2007年VOA标准英语-Scientists Find Gene Linking Lifespan to Calori

By David McAlary
Washington
02 May 2007

U.S. researchers have discovered a gene¹ that promotes longer life in earthworms that eat much less than normal. Humans have similar genes², and VOA's David McAlary reports that, if they work the same way as in the worms, a drug that mimics³ them might someday, if not extend life, at least make it healthier.

Studies since the 1930s have shown that animals from fruitflies to monkeys increase their lifespan as much as 40 percent if they subsist⁴ on a near starvation diet. They also have less risk of cancer, diabetes⁵, and heart disease and ailments⁶ caused by nerve degeneration.

But why is such a regimen beneficial? The answer has been elusive⁷, but researchers at the Salk Institute for Biological Studies in La Jolla, California say they have found a genetic⁸ reason. In a paper in the journal Nature, they identify a gene called pha-four that makes hungry worms live longer.

"This is the first gene that is absolutely essential and specific for eliciting⁹ the dietary restriction¹⁰ response," says Salk Institute researcher Andrew Dillin, speaking on a Nature magazine podcast.

He says his experiments lengthened¹² or shortened the lifespan of earthworms by altering the impact of the pha-four gene. Those worms with normal levels of the gene lived longer when on a very low calorie regimen. When researchers amplified¹³ the gene, the worms lived even longer, even with a normal amount of food. When they inactivated¹⁴ it, the worms had a standard lifespan.

Dillin says humans have three genes similar to pha-four and suggests that they are part of an internal defense¹⁶ mechanism¹⁷ to protect against famine.

"Definitely starvation is going to shorten your lifespan, but also the really high calorie diets are going to shorten our lifespan as well," he said. "But there is an intermediate level that actually increases lifespan in mammals by 30 to 40 percent. So there is this really small window where you are on the borderline of crossing into starvation or crossing into being fat. That is the calorie restriction window that we actually need to be in to increase longevity¹⁸."

Dillin says that activating¹⁹ the pha-four gene is one of two major ways to lengthen¹¹ life in laboratory animals. Another is to decrease their sensitivity to insulin, a hormone²⁰ that regulates blood sugar. But this has unwelcome side effects, such as stunting²¹ and reproductive problems.

It is a long evolutionary²² leap from earthworms to people, but Dillin says it is worth determining if the human versions of the pha-four gene operate the same way. The goal would be to develop a drug that could activate¹⁵ them so people could benefit from their effects without going on a near-starvation diet.

"Whether or not it is going to extend human longevity - I don't think that is actually the goal. The goal is actually to reduce the onset²³ of these age-related diseases," he said.

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 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

3 mimics   

n.模仿名人言行的娱乐演员，滑稽剧演员( mimic的名词复数 )；善于模仿的人或物v.（尤指为了逗乐而）模仿( mimic的第三人称单数 )；酷似

参考例句：

• Methods:Models were generate by CT scan,Mimics software and Abaqus software. 方法：采用CT扫描，Mimics软件和Abaqus软件的CAD进行三维有限元模型的创建。 来自互联网
• Relaxing the mind and body mimics the effect that some blood-pressure pills would have. 放松身心会产生某些降压药才能产生的效果。 来自辞典例句

4 subsist   

vi.生存，存在，供养

参考例句：

• We are unable to subsist without air and water.没有空气和水我们就活不下去。
• He could subsist on bark and grass roots in the isolated island.在荒岛上他只能靠树皮和草根维持生命。

5 diabetes   

n.糖尿病

参考例句：

• In case of diabetes, physicians advise against the use of sugar.对于糖尿病患者，医生告诫他们不要吃糖。
• Diabetes is caused by a fault in the insulin production of the body.糖尿病是由体內胰岛素分泌失调引起的。

6 ailments   

疾病（尤指慢性病），不适( ailment的名词复数 )

参考例句：

• His ailments include a mild heart attack and arthritis. 他患有轻度心脏病和关节炎。
• He hospitalizes patients for minor ailments. 他把只有小病的患者也送进医院。

7 elusive   

adj.难以表达(捉摸)的；令人困惑的；逃避的

参考例句：

• Try to catch the elusive charm of the original in translation.翻译时设法把握住原文中难以捉摸的风韵。
• Interpol have searched all the corners of the earth for the elusive hijackers.国际刑警组织已在世界各地搜查在逃的飞机劫持者。

8 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。

9 eliciting   

n. 诱发, 引出 动词elicit的现在分词形式

参考例句：

• He succeeded in eliciting the information he needed from her. 他从她那里问出了他所需要的信息。
• A criminal trial isn't a tribunal for eliciting the truth. 刑事审讯并非是一种要探明真相的审判。

10 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。

11 lengthen   

vt.使伸长，延长

参考例句：

• He asked the tailor to lengthen his coat.他请裁缝把他的外衣放长些。
• The teacher told her to lengthen her paper out.老师让她把论文加长。

12 lengthened   

（时间或空间）延长，伸长( lengthen的过去式和过去分词 )

参考例句：

• The afternoon shadows lengthened. 下午影子渐渐变长了。
• He wanted to have his coat lengthened a bit. 他要把上衣放长一些。

13 amplified   

放大，扩大( amplify的过去式和过去分词 )； 增强； 详述

参考例句：

• He amplified on his remarks with drawings and figures. 他用图表详细地解释了他的话。
• He amplified the whole course of the incident. 他详述了事件的全过程。

14 inactivated   

v.使不活泼，阻止活动( inactivate的过去式和过去分词 )

参考例句：

• Molluscicides are quickly inactivated by sunlight and adsorption to mud organic matter. 灭螺剂因阳光作用、泥土及有机物质的吸收会很快失效。 来自辞典例句
• Viruses were inactivated by BPL and the toxicity measured again. BPL对病毒进行灭活，测定残存毒力。 来自互联网

15 activate   

vt.使活动起来，使开始起作用

参考例句：

• We must activate the youth to study.我们要激励青年去学习。
• These push buttons can activate the elevator.这些按钮能启动电梯。

16 defense   

n.防御，保卫；[pl.]防务工事；辩护，答辩

参考例句：

• The accused has the right to defense.被告人有权获得辩护。
• The war has impacted the area with military and defense workers.战争使那个地区挤满了军队和防御工程人员。

17 mechanism   

n.机械装置；机构，结构

参考例句：

• The bones and muscles are parts of the mechanism of the body.骨骼和肌肉是人体的组成部件。
• The mechanism of the machine is very complicated.这台机器的结构是非常复杂的。

18 longevity   

n.长命；长寿

参考例句：

• Good habits promote longevity.良好的习惯能增长寿命。
• Human longevity runs in families.人类的长寿具有家族遗传性。

19 activating   

活动的，活性的

参考例句：

• "I didn't say we'd got to stop activating the masses! “我并没说就此不发动！ 来自子夜部分
• Presumably both the very small size and activating influence of fluorine atoms contribute to this exception. 这大概是由于氟原子半径小和活性高这两个原因的影响，氟原子对这种例外做出了贡献。

20 hormone   

n.荷尔蒙，激素，内分泌

参考例句：

• Hormone implants are used as growth boosters.激素植入物被用作生长辅助剂。
• This hormone interacts closely with other hormones in the body.这种荷尔蒙与体內其他荷尔蒙紧密地相互作用。

21 stunting   

v.阻碍…发育[生长]，抑制，妨碍( stunt的现在分词 )

参考例句：

• Objective To report three-year-old twin brothers with speech stunting. 目的报道孪生兄弟同患语言发育迟缓的临床结果。 来自互联网
• No one should talk while stunting except coach or back spotter. 在技巧进行的过程中，只有教练或后保能说话。 来自互联网

22 evolutionary   

adj.进化的；演化的，演变的；[生]进化论的

参考例句：

• Life has its own evolutionary process.生命有其自身的进化过程。
• These are fascinating questions to be resolved by the evolutionary studies of plants.这些十分吸引人的问题将在研究植物进化过程中得以解决。

23 onset   

n.进攻，袭击，开始，突然开始

参考例句：

• The drug must be taken from the onset of the infection.这种药必须在感染的最初期就开始服用。
• Our troops withstood the onset of the enemy.我们的部队抵挡住了敌人的进攻。