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科学美国人60秒 SSS 恒温动物失去了心脏愈合能力

时间:2019-12-10 09:01:13

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(单词翻译)

 

This is Scientific American's 60-second Science, I'm Christopher Intagliata.

It sounds like a witches' recipe: gather the hearts of a fence lizard1; a little brown bat; a naked-tailed armadillo; and dozens of others. "So initially2 we tried to get them from zoos... but unfortunately that didn't work out very well. We couldn't get any samples, even when the animal died, we couldn't get a heart."

Guo Huang, a developmental biologist at the University of California, San Francisco. He says they had more success obtaining specimens3 from the jars of natural history museums. The reason for this biological scavenger4 hunt? Huang and his colleagues wanted to examine the number of chromosomes5 contained in heart cells across the animal kingdom. Because there's a curious phenomenon in our hearts—which is that most of the human body's cells are diploid, meaning two sets of chromosomes, one from each parent. But the lion's share of our heart cells are actually polyploid, meaning two or more copies from mom, two or more copies from dad. 

What Huang and his team found, looking at that collection of hearts, is that the proportion of polyploid cells in a heart goes up as you go from fish to lizards6 to amphibians7 to transitional species like platypuses8, to mammals. The reason that finding might matter to us, is that recent studies in mice and zebrafish have shown that hearts with more diploid cells—like a zebrafish's—are able to regenerate9 and heal themselves. Hearts with more polyploid cells—like mice and humans—cannot.

So what makes a heart have more polyploid cells, and thus, less chance of regenerating10? "That's actually the million-dollar question." But one answer Huang's team found, is that thyroid hormone11—the same hormone that regulates metabolism12 and makes us warm-blooded creatures—might be to blame. Because when they added extra thyroid hormone to zebrafish's tanks, their tiny hearts were no longer able to regenerate. And, conversely, when they engineered mice to have hearts that were insensitive to thyroid hormone, the mouse hearts could regenerate back after injury.

"When we look at the heart function which is mainly measured by contract ability of the heart, we can see heart function improve over time after injury, while control mice cannot improve."

The results are in the journal Science.

As for fixing human hearts? Perhaps manipulating thyroid hormone levels could be a start. "We know regulating thyroid hormone probably alone is not sufficient to cure heart disease, at least for promoting heart regeneration completely. If we can figure out other major regulators of this process, we might be in a better shape."

Thanks for listening for Scientific American — 60-Second Science. I'm Christopher Intagliata.


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1 lizard P0Ex0     
n.蜥蜴,壁虎
参考例句:
  • A chameleon is a kind of lizard.变色龙是一种蜥蜴。
  • The lizard darted out its tongue at the insect.蜥蜴伸出舌头去吃小昆虫。
2 initially 273xZ     
adv.最初,开始
参考例句:
  • The ban was initially opposed by the US.这一禁令首先遭到美国的反对。
  • Feathers initially developed from insect scales.羽毛最初由昆虫的翅瓣演化而来。
3 specimens 91fc365099a256001af897127174fcce     
n.样品( specimen的名词复数 );范例;(化验的)抽样;某种类型的人
参考例句:
  • Astronauts have brought back specimens of rock from the moon. 宇航员从月球带回了岩石标本。
  • The traveler brought back some specimens of the rocks from the mountains. 那位旅行者从山上带回了一些岩石标本。 来自《简明英汉词典》
4 scavenger LDTyN     
n.以腐尸为食的动物,清扫工
参考例句:
  • He's just fit for a job as scavenger.他只配当个清道夫。
  • He is not a scavenger nor just a moving appetite as some sharks are.它不是食腐动物,也不像有些鲨鱼那样,只知道游来游去满足食欲。
5 chromosomes 11783d79c0016b60332bbf1856b3f77d     
n.染色体( chromosome的名词复数 )
参考例句:
  • Chromosomes also determine the sex of animals. 染色体也决定动物的性别。 来自《简明英汉词典》
  • Each of four chromosomes divide longitudinally. 四种染色体的每一种都沿着纵向分裂。 来自《现代汉英综合大词典》
6 lizards 9e3fa64f20794483b9c33d06297dcbfb     
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
7 amphibians c4a317a734a700eb6f767bdc511c1588     
两栖动物( amphibian的名词复数 ); 水陆两用车; 水旱两生植物; 水陆两用飞行器
参考例句:
  • The skin of amphibians is permeable to water. 两栖动物的皮肤是透水的。
  • Two amphibians ferry them out over the sands. 两辆水陆两用车把他们渡过沙滩。
8 platypuses ef6d2b62ff8fb88be18f72f90e02c299     
n.鸭嘴兽( platypus的名词复数 )
参考例句:
  • Like humans, platypuses carry an X and a Y chromosome. 鸭嘴兽跟人类一样,也有X和Y染色体。 来自互联网
9 regenerate EU2xV     
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。
10 regenerating 0fd51be890ff4b873643d13907e3ab4f     
v.新生,再生( regenerate的现在分词 );正反馈
参考例句:
  • It is not proposed to deal with the detailed histology of regenerating tissues here. 这里未提出详细的再生组织的组织学。 来自辞典例句
  • This is accomplished by using a thermocompressor to recycle regenerating steam through the absorber. 它用热压机使再生蒸汽经吸附器循环完成解吸过程。 来自辞典例句
11 hormone uyky3     
n.荷尔蒙,激素,内分泌
参考例句:
  • Hormone implants are used as growth boosters.激素植入物被用作生长辅助剂。
  • This hormone interacts closely with other hormones in the body.这种荷尔蒙与体內其他荷尔蒙紧密地相互作用。
12 metabolism 171zC     
n.新陈代谢
参考例句:
  • After years of dieting,Carol's metabolism was completely out of whack.经过数年的节食,卡罗尔的新陈代谢完全紊乱了。
  • All living matter undergoes a process of metabolism.生物都有新陈代谢。

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