|1996: Wilmut creates Dolly.
|On July 5, 1996, Dolly, the first
organism ever to be cloned from adult cells, was born. Ian
Wilmut and Keith Campbell, researchers at the Roslin Institute in Scotland created
Dolly using a technique similar to that with which they
created the first sheep from differentiated embryo cells in
1995, Wilmut and Campbell.
Wilmut and Campbell used the udder cells of a Finn Doset sheep in their experiment. From their 1995 cloning experiment, Wilmut and Campbell had learned that a newly fertilized egg entered a phase of suspended animation as it coordinated its newly acquired DNA from sperm with its own DNA. To simulate this state, they starved the adult udder cells until they entered a suspended state, the G0 state, as they had done in their earlier cloning experiments. Then, using an electric current, they fused each cell with an enucleated unfertilized egg. By starving the udder cells to get them to enter the same suspended state, Wilmut and Campbell synchronized the cell cycles of the two cells. This allowed the egg to take up the DNA of the transplanted adult udder cell nucleus.
Of the 277 adult udder cells that they used to perform nuclear transfers, twenty-nine grew into developing embryos, which Wilmut and Campbell let incubate in sheep oviducts for a week before transferring each to surrogate mothers, which were Scottish blackface ewes.
Of these twenty-nine embryos, one turned into a successful pregnancy, and on July 5, 1996, Dolly, the world's first mammal cloned from adult cells, was born. The February 1997 announcement of Dolly's birth absolutely shocked the scientific community, who at the time generally believed that cloning from adult cells could not be done. The discovery also triggered a massive public debate about the ethics of future cloning practices. PPL Theraputics, the principle sponsor of Wilmut and Campbell's research, obtained the patent rights on the cloning process.
Dolly photo courtesy of the Roslin Institute.
Copyright 1998 by team 24355 and Kayotic Development.