The decision to end the life of 6-year-old Dolly was made after a
veterinary examination confirmed the lung disease, a statement from
the Roslin Institute said.
Researchers had previously cloned sheep from fetal and embryonic
cells, but until Dolly it was unknown whether an adult cell could
reprogram itself to develop into a new being.
The death of the famous clone was sure to raise the debate over
whether animal cloneding from adults inevitably produces flawed
copies.
There are now hundreds of animal clones around the world,
including cows, pigs, mice and goats, many of them appearing robust
and healthy.
But many attempts to clone animals have ended in failure.
Deformed fetuses have died in the womb with oversized organs, while
others were born dead. Still others died days after birth, some
twice as large as they should have been.
Dr. Harry Griffin of the institute said Friday that sheep can
live to 11 or 12 years and lung infections are common in older
sheep, particularly those like her which are kept indoors.
"A full post-mortem is being conducted and we will report any
significant findings," Griffin said.
Dolly was born July 5, 1996 in a research compound of the
Scottish institute, and she created an international sensation when
the achievement was announced on Feb. 23, 1997.
Researchers had previously cloned sheep from fetal and embryonic
cells, but until Dolly it was unknown whether an adult cell could
reprogram itself to develop into a new being.
The Dolly breakthrough heightened speculation that human cloning
inevitably would become possible.
Dolly, a Finn Dorset sheep named after the singer Dolly Parton,
bred normally on two occasions with a Welsh mountain ram called
David, first giving birth to Bonnie in April 1998 and then to three
more lambs in 1999.
In 1999, scientists noticed that the cells in Dolly's body —
cloned from a 6-year-old sheep — had started to show signs of wear
more typical of an older animal.
Then in Jan. 2002, her creators announced she had developed
arthritis at the relatively early age of 5 1/2 years, stirring
debate over whether cloning procedures might be flawed.
Some geneticists said the finding provided evidence that
researchers could not manufacture copies of animals without the
original genetic blueprint eventually wearing out.
Dolly's body has been promised to the National Museum of Scotland
and will eventually be put on display in Edinburgh, the Roslin
Institute said.
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On the Net:
Roslin Institute, http://rd.yahoo.com/dailynews/ap/ap_on_sc/inlinks/*http://www.roslin.ac.uk/news/