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A giant leap into the unknown
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迈向未知世界的一步
1997年2月24日，世界第一只克隆羊多利在英国诞生。它的出生是人类历史上的一个重大突破。
AS time goes by, the cloning technology that brought Dolly the sheep into the world has shown that it isn't a one-hit wonder. Researchers are producing clones from fetal cells with relative ease. Others have shown they can combine cloning and genetic engineering to produce cows and sheep that produce therapeutic proteins. There seems to be no doubt that our future is a future filled with clones. In fact，nearly every month，there's news of how cloning technology is poised to change our lives.
随着时间的推移，把多利羊带到人世的克隆技术已经显得不那么惊世骇俗。科研人员现在能相对轻松地用胎细胞来培育克隆。一些研究人员表示他们可以利用克隆和基因工程技术培育能生产具有治疗作用的蛋白质的牛和羊。毫无疑问，我们的未来将是一个充斥着克隆体的未来。而事实上，几乎每个月都会爆出有关克隆技术将如何改变我们生活的新闻。
Four years ago, Dolly's birth showed that the biological development of cells is not as irreversible as scientists once thought. Dolly might look like other lambs, but she was the most remarkable animal ever born. She was not the result of mating between a ewe and a ram but was cloned from a single cell taken from the udder of a six-year-old ewe. She was the first mammal ever created from the non-reproductive tissue of an adult animal.
四年前，多利的诞生证实了细胞的生物蜕变并不象科学家原先认为的那样不可逆转。就外形上看，看不出多利和其他小羊羔有什么差别，但它却是所有出生的动物中最不寻常的。它不是公羊和母羊配种后生出的，而是由一个从母羊的乳腺上取下的单细胞克隆而成的。它是第一只从成年动物身上的非生殖组织中培育出的哺乳动物.
“Three years ago we didn't think it could be done," said Ian Wilmut after Dolly's birth，one of the team from the Roslin Institute and pharmaceuticals company Pharmaceutical Proteins Ltd(PPL) Therapeutics — both based in Edinburgh — which described their breakthrough in nature.
洛斯林研究所和医药蛋白有限公司的成员之一艾恩·威尔马特在多利诞生后说：“三年前我们没想到可以试验成功。"
In 1996 they used the same reproductive technology to create the world's first cloned lambs. They produced identical lambs called Megan and Morag, which originated from different cells of the same embryo. The difference with Dolly was that all her DNA originated in a cell from the udder of an adult sheep.
1996年他们采用同样的再培育技术培养出了世界上第一批克隆羊。他们采用同一胚胎的不同细胞克隆了两只完全一样的羊羔，命名为Megan和Morag。多利的不同之处在于它的DNA取自一只成年羊的乳腺细胞。
The researchers wanted to see whether “mature" cells that differentiated to fulfil a specialized role — such as that of an udder cell or a fetal cell — could be returned to a primitive state from which they could grow into entire organisms.
研究人员想观察象乳腺细胞或胚胎细胞这样具有特殊功能的成熟细胞是否能被还原到原始状态。
“A year ago，we showed that you could do it with cells from embryos," said Wilmut. “This time, we thought we'd take them from a fetus and an adult as well. As you can see, it worked with all three."
“一年以前，我们可以用胚胎细胞做到这一切,”威尔马特说。“而目前，我们又从胚胎和成体上取了细胞。如你所见，试验证实了同一结论。"
The process was very hit and miss，however. Dolly was the only lamb born from 277 fusions of oocytes with udder cells. Wilmut said there were so many failures because it was difficult to ensure that the empty oocyst and the donor cell were at the same stage of the cell division cycle.
然而这一过程非常难以把握。多利是277组卵母细胞和乳腺细胞的配对中唯一克隆成活的。威尔马特说之所以有这么多的试验失败，是因为很难保证空卵囊和供体细胞能处在细胞分裂周期的同一阶段。
But if, as seemed likely, the Roslin team succeeded in making an entire animal from adult tissue, it might be possible to do the same for humans. Wilmut remained cautious: “We've no idea if this would work, and everyone involved thinks it would be unethical to try it in people. It's illegal anyway, even though it makes a good science-fiction story."
如果洛斯林研究小组成功地从成体组织培育了整个动物活体，那就很有可能以同样方式克隆人。但威尔马特仍然非常谨慎：“我们不知道这一想法实现的可能性有多少，但每个参与其中的人都认为在人类身上作这种试验是不人道的。不管怎么说，这种试验都是不合法的，尽管是写科幻小说的好材料。"
Instead，the Roslin team's research was aimed at agricultural applications. Particularly valuable animals could be cloned from adult cells.
相反，洛斯林研究组的目的在于农业运用。珍稀动物可通过成体细胞克隆而成。
More importantly，biotechnologists for the first time was able to manipulate the genes of cells from some animals directly before growing them into embryos. Researchers could insert new genes into these or knock out existing genes with great precision.
更为重要的是，生物技术第一次可以用来直接控制某些动物胚胎形成前的细胞基因。研究人员可以将新基因植入动物体中，或是相当精确地将已有的基因取出。
“In many ways cloning could offer enormous benefits," said Simon Fishel, embryologist of the Nurture fertility clinic in Nottingham. “You could clone from an adult or a child that is sick to produce embryonic stem cells that could be used to repair that individual's damaged tissues."
“在很多方面，克隆技术都能带来巨大的好处，”诺丁汉培育繁殖诊所的胚胎学家塞蒙·菲歇尔说。“有些大人或孩子身体虚弱而无法产生可修复其身体中已损坏的细胞，你们就可以从他们身上克隆出这些细胞来。"
But the prospect of “carbon-copy humans" was a prime concern. Some felt a kind of horror about producing clones while other ethical commentators are more forthright in their objections. “In my view, the current prohibition [on human cloning] should remain in force," said Margaret Brazier, professor of law at Manchester University. “If brain-dead clones were nurtured and used as organ banks, she said, “this would radically change the nature of what it is to be human. And if a clone was allowed to develop as a normal child, who would be responsible for her welfare, who would be her parents, how would she cope psychologically and socially?"
然而“复制人”的进展却是一个热点。有些人对复制人感到一种恐惧，而一些种族评论家则更直接地提出他们的反对意见。“在我看来，现在对克隆人的禁止是完全应该执行的。”曼彻斯特大学的法学教授玛格丽特·布莱扎尔说。“如果没有大脑的克隆人被培育出来，并被用作器官银行的话，那人类的本质就会被根本改变。而如果克隆技术被允许用来培育一个正常的孩子的话，那么谁又该为她的幸福负责？谁来做她的父母？她又如何在心理和社会方面适应这个世界呢?
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