mutation enhances and embryonic lethality in .

In mice, mutation of results in embryonic lethality, which is partially suppressed by mutation. In contrast, mutation of the BRCA1 ortholog, or its binding partner, , lead to only mild embryonic lethality. We show that in , and embryonic lethality is enhanced when ortholog, , is also mutated. This is not a consequence of activating -dependent microhomology-mediated end joining, as mutation does not suppress embryonic lethality of mutants. Together, these results suggest that BRC-1 - BRD-1 and HSR-9 function in parallel pathways and do not act antagonistically as in mammals.