VOA慢速英语--太空生活使身体的防御处于警戒状态

New Study: Life in Space Puts Body’s Defenses on Alert

Living in outer space for nearly a year had some interesting effects on American astronaut Scott Kelly.

Scientists found signs of increased activity in his immune system, the body’s natural defenses against disease. Life in space also changed the activity of some of Kelly’s genes³ compared to those of his identical twin brother, who stayed on Earth.

The scientists reported their findings at a conference earlier this month. But they admit they do not yet know if the changes are good or bad.

The findings are part of a larger, special study of twins from NASA, the United States government’s space agency. The study raises new questions for doctors as agency officials make plans to send people to the planet Mars.

Tests of Kelly and his genetically⁵ identical brother have given scientists a chance like never before to study details of human biology. They are able to examine how an astronaut’s genes turn on and off in space differently than on Earth.

One unexpected change announced at the recent meeting of the American Association for the Advancement⁶ of Science: Kelly’s immune system was hyperactivated.

Geneticist Christopher Mason helped lead the study. Mason is with Weill Cornell Medicine, Cornell University’s medical school in New York City. He told the Associated Press that doctors are now looking for this unusual condition in other astronauts.

“It’s as if the body is reacting to this alien environment sort of like you would a mysterious organism being inside you,” Mason said.

The health effects of space exploration

Since the beginning of space exploration, NASA has studied its effects on astronauts’ bodies. One effect is bone loss, which results from being in a low-gravity environment over an extended period. As a result, astronauts are now required to perform physical exercise during long space flights.

Usually astronauts are in space about six months at a time. Kelly, who lived on the International Space Station, spent 340 days in space and set a U.S. record.

“I’ve never felt completely normal in space,” Kelly wrote in an email to The Associated Press. He noted⁷ congestion⁸ and pain in his head, trouble paying attention, and stomach problems.

But this study was a look into the molecular⁹ level, with former astronaut Mark Kelly, Scott’s twin brother, on the ground for comparison.

A number of genes connected to the immune system became hyperactive, Charles Mason said. It is not a change in DNA¹⁰, the carrier of genetic⁴ information, but in what is called “gene² expression.” This term is used to describe how genes turn off and on and increase or decrease their production of proteins.

Mason also noted an increase in the bloodstream of another marker that prepares the immune system. Yet at the same time, Kelly’s blood showed fewer of another kind of cell that is an early defense¹ against viruses.

New discoveries

It is not a surprise that gene activity would change in space — it changes in reaction to all kinds of conditions.

The good news is most everything returned to normal shortly after Kelly returned to Earth in March 2016. However, those immune-related genes, “seemed to have this memory or this need to almost be on high alert” even six months later, Mason added.

Craig Kundrot heads space life and science research for NASA. He seemed pleased with the findings.

“There are no major new warning signs. We are seeing changes that we didn’t necessarily anticipate” but it is unclear if those changes are important, Kundrot noted.

From four Russians living in space for more than a year, NASA already knew it is possible for people to spend large amounts of time away from Earth, Kundrot said. He added, “We also aim for more than just possible. We want our astronauts to do more than just survive.”

In the end, the twin study gives NASA a list of things to watch for on future space missions to see if other astronauts react the same way. Astronauts on future flights will be able to do some of this testing in space instead of freezing blood and other material for scientists back home, Mason said.

A human mission to Mars, which NASA hopes to launch in the 2030s, would take 30 months, including time on the surface, said Kundrot.

Radiation is a top concern. The trip would expose astronauts to radiation levels higher than NASA’s own safety limits. It’s “just a little bit over,” he said.

On Earth and even on the space station, Earth’s magnetic field protects astronauts from high levels of radiation. There would be no such protections on the way to Mars and back, but special structures could help them on the planet, Kundrot said.

I’m Anna Matteo.

And I’m Pete Musto.

Words in This Story

identical twin – n. either member of a pair of two babies that are produced from a single egg and who look exactly alike

hyperactivated – adj. made more active than is usual or desirable

alien – adj. not familiar or like other things you have known

congestion – n. a condition where a part of the body is blocked with fluid, such as blood or mucus

DNA (deoxyribonucleic acid) – n. a substance that carries genetic information in the cells of plants and animals

alert – n. the state of being ready for something you have been warned about, such as an attack

anticipate – v. to think of something that will or might happen in the future

expose – v. to cause someone to experience something or to be influenced or affected¹¹ by something

mission – n. ?a flight by an aircraft or spacecraft to perform a specific task

1 defense   

n.防御，保卫；[pl.]防务工事；辩护，答辩

参考例句：

• The accused has the right to defense.被告人有权获得辩护。
• The war has impacted the area with military and defense workers.战争使那个地区挤满了军队和防御工程人员。

2 gene   

n.遗传因子，基因

参考例句：

• A single gene may have many effects.单一基因可能具有很多种效应。
• The targeting of gene therapy has been paid close attention.其中基因治疗的靶向性是值得密切关注的问题之一。

3 genes   

n.基因( gene的名词复数 )

参考例句：

• You have good genes from your parents, so you should live a long time. 你从父母那儿获得优良的基因，所以能够活得很长。 来自《简明英汉词典》
• Differences will help to reveal the functions of the genes. 它们间的差异将会帮助我们揭开基因多种功能。 来自英汉非文学 - 生命科学 - 生物技术的世纪

4 genetic   

adj.遗传的，遗传学的

参考例句：

• It's very difficult to treat genetic diseases.遗传性疾病治疗起来很困难。
• Each daughter cell can receive a full complement of the genetic information.每个子细胞可以收到遗传信息的一个完全补偿物。

5 genetically   

adv.遗传上

参考例句：

• All the bees in the colony are genetically related. 同一群体的蜜蜂都有亲缘关系。
• Genetically modified foods have already arrived on American dinner tables. 经基因改造加工过的食物已端上了美国人的餐桌。 来自英汉非文学 - 生命科学 - 基因与食物

6 advancement   

n.前进，促进，提升

参考例句：

• His new contribution to the advancement of physiology was well appreciated.他对生理学发展的新贡献获得高度赞赏。
• The aim of a university should be the advancement of learning.大学的目标应是促进学术。

7 noted   

adj.著名的，知名的

参考例句：

• The local hotel is noted for its good table.当地的那家酒店以餐食精美而著称。
• Jim is noted for arriving late for work.吉姆上班迟到出了名。

8 congestion   

n.阻塞，消化不良

参考例句：

• The congestion in the city gets even worse during the summer.夏天城市交通阻塞尤为严重。
• Parking near the school causes severe traffic congestion.在学校附近泊车会引起严重的交通堵塞。

9 molecular   

adj.分子的；克分子的

参考例句：

• The research will provide direct insight into molecular mechanisms.这项研究将使人能够直接地了解分子的机理。
• For the pressure to become zero, molecular bombardment must cease.当压强趋近于零时，分子的碰撞就停止了。

10 DNA   

(缩)deoxyribonucleic acid 脱氧核糖核酸

参考例句：

• DNA is stored in the nucleus of a cell.脱氧核糖核酸储存于细胞的细胞核里。
• Gene mutations are alterations in the DNA code.基因突变是指DNA密码的改变。

11 affected   

adj.不自然的，假装的

参考例句：

• She showed an affected interest in our subject.她假装对我们的课题感到兴趣。
• His manners are affected.他的态度不自然。