Confocal and SRRF imaging of exocytic events in the Drosophila SG. Time-lapse video of representative exocytic membrane crumpling events in WT SGs (confocal, top; SRRF, bottom; corresponds to Fig. 1 B). Fusion onset is detected by LSV swelling (Fig. S1 A). LifeAct-Ruby (actomyosin) recruitment is first visible ∼50 s after fusion and followed by content release. Fusion pore diameter was defined and measured at the narrowest aperture observed at the mid-plane through the vesicle, which connects the vesicle and the lumen. The fusion pore expands before actomyosin recruitment and constricts during content release. Time mm:ss, relative to fusion seen in the second frames. Video frames were taken every 16 s for the confocal imaging and every 10 s for the SRRF imaging. LifeAct-Ruby (magenta; left column; expression driven by c135-GAL4) and Glue-GFP (green; middle column; endogenous promoter). The merged image of both imaging channels is presented in the right column. Scale bars = 1 µm.
