Transcriptional analysis of early and late generation nuclear RNAi deficient animals

Germ cells deficient for Piwi and associated small RNA genome silencing factors transmit a form of heritable stress that induces sterility after growth for several generations. The cause of this transgenerational sterility phenotype is not understood but has been attributed to progressive deterioration of heterochromatin and associated DNA damage. Sterile small RNA genome silencing mutants displayed inconsistent increases in DNA damage signaling but consistently altered perinuclear germ granules. Germ granule dysfunction was sufficient to induce phenotypes associated with sterile small RNA genome silencing mutants, including germline atrophy, reproductive diapause and univalents in oocytes. Genes that perturb germ granule structure were not compromised in sterile small RNA mutants, suggesting a post-transcriptional reproductive arrest mechanism. We conclude that the integrity of germ granules, which are intimately associated with Piwi silencing factors, orchestrates the sterility of Piwi deficient mutants and could be generally relevant to regulation of reproductive arrest in response to stress. Sequencing of ribosome-depleted total RNA from wild-type, nrde-1, nrde-2 and nrde-4 L4 worms.