Dolly the cloned sheep has died. The news was confirmed on Friday by the Roslin Institute, the Scottish research centre which created her.
A decision was taken to â€˜euthanaseâ€™ six-year-old Dolly after a veterinary examination showed that she had a progressive lung disease, the institute said in a statement.
Dolly became the first mammal successfully cloned from an adult cell when she was born on July 5, 1996. She was revealed to the public the following year.
Dr Harry Griffin, from the institute, said: â€œSheep can live to 11 or 12 years of age and lung infections are common in older sheep, particularly those housed indoors. A full post-mortem is being conducted and we will report any significant findings.â€
Dollyâ€™s birth was only announced seven months later and was heralded as one of the most significant scientific breakthroughs of the decade. It also prompted a long-running argument over the ethics of cloning, reaching further levels with the latest allegations of human cloning.
Dolly, a Finn Dorset, bred normally on two occasions with a Welsh mountain ram called David. She first gave birth to Bonnie in April 1998 and then to three more lambs in 1999.
But in January last year her condition caused concern when she was diagnosed with a form of arthritis. The condition would usually be expected in older animals and another debate erupted over what could properly be judged as Dolly's true age, and the risks of premature ageing in clones.
Professor Ian Wilmut, who led the team that created Dolly, said at the time that the arthritis showed their cloning techniques were â€œinefficientâ€ and needed more work. Dr. Patrick Dixon, a writer on the ethics of human cloning, said the nature of Dollyâ€™s death would have a huge impact on the possibility of producing a cloned human baby. He said: â€œThe real issue is what Dolly died from, and whether it was linked to premature ageing,â€ he said. â€œShe was not old â€” by sheep standards â€” to have been put down.â€
Speaking to BBC News 24 on Friday, Prof. Wilmut said Dollyâ€™s birth should be the important issue: â€œThe fact that we were able to produce an animal from the cell of another adult â€” it had profound effects on biological research and in medicine.â€
Professor Richard Gardner, chair of the Royal Society working group on stem cell research and therapeutic cloning, said: â€œWe must await the results of the post-mortem on Dolly in order to assess whether her relatively premature death was in any way connected with the fact that she was a clone.
â€œIf there is a link, it will provide further evidence of the dangers inherent in reproductive cloning and the irresponsibility of anybody who is trying to extend such work to humans.â€
Dolly has been promised to the National Museum of Scotland and will be put on display in Edinburgh in due course.
Cloned sheep Dolly, dies prematurely