sina^A4 homozygous and sina^A4/Df(3L)sina^SH transheterozygous females have meiotic defects, as shown by frequent X-chromosome and 4[[th]]-chromosome non-disjunction, which is associated with a severe decrease in X-chromosome crossover/recombination, but not with defects in double strand DNA break formation and repair during oogenesis. In agreement, prometaphase I/metaphase I oocytes show recombination-defective chromosome configurations (i.e. not aligned at the metaphase plate) that are not observed in controls.

sina^A4/Df(3L)sina^SH transheterozygotes exhibit defects in synaptonemal complex assembly during oogenesis: the complex assembles with relatively normal timing, exhibiting tracks in multiple nuclei in early pachytene (region 2A) o the germarium; as the cysts progress, however, the synaptonemal complex loses its curved, track-like pattern and instead its components form narrow rod-like polycomplexes; at early/mid-pachytene (germarium region 2B) the polycomplexes remain in a subset of nuclei that would have normally disassembled their synaptonemal complex to become nurse cells, but the oocyte is correctly specified, as cysts exhibit a single Orb-positive nucleus; polycomplexes persist in nurse cells during mid-prophase (stages 2-9), as well as in the oocyte during late prophase (stages 10-12) and pro-metaphase I/metaphase I (stage 13); while centrosomes can associate with polycomplexes, they fail to cluster into 1 or 2 foci; the polycomplexes that persisted into later stages in both the pro-oocyte and nurse cells frequently are associated with centromeres; small polycomplexes are also observed in the premeiotic region 1, where only foci of synaptonemal complex components are observed in wild type controls.

sina^A4 homozygotes exhibit defects in synaptonemal complex assembly during oogenesis: the complex assembles with relatively normal timing, exhibiting tracks in multiple nuclei in early pachytene (region 2A) o the germarium; as the cysts progress, however, the synaptonemal complex loses its curved, track-like pattern and instead its components form narrow rod-like polycomplexes; at early/mid-pachytene (germarium region 2B) the polycomplexes remain in a subset of nuclei that would have normally disassembled their synaptonemal complex to become nurse cells; however, the oocyte is correctly specified, as cysts exhibit a single Orb-positive nucleus. While centrosomes can associate with polycomplexes, they fail to cluster into 1 or 2 foci.

sina³/sina^A4 transheterozygotes also exhibit frequent X-chromosome and 4[[th]]-chromosome non-disjunction, as well as defects in synaptonemal complex assembly during oogenesis, with components forming abnormal polycomplexes, which remain in both oocytes and nurse cells by stage 2.

Df(3L)sina^SH/sina^A4, Scer\GAL4^{VP16.nanos.UTR}, Usp7^RNAi.UAS.II has abnormal meiotic cell cycle | oogenesis phenotype

Df(3L)sina^SH/sina^A4, Scer\GAL4^{VP16.nanos.UTR}, Usp7^RNAi.UAS.II has synaptonemal complex | oogenesis phenotype