A C. elegans male pheromone feminizes germline gene expression in hermaphrodites and imposes life-history costs.

Sex pheromones improve reproductive success of the recipients, but also impose costs, such as reduced lifespan. The underlying mechanisms largely remain to be elucidated. Here we show that even brief exposure to physiological amounts of the dominant C. elegans male pheromone, ascr#10, alters the expression of thousands of genes in hermaphrodites. The most dramatic effect on the transcriptome is the upregulation of genes expressed during oogenesis and downregulation of genes associated with male gametogenesis. This result reveals a way in which social signals help to resolve the inherent conflict between spermatogenesis and oogenesis in a simultaneous hermaphrodite, presumably to optimally align reproductive function to the presence of potential mating partners. We also found that exposure to ascr#10 increased the risk of persistent intestinal infections in hermaphrodites due to pathological pharyngeal hypertrophy. Thus, our study reveals ways in which the male pheromone can have beneficial effects on the recipients' reproduction, but also cause harmful consequences that reduce lifespan.