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VOA慢速英语2013 New Body Clock Provides Clues to Aging

时间:2013-12-04 13:09来源:互联网 提供网友:nan   字体: [ ]
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New Body Clock Provides Clues to Aging

From VOA Learning English, this is Science in the News. I’m June Simms.

And I’m Jim Tedder1. Today we tell about a newly-discovered body clock that provides clues to aging. We hear how learning new skills may help to keep an aging mind sharp. Finally, we turn to the night skies and tell about efforts to reduce light pollution in the American state of Colorado.

There is good news for people who are searching for the fountain of youth! A new report says you just might find the answer in your DNA2 or genetic3 material. The report offers information on why our bodies age and how we can slow down the biological clock operating in our genes4.

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

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

Methylation is a natural process that chemically changes the DNA. It is important in the development of every organism.

Professor Horvath and his team collected information from 8,000 samples in 82 publicly available DNA-methylation data sets. They used this information to identify methylation in healthy and diseased organs, tissues and cells, from human fetuses5 to people 100 years of age and older.

“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. 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.

Professor Horvath notes that most biological samples matched their chronological6 age – the actual age of the individual. However, some differed greatly. For example, the average human heart appeared to be 12 years younger than its chronological age. And a woman’s healthy breast tissue aged7 faster than the rest of her body.  

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

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

Surprisingly, Professor Horvath says the clock was a good measure of time across the human body.

“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 says the study holds promise for studying human development, aging and disease. It also offers hope for repairing tissue.

“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.”

Steve Horvath says the big question remains9 whether the biological clock actually controls a process that leads to aging or simply is a sign of it. The report was published in the journal Genome Biology.

Another report says older adults who test their minds with increasingly difficult projects have better mental ability than those who do less demanding activities.

To keep our brains sharp as we age, we are often told to keep our minds active. As the old saying goes, “use it or lose it.” But, there is very little scientific evidence to support that. So says Denise Park. She is a psychologist with the University of Texas at Dallas.

“Partially because it is very, very hard to do experiments with humans, where you randomly10 assign them to conditions where, say, you retire, you do not retire; you do interesting things, you do boring things.”

Denise Park is head of the university’s Center for Vital Longevity11. She designed a study in which she and her team placed 221 healthy aging and older adults into one of three groups.

“We asked people to learn new things, like quilting or photography. We asked other people to just do fun things like be in a social group. And then we asked other people to do things at home that seemingly would help their cognition or their mental function but were not likely to have a very large effect.”

The subjects took part in their assigned activity for 15 hours a week over three months. At the end of that time, the researchers found that the adults who learned new skills, such as digital photography, showed the greatest improvements on memory tests.

No improvements were seen in the results of those in the social group that did activities together like go on field trips. There were also no improvements among the third group that listened to classical music or did crossword12 puzzles.

Denise Park believes one reason for improved memory in the active learning group is that its members were being pushed to learn new skills. The other groups took part in what she calls receptive activities.

Learning new skills may not cure age-related mental decline. But, Ms. Park thinks being mentally active slows down the process.

“So, I am not as interested in improving the function of people as they age in their later years. I am more interested in showing ultimately over time that by these novel experiences that involve a lot of mental operations that we can slow the rate at which people cognitively13 age.”

Denise Park says the latest information shows that the improvements lasted for at least a year. She and her team plan to do longer follow-up studies with all three groups. She also is interested in learning whether taking part in demanding mental activities delays the development of conditions like Alzheimer’s disease.

The report on the value of learning new skills was published in the journal Psychological Science.

Light Pollution Is a Problem for Scientists

One of life’s great wonders is a starry14 night sky. But as electric lights turn city streets and neighborhoods bright as day, it is getting harder to see those stars. That has astronomers16, politicians and others looking for ways to reduce what is called light pollution.

Nightfall has come to the University of Colorado Observatory17 in Boulder18, Colorado. As the skies darken, student astronomers work under the glow of lamps that have red filters. Astronomer15 Eric McNeil says there is just enough light to use the telescopes and see stars.

“White light has a tendency to ruin your night vision, so astronomers like to use red light which has a tendency not to do that.”

Fabio Mezzalira is the director of the observatory. He says for most people living in the cities, stars are rare.

“The one thing missing in the modern experience is that people at one time, knew, by default, the sky. They saw it every night, simply because there was no light pollution to be worried about.”

While he covers his own lamps with reddish filters, Mr. Mezzalira worries about nearby businesses lighting19 up the night skies.

“The biggest offenders20 are the gas stations and liquor stores. Blue lights, blue and green, very bad, they're terrible! Terrible! They're good to see with. But a lot of people like the night sky, they want to see the stars.” 

Writer Paul Bogard agrees that city lights destroy the magic of the night.

“We’re missing about 95, 96, 99 percent, in some cases, of the stars that we should be seeing.”

Mr. Bogard is the author of The End of Night, Searching for Natural Darkness in an Age of Artificial Light.

“You can go to a large city or to an American neighborhood that’s lit up, and you can see the brightest stars, but we quickly lose sight of all the stars that are dimmer than the brightest. And that’s the real loss.” 

He says that dark nights are important for our health. Light pollution can interfere21 with the body's natural sleep cycle.

“All life evolved in bright days and dark nights. And Life needs darkness to be truly healthy. We’re using way too much light.”

To make his point, Paul Bogard takes a walk through an outdoor shopping center at 11 o’clock at night. At this hour, these businesses are closed, but many stores remain lit up. They include a computer shop, where the front wall shines light onto the sidewalk, especially through its big sign.

For examples of less objectionable lighting, Mr. Bogard points to trees on the grounds of the shopping mall. They are decorated with small golden lights.

“The twinkle lights here, are in many ways beautiful.” 

He also praises how the streetlights point down, directing the light to the sidewalk.

“You can’t even see the bulb. They’re shielded, so the light is going down to the street. We have as much light as we need on the street. But we don’t have any light shining into the sky or into our eyes.” 

Nancy Clanton is a lighting engineer and a leader of the International Dark Sky Association. She says Boulder has less light pollution than most cities. She says that is because Boulder passed a light pollution law 10 years ago.

“The ordinance22 was basically saying, let’s start with no uplight, so it says, use what we call full cut-off lights, which are fully23 shielded.”

Boulder also has some area of housing with no streetlights at all. Paul Bogard says that creates an extraordinary view of the stars and constellations24.  

“You can see the big dipper, the summer triangle -- what’s unique to this street is that you can see a lot of other stars that I don’t even know the names of.” 

Back at the University of Colorado, observatory director Fabio Mezzallira says star gazing experiences stay with people. They have definitely stayed with him.

“The first time I really realized more the universe around me was when I was about 11 years old, and I was laying on a beach and there was no light pollution. Zero. You could see the Milky25 Way, and the sky was gray with stars.”

The International Dark Sky Association offers model lighting plans on its website for communities that want to limit light pollution and keep the stars in view.  

This Science in the News was written by June Simms, who also served as our producer. I’m Jim Tedder.

And I’m June Simms. Join us again next week at this time for more news about science on the Voice of America. 


点击收听单词发音收听单词发音  

1 tedder 2833afc4f8252d8dc9f8cd73b24db55d     
n.(干草)翻晒者,翻晒机
参考例句:
  • Jim Tedder has more. 吉姆?特德将给我们做更多的介绍。 来自互联网
  • Jim Tedder tells us more. 吉姆?泰德给我们带来更详细的报道。 来自互联网
2 DNA 4u3z1l     
(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。
3 genetic PgIxp     
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。
4 genes 01914f8eac35d7e14afa065217edd8c0     
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 fetuses eae25b106f4ed68558631a5bf44c9293     
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 8Ofzi     
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 aged 6zWzdI     
adj.年老的,陈年的
参考例句:
  • He had put on weight and aged a little.他胖了,也老点了。
  • He is aged,but his memory is still good.他已年老,然而记忆力还好。
8 acceleration ff8ya     
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 remains 1kMzTy     
n.剩余物,残留物;遗体,遗迹
参考例句:
  • He ate the remains of food hungrily.他狼吞虎咽地吃剩余的食物。
  • The remains of the meal were fed to the dog.残羹剩饭喂狗了。
10 randomly cktzBM     
adv.随便地,未加计划地
参考例句:
  • Within the hot gas chamber, molecules are moving randomly in all directions. 在灼热的气体燃烧室内,分子在各个方向上作无规运动。 来自辞典例句
  • Transformed cells are loosely attached, rounded and randomly oriented. 转化细胞则不大贴壁、圆缩并呈杂乱分布。 来自辞典例句
11 longevity C06xQ     
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。
12 crossword VvOzBj     
n.纵横字谜,纵横填字游戏
参考例句:
  • He shows a great interest in crossword puzzles.他对填字游戏表现出很大兴趣。
  • Don't chuck yesterday's paper out.I still haven't done the crossword.别扔了昨天的报纸,我还没做字谜游戏呢。
13 cognitively d28af4705de1f9218cb8ba1d5bdf8372     
参考例句:
  • Cognitively,man,the subject of cognition,must classify and categorize the objects. 从认知学角度来看 ,作为认知主体的人对于认知对象必须进行分类和范畴化。 来自互联网
  • Cognitively, reference can be studied along with information processing of human mind. 从认知的角度看,要研究人类思维的信息处理过程。 来自互联网
14 starry VhWzfP     
adj.星光照耀的, 闪亮的
参考例句:
  • He looked at the starry heavens.他瞧着布满星星的天空。
  • I like the starry winter sky.我喜欢这满天星斗的冬夜。
15 astronomer DOEyh     
n.天文学家
参考例句:
  • A new star attracted the notice of the astronomer.新发现的一颗星引起了那位天文学家的注意。
  • He is reputed to have been a good astronomer.他以一个优秀的天文学者闻名于世。
16 astronomers 569155f16962e086bd7de77deceefcbd     
n.天文学者,天文学家( astronomer的名词复数 )
参考例句:
  • Astronomers can accurately foretell the date,time,and length of future eclipses. 天文学家能精确地预告未来日食月食的日期、时刻和时长。 来自《简明英汉词典》
  • Astronomers used to ask why only Saturn has rings. 天文学家们过去一直感到奇怪,为什么只有土星有光环。 来自《简明英汉词典》
17 observatory hRgzP     
n.天文台,气象台,瞭望台,观测台
参考例句:
  • Guy's house was close to the observatory.盖伊的房子离天文台很近。
  • Officials from Greenwich Observatory have the clock checked twice a day.格林威治天文台的职员们每天对大钟检查两次。
18 boulder BNbzS     
n.巨砾;卵石,圆石
参考例句:
  • We all heaved together and removed the boulder.大家一齐用劲,把大石头搬开了。
  • He stepped clear of the boulder.他从大石头后面走了出来。
19 lighting CpszPL     
n.照明,光线的明暗,舞台灯光
参考例句:
  • The gas lamp gradually lost ground to electric lighting.煤气灯逐渐为电灯所代替。
  • The lighting in that restaurant is soft and romantic.那个餐馆照明柔和而且浪漫。
20 offenders dee5aee0bcfb96f370137cdbb4b5cc8d     
n.冒犯者( offender的名词复数 );犯规者;罪犯;妨害…的人(或事物)
参考例句:
  • Long prison sentences can be a very effective deterrent for offenders. 判处长期徒刑可对违法者起到强有力的威慑作用。
  • Purposeful work is an important part of the regime for young offenders. 使从事有意义的劳动是管理少年犯的重要方法。
21 interfere b5lx0     
v.(in)干涉,干预;(with)妨碍,打扰
参考例句:
  • If we interfere, it may do more harm than good.如果我们干预的话,可能弊多利少。
  • When others interfere in the affair,it always makes troubles. 别人一卷入这一事件,棘手的事情就来了。
22 ordinance Svty0     
n.法令;条令;条例
参考例句:
  • The Ordinance of 1785 provided the first land grants for educational purposes.1785年法案为教育目的提供了第一批土地。
  • The city passed an ordinance compelling all outdoor lighting to be switched off at 9.00 PM.该市通过一条法令强令晚上九点关闭一切室外照明。
23 fully Gfuzd     
adv.完全地,全部地,彻底地;充分地
参考例句:
  • The doctor asked me to breathe in,then to breathe out fully.医生让我先吸气,然后全部呼出。
  • They soon became fully integrated into the local community.他们很快就完全融入了当地人的圈子。
24 constellations ee34f7988ee4aa80f9502f825177c85d     
n.星座( constellation的名词复数 );一群杰出人物;一系列(相关的想法、事物);一群(相关的人)
参考例句:
  • The map of the heavens showed all the northern constellations. 这份天体图标明了北半部所有的星座。 来自《简明英汉词典》
  • His time was coming, he would move in the constellations of power. 他时来运转,要进入权力中心了。 来自教父部分
25 milky JD0xg     
adj.牛奶的,多奶的;乳白色的
参考例句:
  • Alexander always has milky coffee at lunchtime.亚历山大总是在午餐时喝掺奶的咖啡。
  • I like a hot milky drink at bedtime.我喜欢睡前喝杯热奶饮料。
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