Joining the dots

Therapeutic cloning could provide perfectly matched tissues and cells for use in the treatment of a wide range of diseases such as Parkinson's disease, and for the repair of damaged tissues, such as skin grafts to treat severe burns. In addition, constructing embryos from genetically-manipulated nuclei offers the potential for the production of therapeutic agents. However, the process of nuclear transfer to produce cell lines and clones is highly inefficient and the outcome is unpredictable. In the July 1 Current Biology, Fatima Santos and colleagues at the Babraham Institute demonstrate that embryos constructed by the transfer of nuclei from two different cell sources possess nuclei with different epigenotypes that result in different success rates in cloning, and that each of these parameters in the cloned embryos is different from those in the normally fertilized embryo (Current Biology 13:1116-1121, July 1, 2003).

Santos et al. visualized the methylation status of individual ...