All IOMs imaged at 4d APF. (A) Muscle-targeted RNAi screen of IOM remodeling. In primary screen of 300 selected muscle-targeted RNAi lines (see text), 77 lines exhibited eclosion or adult mobility defects; these lines were used in a secondary screen for mCD8:GFP organization by confocal imaging. Three abnormal phenotype categories were identified for 37 lines. The shared ‘small vesicle’ phenotype was found for 10 RNAi lines for five genes presented here. (B) Rab2, Rab7, Stx17, SNAP29 or Vamp7/8 RNAi resulted in IOMs filled with small, mCD8:GFP-marked vesicles. Top row, brightly-marked dorsal IOMs in whole abdomen. Bottom row, magnified image of mCD8:GFP in single IOM. (C) Schematic of IOM and regions imaged in panel D–E. (D) T-tubule (Dlg1, green) and myofibril (F-actin, pink) organization in IOMs from control and Rab2, Rab7, Stx17, SNAP29, or Vamp7/8 RNAi conditions. (E) RNAi of HOPS components, Vps39, Vps18, or Vps11, exhibited shared phenotypes of (top) many mCD8:GFP-marked small vesicles and (bottom) lack of T-tubules (Dlg1, green) and myofibrils (F-actin, pink). See Figure 3—figure supplement 1 for related data.