3D-05 Involvement of Drosophila Mus3Ol/DmHEL3O8 helicase in meiotic recombination and somatic double-strand break repair

We have analyzed the functions of Drosophila mus301/dmhel308 gene, which encodes a Drosophila homolog of human HEL308 DNA/RNA helicase. An allele mus301D4 had the nonsense mutation at the boundary of the helicase domain and the C-terminal domain. This mutant showed female sterility and strong sensitivity to bleomycin, a typical double-strand break (DSB) inducer; these phenotypes were complemented by the dmhel308 transgenes. We also found that mus301D4 oocyte nuclei displayed the abnormal karyosome-morphology and the accumulation of DSBs. These oogenesis defects were suppressed by adding the mei-W68 null mutation, which inhibits meiotic DSB formation. These results demonstrate that Mus301 helicase functions in mitotic and meiotic DSB repair.