Fig. 7. Pachytene piRNAs control spatiotemporal gene expression in the male germline.

Schematic model for regulation of spatiotemporal gene expression in the male germline by the piRNA pathway. In wild-type animals, PRG-1 is expressed most highly beginning in the TZ through the pachytene stage. This expression corresponds with essential meiotic processes such as pairing of homologous chromosomes and crossover formation. Conversely, PLK-3 is only expressed between the progenitor zone and the early TZ. In PRG-1 mutants, the loss of piRNAs leads to meiotic defects and desilencing of PLK-3 during meiotic stages. Together, our data suggest that loss of piRNA silencing such as PLK-3 during meiosis underlies observed meiotic defects.