2005年1月8日CET6大学英语六级阅读理解文章

文章作者 100test 发表时间 2007:02:25 18:47:41
来源 100Test.Com百考试题网


Text 1
"Ive never met a human worth cloning," says cloning expert Mark Westhusin from the cramped confines of his lab at Texas A&.M University. "Its a stupid endeavor." Thats an interesting choice of adjective, coming from a man who has spent millions of dollars trying to clone a 13-year-old dog named Missy. So far, he and his team have not succeeded, though they have cloned two calves and expect to clone a cat soon. They just might succeed in cloning Missy later this year---or perhaps not for another five years. It seems the reproductive system of mans best friend is one of the mysteries of modern science.
Westhusins experience with cloning animals leaves him vexed by all this talk of human cloning. In three years of work on the Missyplicity project, using hundreds upon hundreds of canine eggs, the A&.M team has produced only a dozen or so embryos carrying Missys DNA. None have survived the transfer to a surrogate mother. The wastage of eggs and the many spontaneously aborted fetuses may be acceptable when youre dealing with cats or bulls, he argues, but not with humans. "Cloning is incredibly inefficient, and also dangerous," he says.
Even so, dog cloning is a commercial opportunity, with a nice research payoff. Ever since Dolly the sheep was cloned in, 1997, Westhusins phone at A&.M College of Veterinary Medicine
has been ringing busily. Cost is no obstacle for customers like Missys mysterious owner, who wishes m remain unknown to protect his privacy. Hes plopped down $3.7 million so far to fund
the research because he wants a twin to carry on Missy.s fine qualities after she dies. But he knows her clone may not have her temperament. In a statement of purpose, Missys owners and the A&.M team say they are "both looking forward to studying the ways that her clone differ from Missy."
The fate of the dog samples will depend on Westhusins work. He knows that even if he gets a dog viably pregnant, the offspring, should they survive, will face the problems shown at
birth by other cloned animals: abnormalities like immature lungs and heart and weight problems. "Why would you ever want to clone humans," Westhusin asks, "when were not even close to getting it worked out in animals yet?"



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