人类能学习鱼类的牙齿再生术么?

AS IT IS 2015-11-02 Can Fish Teach Humans to Regrow Teeth? 人类能学习鱼类的牙齿再生术么?

Most people are born with two sets of teeth. They use baby teeth to break down food as children. As they become adults, the baby teeth are replaced with permanent or adult teeth. By age 65, 30 percent of all people worldwide have lost all their teeth.

But most bony fish can regrow their lost teeth. A team of scientists is wondering if that ability of some fish could somehow lead to human tooth regeneration, with adult men and women producing additional teeth as needed.

Fish do it all the time. Whenever they lose a tooth, a new one drops into place. Cichlids are a popular tropical fish. They keep their teeth throughout adulthood². If a tooth should fall out, another one takes its place.

Todd Streelman teaches biology at the Georgia Institute of Technology in Atlanta. He is working with cichlids to find out which genes³ help the fish keep their teeth.   

"Our approach is to find things that are hard to study otherwise and then target them in these animals.  So in this case, Lake Malawi cichlid fishes and many other fishes regenerate⁴ their dentition throughout their entire life."

As a result, a mouthful of teeth is replaced every 50 days. Professor Streelman and his team reported on their study of cichlids in the journal Proceedings⁵ of the National Academy of Sciences. They looked at embryotic cell tissue that can develop into either teeth or taste buds.

"And what we found were some really interesting commonalities between teeth and taste buds at their earliest development."

Unlike humans, fish have no tongues in the mouth, so their taste buds are mixed in with their teeth.

Last year, the same researchers made a cichlid genome – a map of the fish’s genes. This year, they crossed closely-related cichlids and then compared genetic⁶ differences among the second-generation fish. They found what appeared to be genetic controls that could make the embryonic⁷ cells become either a tooth or taste bud.

"We could identify this because the genes that are typically positive markers of taste buds and the genes that are typically positive markers of teeth were co-expressed. They were expressed in the same places.  So we basically could watch the path through development, where this epithelial ((surface tissue)) which at one point was bi-potent ((similar tissue)) and then became either teeth or taste buds."

Teeth and taste buds begin in the same kind of tissue around the mouth of fish in their earliest stages of development. The researchers made and studied mapped cichlid genomes. They then engineered the undifferentiated tissue in fish to increase production of teeth, but cut back on taste buds. This was done at an early stage, when the fish had eyes and a brain, but were still growing jaws⁹.

It turns out that cichlids are not the only animals that express these genes. Todd Streelman says researchers at Kings College, London, demonstrated that a few poorly studied genes in mice were also involved in the development of teeth and taste buds.

"These genes that we had identified in fishes are in fact also active in the earliest development of teeth on the jaw⁸ margin¹⁰ and taste buds on the tongue of mice."  

Professor Streelman says the studies in fish and mice suggest that with the right signals, the tissue in humans might also be able to develop new teeth. "The direction our research is taking, at least in human health," he says, "is to figure out how to coax¹¹ – work on the tissue to form one type of structure or the other."

Words in This Story

regenerate – v. to grow again after being lost

dentition – n. the arrangement or condition of the teeth in a species or individual

embryonic – adj. showing that you are sure in yourself or your actions

co-expressed – v. to express together with another gene¹

bi-potent – adj. having a function in a biological environment

coax – v. to work or cause something to do something

1 gene   

n.遗传因子，基因

参考例句：

• A single gene may have many effects.单一基因可能具有很多种效应。
• The targeting of gene therapy has been paid close attention.其中基因治疗的靶向性是值得密切关注的问题之一。

2 adulthood   

n.成年，成人期

参考例句：

• Some infantile actions survive into adulthood.某些婴儿期的行为一直保持到成年期。
• Few people nowadays are able to maintain friendships into adulthood.如今很少有人能将友谊维持到成年。

3 genes   

n.基因( gene的名词复数 )

参考例句：

• You have good genes from your parents, so you should live a long time. 你从父母那儿获得优良的基因，所以能够活得很长。 来自《简明英汉词典》
• Differences will help to reveal the functions of the genes. 它们间的差异将会帮助我们揭开基因多种功能。 来自英汉非文学 - 生命科学 - 生物技术的世纪

4 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。

5 proceedings   

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

6 genetic   

adj.遗传的，遗传学的

参考例句：

• It's very difficult to treat genetic diseases.遗传性疾病治疗起来很困难。
• Each daughter cell can receive a full complement of the genetic information.每个子细胞可以收到遗传信息的一个完全补偿物。

7 embryonic   

adj.胚胎的

参考例句：

• It is still in an embryonic stage.它还处于萌芽阶段。
• The plan,as yet,only exists in embryonic form.这个计划迄今为止还只是在酝酿之中。

8 jaw   

n.颚，颌，说教，流言蜚语；v.喋喋不休，教训

参考例句：

• He delivered a right hook to his opponent's jaw.他给了对方下巴一记右钩拳。
• A strong square jaw is a sign of firm character.强健的方下巴是刚毅性格的标志。

9 jaws   

n.口部；嘴

参考例句：

• The antelope could not escape the crocodile's gaping jaws. 那只羚羊无法从鱷鱼张开的大口中逃脱。
• The scored jaws of a vise help it bite the work. 台钳上有刻痕的虎钳牙帮助它紧咬住工件。

10 margin   

n.页边空白；差额；余地，余裕；边，边缘

参考例句：

• We allowed a margin of 20 minutes in catching the train.我们有20分钟的余地赶火车。
• The village is situated at the margin of a forest.村子位于森林的边缘。

11 coax   

v.哄诱，劝诱，用诱哄得到，诱取

参考例句：

• I had to coax the information out of him.我得用好话套出他掌握的情况。
• He tried to coax the secret from me.他试图哄骗我说出秘方。