The creator of Dolly the cloned sheep, Dr Ian Wilmut, vigorously defended his work when asked about recent scientific criticism. "It may be a touch of sour grapes," he suggested yesterday.
Dolly was cloned from an adult sheep cell, but correspondence in the journal Science two weeks ago suggested that a foetal cell may have contaminated the test, making it something other than cloning. Questions were also raised about the very low success rate - one in 277 attempts - at making a clone.
Dr Wilmut said it was "completely premature" to expect proofs so soon after his success a year ago. He was happy with the low success rate because it was successful, and tests would show that foetal cells did not contaminate the Dolly experiment.
"We are in a position to make some tests," he said, using the original source of sheep cells. Tests would be completed by his centre and independent tests using cells from the company holding the original cells. Cells would also be made available to other researchers.
He said this would take time and "in due time we will publish the results in the scientific press".