Fig. 3.

Effect of tango1 and dpy knockdown on Crb and the ER stress response. (A–D) Terminal cells expressing mCD8mCherry (A–D) and Xbp1-GFP (A″–D″) under SRF-gal4. Xbp-1-GFP is translated and accumulated in the nucleus only after activation of the ER-stress response. (A′–D′) In control (A′ and A″) and dpy-IR cells (C′ and C″), Crb localizes to the luminal membrane and Xbp1-GFP is not detectable. In tango1-IR cells (B′ and B″), Crb does not reach the membrane and Xbp1-GFP accumulates in the nucleus. These defects can be suppressed by additionally knocking down dpy (D′ and D″). (E–G) Terminal cells expressing GFP and the ER stress response target Xbp1 under SRF-gal4. (E and E′) Bright field (BF) imaging shows lack of air in the tracheal branches. (F) Quantification of number of branches in tracheal cells expressing Xbp1 under SRF-gal4. Bars represent mean ± SD. Control, n = 5, SRF > Xbp1^spliced, n = 8. Significance was assessed using Student’s t test. (G) Terminal cells expressing Xbp1^spliced where stained against βInt and Crb. Arrowheads point to the normal distribution of both proteins. (Scale bars: A–D and G, 10 μm; E, 40 μm.)