人造生命预计3~10年后出现

Artificial life likely in 3 to 10 years
By SETH BORENSTEIN
AP SCIENCE WRITER

WASHINGTON -- Around the world, a handful of scientists are trying to create life from scratch and they're getting closer.

Experts expect an announcement within three to 10 years from someone in the now little-known field of \"wet artificial life.\"

\"It's going to be a big deal and everybody's going to know about it,\" said Mark Bedau, chief operating officer of ProtoLife of Venice, Italy, one of those in the race. \"We're talking about a technology that could change our world in pretty fundamental ways - in fact, in ways that are impossible to predict.\"

That first cell of synthetic life - made from the basic chemicals in DNA - may not seem like much to non-scientists. For one thing, you'll have to look in a microscope to see it.

\"Creating protocells has the potential to shed new light on our place in the universe,\" Bedau said. \"This will remove one of the few fundamental mysteries about creation in the universe and our role.\"

And several scientists believe man-made life forms will one day offer the potential for solving a variety of problems, from fighting diseases to locking up greenhouse gases to eating toxic waste.

Bedau figures there are three major hurdles to creating synthetic life:

- A container, or membrane, for the cell to keep bad molecules out, allow good ones, and the ability to multiply.

- A genetic system that controls the functions of the cell, enabling it to reproduce and mutate in response to environmental changes.

- A metabolism that extracts raw materials from the environment as food and then changes it into energy.

One of the leaders in the field, Jack Szostak at Harvard Medical School, predicts that within the next six months, scientists will report evidence that the first step - creating a cell membrane - is \"not a big problem.\" Scientists are using fatty acids in that effort.

Szostak is also optimistic about the next step - getting nucleotides, the building blocks of DNA, to form a working genetic system.

His idea is that once the container is made, if scientists add nucleotides in the right proportions, then Darwinian evolution could simply take over.

\"We aren't smart enough to design things, we just let evolution do the hard work and then we figure out what happened,\" Szostak said.

In Gainesville, Fla., Steve Benner, a biological chemist at the Foundation for Applied Molecular Evolution is attacking that problem by going outside of natural genetics. Normal DNA consists of four bases - adenine, cytosine, guanine and thymine (known as A,C,G,T) - molecules that spell out the genetic code in pairs. Benner is trying to add eight new bases to the genetic alphabet.

Bedau said there are legitimate worries about creating life that could \"run amok,\" but there are ways of addressing it, and it will be a very long time before that is a problem.

\"When these things are created, they're going to be so weak, it'll be a huge achievement if you can keep them alive for an hour in the lab,\" he said. \"But them getting out and taking over, never in our imagination could this happen.\"

图：This undated photo provided by ProtoLife Srl.of Venice, Italy, shows vesicles, artificial membranes for cells, made from scratch. Teams around the world, including ProtoLife, are trying to create synthetic life from scratch, and the first step many of them are working on is making a container for the life form such as these vesicles. The large cell container (with little ones inside of it), shown in computer-created coloring, is about the thickness of a human hair. (AP Photo/Protolife Srl., Martin Hanczyc)
编译

人造生命预计3~10年后出现
美联社科学作者：Seth Borenstein

　　华盛顿──世界上有这么一群科学家，他们正“白手起家”，从零开始创造生命。现在，他们离这个目标更近了。专家们希望在未来的3到10年时间里有望在“wet artifical life”领域取得突破。

　　威尼斯ProtoLife公司就是该领域的一个竞争者。公司首席运营官马克·贝度说：“这会是件大事情，每一个人都将知道这个消息。我们谈论的这项技术能够从本质上改变我们的世界，而且这种改变不可预测。”

　　对于一般人来说，这个由DNA基本化合物合成的“第一个人造细胞”可能并不怎么样。比如，你只能在显微镜下看到这种细胞。

　　但是对于贝度来说，“制造原型细胞可以从新的视角来了解我们在宇宙所处的位置，它将可以解开有关宇宙创造和人类角色的基本谜团。” 而其他一些科学家认为，未来的某一天可以利用人造生命来解决各种实际问题，从治疗疾病到吸附温室气体再到清除有毒垃圾。

不过，贝度指出，制造人造生命仍有三大主要障碍：一是人造生命的“细胞膜”，能够允许细胞过滤有害分子而允许有用分子通过，并且具有繁殖能力；二是控制细胞功能的基因系统，能根据环境变化来进行复制和变异；三是新陈代谢的能力，从环境中获取原料当做食物，之后将它变成能量。

该研究领域的主要科学家、哈佛医学院的杰克·斯卓斯达克预计，科学家们会在未来6个月里根据对脂肪酸的努力研究，给出第一步的证据——制造细胞膜不是大问题。斯卓斯达克还看好第二步——将DNA的制造元件核苷酸整合成可工作的基因系统。他认为一旦有了细胞膜的保护，如果科学家能再以适当的比例加入核苷酸，那么达尔文进化理论就能简单实现。 他说，“我们没有足够的智慧来设计，但是进化本身能够解决复杂问题，我们只要指出结果就行了。”

但是，佛罗里达州盖恩斯维尔市的生化专家史蒂夫-贝讷在应用分子进化的成立会议上发表了不同看法：人造生命将跳出自然基因系统！正常DNA由四种碱基组成──腺嘌呤、胞嘧啶、鸟嘌呤、胸腺嘧啶，这些分子以成对的方式组成基因的密码。贝讷正尝试忘基因组成碱基中加入8种其他的碱基。

不过，贝度担心制造人造生命会不会合法，它们会不会成为“杀人狂”，但现在还有很多时间来解决这一问题。贝道表示：“当这些生命被创造出来时，它们将非常脆弱。让它们在实验室里存活一个小时将是一项巨大的成就。但如果说它们会走出实验室、甚至主宰我们，这是绝对不可能的。”

图：该图片由意大利威尼斯的ProtoLife公司提供，这些从零开始合成的小囊泡可以被细胞用来制作人工细胞膜。世界各地的研究队伍，包括ProtoLife公司，正在白手起家创造人工生命，而作为研究的第一步就是合成类似的小囊泡来装载“生命”。大的细胞囊泡，有一个小的囊泡在里面，由电脑绘成了彩色，其厚度大概是一根人类头发丝。（美联社/Protolife公司，Martin Hanczyc）