Dolly the sheep

Dolly (5 July 1996 – 14 February 2003), a ewe, was the first mammal to have been successfully cloned from an adult cell. She was cloned at the Roslin Institute in Scotland and lived there until her death at the age of six. Scientists announced her birth on 22 February 1997.

Controversy

In 1999 research was published in the journal Nature suggesting that Dolly may have been susceptible to premature aging http://news.bbc.co.uk/1/hi/sci/tech/353617.stm, due to shortened telomeres in her cells. It was speculated that these may have been passed on from her parent, who was six years old when the genetic material was taken from her, so that Dolly may have been genetically six years old at birth. However, Dr. John Thomas indicated that most cloned animals actually have telomeres of normal length and in serial clones the telomeres are actually getting longer in each successive generation.

Related Topics:
Nature - Premature aging - Telomere - Serial clones

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Possible signs of this were reported in January 2002, when Dolly was five years old. She had developed a potentially debilitating form of arthritis at an unusually early age. This supported the theory of premature senescence, although Dr Dai Grove-White of the Faculty of Veterinary Science at Liverpool University was reported as saying, "Conceivably arthritis could be due to the cloning but equally it could not be. For all we know, she may have damaged her leg jumping over a gate and developed arthritis."

Related Topics:
Arthritis - Senescence - Liverpool University

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The arthritis further fueled worry among some that this form of cloning may not be appropriate for mammals, and there is now a consensus both within and outside the scientific community that at this point the risk of unforeseen effects of cloning on the clone makes experiments in human reproductive cloning premature and unethical.

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Supporters of this method of cloning counter that the technique used to clone Dolly simply needs to be refined. However, others contend that with very limited understanding of the nascent field of applied genetics, scientists cannot, and should not, attempt to control the action of so many genes at once. Many outside of the scientific community have stated that this is vindication for their initial assertions that any form of cloning is ethically wrong and should be banned.

Related Topics:
Applied genetics - Genes

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