Date: December 9, 2016
Source: University of California, Davis
It has been 20 years since Dolly the sheep was successfully cloned in Scotland, but cloning mammals remains a challenge. A new study by researchers from the U.S. and France of gene expression in developing clones now shows why most cloned embryos likely fail.
Dolly was cloned using the technique of "somatic cell nuclear transfer," when a nucleus from an adult cell is transferred into unfertilized egg that has had its nucleus removed, and is then shocked with electricity to start cell growth. Embryos are then transferred to recipient mothers who carry the clones to birth.
Cloning cattle is an agriculturally important technology and can be used to study mammalian development, but the success rate remains low, with typically fewer than 10 percent of the cloned animals surviving to birth. The majority of losses are due to embryonic death, a failure during the implantation process, or the development of a defective placenta.