Fig. 7

Fig. 7 mTorc1 activation in oogenesis uniquely requires Mios.

a Sex ratio graph for 60 dpf+ mios; tsc2^vu242 double heterozygous, mutant wildtype, and mutant heterozygous fish. Pink represents female fish and blue indicates male fish. Number of fish screened are indicated for each group. Statistical significance was evaluated by performing a two-tailed χ² test with Bonferroni correction against the mios^+/-; tsc2^+vu242 control group. P = 0.0125. bRheb^ca transgene: the rat Rheb^ca expression is driven by the germline ziwi promoter and the heart specific promoter cmlc2 drives mCherry expression as a selectable marker. Sex ratios are presented for 60 dpf+ fish with the ms44, ms46, and ms47 Rheb^ca alleles. Pink represents female and blue represents males; number of fish screened are indicated for each group. Statistical significance was evaluated by performing the two-tailed χ² test with Bonferroni correction against the +/- transgenic control group. P = 0.0125. Source data are provided as a Source Data file. c In mitotic and early meiotic cells, Rbpms2 functions to repress translation of rboRNAs related to testis fates and promotes translation of rboRNAs related to mechanisms supporting oogenesis like ribosomal factors. Correspondingly, Rbpms2 functions upstream of nucleoli amplification and nucleolar localization of RNA pol I, which is required for rRNA transcription. In addition, Rbpms2 promotes translation of Mios. After sufficient nucleolar amplification, Gator2 and Mios activity increase mTorc1 signaling, and the nucleoli of differentiating oocytes expand and mature to support high levels of rRNA synthesis. As nucleoli grow, they develop an additional compartment that supports pre-ribosome biogenesis. Finally, as the cell progresses to diplotene, ribosomal abundance is measured. If sufficient ribosomes are present the cells continue through oogenesis. If a sufficient ribosome pool is not attained, then the gonocytes abort oogenesis and switch to spermatogenesis. We anticipate this pathway operates in oocytes independent of sex determination systems utilized as Mios is required for oocyte maturation in invertebrate and vertebrate organisms that use sex chromosome based or multigenic sex determination mechanisms.