Depletion of PI(3)P at Dscam2 mutant motor neuron terminals. (A–D’) Representative images of Ib and Is axon terminals from control (OK6-GAL4/UAS-2xFYVE-myc-GFP; +) and Dscam2^null (OK6-GAL4/UAS-2xFYVE-myc-GFP; Dscam2^null/Dscam2^null) labeled with HRP (magenta) and anti-GFP (green, A’–D’) to visualize the early endosome marker (2xFYVE-GFP) under resting conditions (A–B’) and following stimulation with 90 mM KCl (C–D’). Scale bars, 5 µm. (E and E’) Quantification of 2xFYVE-GFP immunofluorescence intensity per bouton normalized to resting control for Ib (E) and Is (E’; Ib and Is analyzed with two-way ANOVA; groups within conditions compared with Sidak’s post-test). (F and G) Representative images of FM4-64 labeling (gray) of axon terminals in control (F) and Dscam2^null (G) larvae loaded by stimulation with 90 mM KCl HL3 for 1 min. Scale bar, 5 µm. (H and H’) Quantification of FM4-64 fluorescence intensity relative to control for Ib (H) and Is (H’; unpaired Student’s t test). Data shown as mean ± SEM; n indicated in graph. *, P < 0.05 for all panels. IF, immunofluorescence.