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  3. Scientists have for the first time used cloning to create human embryos that live long enough in a laboratory dish to have their

Scientists have for the first time used cloning to create human embryos that live long enough in a laboratory dish to have their

admin2009-04-26  99
问题     Scientists have for the first time used cloning to create human embryos that live long enough in a laboratory dish to have their stem cells harvested. The feat could set the stage for physicians to produce cells and tissues, tailored to a patient’s genetic identity that can treat a wide variety of human illnesses. The accomplishment also provides a road map for how to clone a person, an even more divisive undertaking.
    The new work, performed in South Korea, represents "a major advance in stem cell research. It could help spur a medical revolution as important as antibiotics and vaccines", says Robert Lanza of Advanced Cell Technology (ACT), a company in Worcester, Mass., that’s also investigating the promising stem cell strategy called therapeutic cloning.
    "However, now that the methodology is publicly available", Lanza adds, "I think it is absolutely imperative that we pass laws worldwide to prevent the technology from being abused for reproductive-cloning purposes".
    While some fertility doctors and a religious cult have claimed success at creating a pregnancy via cloning, they’ve offered no convincing proof. In contrast, the South Korean research is being reported at the meeting of the American Association for the Advancement of Science in Seattle and will appear in an upcoming Science. "This is reality", says stem cell researcher John Gearhart of Johns Hopkins University. "Here is a bona fide, refereed journal saying that a human embryo has been cloned and a cell line derived from it".
    Although ACT has not yet published a report of a cloned human blastocyst, Lanza says that the South Korean success is "consistent with our own results". Therapeutic cloning appeals to Lanza and physicians because cells made this way could have the same DNA as a patient’s cells do and thus avoid rejection after they’re transplanted.
    Seeking a compromise that would permit this strategy to be pursued, many scientists have called for legislation that would ban cloning to produce a baby but allow the creation of cloned embryos to generate stem cells for research or therapies. "The debate has been very polarized", notes bio-ethicist Laurie Zoloth of Northwestern University in Evanston.
选项 A、human embryos are very short-lived outside a human body.
B、human embryos are extremely hard to be cloned.
C、human genetic identity is difficult to be defined.
D、human cloning is strongly opposed by some researchers.
答案A
解析 细节题。文章第一句说"科学家们第一次使用克隆技术创造出在实验室里存活足够久的人类胚胎，以便能够取得这些胚胎的干细胞"。证明干细胞必须在胚胎存活足够久时才能获得，而胚胎是第一次在实验室存活了这么久，说明干细胞难于获得的原因是人类胚胎在人体外存活时间太短。
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