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SSS 2008-12-08

时间:2010-05-15 07:16来源:互联网 提供网友:木渐浅。   字体: [ ]
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    (单词翻译:双击或拖选)

This is Scientific American's 60-Second Science. I'm Karen Hopkin. This will just take a minute.

 

Animals that live in cold climates tend to have stubby limbs—shorter arms and legs—even smaller ears and tails. Picture a penguin1 and you’ll see what I mean. Biologists have long assumed that these stumpy appendages2 are an evolutionary3 adaptation. Shorter extremities4 minimize heat loss, so animals that are more compact are better suited to the cold.

But scientists from Ohio say that temperature may have a more direct effect on the length of an animal’s limbs. Because they find that turning up the heat helps cartilage grow—results that were published in the Proceedings5 of the National Academy of Sciences.

The researchers raised mice at several different temperatures, and they confirmed that those kept at a balmy 80 degrees were longer limbed than those who lived at a more chill 45. But how does a little heat make mice more leggy? The answer, they find, lies in the cartilage. Long bones grow from the cartilage found at either end. And the warmer it is, the more that cartilage grows, even when it’s just sitting in a test tube. Which I guess means it’s possible that the dog days of summer lead to longer-legged dogs.

 

Thanks for the minute for Scientific American's 60-Second Science. I'm Karen Hopkin.

 


点击收听单词发音收听单词发音  

1 penguin W3jzf     
n.企鹅
参考例句:
  • The penguin is a flightless bird.企鹅是一种不会飞的鸟。
  • He walked with an awkward gait like a penguin.他走路的步子难看得就像企鹅。
2 appendages 5ed0041aa3aab8c9e76c5d0b7c40fbe4     
n.附属物( appendage的名词复数 );依附的人;附属器官;附属肢体(如臂、腿、尾等)
参考例句:
  • The 11th segment carries a pair of segmented appendages, the cerci. 第十一节有一对分节的附肢,即尾须。 来自辞典例句
  • Paired appendages, with one on each side of the body, are common in many animals. 很多动物身上有成对的附肢,一侧一个,这是很普遍的现象。 来自辞典例句
3 evolutionary Ctqz7m     
adj.进化的;演化的,演变的;[生]进化论的
参考例句:
  • Life has its own evolutionary process.生命有其自身的进化过程。
  • These are fascinating questions to be resolved by the evolutionary studies of plants.这些十分吸引人的问题将在研究植物进化过程中得以解决。
4 extremities AtOzAr     
n.端点( extremity的名词复数 );尽头;手和足;极窘迫的境地
参考例句:
  • She was most noticeable, I thought, in respect of her extremities. 我觉得她那副穷极可怜的样子实在太惹人注目。 来自辞典例句
  • Winters may be quite cool at the northwestern extremities. 西北边区的冬天也可能会相当凉。 来自辞典例句
5 proceedings Wk2zvX     
n.进程,过程,议程;诉讼(程序);公报
参考例句:
  • He was released on bail pending committal proceedings. 他交保获释正在候审。
  • to initiate legal proceedings against sb 对某人提起诉讼
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TAG标签:   SSS  cartilage
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