EZCNN 易英网

The Longevity Code 长寿基因

课文朗读

课文讲解

繁體中文譯本

While one can determine the age of a car by looking at its wear and tear, estimating the age of a human being is slightly more challenging. The catch lies in the fact that for humans, wasting away is not a sure thing. In other words, unlike most objects, biological systems have the tools to repair themselves. We’ve known this for years. What’s causing waves within the scientific community, however, is the recent discovery that these tools could remain active regardless of age.

我们从车子的耗损程度可以看出它的年龄，但是要估计人的年龄可能就难上一些。困难在于人类不一定会有磨损的现象。换句话说，不同于多数物品，生物系统有自行修复的工具。好几年来，我们都知道这一点。但是，目前引起科学界骚动的是，最近发现这些修复工具在任何年龄下都可以保持活跃。

Scientists once believed that the process of aging is programmed inside us, guiding us slowly but surely all the way to the grave. This implied that the tools which keep us young and healthy by protecting us against the stresses of the environment gradually faded away. In terms of evolution, it seems logical. After all, what good is there in keeping a biological system bustling with life once it has passed its reproductive age? On an already crowded planet, it made sense that after passing this point, biological organisms would make way for the new generations.

科学家过去认为身体内部已经设定老化的进程，缓慢但明确地引导我们，直到我们进入坟墓。这意味着那些藉由对抗环境压力，让我们保持年轻和健康的工具会慢慢消失。就演化的观点来看，这种现象似乎合逻辑。毕竟，一旦这些生物系统过了繁殖年纪，却又让它们充满活力，那又有何用呢？在一个已经拥挤不堪的星球上，在过了繁殖年纪的时间点之后，生物有机体让位给下一代，这么做是说得过去的。

That view has now been challenged. The new theory is that the genes that act as tools to keep the body running well don’t necessarily weaken as we get older. In fact, if we could keep them active long enough, these tools could dramatically enhance our bodies’ health and increase out lifespan. Put differently, we could turn our defense mechanisms, such as our immune system, into weapons against all those things that are associated with aging. We might, it seems, have the codes for longevity already inside us.

这种看法目前受质疑。新的理论认为，让我们身体运转自如的工具－基因－不见得会在我们老化的过程中逐渐削弱。事实上，如果我们让这些基因保持活跃的时间够久，这些工具将能大幅增进我们身体健康和延长我们的寿命。从另外一个角度来看，我们可以将我们的防御机制，例如我们的免疫系统，转变成武器，对抗所有与老化有关的事物。似乎，我们身体内部已经有了长寿密码。

Vocabulary

单词发音

longevity [lɑnˋdʒɛvətɪ] n. 长命，长寿

biological [͵baɪəˋlɑdʒɪk!] adj. 生物的

reproductive [͵riprəˋdʌktɪv] adj. 生殖的

enhance [ɪnˋhæns] v. 提高，增加

mechanism [ˋmɛkə͵nɪzəm] n. 机制

More Information

单词发音

wear [wɛr] and tear [tɛr]  损耗; 折磨  damage, depreciation, or loss resulting from ordinary use

challenging [`tʃælɪndʒɪŋ] adj. 具有挑战性的

catch [kætʃ] n.【口】圈套；隐藏的困难

waste away 消瘦下去  to gradually become thin and weak

wave [wev] n. 浪潮；（情绪的）高涨；（活动等的）高潮

imply [ɪmˋplaɪ] v. 暗指；暗示；意味着

fade away 消失, 消退, 逐渐衰弱  become weaker

make way  让路, 让开

put differently  换句话说  in other words

课文讲解

Recently, scientists have narrowed their focus on one gene, SIR2, which in various forms is found in many living organisms. Tests have demonstrated that extra copies of this gene increased longevity in a variety of organisms, including yeast and fruit flies.

近来，科学家专注研究SIR2基因，这个基因在许多活着的有机体当中以不同型态出现。测验指出额外的SIR2基因会增加不同有机体的寿命，当中包含酵母菌和果蝇。

To test out the properties of SIR2, scientists turned to simple baker’s yeast. Aging in yeast is measured by counting how many times the original mother cells divide before dying. The average lifespan of yeast is 20 divisions.

为了测试SIR2的属性，科学家针对制作面包的酵母菌加以研究。他们计算酵母菌原始母细胞在死亡前进行多少次的分裂，来测量它的老化过程。通常酵母菌的平均寿命是20次的细胞分裂。

As they divide, yeast cells produce ribosomal DNA (rDNA) circles. They multiply with every cell division and become part of the cell chromosomes, which contain genetic information. This means that after a while the cells are not only copying their chromosomes, but also the rDNA circles, which are like parasites. So much of the cells’ energy may be consumed in the process that they eventually run out of steam and are unable to replicate. In other words, they’ve aged.

在酵母菌细胞分裂的时候，它们会产出核醣体DNA(rDNA)环。每次细胞分裂时，这些rDNA环也会跟着繁殖，并且成为细胞染色体的一部份，这些染色体中含有基因讯息。这意味着，经过一段时间之后，细胞不单单复制自己的染色体，同时间也复制了rDNA环，而这些rDNA环就像寄生虫一般。在这个过程当中，细胞能量可能消耗甚多，以致于它们最后终于筋疲力竭，无法再度复制。换句话说，细胞变老了。

That’s where SIR2 comes in. When an extra copy of this gene is added to the yeast cells, the formation of rDNA circles is repressed, and the cells’ lifespan extends by approximately 30 percent. SIR2 was also found to extend the life of roundworms by 50 percent.

这时便是SIR2发挥效用的时候。当额外的SIR2基因加到酵母细胞内，rDNA环的形成受到抑制，然后细胞的寿命可延长约百分之三十。此外，SIR2基因也可以让蛔虫的寿命延长百分之五十。

We have a long way to go before experiments can be made involving SIR2 in larger organisms, including human beings. But it’s starting to look like we may have more steam in us than we previously thought!

在我们将SIR2基因运用在较大型的有机体（包括人类）之前，我们还有很长一段路要走。但是，目前似乎我们体内所蕴含的动力可能比我们先前所想得还要来得多。

−by J. Michael Cole

Vocabulary

单词发音

multiply [ˋmʌltəplaɪ] v. 使（成倍地）增加

consume [kənˋsjum] v. 消耗，花费；耗尽

repress [rɪˋprɛs] v. 抑制

approximately [əˋprɑksəmɪtlɪ] adv. 大概；近乎

More Information

单词发音

SIR2  (Silent Information Regulator)   SIR2 基因

test out 进行彻底检验 to try something out; to test something to see if it works

circle [ˋsɝk!] n. 环状物；圈

chromosome [ˋkromə͵som] n. 染色体

parasite [ˋpærə͵saɪt] n. 寄生虫

run out of steam  耗尽力气  to lose the energy or interest to continue

roundworm [ˋraʊnd͵wɝm] n. 蛔虫

steam [stim] n.【口】精力；气力

Reading Questions

1.  What contains a cell’s genetic information?

A.  rDNA circles.

B.  Chromosomes

C.  SIR2

D.  Cell divisions

2.  What is being challenged by the new theory about longevity?

A.  That the tools that fix biological systems gradually fade away.

B.  That organisms die in order to make room for new generations.

C.  That we have tools that can dramatically enhance our bodies’ health.

D.  That objects can repair themselves as easily as biological systems do.

3.  Which of the following statements is true?

A.  The effect of SIR2 can increase the lifespan of humans.

B.  The lifespan of roundworms was doubled by the gene SIR2.

C.  The effect of rDNA circles on fruit flies has been found to help humans.

D.  Circles of rDNA are formed when yeast cells divide.

4.  Which of the following would be the best title for the story?

A.  SIR2 versus rDNA

B.  The Never-Ending Aging process

C.  The Fountain of Youth in All of US

D.  The Genetic Code

Answer