| Abstract: | Caenorhabditis elegans spermiogenesis involves spermatid activation into spermatozoa. Activation occurs through either SPE‐8 class‐dependent or class‐independent pathways. Pronase (Pron) activates the SPE‐8 class‐dependent pathway, whereas no in vitro tools are available to stimulate the SPE‐8 class‐independent pathway. Thus, whether there is a functional relationship between these two pathways is currently unclear. In this study, we found that proteinase K (ProK) can activate the SPE‐8 class‐independent pathway. In vitro spermiogenesis assays using Pron and ProK suggested that SPE‐8 class proteins act in the hermaphrodite‐ and male‐dependent spermiogenesis pathways and that some spermatid proteins presumably working downstream of spermiogenesis pathways, including MAP kinases, are preferentially involved in the SPE‐8 class‐dependent pathway. We screened a library of chemicals, and a compound that we named DDI‐1 inhibited both Pron‐ and ProK‐induced spermiogenesis. To our surprise, several DDI‐1 analogues that are structurally similar to DDI‐1 blocked Pron, but not ProK, induced spermiogenesis. Although the mechanism by which DDI‐1 blocks spermiogenesis is yet unknown, we have begun to address this issue by selecting two DDI‐1‐resistant mutants. Collectively, our data support a model in which C. elegans male and hermaphrodite spermiogenesis each has its own distinct, parallel pathway. |
