新編英語(yǔ)教程 4 Unit 13 背景知識(shí) 2.doc

To clone or not to clone, is that the question?An American biotech company has claimed that it has created the first human embryos (胚胎）ever produced by cloning, provoking a storm of criticism and reigniting (再點(diǎn)燃，重新激起）the ethical （倫理的）debate about the promises and dangers of biologys most controversial new technologyADVANCED CELL TECHNOLOGY may be a small, privately financed company that few outside the rarefied （純凈的, 稀薄的）world of biotechnology, and not many within it, have ever heard of. But whatever else that can be said about the firm, its managers certainly know how to make a splash（發(fā)出濺潑聲）. On November 25th, the company claimed to have created the first cloned human embryos, and made the announcement with all the skill of a Hollywood publicist（時(shí)事評(píng)論員; 新聞發(fā)布官員）. It published its results not in a major scientific journal such as Nature or Science, but in an obscure online journal called e-biomed: The Journal of Regenerative Medicine, which many leading medical scientists dont read. To make sure that the wider world paid attention, the three scientists behind the experiments wrote a dramatic first-person account of their research for Scientific American, a popular journal for lay （外行）readers, and they seem to have given a thorough advanced briefing to US News & World Report, a mass-market news magazine, which portrayed the three as intrepid （勇猛無(wú)畏的）pioneers, and even described one of them, Robert Lanza, “as the living embodiment of the character played by Matt Damon in the movie Good Will Hunting”. Not just scientific pioneers; Hollywood heart-throbs （心跳，情人）to boot.Despite all this, the announcement immediately provoked a storm of protest. President George Bush declared that “the use of embryos to clone is wrong. We should not as a society grow life to destroy it. And thats exactly whats taking place.” The Vatican （梵蒂岡, 羅馬教廷）joined in, saying that the firms announcement “called for unequivocal （明確的，不含糊的）condemnation”. The European Commission said that it would never finance any similar projects. “Not everything scientifically possible and technologically feasible is necessarily desirable or admissible,” observed Philippe Busquin, the commissioner for research. The firms experiments, declared Jorg-Dietrich Hoppe, the president of the Association of German Doctors, were “unethical and testify to a horrifyingly low estimation of human life.” Michael West, Advanced Cell Technologys chief executive, denied this: “We are not talking about a human life. We are talking about cellular life. There is a fundamental distinction.”Ironically, all this fuss was caused by what many rival researchers promptly announced was a scientific “failure”. That may be a little harsh, but what the firms scientists have actually managed to do does not quite match their sweeping claims either. The company, based in Worcester, Massachusetts, used two different methods to create human “embryos”, but all died within days, failing to live long enough to produce the kind of material that would yield “stem cells” （干細(xì)胞）in the laboratory, which was the purpose of the experiment. Stem cells are special cells which can, theoretically, grow into almost any kind of human cell type. Many believe that if a way can be found to grow and harvest these cells, they can be used as replacement tissue to combat a variety of human diseases and ailments, from diabetes （糖尿病）to organ failure. Tissue cloned in this way from the patients own cells would not, it is thought, be rejected by the bodys immune system, which is currently a major obstacle to organ transplants and many other treatments.Advanced Cell Technology, according to its paper, adopted the same method as that used to clone Dolly, the first cloned sheep, a few years ago, inserting genetic material from an adult cell into a human egg. But of the 19 eggs used, 16 died before they could divide even once. Only three divided once or twice before dying. None of the eggs lived long enough to produce stem cells. “Its a complete failure,” Dr George Seidel, a cloning expert at Colorado State University, told the New York Times. Moreover, the company is not really the first to claim human cloninga group of South Korean researchers said they had managed to do the same in 1998, but their claim was never verified.Nevertheless, the firms scientists claimed that their paper “provides the first proof that reprogrammed human cells can supply tissue for transplantation.” Declared Dr Lanza: “These are exciting preliminary results”.In fact, the results published by the Advanced Cell team seem to confirm that big technical hurdles still stand in the way, despite what seems like the dizzying pace of recent progress. Deriving （衍生，獲得）human embryonic stem cells is not an easy matter, even from embryos created in the well-established technique of in vitro （在生物體外）fertilisation（受精）. Proving that cells are truly stem cellswith the capacity to renew themselves and become virtually any tissue in the bodyis tricky. Controlling the fate of these cellsdriving them to become, say, nerve or heart-muscle cellsis nearly impossible at the moment.As for deriving stem cells from cloned embryos, there is only one published example of this having been done successfully, by a group of researchers at Monash University in Melbourne, who have managed it in mice. This established the theoretical possibility that it could be done in humans as well. But extrapolating （推斷，推測(cè)）from mice to man, biologists have learned, is fraught （充滿.的）with peril（危險(xiǎn)）.Despite the remaining obstacles, most scientists believe that human cloning is now on the horizon. This prospect has provoked intense controversy. The Catholic church, other religious groups and many people concerned about the use of humans for medical experiments have condemned cloning. Many of the scientists involved in the research have countered by pointing out the huge potential gains from cloning and other new genetic techniques.The debate has tended to distinguish between two kinds of cloning. So-called “reproductive” cloning would use the technique to create a human being, much as Dolly the sheep was created. Although a few mavericks （獨(dú)行其是者；言行與眾不同者）have insisted that they will do this as soon as possible, most responsible scientists argue that reproductive cloning is still far too dangerous to be tried on humans. When done with animals, it produces many foetuses （胎兒）with abnormalities. Most die at birth.So-called “therapeutic” （治療的）cloning would use the technique to create embryos to produce stem cells, which could then be used to produce material for the treatment of diseases. In this instance, the embryos are not allowed to develop beyond a very early stage. Advanced Cell Technologies insists that it is only interested in the latter. “Our intention is not to create cloned human beings, but rather to make life-saving therapies for a wide range of human disease conditions, including diabetes, strokes, cancer, AIDS, and neurodegenerative （神經(jīng)退化）disorders such as Parkinsons and Alzheimers disease, declared Dr Lanza.Governments have struggled to navigate these conflicts, and to pass new laws to control research in this area. So far, few have managed to arrive at enough of a consensus to pass new regulations. America, where the debate has been the most strident（刺耳的, 尖銳的）, is typical. In August, Mr. Bush decided to deny the use of federal funds for any research using human embryos, and to allow it only for research on stem cells that had already been harvested from embryos which had been killed and discarded. Americas Congress has