea. Many people say these genetically modified, or GM, foods may end up harming the environment and humans. They fear that plants with new genes forced into them will accidentally crossbreed with wild plants and create pesticide-resistant superweeds. They also say GM foods could carry genes that trigger allergies or other side effects. Already, there's evidence that some GM corn crops may be harmful to the caterpillars that turn into monarch butterflies.




匿名网友 填写信息

:?: :razz: :sad: :evil: :!: :smile: :oops: :grin: :eek: :shock: :???: :cool: :lol: :mad: :twisted: :roll: :wink: :idea: :arrow: :neutral: :cry: :mrgreen: