mRNAs that co-purify with OMA-1 in the C. elegans germline (sequencing)

The oocytes of most animals arrest at diplotene or diakinesis, but resume meiosis (meiotic maturation) in response to hormones. In C. elegans, maturation of the –1 oocyte requires the presence of sperm, Gas-adenylate cyclase-PKA signaling in the gonadal sheath cells, and germline function of two Tis11-like CCCH zinc-finger proteins, OMA-1 and OMA-2 (OMA proteins). Prior studies indicate that the OMA proteins redundantly repress the translation of specific mRNAs in oocytes (zif-1, mom-2, nos-2, glp-1) and early embryos (mei-1). We purified OMA-1-containing ribonucleoprotein particles (RNPs) and identified mRNAs that associate with OMA-1 in oocytes using microarrays. We examined the relative abundances of mRNAs in OMA-1 RNPs using high-throughput RNA sequencing. Previously identified targets of OMA-dependent translational repression in oocytes were found to be both enriched (>2-fold relative to input RNA) and abundant in purified OMA-1 RNPs. Furthermore, we verified that some of the newly identified mRNAs that share these characteristics are translationally repressed by OMA-1/2 in oocytes through sequences in their 3’UTRs. Although meiotic maturation is stimulated by sperm, we found that the mRNAs copurifying with OMA-1 are not significantly different in the presence and absence of sperm, suggesting that sperm-dependent signaling does not modify the suite of mRNAs stably associated with OMA-1. Further, several tested OMA-1-associated mRNAs were shown to be translationally repressed in both the presence and absence of sperm. C. elegans mRNAs that co-purify with OMA-1 were identified by deep-sequencing using the Illumina HiSeq 2000