SHEEP CLONING HITS NEW TARGET
Gene targeting has been successfully carried out in sheep, researchers announce in Nature (Vol. 405, 29 June 2000) this week. Two female lambs - Cupid and Diana - have been cloned from sheep DNA altered to contain specific changes. The technique could offer a way to introduce bespoke genetic alterations into other mammals.
Gene targeting of mice is common because mice stem cells are easy to change. Researchers can 'knock-out' individual mice genes to recreate many human disorders. But modifying the stem cells of other mammals - including sheep - is not effective.
Now, Alexander Kind and colleagues at PPL Therapeutics, Edinburgh, UK, report that gene targeting in sheep does not need stem cells. The researchers (who created Dolly the sheep) first insert a DNA sequence into a specific chromosome region of an adult sheep cell. Then they fuse these modified cells with sheep eggs from which the nucleus has been removed. Sheep grown from these eggs incorporate the targeted genetic change.
"We are clearly at the dawn of a new era in mammalian genetic technology", Milind Suraokar and Allan Bradley of the Howard Hughes Medical Institute, Houston, Texas, say in an accompanying News and Views article.
Alexander Kind tel +44 131 440 4777, fax +44 131 440 4888,
Allan Bradley tel +1 713 798 6671, fax +1 713 798 8142,
(C) Nature press release.
Nature Vol. 405, pp. 1066-1069, 29 June 2000
Message posted by: Trevor M. D'Souza