Washington, Feb. 15 (Reuters): She may not have been exactly one of a kind but Dolly the sheep, the first cloned adult mammal, was definitely unique.
Dolly, aged 6, was put to sleep by veterinarians yestreday after they failed to cure her of a severe lung infection, her creators said.
Dolly’s birth in July 1996 was kept secret for months while her creators at the Roslin Institute and PPL Therapeutics Plc., a tiny biotech company in Edinburgh, Scotland, carefully checked her lineage. The announcement of her birth, in February 1997, sent shockwaves around the world.
Now cloning of farm animals has become almost routine and headlines were made this week when the offspring of some cloned pigs made it to market. Cloned animals are being bred to produce human proteins for medicine, and for meat.
But no one would have dreamed of slaughtering Dolly, or any of her lambs.
Dolly was a breed called a Finn Dorset, with a white face and cream-coloured curly wool. Hand-fed from birth, she was friendly even after she outgrew the curious lamb stage.
In contrast to her hardy cousins, put out to graze on steep hillsides in Scotland, Dolly lived indoors. She reared up on her hind legs to nuzzle visitors, looking for handouts.
Some scientists believe this behaviour, and not her lab-dish origins, led to Dolly’s well-documented arthritis. “There is a very real chance Dolly’s illness had nothing to do with cloning,” said Dr Robert Lanza of Advanced Cell Technology in Massachusetts, a private firm doing cloning research.
“There is a virus ... that sheep get at almost precisely Dolly’s age. This virus can cause arthritis and respiratory infections, particularly in animals raised indoors,” he said in a telephone interview.
Dolly’s creator, Ian Wilmut, said her body would be carefully autopsied to determine the cause of death.
“Obviously it is very sad news. We were all hoping Dolly would live to a ripe old age,” said Lanza. “She’s a symbol of all the research that we are doing.”
For Lanza her death illustrated why most scientists oppose cloning a human baby. “Dolly’s death confirms what we all know — which is that there are problems with cloning,” he said. “Cloning is still just as much an art as a science.”
Shares in California-based Geron , which bought the rights to the technology that created Dolly, fell 16 per cent on the news but later rebounded.
Dolly’s mother/twin died years before Dolly was born. She was made from a frozen cell taken from the mammary gland of the anonymous ewe and Wilmut said he named her after Dolly Parton, the American singer famous for her own mammaries.
While Dolly is best known for being an almost precise copy, she was unique in her birth. Wilmut’s team tried to clone 276 sheep embryos in an experiment that resulted in just one lamb — Dolly. Mike Bishop, former president of the privately owned firm Infigen Inc., which also clones farm animals, said Dolly’s death was clearly premature. “We’ve got ewes here that are eight, nine years old,” Bishop said from a farm in Wisconsin.
“We are in the middle of lambing now in the frigid Midwest and we have ewes that are eight, nine years old that are lambing.”