VOA慢速英语--一些海蛞蝓砍掉头部后重新长出全新身体

Heads up! Some Sea Slugs Grow New Bodies after Losing Head

Scientists have discovered an extreme case of regeneration: Some sea slugs can regrow hearts and whole new bodies after having their heads cut off!

It is being called a "wonder of nature" and was recently reported in Current Biology. This discovery could help scientists better understand how to regenerate¹, or regrow, human tissue in the future.

Biology researcher Sayaka Mitoh said she loves studying Japanese sea slugs because they are small, cute, and strange. They can even briefly² photosynthesize like a plant drawing food from the sun.

Her research at Nara Women's University sounds like something from out of scary movie. While studying these small, cute creatures in the lab one day, she saw something strange. A sea slug had cut off its own head but kept on living and moving. Then a couple more sea slugs did the same!

So, Mitoh and another researcher Yoichi Yusa tried it themselves. They cut off the heads of 16 sea slugs. Six of the creatures started regeneration. Three of them survived. One of the three even lost and regrew its body twice. And two different kinds of Japanese sea slugs went through the regeneration process.

Other creatures can lose body parts when needed. For example, some lizards³ drop their tails to get away from danger and regrow them later. This is a biological event called autotomy.

"We think that this is the most extreme case of autotomy," Yusa said. He added that some animals can autonomize their legs or tails but no other can drop their whole body.

One kind of sea slug can grow to 15 centimeters long. Scientists had long thought that a creature that size could not survive without a heart to pump blood and nutrients⁴ to the brain.

Canadian marine⁵ biologist Susan Anthony is not part of the study. But she agreed with Yusa: the thing that makes Japanese sea slug special is probably what helps it do this trick.

When these sea slugs eat a certain type of algae⁶, Yusa said, they can photosynthesize their food from sunlight and oxygen, just like a plant, for about 10 days. He guessed that after decapitation the head sort of acts like a plant. It turns green and gets its energy from oxygen and sunlight.

Mitoh and Yusa said that sea slugs probably developed this ability as a way of fighting off parasites⁸.

Humans may be able to learn something useful from the sea creatures, several scientists have said. Nicholas Curtis is a biology professor at Ave Maria University. He also was not part of the study. What is especially interesting, he said, is that these sea slugs are more complex than other creatures that are known to regenerate.

In an email Curtis wrote: "It is of course a wonder of nature. But understanding the underlying⁹ molecular¹⁰ mechanisms¹¹ involved could help us to understand how our cells and tissues can be used to repair damage."

Words in This Story

regeneration – n.: the renewal¹², regrowth, or restoration of a body or a bodily part, tissue, or substance after injury or as a normal bodily process

photosynthesize – n. biology : the process by which a green plant turns water and carbon dioxide into food when the plant is exposed to light

decapitate – v. to cut off the head of (a person or animal)

autotomy – n. reflex separation of a part (such as an appendage) from the body : division of the body into two or more pieces

algae – n. any of a large group of simple plants and plant-like organisms (as a seaweed) that usually grow in water and produce chlorophyll like plants but do not produce seeds

parasite⁷ – n. an animal or plant that lives in or on another animal or plant and gets food or protection from it

1 regenerate   

vt.使恢复，使新生；vi.恢复，再生；adj.恢复的

参考例句：

• Their aim is to regenerate British industry.他们的目的是复兴英国的工业。
• Although it is not easy,you have the power to regenerate your life.尽管这不容易，但你有使生活重获新生的能力。

2 briefly   

adv.简单地，简短地

参考例句：

• I want to touch briefly on another aspect of the problem.我想简单地谈一下这个问题的另一方面。
• He was kidnapped and briefly detained by a terrorist group.他被一个恐怖组织绑架并短暂拘禁。

3 lizards   

n.蜥蜴( lizard的名词复数 )

参考例句：

• Nothing lives in Pompeii except crickets and beetles and lizards. 在庞培城里除了蟋蟀、甲壳虫和蜥蜴外，没有别的生物。 来自辞典例句
• Can lizards reproduce their tails? 蜥蜴的尾巴断了以后能再生吗？ 来自辞典例句

4 nutrients   

n.（食品或化学品）营养物，营养品( nutrient的名词复数 )

参考例句：

• a lack of essential nutrients 基本营养的缺乏
• Nutrients are absorbed into the bloodstream. 营养素被吸收进血液。 来自《简明英汉词典》

5 marine   

adj.海的；海生的；航海的；海事的；n.水兵

参考例句：

• Marine creatures are those which live in the sea. 海洋生物是生存在海里的生物。
• When the war broke out,he volunteered for the Marine Corps.战争爆发时，他自愿参加了海军陆战队。

6 algae   

n.水藻，海藻

参考例句：

• Most algae live in water.多数藻类生长在水中。
• Algae grow and spread quickly in the lake.湖中水藻滋蔓。

7 parasite   

n.寄生虫；寄生菌；食客

参考例句：

• The lazy man was a parasite on his family.那懒汉是家里的寄生虫。
• I don't want to be a parasite.I must earn my own way in life.我不想做寄生虫，我要自己养活自己。

8 parasites   

寄生物( parasite的名词复数 )； 靠他人为生的人； 诸虫

参考例句：

• These symptoms may be referable to virus infection rather than parasites. 这些症状也许是由病毒感染引起的，而与寄生虫无关。
• Kangaroos harbor a vast range of parasites. 袋鼠身上有各种各样的寄生虫。

9 underlying   

adj.在下面的，含蓄的，潜在的

参考例句：

• The underlying theme of the novel is very serious.小说隐含的主题是十分严肃的。
• This word has its underlying meaning.这个单词有它潜在的含义。

10 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。

11 mechanisms   

n.机械( mechanism的名词复数 )；机械装置；[生物学] 机制；机械作用

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。 来自《简明英汉词典》
• He explained how the two mechanisms worked. 他解释这两台机械装置是如何工作的。 来自《简明英汉词典》

12 renewal   

adj.(契约)延期，续订，更新，复活，重来

参考例句：

• Her contract is coming up for renewal in the autumn.她的合同秋天就应该续签了。
• Easter eggs symbolize the renewal of life.复活蛋象征新生。