research: animal cloning and genetic 'memory'

31 January 2005

Cloning animals by transplanting adult cell nuclei into eggs may be more difficult than expected, suggests research by Ray Kit Ng and Sir John Gurdon. The genes of the transplanted nuclei should, in theory, revert back to an embryonic expression pattern. But the latest research finds that some genes maintain a 'memory' of their origins.

The researchers, at the Wellcome Trust/Cancer Research UK Gurdon Institute of Cancer and Developmental Biology in Cambridge, transplanted frog nuclei into eggs that had had their nuclei removed. As they developed into embryos, some were found to be showing abnormal gene activity. Genes were active that are not normally turned on in an embryo, but had been active in the adult cells that had donated nuclei for transfer.

The genes in the transplanted nuclei thus seem to remember their original life, and this memory persists through early embryonic development. The researchers hope to identify the basis of this persistent memory, and by reversing it increase the success of nuclear reprogramming and, ultimately, of therapeutic cloning by cell replacement.

External links

• Epigenetic memory of active gene transcription is inherited through somatic nuclear transfer (Research paper, Ng RK and Gurdon JB)