刘植荣/译
英国《泰晤士报》10日报道说，科学家首次完成由人工精子培育出生命的实验，有6只通过人工精子培育出的老鼠活到了“成年”。由于人工精子是从胚胎细胞中培育出来的，因此可以说，这6只小老鼠在“爸爸”还没有出世的时候就呱呱落地了。设菲尔德大学生物学教授哈里·穆尔说：“纳耶尼亚博士的研究成果是令人激动的，这首次暗示由人类培育出的不成熟的精子可以最终形成完整的生物个体。”从理论上说，人类不仅可以利用人造精子或卵子技术解决不育症等疾病，还可以帮助同性恋者生产出具有“双亲遗传特征”的孩子。更让人吃惊的是，男人（女人）将可以用自己的精子（卵子）和由自己干细胞造出的卵子（精子）进行受精，不需另外一个人的基因参与就造出一个“单性繁殖”的婴儿。由此引起了生命科学与伦理道德之间的激烈冲突。
2006年7月17日，美国参议院就增加政府对胚胎干细胞研究经费拨款进行辩论。布什再次声明，如果议案通过，不惜动用否决权。美国总统布什对干细胞研究一直持谨慎态度，反对用毁灭一个生命的方式制造或挽救另一个生命。以下是布什在2004年总统大选期间与克里就干细胞研究问题的激烈辩论：
提问者：克里参议员，数千人已经接受成体干细胞或脐带 干细胞的治疗，有的已经被治愈。然而，还没有人接受胚胎干细胞的治疗。不应该广泛使用通过不销毁胚胎手段获取的干细胞么？
克里：我知道，是伦理道德驱使你提这个问题的，并且我非常重视这个问题。
一天，我在新罕布什尔州的一次论坛会上见到迈克尔·J·福克斯，他正遭受帕金森病的折磨，他让我们使用干细胞，胚胎干细胞。这个人站起来，只见他全身不停地颤抖。他的整个身体由于神经疾病而不断震颤，他患的是肌肉疾病。他对我和大厅里所有的人说：“你们知道，不要让我的希望破灭，因为我的希望就是让我活下去。”
克里斯·里夫是我的朋友。为了让肌肉不萎缩，克里斯·里夫每天都坚持锻炼，他坚信总有一天他能够重新走路，而且我要让他重新走路，我认为我们能够救助这些生命。
现在，我认为我们可以在伦理道德的约束下进行胚胎干细胞研究。今天，我们在各个实验室通过液氮冷冻着10万—20万个胚胎。胚胎不是通过堕胎或者类似的手段获取。他们是在一些实验室培育的。他们要么被毁坏，要么一直冷冻在那里。我认为，如果科学家告诉我们可以，我们就有这种选择权，用胚胎干细胞去治疗帕金森病，去治疗糖尿病，去治疗下身瘫痪、或四肢麻痹或者脊髓损伤等等，那才是人类精神的本质。
我认为进行那项治疗研究是对生命的尊重。我认为用符合伦理道德的方式去做那件事情是对生命的尊重。但这位总统选择了让我们的科学家根本不可能去做那件事的政策。我向往未来，并且我认为我们必须把握住它。
布什：胚胎干细胞研究需要通过对生命的毁灭来获取一个干细胞，我是美国历史上第一个允许联邦拨款给胚胎干细胞研究的总统。我之所以这样做，是因为我也希望我们通过干细胞极其相关的研究找到治疗一些疾病的方法。
但是我认为我们必须非常谨慎地去权衡伦理道德和科学之间的关系。所以我才决定不再给超出这70株胚胎干细胞以外的研究增加任何经费，这70株胚胎干细胞中的22个正在研究中。科学重要，伦理道德同样重要，生命的平衡也很重要。通过毁灭生命来挽救生命确实是我们所面对的一个伦理道德的两难选择。
现在正在对现有存活的22株胚胎干细胞进行数百次实验，我们很有希望找到一种治疗方法。然而，我们需要继续进行成体干细胞研究。
我帮助把给美国国家卫生院的财政预算翻了一番，达到每年280亿美元，用于研究疾病的治疗。我所采取的是这样一个方法，我认为是一个权衡利弊和必须的方法，那就是在科学和生命价值之间找平衡。
克里：好的，你谈到一个胡乱划的线（译者注：英文line有线和株的意思，克里用这个双关语讽刺布什混淆事实）——他说他允许做这件事，这就意味着他允许在一定规模上对生命的毁灭，然后他又不允许那样做。
我不知道你是怎么划那条线的。还是让我告诉你吧，什么，他说的可应用的胚胎干细胞株数目，这个国家的每个科学家会告诉你“不够用”，因为它们被老鼠细胞给污染了，因为没有60—70株，现在只有11—20株，所以没有足够的胚胎干细胞株供研究使用，因为它们被污染了。我们必须尽一切可能来进行这项研究。如果我当了总统，我就要这样做，因为我们必须这样做。
布什：我想让你明白我的决策。那些胚胎干细胞株已经有了。胚胎在我做的决策之前就被毁掉了。我必须作出毁灭更多生命决策，所以我们要继续毁灭生命（译者注：这里布什又犯了满嘴跑火车的毛病）——我做的这个决策是平衡科学与伦理道德。（选自《美国历届总统竞选辩论精选》，江西人民出版社，2006年4月 www.aifeier.cn ）
附英文原文：
Is stem-cell research legal
QUESTIONGER: Senator Kerry, thousands of people have already been cured or treated by the use of adult stem cells or umbilical cord stem cells. However, no one has been cured by using embryonic stem cells. Wouldn’t it be wide to use stem cells obtained without the destruction of an embryo?
KERRY: I know the morality that’s prompting that question, and I respect it enormously.
I was at a forum with Michael J. Fox the other day in New Hampshire, who’s suffering from Parkinson’s, and he wants us to do stem cell, embryonic stem cell. And this fellow stood up, and he was quivering. His whole body was shaking from the nerve disease, the muscular disease that he had. And he said to me and to the whole hall, he said, “You know, don’t take away my hope, because my hope is what keeps me going.”
Chris Reeve is a friend of mine. Chris Reeve exercises every single day to keep those muscles alive for the day when he believes he can walk again, and I want him to walk again. I think we can save lives.
Now, I think we can do ethically guided embryonic stem-cell research. We have 100,000 to 200,000 embryos that are frozen in nitrogen today from fertility clinics. These weren’t taken from abortion or something like that. They’re from a fertility clinic. And they’re either going to be destroyed or left frozen. And I believe if we have the option, which scientists tell us we do, of curing Parkinson’s, curing diabetes, curing paraplegic or quadriplegic or, a spinal cord injury, anything, that’s the nature of the human spirit.
I think it is respecting life to reach for that cure. I think it is respecting life to do it in an ethical way. And the president has chosen a policy that makes it impossible for our scientists to do that. I want the future, and I think we have to grab it.
BUSH: Embryonic stem-cell research requires the destruction of life to create a stem cell. I’m the first president ever to allow federal funding for embryonic stem-cell research. I did so because I too hope that we’ll discover cures from the stem cells and from the research derived.
But I think we’ve got to be very careful in balancing the ethics and the science. And so I made the decision we wouldn’t spend any more money beyond the 70 lines, 22 of which are now in action, because science is important, but so is ethics, so is balancing life. To destroy life to save life is one of the real ethical dilemmas that we face.
There is going to be hundreds of experiments off the 22 lines that now exist that are active, and hopefully we find a cure. But as well, we need to continue to pursue adult stem-cell research.
I helped double the NIH budget to $28 billion a year to find cures. And the approach I took is one that I think is a balanced and necessary approach, to balance science and the concerns for life.
KERRY: Well, you talk about walking a waffle line—he says he’s allowed it, which means he’s going to allow the destruction of life up to a certain amount and then he isn’t going to allow it.
I don’t know how you draw that line. But let me tell you, point blank, the lines of stem cells that he’s made available, every scientist in the country will tell you, “Not adequate,” because they’re contaminated by mouse cells, and because there aren’t 60 or 70, they’re are only about 11 to 20 now, and there aren’t enough to be able to do the research because they’re contaminated. We’ve got to open up the possibilities of this research. And when I am president, I’m going to do it because we have to.
BUSH: Let me make sure you understand my decision. Those stem-cells lines already existed. The embryo had already been destroyed prior to my decision. I had to make the decision to destroy more life, so we continue to destroy life — I made the decision to balance science and ethics.