Dolly at 20
Twenty years ago today on February 22, 1997, Ian Wilmut, Keith Campbell and colleagues at the Roslin Institute, announced the existence of a 7 month old sheep named Dolly, the product of cloning. She was cloned using and adult cell and born on July, 5, 1996 and raised under the auspices of the UK Ministry of Agriculture and Scottish company PPL Therapeutics. A Dorset Finn sheep, Dolly lived for six and half years before she was euthanized due to illness. Dolly was created with a process called somatic cell nuclear transfer, in which a donor cell (in this case and adult cell from another sheep) has the nucleus removed that is then transfered into an unfertilized egg cell (an oocyte) which in turn has had its cell nucleus removed to make way for the donor nucleus. The host cell is then stimulated and implanted into a host sheep for gestation. Although other animals had been cloned before Dolly, Dolly is celebrated as the first ‘clone’ because her donor cell came from an adult cell.
The word clone entered English as a noun used in botany in 1903 from the Ancient Greek word klon (κλον) meaning a twig or spray, related to klados (κλαδος) meaning a sprout, young offshoot, branch. Botanists used the word to describe the results of the techique of grafting a shoot of one plant or tree onto another. The word clone (verb) wasn’t used until 1959, and it wasn’t until the 1970s that clone was used in connnection with animals and humans. Since Dolly, scientists have successfully cloned many other animals, including pigs, horses, goats, and deer.
Image of ‘v’ graft courtesy ghadjikyriacou, via flickr, used with permission under a Creative Commons 3.0 license.