Figure 4.

Zili has a function in meiosis. (A) Relative expression of transposon transcripts compared with vasa transcripts in zili^L590P/− ovaries. Several LTR (GypsyDR2, LTR2, DIRS1a), non-LTR (Ngaro, L1) and DNA (Polinton, EnSpmN1) elements were tested and show no difference in zili^L590P/− ovaries compared with wild-type siblings. Error bars show average±s.d. for three replicates. (B) DAPI staining on embryos before fertilization, at 10 min post-fertilization (mpf) and 30 mpf show a meiotic arrest in zili^L590P/−. In wild-type embryos, meiosis I is completed immediately after egg-laying, and meiosis II is completed after sperm entrance (arrow indicates male pronucleus), and both polar bodies are extruded (1 asterisk is first polar body, 2 asterisk is second polar body). The male and female pronuclei fuse and form a two-cell embryo at 30 mpf. When the embryo is unfertilized, meiosis II is completed, although the DNA eventually starts breaking down. In eggs laid by zili^L590P/− females, the egg is fertilized (arrow), but meiosis I is not completed, a first polar body is not formed and the cell fails to divide. Scale bar is 25 μm. (C) After 15 mpf, the male and female pronuclei have fused and the second polar body (2 asterisk) is surrounded by tubulin. In eggs laid by zili^L590P/− females, tubulin surrounds part of the arrested female pronucleus, but no polar body is formed. Scale bar is 25 μm. (D) vasa mRNA in zili^L590P/− localizes normally to Balbiani body (asterisk), whereas vitellogenic oocytes (IV) display a peripheral position of the nucleus (arrow). Diagram shows quantification of nuclear position by ratio of the longest distance and shortest distance from the nuclear membrane to the cell membrane. Error bars are s.e.m. (t-test P<0.01).