手機(jī)版
Longer Limbs
Animals that live in cold climates tend to have stubby limbs—shorter arms and legs—even smaller ears and tails. Picture a penguin and you’ll see what I mean. Biologists have long assumed that these stumpy appendages are an evolutionary adaptation. Shorter extremities 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 Proceedings 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.
更長(zhǎng)的四肢
生活在寒冷地方的動(dòng)物其四肢傾向于長(zhǎng)得短而粗——就是耳朵和尾巴也要小一些。想想企鵝你就明白我的意思了。生物學(xué)家們長(zhǎng)久以來認(rèn)為這些短而粗的附肢是一種進(jìn)化過程中的適應(yīng)。更加短小的四肢能使熱損失降到最低，所以，體型粗短的動(dòng)物能更好地適應(yīng)寒冷氣候。
不過來自俄亥俄 (Ohio)的科學(xué)家們報(bào)道說，溫度可能對(duì)動(dòng)物四肢的長(zhǎng)度有更直接的影響。因?yàn)椋麄儼l(fā)現(xiàn)提高溫度能幫助軟骨組織的生長(zhǎng)——這些研究結(jié)果發(fā)表在《美國(guó)國(guó)家科學(xué)院院刊》(Proceedings of the National Academy of Sciences)上。
研究者們?cè)诓煌臏囟认嘛曫B(yǎng)老鼠，他們證實(shí)與生長(zhǎng)在寒冷的45度 （譯者注：這里指華氏度，45華氏度相當(dāng)于7.2攝氏度）下的老鼠相比，那些生長(zhǎng)在溫和的80度 （80華氏度相當(dāng)于26.7 攝氏度 ）下的老鼠的四肢要長(zhǎng)一些。但是溫度的提高是怎樣使老鼠的腿長(zhǎng)得更細(xì)長(zhǎng)的呢？研究者們發(fā)現(xiàn)答案在于軟骨組織。長(zhǎng)的骨骼是從骨頭兩端的軟骨組織生長(zhǎng)而來。氣溫越暖和，軟骨組織長(zhǎng)得越長(zhǎng)，即使在試管中也是如此。根據(jù)這個(gè)研究，我猜想這可能意味著炎熱的夏天會(huì)使狗的腿長(zhǎng)的更長(zhǎng)。
Vocabulary:
Limb: 四肢
Stubby: 短而粗的
Penguin: 企鵝
Assume: 假設(shè)；
Stumpy: 樹墩似的；短而粗的
Appendage: 附屬物
Evolutionary: 進(jìn)化的
Extremities: (醫(yī)學(xué))四肢，手足
Minimize: 最小化
Compact: 緊密的；簡(jiǎn)潔的
Cartilage: 軟骨組織
Confirm: 確認(rèn)
Balmy: （氣候）溫和的
Chill: 寒冷的
Leggy: 腿細(xì)長(zhǎng)的；露腿的
The dog days of summer： 夏季最悶熱的時(shí)候
