VOA慢速英语--研究人员通过转基因来增加玉米营养

（单词翻译）

Researchers Genetically Modify Corn to Increase Nutrition

Researchers in the United States say they have discovered how to genetically engineer corn to produce a kind of amino acid usually found in meat.

The result is a food with increased nutrition that could feed animals and people around the world. The new corn, also called maize, could reduce the cost of animal food.

The discovery was published online in the Proceedings of the National Academy of Sciences, a scientific journal in early October.

The researchers say the process involves putting genetic material from a bacterium into corn.

Methionine is very important for humans and animals. It is one of nine necessary amino acids that humans get from food, according to the National Center for Biotechnology Information. It supports growth, helps repair skin injuries, improves hair quality and strengthens fingers and toe nails. It also helps protect cells from pollution and slows the aging process.

Thomas Leustek is a professor of Plant Biology at Rutgers University in New Jersey and one of the writers of the study. He told VOA, "We improved the nutritional value of corn, the largest commodity crop grown on Earth." He added, "Most corn is used for animal feed, but it lacks methionine -- a key amino acid -- and we found an effective way to add it."

The new method

The scientists genetically modified corn by adding the bacterium called E. coli into the genome of the corn plant.

The scientists said they directed their efforts to increase the plant’s production of the amino acid in its leaves. In an earlier version of their experiment, they found that causing the whole plant to produce methionine had bad effects on the plant’s growth.

According to the study, the amount of methionine in the corn kernels increased by about 57 percent.

Joachim Messing is a Rutgers professor and Director of the Waksman Institute of Microbiology. Messing said scientists fed the genetically modified corn to chickens at Rutgers University to test whether the corn was healthy to eat.

The authors said that normally chicken food is a mixture of corn and soybean. Soybean contains some methionine.

However, additional amounts of the amino acid are often added to animal food.

"Methionine is added because animals won't grow without it. In many developing countries where corn is a staple, methionine is also important for people, especially children. It's vital nutrition, like a vitamin,” Messing said.

If the genetically modified corn can be successfully marketed and sold, people who live in developing countries “wouldn't have to purchase methionine supplements or expensive foods that have higher methionine," Leustek said.

Currently, synthetic methionine is added to corn seeds every year, an expensive process costing several billion dollars, said co-writer Messing.

Leustek told VOA that he felt that farmers could save a lot of money every year because of this discovery.

He added that, in the future, it may be possible to grow corn to have higher levels of methionine without having to genetically modify it.

But until then, he said, the genetically modified version “is available currently and ready to go!”

I’m Phil Dierking.

Words in This Story

amino acid - n. any one of many acids that occur naturally in living things and that include some which form proteins?

commodity - n. something that is bought and sold?

genome - n. the complete set of genes or genetic material present in a cell or organism.?

kernel - n. one of the yellow seeds that cover an ear of corn?

nutrition - n. the process of eating the right kind of food so you can grow properly and be healthy?

methionine - n. a sulfur-containing amino acid that is a constituent of most proteins. It is an essential nutrient in the diet of vertebrates.?

staple - n. an important food that is eaten very often?

synthetic - adj. something made by combining different artificial substances