EXTRACTO DEL ARTICULO DE SCIENTIFIC AMERICAN DEL MES DE COTUBRE 2016
By Karen Weintraub
Credit: UNIVERSITY OF NOTTINGHAM
The birth of Dolly the sheep 20 years ago proved that DNA from an adult cell of a mammal could be transferred to an unfertilized egg and give rise to an animal genetically identical to the donor. Yet Dolly died prematurely, which left the impression that cloned animals have shorter life spans.
To figure out if clones are inherently less healthy than their “natural” counterparts, University of Nottingham developmental biologist Kevin Sinclair followed four of Dolly’s clones—Debbie, Denise, Dianna and Daisy (above)—from birth through middle age. All four were derived from the same batch of frozen mammary gland cells as Dolly was. Sinclair and his colleagues also monitored nine cloned sheep of other breeds. The 13 ruminants are now more than nine years old—the equivalent of a human’s seventh or eighth decade—and all are as healthy as regular sheep, according to scans of their bones, blood glucose readings and detailed blood pressure monitoring. “We can say these [clones] are perfectly normal,” Sinclair says. The results were published in Nature Communications.