Scientists Building Redesigned Life Forms

时间 : 2017-08-07 06:41来源 : VOA官网 收听下载次数 :
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For thousands of years, humans have used yeast for making bread and alcoholic drinks, such as beer. But scientists are now constructing synthetic yeast that can do more than make a sandwich or a drink. The synthetic yeast can be used for medicines, vaccines, and biofuels – among other things.

What is DNA?

So, how does it work?

Yeast, like humans, are living organisms with DNA. DNA is short for deoxyribonucleic acid. On long strings it carries the genetic instructions used in the growth, functioning and reproduction of all living things.

Scientists Building Redesigned Life Forms

Modern science allows researchers to cut and move around the four biological compounds that make up DNA. The compounds are known by the letters A,C, G and T. The yeast genome, or its genetic material map, has more than 10 million of these DNA letters. But that is nothing compared to us: Humans have about three billion.

Making synthetic yeast

Scientists have long been able to make changes in the DNA code. But now, some scientists are doing something different.

When you walk into Jef Boeke’s lab it smells like bread rising. But his team is not making homemade dough. Instead, they are changing the order of genes in yeast cells.

Boeke manages a team of 11 labs on four continents. He spoke to VOA Learning English about this project.

“What we're doing basically is writing that DNA and we also modify it along the way, so we kind of redesign it on a computer, and then it's that modified DNA that we actually put into cells. We swap it in place of the DNA that's already there.”

So far, the scientists have constructed and replaced six of yeast’s 16 chromosomes. The new chromosomes have all worked well.

Yeast is already used to produce many other valuable compounds, such as medicines, vaccines and biofuels. By making synthetic yeast, researchers could make different combinations used for different jobs.

For example, one combination may be better for making biofuel, and another for making medicine. These compounds could then be made in large, industrial amounts.

Synthetic yeast could also be used to make bioplastic—a material that, unlike plastic made from petroleum, would be biodegradable. Using this material would help reduce pollution.

Boeke says the possible uses for yeast are limited only by one’s imagination.

“They can be programmed through DNA writing to produce really an almost limitless range of products in terms of molecules or chemical compounds that that can replace things that we currently make from petroleum or other sources and as well as some new materials that don't even exist today."

So far, scientists have engineered yeast to produce bright colors. The yeast can make artwork, and in the future, may even be used to paint a house.

But, to be clear, Boeke says, his teams are not creating new life.

“No one's ever created life out of non-living material. All the experiments we do start with pre-existing living cells and we introduced modified DNA into it so that's actually a common misunderstanding that we're creating life. We are not creating life.”

Too much power?

However, redesigning DNA worries some people. Laurie Zoloth is a bioethicist at Northwestern University. She told the Associated Press (AP) that she is concerned about making organisms with “properties we cannot fully know.” She said the work would concern people who believe creating life from scratch would give humans power they should not have.

“It is not only a science project,” she wrote to AP. “It is an ethical and moral and theological proposal of significant proportions.”

Boeke says he does not think his team is doing anything dangerous. He says he and other scientists always look at the risks, especially when it comes to food safety, or when researchers engineer viruses.

Boeke says safety regulations help people who want to work in those areas.

Other researchers experimenting with DNA are waiting to see the results of this yeast work.

June Medford is with the University of Colorado.

“I paid very careful attention to when they say ‘here are the lessons learned,’ because if they can’t do it in a simple thing like yeast, I will never be able to do it in a plant."

But Medford and other DNA researchers will have to wait. Boeke needs at least another year to finish his pioneering project.

I’m Anne Ball.

Anne Ball wrote this story for Learning English with information from the Associated Press and VOA News. Kelly Jean Kelly was the editor.

What do you think of the researchers' work to rebuild the yeast DNA?

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