经济学人132:延长寿命 谢啦,老妈!

 　　Science and Technology Extending lifespan Thanks, Mum!

　　科技 延长寿命 谢啦，老妈！

　　An obscure group of animals may reveal the secret of elongating¹ life

　　一群不为人知的动物可能会揭开长寿之谜

　　THE one sure way to prolong an animal's life is, paradoxically, to starve it. "Caloric restriction²", as it is known in the trade, works for everything from threadworms to mammals (people included, as far as can be ascertained³ without the luxury of controlled experiments). So it is no surprise that it also works for a group of small creatures known as rotifers. If that were the only result of Shugo Watabe's experiments on the critters, at the University of Tokyo, it would scarcely be worth reporting. What makes this news is that the offspring of the rotifers in question also lived longer than normal. And that—the inheritance of an acquired characteristic—is quite startling.

　　矛盾的是，延长动物寿命的方法，竟然是使其挨饿。科学界的同行都知道，有名的"热量限制"法则对小至线虫，大至哺乳动物的动物界都适用（包括人类，就还未有大量的对照实验验证而言）。所以当该条法则运用到一群名叫轮虫的生物上也就不足为奇了。如果东京大学的修吾渡部的轮虫实验仅是如此的话，也就没有报道的价值了。具有新闻价值的是，上述轮虫后代的生命也比普通轮虫要长。那后天的从父辈继承下的特质实在很令人吃惊。

　　Rotifers are unusual in that they often reproduce by parthenogenesis (some species, indeed, can reproduce only in this way). A parthenogenetic population is, by definition, all female and the result, give or take the odd mutation⁵, is that a rotifer's daughters are genetically⁶ identical to her. That makes rotifers convenient subjects for studies of the controversial idea that characteristics acquired during an individual's life can be passed down the generations in ways that are independent of mutations in the DNA⁷.

　　轮虫并不普通，因为他们的繁殖方式是孤雌生殖（确实，一些物种甚至只有这一种繁殖方式）。顾名思义，孤雌生殖群体全是雌性；如果没有接受和传递罕见基因突变，那么轮虫的雌性后代与母体是完全相同的。这使得轮虫成为十分方便的研究对象：人们对在个体生命期中，后天习得的特征与繁殖后代中的DNA突变并不相关这个观点存在争议。

　　Dr Watabe and his colleagues first looked at whether caloric restriction does, indeed, work its magic on rotifers. It does. Without it, as they report in Functional⁸ Ecology, their animals lived for an average of 8.8 days. With it they lived for 13.5 days. The intriguing⁹ result came when they did the same thing with the rotifers' offspring. The daughters of those rotifers which had been fed as much as they could eat lived for 9.5 days if treated likewise (not significantly different from their mothers) and 14.4 if put on short commons. Those born of calorie-restricted mothers lived for 12.7 and 16.8 days respectively. Something, then, is being passed on that is having an effect down the generations.

　　渡边博士和他的同事第一次研究热量限制的机制是否对轮虫同样有效。确实有效。他们在《机能生态学》杂志上报道说，没有了热量限制，轮虫的平均生命期为13.5天。当它们对轮虫的后代采取了同样的热量限制后，得到了有趣的结果。轮虫的母系如果得到了饱和的食物量，它们那些也同样饱食的后代可以存活了9.5天（与其母系的上一代并无明显区别），如果后代食物量减少，则可以活14.4天。那些诞生于热量限制的母系后代则在饱食和不饱食的情况下分别存活了12.7 和16.8天。那么，一定有某种物质通过上下代传递，对个体生命产生了影响。

　　That something seems to be related to an enzyme¹⁰ called catalase. This enzyme degrades hydrogen peroxide, a highly reactive chemical that creates cellular¹¹ damage of the sort associated with ageing. Dr Watabe found that the offspring of calorie-restricted mothers have more catalase than those of mothers who were fed without restriction.

　　这种物质似乎与一种名叫过氧化氢酶的酶有关。这种酶分解过氧化氢这种反映活性很高、可以在细胞老化过程中损害细胞的物质。渡边博士发现这种经过热量限制的母体的后代，其过氧化氢酶含量比没有食量限制的母体后代更多。

　　The researchers also detected higher levels of the enzyme in the eggs of calorie-restricted mothers, so it could be that their offspring are simply endowed with the stuff. A more intriguing possibility, though, is that the relevant genes⁴ are affected¹² by epigenesis, a process in which chemicals attached to the DNA control its activity. Epigenetic modifications¹³ are often retained when cells divide, and can sometimes be passed on to offspring.

　　研究人员同时检测了得到热量控制的母体产下的卵，它的过氧化氢酶浓度较高，所以这可能是这些后代与生俱来的。然而，一个更有意思的可能性是后生作用影响了这些基因。后生作用是指与DNA相接的化学物质来控制其活动。细胞分裂期往往阻碍表观遗传修饰，并且会把这种机制传递给下一代。

　　If inherited epigenetic changes were causing daughter rotifers to produce more catalase, it would raise the question of whether a similar thing happens in other species and, if so, whether it might be induced artificially, without all the tedious business of a lifetime's starvation. That would certainly be worth looking at. The search for an elixir¹⁴ of life has taken people to some strange places. Few, though, are stranger than rotifers.

　　如果母系轮虫后代从母体继承了后生变化，产生了更多的过氧化氢酶，人们同样也会考虑相似的事情会不会也发生在其他物种上；而且，如果同样发生，可否通过人工诱导的方法，而不是通过冗长到一辈子都饿着肚子。长生不老的研究已经将人类指向了一些奇怪的领域。而没有几个比轮虫更奇怪的了。

1 elongating   

v.延长，加长( elongate的现在分词 )

参考例句：

• The original structure of three-rolls piercing-elongating mill is improved. And good results have been achieved. 对原有三辊联合穿轧机结构上存在的问题进行了改进设计，并取得良好效果。 来自互联网
• The torch can bring higher arc voltage with lower fluctuation by elongating the arc. 该喷枪能够提高电弧电压并减小电弧电压波动。 来自互联网

2 restriction   

n.限制，约束

参考例句：

• The park is open to the public without restriction.这个公园对公众开放，没有任何限制。
• The 30 mph speed restriction applies in all built-up areas.每小时限速30英里适用于所有建筑物聚集区。

3 ascertained   

v.弄清，确定，查明( ascertain的过去式和过去分词 )

参考例句：

• The previously unidentified objects have now been definitely ascertained as being satellites. 原来所说的不明飞行物现在已证实是卫星。 来自《简明英汉词典》
• I ascertained that she was dead. 我断定她已经死了。 来自《简明英汉词典》

4 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

5 mutation   

n.变化，变异，转变

参考例句：

• People who have this mutation need less sleep than others.有这种突变的人需要的睡眠比其他人少。
• So far the discussion has centered entirely around mutation in the strict sense.到目前为止，严格来讲，讨论完全集中于围绕突变问题上。

6 genetically   

adv.遗传上

参考例句：

• All the bees in the colony are genetically related. 同一群体的蜜蜂都有亲缘关系。
• Genetically modified foods have already arrived on American dinner tables. 经基因改造加工过的食物已端上了美国人的餐桌。 来自英汉非文学 - 生命科学 - 基因与食物

7 DNA   

(缩)deoxyribonucleic acid 脱氧核糖核酸

参考例句：

• DNA is stored in the nucleus of a cell.脱氧核糖核酸储存于细胞的细胞核里。
• Gene mutations are alterations in the DNA code.基因突变是指DNA密码的改变。

8 functional   

adj.为实用而设计的，具备功能的，起作用的

参考例句：

• The telephone was out of order,but is functional now.电话刚才坏了，但现在可以用了。
• The furniture is not fancy,just functional.这些家具不是摆着好看的，只是为了实用。

9 intriguing   

adj.有趣的；迷人的v.搞阴谋诡计(intrigue的现在分词)；激起…的好奇心

参考例句：

• These discoveries raise intriguing questions. 这些发现带来了非常有趣的问题。
• It all sounds very intriguing. 这些听起来都很有趣。 来自《简明英汉词典》

10 enzyme   

n.酵素，酶

参考例句：

• Above a certain temperature,the enzyme molecule will become unfolded.超过一定温度，酶分子将会展开。
• An enzyme that dissolves the fibrin of blood clots.能溶解血凝块中的纤维的酶。

11 cellular   

adj.移动的；细胞的，由细胞组成的

参考例句：

• She has a cellular telephone in her car.她的汽车里有一部无线通讯电话机。
• Many people use cellular materials as sensitive elements in hygrometers.很多人用蜂窝状的材料作为测量温度的传感元件。

12 affected   

adj.不自然的，假装的

参考例句：

• She showed an affected interest in our subject.她假装对我们的课题感到兴趣。
• His manners are affected.他的态度不自然。

13 modifications   

n.缓和( modification的名词复数 )；限制；更改；改变

参考例句：

• The engine was pulled apart for modifications and then reassembled. 发动机被拆开改型，然后再组装起来。 来自《简明英汉词典》
• The original plan had undergone fairly extensive modifications. 原计划已经作了相当大的修改。 来自《简明英汉词典》

14 elixir   

n.长生不老药，万能药

参考例句：

• There is no elixir of life in the world.世界上没有长生不老药。
• Keep your mind awake and active;that's the only youth elixir.保持头脑清醒和灵活便是保持年轻的唯一灵丹妙药。