Born in Scotland in 1996 and the first mammal to be experimentally cloned. This was done by fusing the nucleus of an adult somatic cell from one sheep with an enucleated egg from another, followed by implantation into a surrogate mother. Dolly's chromosomes were therefore genetically identical to those of the somatic cell that provided the nucleus. When Dolly was two and a half years old, the lengths of her telomeres were determined. The lengths corresponded to telomeres the age of the nuclear donor, not to telomeres of her chronological age. It was later found that the cloned adult sheep contained mtDNA derived solely from the recipient egg. So Dolly was actually a genetic chimera (q.v.). Her cells contained nuclear DNA of somatic origin, while her mitochondria were derived from ooplasm. Dolly was euthanized in February of 2003 after developing progressive lung disease. Dolly's skin was used in a taxidermic mount currently on display at the Royal Museum of Edinburgh. See Chronology, 1997, Wilmut et al.; cloning, mitochondrial DNA (mtDNA), nuclear reprogramming, nuclear transfer, telomere.
Subjects: Genetics and Genomics.