VOA慢速英语2015 三人创造的人类胚胎辩论超越科学和宗教

'Three-Person Babies' Debate Goes Beyond Science and Religion 三人创造的人类胚胎辩论超越科学和宗教

Britain has become the first country to permit doctors to use genetic² material from three people to create human embryos⁴. The process is called “mitochondrial replacement⁵ therapy.” But some call it making “three-person babies.”

The treatment is meant to help women avoid passing certain diseases and disorders⁶ to their children.

Members of Britain’s upper house of parliament approved the measure in a vote on Tuesday. The lower house passed it earlier this month.

Public reaction and debate was immediate⁷. The therapy could potentially end several severe, sometimes deadly, health problems. But the process behind that goal frightens many people and offends some others.

Mitochondrial replacement therapy

Here is the science of mitochondrial replacement therapy, or MRT.

A human is made from the genetic information provided by our mother and father. Almost all our DNA⁸ is in the nucleus⁹ of our cells. That DNA is called nuclear DNA and makes up about 99.99 percent of our genes¹⁰.

But about one-tenth of one percent of our DNA comes from only our mothers and is found in organelles called mitochondria. That DNA is called mitochondrial DNA.

Mitochondrial DNA does not create the color of your hair or the texture¹¹ of your skin. It does not make you walk like your mom or talk like your dad. The genes that create the personal characteristics that make each of us individual are in the nuclear DNA.

Instead, mitochondria have one major job. They use oxygen to help the body turn food into energy. The mitochondria are like the cell’s power factory.

Mitochondria gone bad

A small percentage of women have mitochondrial mutations that can be passed on to children. These mutations cause severe diseases in an even smaller number of those children.

Worldwide about one in 6,500 children suffers from mitochondrial disease.

Mitochondrial disease can affect all the body’s systems. It can cause blindness, hearing loss, muscle failure, developmental delays, heart defects, liver and kidney failure and breathing problems.

The United Mitochondrial Disease Foundation says mitochondrial disease often affects three or more of a sufferer’s organs.

Mutated mitochondria do not always make children sick. But healthy girls with such mutations still could face the problem of passing the mutations, and possible disease, to their own children.

How mitochondrial replacement therapy works

There are two ways to replace bad mitochondrial DNA with healthy mitochondrial DNA. The first uses unfertilized eggs from two women, the mother and the donor¹⁴.

The nucleuses of both eggs are removed. The mother’s egg nucleus is then placed in the donor’s egg, which has healthy mitochondrial DNA. Then, doctors use the father’s sperm¹⁵ to fertilize¹² the egg. The resulting embryo³ is put into the mother’s womb.

The embryo contains nuclear DNA from the father and mother and mitochondrial DNA from the donor.

The other replacement process uses a donor egg and a fertilized¹³ egg, or embryo, from the mother. The nucleus is removed from the donor egg and replaced with the fertilized nucleus from the mother. Again the embryo has nuclear DNA from its parents, and mitochondrial DNA from a third person.

Human health concerns

Mitochondrial replacement therapy – MRT – is widely controversial. Religious leaders, bioethics experts, doctors, scientists, activists¹⁶, politicians and others have entered the debate.

Many are concerned that MRT crosses what is called the germ line. The germ line is all the genetic information that parents pass to their children. Children born of MRT would have genetic information that is outside their germline.

But MRT does not necessarily result in just one genetically¹⁷ modified individual. If the individual is female, the genetic changes would also be passed to children born to her. That genetic alteration¹⁸ is permanent.

Scientists have experimented with crossing the germ line on insects and animals. But the research is new. Scientists have known of the existence of mitochondrial DNA for only about 50 years.

There is no way to know the long-term impact of introducing unrelated mitochondrial DNA to human embryos until it is actually done. And, even then, several following generations would have to be studied.

So the unknowns scare many people. Their fear should not be a surprise considering the public’s concern over genetically modified food.

Ethical¹⁹ concerns

People with human health concerns are joined by others offering wide ethical and religious arguments. 

Critics of MRT say it is the first step onto a dangerous path of human gene¹ engineering. They warn of “designer babies” in the future.

For example, they fear people will use genetic technology to create babies with certain traits, such as blue eyes, high intelligence or athletic²⁰ ability.

But MRT supporters dismiss this argument. Robert Klitzman is a bioethicist and professor of psychiatry²¹ at Columbia University in New York City. He recently wrote an opinion piece supporting mitochondrial replacement therapy for the “Wall Street Journal.”

Mr. Klitzman says MRT cannot be fairly compared to baby design.

“I would argue that it’s not, that this is equivalent to changing the batteries in some fancy machine. The machine is the same. Sort of like getting a blood transfusion²² or an organ transplant, it doesn’t change the identity of the person.”

Religious objections

Anglican Church officials in Britain spoke²³ out against the measure to approve mitochondrial replacement therapy. The Church supports some embryonic²⁴ study for the purpose of easing human suffering. But Anglican leaders say too little is known about the part mitochondria plays in heredity. They argue that more research must be done to guarantee the therapy is safe, ethical and effective.

The Roman Catholic Church goes further. It strongly objects to the destruction of embryos that can result from MRT. But it also says the process attacks the dignity of human life.

Christa Lopicollo is Executive Director of the Department of Life Issues with the Catholic Archdiocese of Washington.

“It threatens the dignity of the child to be seen as a product of technology rather than a product of love, and threatens the dignity of the marriage as well by adding an additional parent into the picture here. The Church recognizes than an embryo, while very, very early in life, is still a unique distinct life that deserves respect and protection.”

MRT interest in the US

Scientists in the United States were among the leaders in researching mitochondrial replacement therapy. They are seeking permission to move forward with the process in the U.S.

The U.S. Food and Drug administration held a conference on the issue a year ago. The agency has also asked the independent Institute of Medicine to examine the ethical and social issues connected to the treatment.

But some say the government is not moving fast enough. Susan Solomon is the chief executive officer of the New York Stem Cell Foundation. She wrote an editorial in “Roll Call,” a newspaper covering the U.S. Congress and politics.

Ms. Solomon noted²⁵ that U.S. researchers helped develop the treatment and yet American women cannot benefit from that effort. She criticized lawmakers, the president and federal agencies. She wrote that they had “half-ignored, half-slighted the issue” of mitochondrial replacement therapy. Ms. Solomon called on congress and the federal government to act now. She wrote that debate over MRT cannot, in her words “continue delaying our ability to save lives now.”

Words In This Story

organelle – n. a specialized²⁶ cellular²⁷ part (as a mitochondrion, lysosome, or ribosome) that is analogous²⁸ to an organ

controversial – adj. relating to or causing much discussion, disagreement, or argument 

modification²⁹ – n.  the act or process of changing parts of something

impact – n. a powerful or major influence or effect

trait – n. a quality that makes one person or thing different from another

heredity – n. the natural process by which physical and mental qualities are passed from a parent to a child

1 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。

2 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。

3 embryo   

n.胚胎，萌芽的事物

参考例句：

• They are engaging in an embryo research.他们正在进行一项胚胎研究。
• The project was barely in embryo.该计划只是个雏形。

4 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

5 replacement   

n.取代，替换，交换；替代品，代用品

参考例句：

• We are hard put to find a replacement for our assistant.我们很难找到一个人来代替我们的助手。
• They put all the students through the replacement examination.他们让所有的学生参加分班考试。

6 disorders   

n.混乱( disorder的名词复数 )；凌乱；骚乱；（身心、机能）失调

参考例句：

• Reports of anorexia and other eating disorders are on the increase. 据报告，厌食症和其他饮食方面的功能紊乱发生率正在不断增长。 来自《简明英汉词典》
• The announcement led to violent civil disorders. 这项宣布引起剧烈的骚乱。 来自《简明英汉词典》

7 immediate   

adj.立即的；直接的，最接近的；紧靠的

参考例句：

• His immediate neighbours felt it their duty to call.他的近邻认为他们有责任去拜访。
• We declared ourselves for the immediate convocation of the meeting.我们主张立即召开这个会议。

8 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。

9 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。

10 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

11 texture   

n.(织物)质地；(材料)构造；结构；肌理

参考例句：

• We could feel the smooth texture of silk.我们能感觉出丝绸的光滑质地。
• Her skin has a fine texture.她的皮肤细腻。

12 fertilize   

v.使受精，施肥于，使肥沃

参考例句：

• Fertilizer is a substance put on land to fertilize it.肥料是施在地里使之肥沃的物质。
• Reading will fertilize his vocabulary.阅读会丰富他的词汇。

13 Fertilized   

v.施肥( fertilize的过去式和过去分词 )

参考例句：

• The study of psychology has recently been widely cross-fertilized by new discoveries in genetics. 心理学研究最近从遗传学的新发现中受益匪浅。
• Flowers are often fertilized by bees as they gather nectar. 花常在蜜蜂采蜜时受粉。

14 donor   

n.捐献者；赠送人；(组织、器官等的)供体

参考例句：

• In these cases,the recipient usually takes care of the donor afterwards.在这类情况下，接受捐献者以后通常会照顾捐赠者。
• The Doctor transplanted the donor's heart to Mike's chest cavity.医生将捐赠者的心脏移植进麦克的胸腔。

15 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。

16 activists   

n.（政治活动的）积极分子，活动家( activist的名词复数 )

参考例句：

• His research work was attacked by animal rights activists . 他的研究受到了动物权益维护者的抨击。
• Party activists with lower middle class pedigrees are numerous. 党的激进分子中有很多出身于中产阶级下层。 来自《简明英汉词典》

17 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

18 alteration   

n.变更，改变；蚀变

参考例句：

• The shirt needs alteration.这件衬衣需要改一改。
• He easily perceived there was an alteration in my countenance.他立刻看出我的脸色和往常有些不同。

19 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。

20 athletic   

adj.擅长运动的，强健的；活跃的，体格健壮的

参考例句：

• This area has been marked off for athletic practice.这块地方被划出来供体育训练之用。
• He is an athletic star.他是一个运动明星。

21 psychiatry   

n.精神病学，精神病疗法

参考例句：

• The study appeared in the Amercian science Journal of Psychiatry.这个研究发表在美国精神病学的杂志上。
• A physician is someone who specializes in psychiatry.精神病专家是专门从事精神病治疗的人。

22 transfusion   

n.输血，输液

参考例句：

• She soon came to her senses after a blood transfusion.输血后不久她就苏醒了。
• The doctor kept him alive by a blood transfusion.医生靠输血使他仍然活着。

23 spoke   

n.（车轮的）辐条；轮辐；破坏某人的计划；阻挠某人的行动 v.讲，谈（speak的过去式）；说；演说；从某种观点来说

参考例句：

• They sourced the spoke nuts from our company.他们的轮辐螺帽是从我们公司获得的。
• The spokes of a wheel are the bars that connect the outer ring to the centre.辐条是轮子上连接外圈与中心的条棒。

24 embryonic   

adj.胚胎的

参考例句：

• It is still in an embryonic stage.它还处于萌芽阶段。
• The plan,as yet,only exists in embryonic form.这个计划迄今为止还只是在酝酿之中。

25 noted   

adj.著名的，知名的

参考例句：

• The local hotel is noted for its good table.当地的那家酒店以餐食精美而著称。
• Jim is noted for arriving late for work.吉姆上班迟到出了名。

26 specialized   

adj.专门的，专业化的

参考例句：

• There are many specialized agencies in the United Nations.联合国有许多专门机构。
• These tools are very specialized.这些是专用工具。

27 cellular   

adj.移动的；细胞的，由细胞组成的

参考例句：

• She has a cellular telephone in her car.她的汽车里有一部无线通讯电话机。
• Many people use cellular materials as sensitive elements in hygrometers.很多人用蜂窝状的材料作为测量温度的传感元件。

28 analogous   

adj.相似的；类似的

参考例句：

• The two situations are roughly analogous.两种情況大致相似。
• The company is in a position closely analogous to that of its main rival.该公司与主要竞争对手的处境极为相似。

29 modification   

n.修改，改进，缓和，减轻

参考例句：

• The law,in its present form,is unjust;it needs modification.现行的法律是不公正的，它需要修改。
• The design requires considerable modification.这个设计需要作大的修改。