Innovators and Innovations

INNOVATOR TIMELINE

For many years different discoveries have been made before & after sheep dolly was created. In 1952,Robert Briggs  and Thomas J. King cloned a northern leopard frogs by using a method of nuclear transfer and made nearly two decades of heavy scientific interest in cloning research. Robert Briggs saw the cloning experiment as a way to study the activation and deactivation of genetic genes during cell development. He transferred a  nucleus of a blastula cell, into a   fertilized egg.  

                                                                                                                           CLONED LEOPARD FROG

In 1977 Karl Illmensee and Peter Hoppe created mice by  using a single parent. Karl and peter grew mice with only a father as well as mice with only a mother. after the fertilization the genes of the father and mother were separated and made up of two different pronuclei in the egg cell. Karl then removed one of the pronuclei from a fertilized mouse egg then used special enzymes to duplicate the remaining pronuclei. As a result of this process the egg now carried the genes of only one of its parents. 

     Megan & Morag, two domestic sheep, were the first mammals to have been successfully cloned  from differentcells. Unlike Dolly the Sheep,who was the first animal to be successfully cloned from an adult somatic cell, or Polly the sheep who was the first  cloned and transgenic animal. The nuclear material from blastocyst cells were transferred into an unfertilized sheep egg cell  where the nucleus had been removed. To double the chances of successful nuclear transfer, they put the cultured cells into a state of quiescence. Nuclear transfer was done, using electrical stimuli both to fuse the cultured cell with the enucleated egg the nuclear transfer  was done to start the embryonic development. The production of Megan and Morag demonstrated that viable sheep can be produced by nuclear transfer from cells which have been cultured in vitro. They signified the technical breakthrough that made Dolly the sheep possible. The birth of Megan and Morag, a year before Dolly, with their huge beneficial potential, made no headlines. As of 2005, Megan was still alive and known as the oldest cloned animal at the time

http://library.thinkquest.org/20830/Frameless/Manipulating/Experimentation/Cloning/longdoc.htm