PPL Therapeutics Ltd of Roslin, Edinburgh, showed today how they succeeded a year ago (the delay was to secure a patent) in targeting a gene to a chosen location in embryonic sheep fibroblasts. Then they transferred the nucleus to stem cells and created whole transformed, gene-targeted sheep (
We have succeeded in cloning sheep, goats, cows, pigs and mice, and now we have gene targeting in sheep. But it is proving difficult to clone whole animals efficiently, as the science involved is obscure (see