Germ cell survival in C. elegans and C. remanei is affected when the DEAD box RNA helicases VBH-1 or Cre-VBH-1 are silenced.

The Vasa family of proteins comprises several conserved DEAD box RNA helicases important for mRNA regulation whose exact function in the germline is still unknown. In Caenorhabditis elegans, there are six known members of the Vasa family, and all of them are associated with P granules. One of these proteins, VBH-1, is important for oogenesis, spermatogenesis, embryo development, and the oocyte/sperm switch in this nematode. We decided to extend our previous work in C. elegans to sibling species Caenorhabditis remanei to understand what is the function of the VBH-1 homolog in this gonochoristic species. We found that Cre-VBH-1 is present in the cytoplasm of germ cells and it remains associated with P granules throughout the life cycle of C. remanei. Several aspects between VBH-1 and Cre-VBH-1 function are conserved like their role during oogenesis, spermatogenesis, and embryonic development. However, Cre-vbh-1 silencing in C. remanei had a stronger effect on spermatogenesis and spermatid activation than in C. elegans. An unexpected finding was that silencing of vbh-1 in the C. elegans caused a decrease in germ cell apoptosis in the hermaphrodite gonad, while silencing of Cre-vbh-1 in C. remanei elicited germ cell apoptosis in the male gonad. These data suggest that VBH-1 might play a role in germ cell survival in both species albeit it appears to have an opposite role in each one.