VOA慢速英语2015 蠕虫准备在太空中飞行（在线收听）

Worms Get Ready to Fly in Space 蠕虫准备在太空中飞行

Humans are well-equipped for life on Earth. But in space, it is a different story. Low or zero gravity changes how the blood flows and causes motion sickness, muscle loss and tiredness. Weightlessness can also cause bone loss.  But scientists at the University of Delaware are experimenting with little worms to better understand how space travel affects astronauts.  

人类完全具备在地球上生活的条件，但在太空却不一样，低重力和零重力改变了血液流动，并导致晕动症、肌肉损失和疲倦，失重还会导致骨骼损失。但特拉华大学的科学家们在用小蠕虫做实验，以更好地理解太空旅行是如何影响宇航员的。

The millimeter-long worm is called C. elegans.  The see-through invertebrate is often used in medical studies because its life is only about two weeks long.  Seventy percent of its DNA is the same as human DNA.

这种几毫米长的蠕虫叫线虫，这种透明的无脊椎动物寿命只有两周，因此经常被用在医学研究中，其70%的DNA和人类DNA相同。

Chandran Sabanayagam is a scientist with the University of Delaware. He built a micro-gravity simulator to test how C. elegans would perform in the actual zero gravity of space. 

Sabanayagam是特拉华大学的一名科学家，他建造了一个微重力模拟器，来测试线虫在太空失重状态下的情况。

"Imagine, if you have a container of water and you put an object in it, and it begins to settle to the bottom.  But, before it hits the bottom, you flip the container upside down. And now it has to fall back down to the bottom. Before it reaches it, you flip it again. Essentially this instrument rotates and the object never hits the bottom. So essentially it's in freefall, similar to a satellite orbiting the earth."

“想象一下有个装着水的容器，然后把一个物体放进容器里，然后物体开始落在容器底部。但在接触底部之前，你将容器翻转过来。现在物体就开始回落到底部，在接触底部之前，再次将容器翻转。基本上来说，这个仪器会旋转，这个物体永远不会触底。所以这就是自由落体，和绕地球运转的卫星类似。”

Scientists use a computer to watch the worms as they turn. The computer shows the worms as they would look under a microscope.  Mr. Sabanayagam says the worms turn around and around in the simulator for about one week.

科学家用电脑来观察蠕虫是如何翻转的，电脑显示蠕虫在显微镜下的样子。Sabanayagam说蠕虫在模拟器里反复翻转一周左右。

After about a week the scientists take out the worms. They look for changes in the worms' epigenome. The epigenome are chemical markers that tell the DNA in the cells how to perform. The epigenome can be changed by the environment. And those changes pass from one generation of worms to the next.

一周后科学家将蠕虫取出，然后观察蠕虫表观基因组的改变。表观基因组是能告诉细胞中DNA如何表现的化学性状，表观基因组可以被环境改变，这些改变从一代蠕虫传递到下一代。

Mr. Sabanayagam studies the epigenome as it relates to microgravity.

Sabanayagam研究了微重力下的表组基因组。

"When the worms are in a liquid environment some epigenomic marks persist (remain) even when we take the animal out of the liquid environment and put it back into normal ground conditions. So its offspring retains this epigenomic memory of the parents' liquid environment or microgravity environment."

“当蠕虫在液体环境中时，一些表观基因组的形状会保持不变，即使是将它从这种液体环境中取出，并放回正常的地面环境中也是如此。所以它的后代会保留其父辈在液体环境或微重力环境下的表观基因组的记忆。”

The information the scientists have gathered suggests that the epigenomic marks appear during the early part of a worm’s life. Mr. Sabanayagam says identifying epigenomic marks is important for human studies in the future. 

科学家收集的信息表明，表观基因组性状在蠕虫的早期生命就出现了，Sabanayagam说识别表观基因组性状对未来的人类研究来说很重要。

He says he thinks scientists can find genes in the human genome similar to those in the worms that responded to microgravity. He says scientists could possibly observe those genes closely when astronauts travel in space.

他说他认为科学家能在人类基因组中找到与应对微重力类似基因的基因，他说科学家可以在宇航员进行太空旅行时密切观察这些基因。

Chandran Sabanayagam expects C. elegans to visit the International Space Station within two years.  He says he hopes information gathered from the worm studies can be used to develop simple, low-cost and quick tests to measure an astronaut's health.

Sabanayagam期待线虫能在两年内来到国际太空站，他说希望从蠕虫研究中得到的信息可以用来开发简单、廉价且快速的测试方法来衡量宇航员的健康状况。

Words in this Story

invertebrate – n. a type of animal that does not have a backbone

DNA – n. a substance that carries genetic information in the cells of plants and animals; an abbreviation of deoxyribonucleic acid

rotate – v. to move or turn in a circle

simulator – n. a machine that is used to show what something looks or feels like and is usually used to study something or to train people