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VOA慢速英语2012 SCIENCE IN THE NEWS - Scientists Search for New Ways to Treat Infection

时间:2012-10-24 08:58:55

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SCIENCE IN THE NEWS - Scientists Search for New Ways to Treat Infection

This is SCIENCE IN THE NEWS, in VOA Special English. I’m Christopher Cruise.

And I’m Jim Tedder1. Today, we report on the search for new ways to treat infections. We tell how researchers used DNA2, deoxyribonucleic acid, to study the roots of the English language. And we tell about an experiment that shows you can learn while you sleep.

In nineteen twenty-eight, a British scientist made a chance observation. He found that some mold had grown in bacteria in a culture plate in his laboratory. Molds can do that. But this mold that had somehow gotten into the plate had the ability to kill the bacteria around it.

The scientist, Alexander Fleming, found that the mold was a member of a common group known as Penicillium. Fleming and two other scientists, Ernst Boris Chain and Howard Walter Florey, went on to win the Nobel Prize in nineteen forty-five. They were honored "for the discovery of penicillin3 and its curative effect in various infectious diseases." 

Other powerful antibiotics4 have been discovered since penicillin. But many antibiotics have become less effective as the germs they are designed to kill develop resistance.

So scientists are searching for new ways to treat infections. Recently, researchers in Australia said they made an important discovery. Scientists at Monash University in Melbourne believe an antibacterial viral protein called PlyC could be used as an alternative to antibiotics.

This protein was first identified as a possible treatment for infections in nineteen twenty five. But the research ended following the discovery of antibiotics.

Now, scientists have spent six years studying the structure of the protein. They have found how it kills the bacteria that cause sore throats, pneumonia6 and streptococcal toxic7 shock syndrome8.

Australian researchers worked with scientists at the Rockefeller University in New York and the University of Maryland. Their findings appeared in the Proceedings9 of the National Academy of Sciences.

Sheena McGowan from Monash University describes the protein as a powerful bacterial5 killing10 machine. She says it looks like a flying saucer carrying a pair of warheads. It connects to the surface of the bacterium11 and then cuts through the outside to destroy it.

Dr. McGowan says it could be highly valuable when conditions like pneumonia do not respond to traditional treatments.

"There's antibiotics at the moment for those particular types of diseases. We sort of see that there's a bit of resistance being built up in the bacterial community almost, and some of our antibiotics aren't quite as effective as they used to be. So this kind of ground route, basic research needs to be done quite early so that we have some time to develop them as safe human therapeutic12 over the timeframe when the antibiotics can keep working." 

The researchers have been studying PlyC's atomic structure in hopes of developing a drug. They say they have had success in treating streptococcal infections in mice. But an effective human treatment in the form of a pill or nasal spray may be at least ten years away.

One of the jobs of an evolutionary13 biologist is to study the genetic14 material of viruses. Studying the DNA can show where a virus came from, how it changed over time and how it is related to other viruses.

Now, scientists have borrowed this idea for a completely different purpose: to study the roots of the first Indo-European language. Indo-European is a family of several hundred related languages including English, French, Russian and Persian.

Indo-European is one of the largest language families in the world. It covers an area from Iceland in the west to Sri Lanka in the east. One theory says it developed six thousand years ago and was spread by a horse-riding people in the Russian Steppes north of the Caspian Sea. Another theory says the common ancestor of Indo-European was first spoken in what is now Turkey. This theory says it began eight thousand to nine thousand five hundred years ago and spread with agriculture.

The new study offers support for this second theory. Quentin Atkinson, an evolutionary psychologist at the University of Auckland in New Zealand, led the study. He says his team worked in much the same way that evolutionary biologists do to identify the origin of virus outbreaks.

“They use the DNA to reconstruct the family tree of the viruses. But rather than looking at viruses, we were looking for languages. And rather than looking at DNA, we were looking at the words in the different languages.”

The researchers used a statistical15 method that evolutionary biologists use to show how different species are related on a family tree. They analyzed16 two hundred two cognates, or words with shared meanings and similar sounds. They studied them across one hundred three languages, including twenty that are no longer spoken.

Quentin Atkinson says examining the similarities and differences in these cognates helped establish family ties. For example, in English and other Germanic languages, the word for "water" sounds something like the English word "water" or "wasser" in German. But in the Romance languages that came from Latin, the word sounds a lot different, something like "agua" in Spanish or "acqua" in Italian.

Mr. Atkinson says that although some words are more closely related than others, they are tied together on branches of the Indo-European family tree. 

“We know where the languages are. They are like the leaves of the tree, and we know how they are connected, and we trace back along those branches back through time and space to work out where the origin is.”

He argues that Indo-European started to expand across Europe with the spread of agriculture.

“We can see the spread in the archeological record. So the argument is that agricultural populations were able to increase their population density17 relative to hunter gatherer populations around them, and so they expanded out generation by generation.”

The study appeared in the journal Science. Quentin Atkinson says the method used to study the origins of the Indo-European language family could also be used with other language groups.

Last year, he published a report in Science exploring the earliest history of human language. He suggested that modern languages began in southwestern Africa. For that study, he borrowed an idea that comes not from evolutionary biologists but from scientists who study population genetics. They call it the "serial18 founder19 effect." It offers a scientific explanation for why there are fewer genetic differences in populations the farther away they live from Africa. Scientists say this decrease in diversity shows that modern humans originated on the continent. 

Quentin Atkinson reported finding a similar effect in language. He based his study on the phonemes -- the basic speech sounds, like vowels20 and consonants21 -- in about five hundred different languages. He reported that languages in southwestern Africa had the most phonemes, while the numbers decreased with distance from the continent. Mr. Atkinson says his findings support the theory that modern humans expanded from Africa. Some other scientists, however, suggested that the results of his study were weak and failed to prove where language started.

Imagine you are walking down the street. As you pass a bakery, someone opens the door.

Ah…what a wonderful smell. Freshly baked bread, just out of the oven. You breathe deeply, letting that great smell fill your lungs. Life is good!

Now imagine that as you keep walking, you pass a fish market. A worker has just thrown a box full of rotting fish parts into a waste basket. 

Oooh! Whew! The smell is so bad, you take only a short breath and hurry on your way.

Anat Arzi of the Weizmann Institute of Science in Israel imagined this kind of reaction recently when she performed sleep experiments in her laboratory. First, she made sure that her volunteers were in a deep sleep…no peeking22 …eyes tightly closed.

Then she opened a bottle of sweet smelling shampoo…and then…and this is important… played a soft musical note.

Then, she held something rotten under the volunteer’s nose …and played a different sound.

One of the best things about this kind of experiment is that it did not wake the volunteers. And when they were awakened23, they had no memory of what had happened. 

The next morning, after the people woke up, they thought the experiment was done. It was then that Anat Arzi played one of the sounds used while they were asleep and carefully measured their breathing. What she found was that the human brain, even while asleep, had learned to connect the smell with the sound.

This caused the patient to take a long, deep breath. 

This caused a short intake24 of air. 

So, what does all this mean? Ms. Arzi and her professor, Noam Sobel say it shows that we can learn while we are asleep. They may be the first scientists to use the sense of smell in this way as part of a sleep experiment. Their study was published in the journal Nature Neuroscience.

They hope that future experiments will show that we can learn much more difficult things while sleeping. Like chapter three in your calculus25 book, or how to write a new computer software program. Now that would be a sweet dream!


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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 penicillin sMXxv     
n.青霉素,盘尼西林
参考例句:
  • I should have asked him for a shot of penicillin.我应当让他给我打一针青霉素的。
  • Penicillin was an extremely significant medical discovery.青霉素是极其重要的医学发现。
4 antibiotics LzgzQT     
n.(用作复数)抗生素;(用作单数)抗生物质的研究;抗生素,抗菌素( antibiotic的名词复数 )
参考例句:
  • the discovery of antibiotics in the 20th century 20世纪抗生素的发现
  • The doctor gave me a prescription for antibiotics. 医生给我开了抗生素。
5 bacterial dy5z8q     
a.细菌的
参考例句:
  • Bacterial reproduction is accelerated in weightless space. 在失重的空间,细菌繁殖加快了。
  • Brain lesions can be caused by bacterial infections. 大脑损伤可能由细菌感染引起。
6 pneumonia s2HzQ     
n.肺炎
参考例句:
  • Cage was struck with pneumonia in her youth.凯奇年轻时得过肺炎。
  • Pneumonia carried him off last week.肺炎上星期夺去了他的生命。
7 toxic inSwc     
adj.有毒的,因中毒引起的
参考例句:
  • The factory had accidentally released a quantity of toxic waste into the sea.这家工厂意外泄漏大量有毒废物到海中。
  • There is a risk that toxic chemicals might be blasted into the atmosphere.爆炸后有毒化学物质可能会进入大气层。
8 syndrome uqBwu     
n.综合病症;并存特性
参考例句:
  • The Institute says that an unidentified virus is to blame for the syndrome. 该研究所表示,引起这种综合症的是一种尚未确认的病毒。
  • Results indicated that 11 fetuses had Down syndrome. 结果表明有11个胎儿患有唐氏综合征。
9 proceedings Wk2zvX     
n.进程,过程,议程;诉讼(程序);公报
参考例句:
  • He was released on bail pending committal proceedings. 他交保获释正在候审。
  • to initiate legal proceedings against sb 对某人提起诉讼
10 killing kpBziQ     
n.巨额利润;突然赚大钱,发大财
参考例句:
  • Investors are set to make a killing from the sell-off.投资者准备清仓以便大赚一笔。
  • Last week my brother made a killing on Wall Street.上个周我兄弟在华尔街赚了一大笔。
11 bacterium BN7zE     
n.(pl.)bacteria 细菌
参考例句:
  • The bacterium possibly goes in the human body by the mouth.细菌可能通过口进入人体。
  • A bacterium is identified as the cause for his duodenal ulcer.一种细菌被断定为造成他十二指肠溃疡的根源。
12 therapeutic sI8zL     
adj.治疗的,起治疗作用的;对身心健康有益的
参考例句:
  • Therapeutic measures were selected to fit the patient.选择治疗措施以适应病人的需要。
  • When I was sad,music had a therapeutic effect.我悲伤的时候,音乐有治疗效力。
13 evolutionary Ctqz7m     
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。
14 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。
15 statistical bu3wa     
adj.统计的,统计学的
参考例句:
  • He showed the price fluctuations in a statistical table.他用统计表显示价格的波动。
  • They're making detailed statistical analysis.他们正在做具体的统计分析。
16 analyzed 483f1acae53789fbee273a644fdcda80     
v.分析( analyze的过去式和过去分词 );分解;解释;对…进行心理分析
参考例句:
  • The doctors analyzed the blood sample for anemia. 医生们分析了贫血的血样。 来自《简明英汉词典》
  • The young man did not analyze the process of his captivation and enrapturement, for love to him was a mystery and could not be analyzed. 这年轻人没有分析自己蛊惑著迷的过程,因为对他来说,爱是个不可分析的迷。 来自《简明英汉词典》
17 density rOdzZ     
n.密集,密度,浓度
参考例句:
  • The population density of that country is 685 per square mile.那个国家的人口密度为每平方英里685人。
  • The region has a very high population density.该地区的人口密度很高。
18 serial 0zuw2     
n.连本影片,连本电视节目;adj.连续的
参考例句:
  • A new serial is starting on television tonight.今晚电视开播一部新的电视连续剧。
  • Can you account for the serial failures in our experiment?你能解释我们实验屡屡失败的原因吗?
19 Founder wigxF     
n.创始者,缔造者
参考例句:
  • He was extolled as the founder of their Florentine school.他被称颂为佛罗伦萨画派的鼻祖。
  • According to the old tradition,Romulus was the founder of Rome.按照古老的传说,罗穆卢斯是古罗马的建国者。
20 vowels 6c36433ab3f13c49838853205179fe8b     
n.元音,元音字母( vowel的名词复数 )
参考例句:
  • Vowels possess greater sonority than consonants. 元音比辅音响亮。 来自《现代英汉综合大词典》
  • Note the various sounds of vowels followed by r. 注意r跟随的各种元音的发音。 来自超越目标英语 第3册
21 consonants 6d7406e22bce454935f32e3837012573     
n.辅音,子音( consonant的名词复数 );辅音字母
参考例句:
  • Consonants are frequently assimilated to neighboring consonants. 辅音往往被其邻近的辅音同化。 来自《简明英汉词典》
  • Vowels possess greater sonority than consonants. 元音比辅音响亮。 来自《现代英汉综合大词典》
22 peeking 055254fc0b0cbadaccd5778d3ae12b50     
v.很快地看( peek的现在分词 );偷看;窥视;微露出
参考例句:
  • I couldn't resist peeking in the drawer. 我不由得偷看了一下抽屉里面。
  • They caught him peeking in through the keyhole. 他们发现他从钥匙孔里向里窥视。 来自辞典例句
23 awakened de71059d0b3cd8a1de21151c9166f9f0     
v.(使)醒( awaken的过去式和过去分词 );(使)觉醒;弄醒;(使)意识到
参考例句:
  • She awakened to the sound of birds singing. 她醒来听到鸟的叫声。
  • The public has been awakened to the full horror of the situation. 公众完全意识到了这一状况的可怕程度。 来自《简明英汉词典》
24 intake 44cyQ     
n.吸入,纳入;进气口,入口
参考例句:
  • Reduce your salt intake.减少盐的摄入量。
  • There was a horrified intake of breath from every child.所有的孩子都害怕地倒抽了一口凉气。
25 calculus Is9zM     
n.微积分;结石
参考例句:
  • This is a problem where calculus won't help at all.对于这一题,微积分一点也用不上。
  • After studying differential calculus you will be able to solve these mathematical problems.学了微积分之后,你们就能够解这些数学题了。

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