生物钟为你提供老去的线索

 　　If you’re searching for the fountain of youth, you might find it in your DNA¹. That’s according to a new study that sheds light on the biological clock ticking in our genomes, why our bodies age and how we can slow down the process.

　　University of California genetics professor Steve Horvath has created a new tool that can accurately³ measure the aging body.

　　“Basically I developed a way of predicting age based on DNA," Horvath said. "To achieve this goal I identified 353 markers on the DNA which measure DNA methylation levels.”

　　Methylation is a naturally occurring epigenetic - or gene² altering - process that chemically modifies the DNA and is critical in the development of every organism. Horvath and his colleagues gleaned⁴ information from 8,000 samples to chart methylation in healthy and diseased organs, tissues and cells, from fetuses⁵ to centenarians.

　　“For one thing, I find that this epigenetic clock ticks fastest during development, and after age 20 it slows down to a constant ticking rate," he said. "But also I find that cancer tissue is on average 36 years older than healthy tissue and I observed that effect in all 20 cancer types that I studied.”

　　In other words, some cells age faster than others.

　　Horvath notes that while most biological samples matched their chronological⁶ age, some diverged⁷ significantly. The average human heart, for example, appears to be 12 years younger than its chronological age, and a woman’s healthy breast tissue ages faster than the rest of her body.

　　“So it is possible that the cancer that is adjacent to this tissue accelerates the age," he said. "Having said this, I had one data set that was composed of truly healthy breast tissue and even there I observed a significant age acceleration⁸.”

　　The results may explain why breast cancer is the most common cancer in women.

　　Remarkably⁹, Horvath says the clock kept reliable time across the human anatomy¹⁰, irrespective of where the DNA came from.

　　“This new epigenetic clock really frees us up from focusing on one tissue at a time because it really works in most tissues and organs and cell types, and the great advantage is that we now can compare the ages of different tissues and organs from the same individual,” he said.

　　Horvath says the work holds promise for studying human development, aging and disease, but also shows potential for rejuvenating¹¹ tissues.

　　"Of course it has been a long-standing hope to find therapies or compounds that keep us young, and if this epigenetic clock measures a process that causes aging, then we will have a tool that allows us to evaluate compounds that keep us young,” he said

　　So has Horvath found the Fountain of Youth?

　　"I have unfortunately no data that would support that,” he said with a laugh.

1 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。

2 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。

3 accurately   

adv.准确地，精确地

参考例句：

• It is hard to hit the ball accurately.准确地击中球很难。
• Now scientists can forecast the weather accurately.现在科学家们能准确地预报天气。

4 gleaned   

v.一点点地收集（资料、事实）( glean的过去式和过去分词 )；（收割后）拾穗

参考例句：

• These figures have been gleaned from a number of studies. 这些数据是通过多次研究收集得来的。
• A valuable lesson may be gleaned from it by those who have eyes to see. 明眼人可从中记取宝贵的教训。 来自《现代汉英综合大词典》

5 fetuses   

n.胎，胎儿( fetus的名词复数 )

参考例句：

• DNA was extracted from fetuses at mid-gestation, about 10 days past conception. DNA从受孕大约10天后的中期妊娠胚胎中提取。 来自互联网
• Brucellosis is a disease that causes fetuses to abort in cattle. 普鲁士菌病是一种可以导致牲畜胎儿夭折的疾病。 来自互联网

6 chronological   

adj.按年月顺序排列的，年代学的

参考例句：

• The paintings are exhibited in chronological sequence.这些画是按创作的时间顺序展出的。
• Give me the dates in chronological order.把日期按年月顺序给我。

7 diverged   

分开( diverge的过去式和过去分词 )； 偏离； 分歧； 分道扬镳

参考例句：

• Who knows when we'll meet again? 不知几时咱们能再见面！
• At what time do you get up? 你几时起床？

8 acceleration   

n.加速，加速度

参考例句：

• All spacemen must be able to bear acceleration.所有太空人都应能承受加速度。
• He has also called for an acceleration of political reforms.他同时呼吁加快政治改革的步伐。

9 remarkably   

ad.不同寻常地，相当地

参考例句：

• I thought she was remarkably restrained in the circumstances. 我认为她在那种情况下非常克制。
• He made a remarkably swift recovery. 他康复得相当快。

10 anatomy   

n.解剖学，解剖；功能，结构，组织

参考例句：

• He found out a great deal about the anatomy of animals.在动物解剖学方面，他有过许多发现。
• The hurricane's anatomy was powerful and complex.对飓风的剖析是一项庞大而复杂的工作。

11 rejuvenating   

使变得年轻，使恢复活力( rejuvenate的现在分词 )

参考例句：

• The rejuvenating ambience of autumn is immeasurably more ancient than even the calendar. 秋天那让人恢复青春活力的气氛远比历法还要古老。 来自名作英译部分
• Rhoda says that it's embarrassing to be so idolized, but also very sweet and rejuvenating. 罗达说，给人这样过份地崇拜是很发窘的，不过也是愉快惬意使人年轻的。