Gene conversion in mitotically dividing cells: a view from Drosophila

It was about 25 years ago that Hiraizumi noticed that the males of some strains of flies transmitted recombinant progeny [1]. This was in apparent contrast to Morgan's 1914 observation that recombination was absent in the Drosophila melanogaster male [2]. Were the rules of recombination changing in Drosophila, or was there an external agent at work? Kidwell et al. linked the male recombination phenomenon to a syndrome of other traits including sterility, chromosome rearrangements and mutations [3]. Investigation of mutations caused by this syndrome led to the identification of the P family of transposable elements, but it was not clear how P elements related to male recombination [4]. Two groups led by Sved and Engels recently solved this enigma [5–7]and, as so often happens in science, the answer to one problem gives insights into seemingly unrelated areas. The work initiated by Hiraizumi is providing a new understanding of how somatic genomes might maintain their integrity.