SCIENCE IN THE NEWS

SCIENCE IN THE NEWS
By

Broadcast: Tuesday, May 04, 2004

(THEME)

VOICE ONE:

This is SCIENCE IN THE NEWS, in VOA Special English. I'm Bob Doughty¹.

VOICE TWO:

And I'm Sarah Long. On our program this week -- making a mouse with two mothers, no father required.

 
Male baboons² can be nice, too, as Joan Silk of UCLA found in a study in Kenya. Here, she photographed a father providing refuge for one of his offspring as another youngster acts mildly aggressive.
VOICE ONE:

A monkey society where females teach males to be less aggressive.

VOICE TWO:

And a theory why people have a bigger brain but a smaller mouth than early humans.

(THEME)

VOICE ONE:

There is a mouse in Japan with two mothers and no father. How could this happen? Scientists explain how in the magazine Nature. However, the process they used to create this small animal is not new. It is called parthenogenesis.

Parthenogenesis is development with an unfertilized egg or reproductive cell. Some plants and animals reproduce this way. Among them are a number of fish and birds. Scientists thought mammals had to have an egg from a female and sperm⁵ from a male to reproduce.

VOICE TWO:

Tomohiro Kono of Tokyo University of Agriculture led a team of Japanese and Korean scientists. They used only female mice in their experiment. They joined the nucleus⁶ of an egg from one mouse with the nucleus of an egg from a second mouse.

They combined a young egg with an older egg. The young egg had not yet gone through an important part of development. Its genes⁴ were not yet imprinted⁸. During this process, some genes are ordered to work and others are not.

VOICE ONE:

The imprint⁷ depends on whether the gene³ comes from the mother or the father. Eggs and sperm have similar sets of genes. But the imprint decides which gene in a set should be active and which should not.

The young egg came from a genetically¹⁰ engineered mouse. This mouse was made to lack two genes linked to the growth of a fetus¹¹.

Tomohiro Kono says he thinks the young egg acted more like a sperm because of the missing genes. The older egg was already imprinted. It had all the normal genes.

In their experiment, the scientists produced hundreds of embryos¹². They placed them inside female mice to grow. Only ten live mice, all female, were born. Just one of these survived to grow into an adult.

VOICE TWO :

The scientists named her Kaguya, after a princess in a Japanese story. Kaguya is now more than a year old. She has already had babies through the way mice normally reproduce.

The team says the results of the experiment suggest that imprinting¹³ with genes from the father prevents parthenogenesis. This would make sure that the father has a part in the development.

Scientists say this experiment should not worry men. They say parthenogenesis will not replace them anytime soon. But experts in genetics and biology say the experiment did teach a lot about the mysterious process of imprinting.

And Tomohiro Kono has other plans. He told Nature magazine that next he wants to make pigs.

(MUSIC)

VOICE ONE:

This is Science in the News, in VOA Special English.

Biologists have reported about a group of male baboons that are unusually nice. The biologists are Robert Sapolsky and Lisa Share of Stanford University in California.

Their work involves a group of olive baboons at the Masai Mara Reserve in Kenya. Mister Sapolsky began the study in nineteen-seventy-eight. The baboons slept in the trees near the visitors center. So Mister Sapolsky called them the Forest Troop.

In the early nineteen-eighties, workers dug a large hole near the building to throw trash away. Members of Forest Troop began to search through the waste for meat and other food. However, another troop of baboons had already claimed the area. They became known as the Garbage Dump Troop.

VOICE TWO:

Adult male baboons are not known for their ability to share. The Garbage Dump males and the Forest Troop males often fought. So, only the most aggressive males from Forest Troop would go. These were the high-ranking baboons in the troop. Such males are at the top of the social order.

In nineteen-eighty-three, however, tuberculosis¹⁴ began to spread in the garbage dump area. All the high-ranking Forest Troop males got sick with the lung disease and died. Only the least socially powerful males remained.

After that, Mister Sapolsky observed that aggressive actions within Forest Troop greatly decreased. He ended his observation in nineteen-eighty-six. He began to study another troop of baboons.

Then, in nineteen-ninety-three, Mister Sapolsky again observed the Forest Troop. This time he went with Lisa Share. They found that the males were still much more gentle compared to other baboons. But the scientists also found something else. All the adult males in Forest Troop at that time were from other troops.

All the ones that were in Forest Troop in nineteen-eighty-six had died or moved on. Male baboons move into other troops when they become adults. The scientists wondered why the new members of Forest Troop were not aggressive like other male baboons.

VOICE ONE:

They say it appears that the females are teaching cooperation to males that enter the troop. They say the females present themselves to the new males sooner than females of other troops. The female also begin to care for the males by cleaning insects from their hair sooner than normal. The males also groom¹⁵ the females this way.

Robert Sapolsky and Lisa Share say adult males in Forest Troop do have some things in common with other male baboons. For example, those at the top of the social order stay at that level for about a year. High-ranking Forest Troop males mistreat lower-level males, just like in other troops. However, the mistreatment is less severe.

VOICE TWO:

The scientists took blood from lower-ranking members of Forest Troop. They did this to measure levels of hormones¹⁶ produced by tension. They say the blood tests found lower levels of these stress-related hormones than usual.

The two biologists plan to continue to watch the Forest Troop in Kenya. They note that some animals pass along culture by teaching things like tool making or communication. They say the baboons in Forest Troop pass along their unusual social rules as part of their culture. And the scientists suggest this is mainly thanks to female guidance.

The findings appear in PLoS (pronounced ploss) Biology. PLoS is the Public Library of Science. Internet users can read this scientific journal free of charge. The Web site is publiclibraryofscience-dot-o-r-g. Again, the address is publiclibraryofscience -- all one word -- dot o-r-g.

(MUSIC)

VOICE ONE:

Modern humans have a bigger brain and a smaller jaw¹⁷ than our ancestors. Some scientists in the United States have a theory to explain why. They say this may all have been the result of a change in one gene.

The scientists are from the University of Pennsylvania in Philadelphia. Their report is in Nature magazine. Hansell (HAHN-sul) Stedman and Nancy Minugh (mi-nyew)-Purvis led the team.

The team studied a protein called myosin. Myosin is what provides power to muscles. It permits them to tighten¹⁸ for movement.

The scientists say they found that a change took place in a myosin gene about two-and-one-half-million years ago. This change, or mutation¹⁹, prevented the gene from producing a form of myosin called M.Y.H.-sixteen. The scientists tested genetic⁹ material of people from all over the world. They found this change in all cases.

VOICE TWO:

The scientists also looked at D.N.A. from seven other kinds of primates²⁰ besides humans. These included the chimpanzee and macaque monkey. The scientists did not find the mutated gene in any of them. All of these animals have the gene that produces M.Y.H-sixteen. The scientists found that this kind of myosin is involved mainly in biting and chewing.

Two-point-five-million years ago was just before a period of major change in the human head. The fossil record shows that our jawbones shrank and brains grew larger beginning around two-million years ago.

Nancy Minugh-Purvis offers a possible explanation: Without the myosin, jaw-muscle size and force decreased. This removed pressure on the skull²¹. And that freed the brain to expand. Something to keep in mind.

(THEME)

VOICE ONE:

SCIENCE IN THE NEWS was written by Caty Weaver²². Cynthia Kirk was our producer. This is Bob Doughty.

VOICE TWO:

And this is Sarah Long. Listen next week for more news about science, in Special English, on the Voice of America.

1 doughty   

adj.勇猛的，坚强的

参考例句：

• Most of successful men have the characteristics of contumacy and doughty.绝大多数成功人士都有共同的特质：脾气倔强，性格刚强。
• The doughty old man battled his illness with fierce determination.坚强的老人用巨大毅力与疾病作斗争。

2 baboons   

n.狒狒( baboon的名词复数 )

参考例句：

• Baboons could break branches and leaders. 狒狒会折断侧枝和顶梢。 来自辞典例句
• And as nonprimates, they provoke fewer ethical and safety-related concerns than chimps or baboons. 而且作为非灵长类，就不会产生像用黑猩猩或狒狒那样的伦理和安全方面的顾虑。 来自英汉非文学 - 生命科学 - 医学的第四次革命

3 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。

4 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

5 sperm   

n.精子，精液

参考例句：

• Only one sperm fertilises an egg.只有一个精子使卵子受精。
• In human reproduction,one female egg is usually fertilized by one sperm.在人体生殖过程中，一个精子使一个卵子受精。

6 nucleus   

n.核，核心，原子核

参考例句：

• These young people formed the nucleus of the club.这些年轻人成了俱乐部的核心。
• These councils would form the nucleus of a future regime.这些委员会将成为一个未来政权的核心。

7 imprint   

n.印痕，痕迹；深刻的印象；vt.压印，牢记

参考例句：

• That dictionary is published under the Longman imprint.那本词典以朗曼公司的名义出版。
• Her speech left its imprint on me.她的演讲给我留下了深刻印象。

8 imprinted   

v.盖印（imprint的过去式与过去分词形式）

参考例句：

• The terrible scenes were indelibly imprinted on his mind. 那些恐怖场面深深地铭刻在他的心中。
• The scene was imprinted on my mind. 那个场面铭刻在我的心中。 来自《简明英汉词典》

9 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。

10 genetically   

adv.遗传上

参考例句：

• All the bees in the colony are genetically related. 同一群体的蜜蜂都有亲缘关系。
• Genetically modified foods have already arrived on American dinner tables. 经基因改造加工过的食物已端上了美国人的餐桌。 来自英汉非文学 - 生命科学 - 基因与食物

11 fetus   

n.胎，胎儿

参考例句：

• In the fetus,blood cells are formed in different sites at different ages.胎儿的血细胞在不同时期生成在不同的部位。
• No one knows why a fetus is not automatically rejected by the mother's immune system. 没有人知道为什么母亲的免疫系统不会自动排斥胎儿。

12 embryos   

n.晶胚；胚，胚胎( embryo的名词复数 )

参考例句：

• Somatic cells of angiosperms enter a regenerative phase and behave like embryos. 被子植物体细胞进入一个生殖阶段，而且其行为象胚。 来自辞典例句
• Evolution can explain why human embryos look like gilled fishes. 进化论能够解释为什么人类的胚胎看起来象除去了内脏的鱼一样。 来自辞典例句

13 imprinting   

n.胚教，铭记（动物生命早期即起作用的一种学习机能）；印记

参考例句：

• He gathered her to himself, imprinting kisses upon her lips and cheeks. 他把她抱过来，吻着她的嘴唇和面颊。 来自辞典例句
• It'seems likely that imprinting is an extreme case of conditioning. 看来似乎铭记是适应的一种极端的情况。 来自辞典例句

14 tuberculosis   

n.结核病，肺结核

参考例句：

• People used to go to special health spring to recover from tuberculosis.人们常去温泉疗养胜地治疗肺结核。
• Tuberculosis is a curable disease.肺结核是一种可治愈的病。

15 groom   

vt.给（马、狗等）梳毛，照料，使...整洁

参考例句：

• His father was a groom.他父亲曾是个马夫。
• George was already being groomed for the top job.为承担这份高级工作，乔治已在接受专门的培训。

16 hormones   

n. 荷尔蒙，激素 名词hormone的复数形式

参考例句：

• 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。
• The adrenals produce a large per cent of a man's sex hormones. 肾上腺分泌人体的大部分性激素。

17 jaw   

n.颚，颌，说教，流言蜚语；v.喋喋不休，教训

参考例句：

• He delivered a right hook to his opponent's jaw.他给了对方下巴一记右钩拳。
• A strong square jaw is a sign of firm character.强健的方下巴是刚毅性格的标志。

18 tighten   

v.(使)变紧；(使)绷紧

参考例句：

• Turn the screw to the right to tighten it.向右转动螺钉把它拧紧。
• Some countries tighten monetary policy to avoid inflation.一些国家实行紧缩银根的货币政策，以避免通货膨胀。

19 mutation   

n.变化，变异，转变

参考例句：

• People who have this mutation need less sleep than others.有这种突变的人需要的睡眠比其他人少。
• So far the discussion has centered entirely around mutation in the strict sense.到目前为止，严格来讲，讨论完全集中于围绕突变问题上。

20 primates   

primate的复数

参考例句：

• Primates are alert, inquisitive animals. 灵长目动物是机灵、好奇的动物。
• Consciousness or cerebration has been said to have emerged in the evolution of higher primates. 据说意识或思考在较高级灵长类的进化中已出现。

21 skull   

n.头骨；颅骨

参考例句：

• The skull bones fuse between the ages of fifteen and twenty-five.头骨在15至25岁之间长合。
• He fell out of the window and cracked his skull.他从窗子摔了出去，跌裂了颅骨。

22 weaver   

n.织布工；编织者

参考例句：

• She was a fast weaver and the cloth was very good.她织布织得很快，而且布的质量很好。
• The eager weaver did not notice my confusion.热心的纺织工人没有注意到我的狼狈相。