Dolly (sheep)
Dolly was born on 5 July 1996 and had three mothers: one provided the egg, another the DNA, and a third carried the cloned embryo to term. She was created using the technique of somatic cell nuclear transfer, where the cell nucleus from an adult cell is transferred into an unfertilized oocyte (developing egg cell) that has had its cell nucleus removed. The hybrid cell is then stimulated to divide by an electric shock, and when it develops into a blastocyst it is implanted in a surrogate mother. Dolly was the first clone produced from a cell taken from an adult mammal. The production of Dolly showed that genes in the nucleus of such a mature differentiated somatic cell are still capable of reverting to an embryonic totipotent state, creating a cell that can then go on to develop into any part of an animal. Dolly's existence was announced to the public on 22 February 1997. It gained much attention in the media. A commercial with Scottish scientists playing with sheep was aired on TV, and a special report in "Time" magazine featured Dolly the sheep. "Science" featured Dolly as the breakthrough of the year. Even though Dolly was not the first animal cloned, she received media attention because she was the first cloned from an adult cell.
In Re Roslin Institute (Edinburgh)
Dolly was cloned in 1996 by Ian Wilmut, Keith Campbell and colleagues at the Roslin Institute, part of the University of Edinburgh Scotland. BBC News and Scientific American called Dolly "the world's most famous sheep," The cloning method Campbell and Wilmut used to create Dolly constituted a breakthrough in scientific discovery. Known as somatic cell nuclear transfer, this process involves removing the nucleus of a regular body cell and implanting that nucleus into an egg cell that has had its cell nucleus removed. A nucleus is the organelle that holds a cell's genetic material (its DNA). Campbell and Wilmut found that if the donor, somatic cell is arrested in the stage of the cell cycle where it is dormant and non-replicating (the quiescent phase) prior to nuclear transfer, the resulting fused cell will develop into an embryo. The resulting cloned animal is an exact genetic replica of the adult mammal from which the somatic cell nucleus was taken.