Optimal male fertility and fecundity in <i>Caenorhabditis elegans</i> require Microprocessor and Argonaute gene function

Small RNA pathways play key roles in the regulation of gene expression in the germ line and in somatic cells. The germ line in Caenorhabditis elegans has multiple classes of small RNAs that can interact with its 19 Argonaute family proteins, including microRNAs (miRNAs), Piwi-interacting RNAs (piRNAs) and endogenous small interfering RNAs (endo-siRNAs). The pathway for miRNA biogenesis and activity requires stepwise processing before the mature miRNA is bound to an Argonaute protein and can function in a miRNA induced silencing complex (miRISC). To understand whether the small RNA pathway responsible for producing miRNAs is required for optimal male fertility and fecundity, we analyzed male fertility, sperm production, and gonad morphology in mutants with reduced Microprocessor activity and miRNA-associated Argonaute activity. Optimal male fertility requires the Microprocessor genes, drsh-1 and pash-1, as well as multiple miRNA-associated Argonaute genes. Although mutant male sperm display normal in vitro sperm activation, multiple mutants displayed defects in the ability to generate cross progeny upon successful mating. Together, our results support a role for small RNA pathway genes in germline or somatic cells to promote optimal male fertility and fecundity.