CLONING SPECIAL REPORT + + + + + + + + + + + + + + + + + + + + + + + + Dolly's mixture Clones are not the perfect replicas we thought.By Philip Cohen Dolly the sheep does not have precisely the same genetic make-up as the adult sheep from which she was cloned. A study shows that the genes in her mitochondria--the powerhouses of cells--came from another sheep involved in the experiment. The result leaves scientists wondering: exactly how similar are Dolly and her genetic twin? In a cloning technique called nuclear …showed first 75 words of 517 total…

…showed last 75 words of 517 total…news for another application of nuclear transfer technology. Some researchers hoped to use the technique to create human tissue for transplants by fusing cells from people with cow eggs and harvesting stem cells from the resulting embryonic clone (New Scientist, 11 July 1998, p 4). But if only cow mitochondria remain, there may be unforeseen problems. "This confirms what has always been a worry," says Steven Stice of the University of Georgia in Athens. From New Scientist, 4 September 1999