Egl promotes ooplasmic enrichment of Staufen mRNA and protein. (A–C′) Distribution of endogenous Staufen protein (A and A′; magenta), oskar mRNA (B and B′; green), and stau mRNA (C and C′; cyan) in early egg chambers (stage 4–6) expressing control RNAi (A–C) or egl RNAi driven by osk-Gal4 (A′, B′, and C′). Oocytes of egl RNAi egg chambers contain trace amounts of oskar mRNA, likely due to the action of residual Egl protein. (D) Quantification of early oocyte enrichment of stau mRNA or Staufen protein relative to the sibling nurse cells. Stage 4–6 oocytes were identified through their enrichment of oskar mRNA. Enrichment of stau RNA or Staufen protein in the somatic follicle cells, which do not express the shRNA, is used as a control. 19 control RNAi and 16 egl RNAi samples were analyzed, respectively (also indicated on the panel). (E and E′) Localization of stau mRNA in wild-type and Egl-overexpressing stage 8 oocytes. (F and G) Fraction of stau RNPs associating with Egl in the nurse cells and in the oocyte (F), and Staufen in the oocyte (G). (F) The number of analyzed stau RNPs was 4,075 (stage 5–7 nurse cells), 3,420 (stage 9 nurse cells), 1,283 (stage 5–7 oocytes), and 1,455 (stage 9 oocytes). (G) 8,597 and 4,114 stau RNPs were analyzed in nurse cells and in oocytes, respectively. Transparent bar for nurse cells indicates non-significant difference to zero (P > 0.01, one sample t test; D and F). P values of unpaired, two-sample Student’s t test are shown. Scale bars represent 10 μm.