英语听力文摘 English Digest 708 短嘴鳄可以再长牙齿？

Fun Fact: Alligators² Can Regrow Teeth

Fun fact about alligators: they can regrow any of their eighty teeth up to fifty times. Which is pretty impressive, especially compared to us relatively³ dentally challenged humans: when we lose adult teeth, there’s no regrowing them.

Regrowing Teeth

But that may change. Hoping to save the toothless among us from being fated to wearing dentures, scientists are studying how alligators regrow teeth and how the same process may be able to work in humans.

Using X rays and tissue samples, plus lab grown gator tooth cells and computer models, scientists have learned that for each gator tooth there are two tooth precursors⁴, both of which are triggered to grow when a mature tooth is lost.

The growth process begins when a band of tissue called the dental lamina begins to bulge⁵. This wakes up stem cells and signaling molecules⁶ that kick start new tooth growth. And finally a new tooth grows in to replace the one that was lost.

Evolution

Now, it’s difficult to take what nature and evolution have combined to create in one species and somehow make it happen in another. But we humans do have remnants of dental lamina. And scientists are trying to figure out how to manipulate it to enable tooth growth in people similar to how it works in alligators. We could potentially use that same knowledge to turn off the processes in humans that sometimes cause problems like growing too many teeth or oddly shaped and spaced teeth.

The alligator¹ research is still in the early stages, so regrowing human teeth is still a ways away. But before too long, replacing a lost adult tooth may be as simple as growing it back.

短嘴鳄可以再长牙齿？

关于短吻鳄的有趣事实是：它们的80颗牙齿中的任何一颗都可以再生50次。这是非常令人印象深刻的，尤其是与我们这些牙齿发育相对困难的人相比：当我们失去成年牙齿时，它们就不会再长了。

重新排列牙齿

但这可能会改变。为了避免我们中的无牙者注定要戴假牙，科学家们正在研究短吻鳄如何再生牙齿，以及同样的过程如何在人类身上发挥作用。

利用X射线和组织样本，加上实验室培育的鳄鱼牙细胞和计算机模型，科学家们发现，每一颗鳄鱼牙都有两种牙齿前体，当一颗成熟的牙齿缺失时，这两种牙齿都会被触发生长。

当一个叫做牙板的组织带开始隆起时，生长过程开始。这会唤醒干细胞和信号分子，启动新的牙齿生长。最后，一颗新的牙齿长出来，以替换掉的那颗牙齿。

进化

现在，很难将自然和进化结合在一起，在一个物种中创造出来，并以某种方式在另一个物种上发生。但我们人类确实有牙板的残余。科学家们正试图弄清楚如何操纵它，使人的牙齿生长，这与鳄鱼的牙齿生长方式相似。我们可能会利用同样的知识来关闭人类的某些过程，这些过程有时会导致诸如长太多牙齿或牙齿形状和间距奇怪等问题。

鳄鱼的研究还处于早期阶段，因此人类牙齿的再生还有很长的路要走。但过不了多久，更换丢失的成人牙齿可能和长回牙齿一样简单。

1 alligator   

n.短吻鳄(一种鳄鱼)

参考例句：

• She wandered off to play with her toy alligator.她开始玩鳄鱼玩具。
• Alligator skin is five times more costlier than leather.鳄鱼皮比通常的皮革要贵5倍。

2 alligators   

n.短吻鳄( alligator的名词复数 )

参考例句：

• Two alligators rest their snouts on the water's surface. 两只鳄鱼的大嘴栖息在水面上。 来自辞典例句
• In the movement of logs by water the lumber industry was greatly helped by alligators. 木材工业过去在水上运输木料时所十分倚重的就是鳄鱼。 来自辞典例句

3 relatively   

adv.比较...地，相对地

参考例句：

• The rabbit is a relatively recent introduction in Australia.兔子是相对较新引入澳大利亚的物种。
• The operation was relatively painless.手术相对来说不痛。

4 precursors   

n.先驱( precursor的名词复数 )；先行者；先兆；初期形式

参考例句：

• Phenyl (or polyphenyl) substituted epoxides serve as excellent precursors to phenyl (or diphenyl) carbenes. 某些苯代（或多苯）环氧乙烷是制取带苯环（或二苯）碳烯的极好原料。 来自辞典例句
• Note the presence of megakaryocytes, erythroid islands, and granulocytic precursors. 可见巨核细胞，红细胞岛和粒细胞前体细胞。 来自互联网

5 bulge   

n.突出，膨胀，激增；vt.突出，膨胀

参考例句：

• The apple made a bulge in his pocket.苹果把他口袋塞得鼓了起来。
• What's that awkward bulge in your pocket?你口袋里那块鼓鼓囊囊的东西是什么？

6 molecules   

分子( molecule的名词复数 )

参考例句：

• The structure of molecules can be seen under an electron microscope. 分子的结构可在电子显微镜下观察到。
• Inside the reactor the large molecules are cracked into smaller molecules. 在反应堆里，大分子裂变为小分子。