VOA慢速英语2010年-SCIENCE IN THE NEWS - 'Synthia' Brings

BOB DOUGHTY¹: This is SCIENCE IN THE NEWS, a program in VOA Special English. I’m Bob Doughty.

SHIRLEY GRIFFITH: And I’m Shirley Griffith. Today we tell about the development of what scientists are calling a synthetic² cell – a cell produced by people instead of by nature.

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BOB DOUGHTY: Ten years have passed since the announcement of the first version of the human genome. In two thousand, then-President Bill Clinton told the world that international and private groups had identified the genetic⁴ structure of a human being. The president praised scientists working with the Human Genome Project and Celera Genomics Corporation. He said they had organized a design that shows all the information that makes up a human life.

Experts welcomed the announcement as a major development toward the understanding, identification and treatment of disease. They predicted progress against genetic diseases like cystic fibrosis and Parkinson’s disease.

SHIRLEY GRIFFITH: Tony Blair, then the prime minister of Britain, joined President Clinton in Washington for the announcement. The event came after negotiations⁵ involving the international and private-laboratory scientists.

Francis Collins led the international group from his position at America's National Institutes of Health. J. Craig Venter led the private laboratory efforts at Celera. The two men denied they were competing. However, observers said the negotiations clearly settled the race to be first.

Three years later, the Human Genome Project announced an almost-completed human genome. Mister Venter’s laboratory announced a different, completed version in two thousand seven.

BOB DOUGHTY: Today, Mister Venter is head of the J. Craig Venter Institute. He has continued his genetics work to carry out another highly publicized project. He and his research team have developed a synthetic, or manmade, cell he calls “Synthia.” A recent report in Science magazine describes the development of the cell.

Craig Venter

Mister Venter says Synthia is a new species. He says it is the first cell whose parent was in a computer. He says his team changed existing life into new life because the synthetic cell can control and reproduce a living cell.

To many people, the ability of a cell to reproduce itself is the definition of life itself.

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SHIRLEY GRIFFITH: The goal of the Venter team's research is to create bacteria designed to solve problems in medicine and energy production. They hope that future synthetic cells can make useful bacteria for products like bio-fuels or vaccines⁶, and to clean up polluted water.

Scientists Daniel Gibson, Hamilton Smith and Mister Venter worked with more than twenty other researchers to develop Synthia. The project took fifteen years and cost forty million dollars.

The cell is made from a synthetic genome. To make that genome, the researchers replaced all the natural genetic material in a bacterial⁷ cell with a synthetic set of genes⁸. At the announcement of the cell's creation, Mister Venter described the steps his team followed to develop Synthia.

CRAIG VENTER: “We are here today to announce the first synthetic cell -- a cell made by starting with the digital code in the computer, building the chromosome⁹ from four bottles of chemicals, assembling that chromosome in yeast¹⁰, transplanting it into a recipient¹¹ bacterial cell and transforming that cell into a new bacterial species.”

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BOB DOUGHTY: Craig Ventner's research team used a simple natural bacterium¹² that infects goats. It is called Mycoplasma mycoides. The team says the bacterium was changed so it cannot cause harm if it escapes. All the information in its genes is organized into more than one million letters. The letters of this code tell what qualities the bacterium contains.

The researchers placed the coded letters in a computer. Then they made small changes to the bacterium’s deoxyribonucleic acid -- DNA¹³ for short. DNA makes chemicals in cells.

The researchers removed four thousand letters . Their removal stopped two genes from operating. Then the team replaced ten genes with four sequences, or four sets, of organized DNA. The researchers call the four sets “watermark” sequences. Each watermark has more than one thousand letters. The coded letters contain people’s names, famous sayings and a website to help identify the cell.

CRAIG VENTER: “And we also built in a website address so that if somebody decodes¹⁴ the code within the code, they can send an e-mail to that address. So it’s clearly distinguishable from any other species.”

SHIRLEY GRIFFITH: Mister Venter says his team made each watermark sequence with the contents of four different bottles of chemicals. The chemicals changed the DNA of each watermark. The DNA particles were designed so pieces next to each other contained eighty letters that overlapped¹⁶, with one placed over the other. That design provided the pieces with special places to link together.

The researchers added the changed DNA to yeast -- a simple, single-cell organism. Inside the yeast cell, the yeast machinery¹⁷ recognized that the two DNA pieces had the same order. The yeast machinery put them together at this place of overlap¹⁵.

The genome was created in three steps. When finished, the cell contained more than one million letters. Its creators said it is the longest chemically designed DNA structure ever produced in a laboratory.

BOB DOUGHTY: The researchers placed the genome into a receiving cell of a bacterium called Mycoplasma capricolum. They made the genome active in the bacteria. But first, Mister Venter said, they had to de-activate a gene³ in the receiving cell that would have killed the synthetic genome.

In late March, the synthetic genome started to produce a new form of cells.

(MUSIC)

SHIRLEY GRIFFITH: To some scientists, the work of Craig Venter's research offers hopeful possibilities. For example, Mister Venter is working to design cells that can make it easier to capture carbon dioxide. His team is also attempting to produce new food oils and make synthetic parts of every known influenza¹⁸ virus. The process may help build new vaccines much faster than is done now.

However, some people see other, far less pleasant possibilities for the new technology. The environmental activist¹⁹ group Friends of the Earth says it is dangerous. The group says it could be hard to stop experimental organisms from entering the natural environment.

It says the synthetic cells might take control of living things in nature. Friends of the Earth has called for suspending further research until rules are made for the technology.

BOB DOUGHTY: University of Pennsylvania professor Arthur Caplan is bioethicist -- an expert in ethical²⁰ and moral issues of biological medicine and technology. He says the new cell is one of the most important scientific gains ever made. Professor Caplan also believes that concerns about the possible escape of manufactured cells into the atmosphere are real.

Mark Bedau of Reed College in Oregon says Mister Venter’s work marks an important step over traditional genetic engineering of individual genes. But Professor Bedau says that nobody can be sure about the results of making new forms of life. He says science must expect results that are unexpected and unmeant.

President Obama has ordered a report about the possible risks of the technology.

Also, some people may find that manufactured cells threaten their belief that only God should create life. But Nobel Prize-winning scientist David Baltimore says the team created only a representation of real life. Mister Baltimore is a former president of the California Institute of Technology.

SHIRLEY GRIFFITH: Other scientists praise the Venter team’s amazingly big piece of DNA. Still others question whether the cell and those to follow can really help improve health and make biofuels.

Divided opinions of his work are not new to Craig Venter. Over the years, he has sometimes earned enemies by expressing opinions that offend other scientists.

Mister Venter will be sixty-four years old in October. At that age, many people are retired²¹. But he is hard at work. He and his team currently are trying to make algae²² that can change carbon dioxide back into fossil fuel.

(MUSIC)

BOB DOUGHTY: This SCIENCE IN THE NEWS was written by Jerilyn Watson. Our producer was Mario Ritter. I’m Bob Doughty.

SHIRLEY GRIFFITH: And I’m Shirley Griffith. Join us again 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 synthetic   

adj.合成的，人工的；综合的；n.人工制品

参考例句：

• We felt the salesman's synthetic friendliness.我们感觉到那位销售员的虚情假意。
• It's a synthetic diamond.这是人造钻石。

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 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。

5 negotiations   

协商( negotiation的名词复数 )； 谈判； 完成（难事）； 通过

参考例句：

• negotiations for a durable peace 为持久和平而进行的谈判
• Negotiations have failed to establish any middle ground. 谈判未能达成任何妥协。

6 vaccines   

疫苗，痘苗( vaccine的名词复数 )

参考例句：

• His team are at the forefront of scientific research into vaccines. 他的小组处于疫苗科研的最前沿。
• The vaccines were kept cool in refrigerators. 疫苗放在冰箱中冷藏。

7 bacterial   

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。

8 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

9 chromosome   

n.染色体

参考例句：

• Chromosome material with exhibits of such behaviour is called heterochromatin.表现这种现象的染色体物质叫做异染色质。
• A segment of the chromosome may become lost,resulting in a deletion.染色体的一个片段可能会丢失，结果产生染色体的缺失。

10 yeast   

n.酵母；酵母片；泡沫；v.发酵；起泡沫

参考例句：

• Yeast can be used in making beer and bread.酵母可用于酿啤酒和发面包。
• The yeast began to work.酵母开始发酵。

11 recipient   

a.接受的,感受性强的 n.接受者,感受者,容器

参考例句：

• Please check that you have a valid email certificate for each recipient. 请检查是否对每个接收者都有有效的电子邮件证书。
• Colombia is the biggest U . S aid recipient in Latin America. 哥伦比亚是美国在拉丁美洲最大的援助对象。

12 bacterium   

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。

13 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。

14 decodes   

v.译（码），解（码）( decode的第三人称单数 )；分析及译解电子信号

参考例句：

• Figure 5.1 shows a network that decodes a given bIt'sequence. 图5．1是一个对给定二进制序列进行解码的网络。 来自辞典例句
• The receive decodes the message and attempts to interpret the sender's meaning. 接收者解码收到的信息，并解释发送者的意思。 来自互联网

15 overlap   

v.重叠，与…交叠；n.重叠

参考例句：

• The overlap between the jacket and the trousers is not good.夹克和裤子重叠的部分不好看。
• Tiles overlap each other.屋瓦相互叠盖。

16 overlapped   

_adj.重叠的v.部分重叠( overlap的过去式和过去分词 )；（物体）部份重叠；交叠；（时间上）部份重叠

参考例句：

• His visit and mine overlapped. 他的访问期与我的访问期有几天重叠。 来自《现代汉英综合大词典》
• Our visits to the town overlapped. 我们彼此都恰巧到那小城观光。 来自辞典例句

17 machinery   

n.(总称)机械，机器；机构

参考例句：

• Has the machinery been put up ready for the broadcast?广播器材安装完毕了吗？
• Machinery ought to be well maintained all the time.机器应该随时注意维护。

18 influenza   

n.流行性感冒，流感

参考例句：

• They took steps to prevent the spread of influenza.他们采取措施
• Influenza is an infectious disease.流感是一种传染病。

19 activist   

n.活动分子，积极分子

参考例句：

• He's been a trade union activist for many years.多年来他一直是工会的积极分子。
• He is a social activist in our factory.他是我厂的社会活动积极分子。

20 ethical   

adj.伦理的，道德的，合乎道德的

参考例句：

• It is necessary to get the youth to have a high ethical concept.必须使青年具有高度的道德观念。
• It was a debate which aroused fervent ethical arguments.那是一场引发强烈的伦理道德争论的辩论。

21 retired   

adj.隐退的，退休的，退役的

参考例句：

• The old man retired to the country for rest.这位老人下乡休息去了。
• Many retired people take up gardening as a hobby.许多退休的人都以从事园艺为嗜好。

22 algae   

n.水藻，海藻

参考例句：

• Most algae live in water.多数藻类生长在水中。
• Algae grow and spread quickly in the lake.湖中水藻滋蔓。