Why clone flies? Using Cloned Drosophila to Monitor Epigenetic Defects

The birth of Dolly the sheep in 1996 transformed nuclear transplantation from an arcane technique to a technology at the core of medical biotechnology. Transplantation of nuclei allows the generation of new individuals and is being exploited to create genetically tailored stem cells for replacement tissues and organs. The list of cloned animals reared to adulthood currently includes the frog, sheep, mouse, cow, goat, pig, rabbit, cat, zebrafish, mule, horse, rat and dog. The addition of Drosophila to this elite bestiary of cloned animals has prompted the question – why clone flies? Organisms generated by nuclear transplantation suffer from a high rate of associated defects. This review summarizes recent literature that demonstrates that the majority of these defects, in both mammals and flies, arise from mis-regulation of imprinted genes. The regulation of imprinted genes relies on a suite of highly conserved chromatin-modifying genes, first identified in Drosophila. Thus, Drosophila can be used to rapidly assess epigenetic dysfunction in cloned animals and could be used to screen for genes that allow the production of healthy clones.