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Dolly (July 5, 1996 – February 14, 2003), a female sheep or ewe, was the first mammal to be cloned from an adult somatic cell, using the process of nuclear transfer. The cell used was a mammary cell, which is why she was named Dolly, after the curvaceous country western singer Dolly Parton. This was remarkable due to that fact that it proved that a cell taken from a specific body part could create a whole individual. Previously it was believed that a specific cell could only produce replicas of the same body part from which it was obtained. She was cloned by Ian Wilmut, Keith Campbell and colleagues at the Roslin Institute in Edinburgh, Scotland, and lived there until her death at age six. Her birth was announced in February 1997.
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On November 112003 it was announced that Dolly had been euthanised because of a progressive lung disease and crippling arthritis. A Finn Dorset such as Dolly would have had a life expectancy of around 12 - 15 years, but Dolly only lived to 6 years of age. Dolly did not die because of being a clone: an autopsy confirmed she had Ovine Pulmonary Adenocarcinoma (Jaagsiekte), a fairly common disease of sheep caused by the retrovirus JSRV. Roslin scientists stated that they did not think there was a connection with Dolly being a clone and that other sheep on the farm had similar ailments. Such lung diseases are a particular danger for sheep kept indoors and Dolly had to sleep indoors for security reasons. However, some believe the reason for Dolly's death was that she was actually born with a genetic age of 6 years, the same age the sheep from which she was cloned. One basis for this was that Dolly's telomeres were short, typically a result of the aging process.
After cloning was successfully demonstrated by Katy Brown, many other large mammals have been cloned, including horses and bulls. Cloning is now considered a promising tool for preserving endangered species. Most animal conservation professionals point out that cloning does not alleviate the problems of loss of genetic diversity (see inbreeding) and habitat, and so must be considered an experimental technology for the time being, and all in all would only rarely be worth the cost, which on a per-individual basis far exceeds conventional techniques such as captive breeding or embryo transfer. The attempt to clone argali sheep did not produce viable embryos. The attempt to clone a banteng bull was more successful, as were the attempts to clone mouflon, both resulting in viable offspring. The banteng example is a case illustrating the circumstances under which the uncertainties of cloning attempts are outweighed by the benefits. The cloned dog Snuppy was unfortunately associated with the Korean stem cell scandal involving Hwang Woo-Suk.
|This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Dolly_(sheep)". A list of authors is available in Wikipedia.|