Fig. 3: JAK-STAT activity in PACs maintains a tight contact with the oocyte and defines the size of oskar mRNA anchoring zone in the oocyte.

Posterior is to the right. Stage 10a follicles stained for F-Actin (gray, phalloidin), DNA (cyan, DAPI) and Staufen (fire filter) are shown. PACs (pink dotted rectangles) and adjacent PFCs (white dotted rectangles) are magnified. Yellow, orange, green and red stars indicate PCs, PC + 1, +2 and +3 rows respectively. Arrowheads indicate the anchoring zone boundary on oocyte (pink) and FC (white) sides. “Tight” and “Spaced” refer to the perivitelline space. In (A”,E), white arrows point to the limit of the increased region of tight oocyte-PFC contact. A,A’,A” Control follicle, and follicles expressing upd-RNAi in PCs under the control of upd-Gal4 or hop^TUM in PFCs under the control of E4-Gal4. In (A’), “Partial” Staufen localization phenotype (smaller anchoring zone and detection in the oocyte cytoplasm, pink arrow) is shown. See Supplementary Fig. 5 for other phenotypes and quantifications. B Scheme of how the perivitelline space was measured and (B’) graph presenting these measurements made on control follicles (fruitless-Gal4/+). Data are presented as mean values ± SD. Gray stars indicate statistically significant differences between zones 1 and 2 (in red) of the corresponding stages. C,C’,D Measurements of the perivitelline space in control, upd>upd-RNAi and E4>hop^TUM follicles. Data are presented as mean values ± SD. E E4>hop^TUM follicle expressing 10XSTAT92E-GFP. The white star highlights the wider perivitelline space in front of a JAK-STAT inactive FC in between active FCs. F Scheme representing the correlation between the oskar mRNA anchoring zone and JAK-STAT activity in section and pole views. Oo: oocyte. St: stage. Scale: 30 µm except magnifications 15 µm. Statistical tests: two-sided unpaired t test. Information about statistics and reproducibility is provided in Supplementary Tables 8–13. Source data are provided as a Source Data file.