Fly stocks

Fly stocks were maintained on cornmeal/agar/yeast food at 21°C, except where noted. Before immunofluorescence staining, newly eclosed flies were fed wet yeast paste every day for 2–4 days. Unless specified, yw (BDSC 1495) was used as the control. The following stocks were obtained from the Bloomington Drosophila Stock Center: c355 GAL4 (BDSC 3750), c306 GAL4 (BDSC 3743), mgst1^KG04713 (BDSC 13839), Su(P)^EY13245 (BDSC 20866), p23^EY05607(BDSC 16661), akr1B^PL00034 (BDSC 19594), akr1B^EY07011 (BDSC 16777), p23 RNAi HMJ24151 (BDSC 62911), p23 RNAi-2 GL01292 (BDSC 41862), akr1B RNAi HMS05657 (BDSC 67838), akr1B RNAi-2 HMC05226 (BDSC 62219) and UAS Dicer 2 (BDSC 24651). The following stocks were obtained from the Exelexis Stock Center: mgst1^d10243, akr1B^d00405 and pxt^f01000 (^{Thibault et al., 2004}). The oskar GAL4 line (second chromosome; BDSC 44241) was a generous gift from Anne Ephrussi (European Molecular Biology Laboratory; (^{Telley et al., 2012})). Expression of the RNAi lines were achieved by crossing to c355 GAL4 or oskar GAL4, maintaining fly crosses at 21°C and maintaining progeny at 29°C for 5–6 days. UAS Dicer was used in combination with c355 to enhance RNAi efficiency were noted in the figure legends.