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Cloned Snuppy's genuine puppy
09/03/2006 18:29 - (SA)
Paris - Two DNA tests have backed claims by disgraced South Korean scientist Hwang Woo-Suk that he made the world's first cloned dog.
The probes are published on Thursday in Nature, the weekly British science journal, which had printed the original research last August, five months before Hwang was exposed as a fraud for his work on stem cells.
Snuppy, as the copycat canine was called, initially stirred admiration among scientists as dogs are among the trickiest of animals to clone.
But, this feeling quickly gave way to suspicion when the scandal broke.
One of the inquiries was conducted by a panel at Seoul National University, where Hwang carried out the work at the college of veterinary medicine, said Nature.
The panel had previously announced that Snuppy was believed to be a genuine clone.
Made a DNA fingerprint
This probe was then double-checked by genome specialists, led by Elaine Ostrander, at the US National Institute of Health, using samples provided by the Seoul team.
The two investigations entailed making a DNA fingerprint of Snuppy, looking notably for telltale markers on the genome called microsatellites.
They then did a microsatellite comparison between the puppy and his genetic donor, a three-year-old Afghan hound named Tai; the surrogate mother, a yellow Labrador retriever; the unidentified donor of the egg; and other pedigreed dogs.
The tests showed a perfect match between Snuppy and Tai, confirming that Snuppy was created by placing Tai's DNA in the empty donated egg, they said.
Unlikely dog was inbred
"It is highly unlikely that Snuppy came either from extreme inbreeding or from... twinning," said the Seoul panel. "It is virtually certain that he was generated from somatic-cell nuclear transfer, as claimed."
Somatic-cell nuclear transfer entails taking an egg and removing the nucleus - the DNA programme that contains the instructions for life.
This nucleus is then replaced by the nucleus of an adult cell taken from the animal to be cloned.
The reconstructed egg is then given a jolt of electricity, or treated to a chemical cocktail to make it divide.
After this, it is placed in a bath of nurturing chemicals to continue growing.
The embryo is then placed in the uterus of a surrogate mother, which, if all goes well, brings it to term.
This technique was used for the first cloned mammal, Dolly the Sheep, in 1997, and has been used on a dozen other species since then.
- AFP
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