Figure 6.

Rab3 ectopic expression partially ameliorates unc-104^bris mutant phenotypes at the NMJ but not VNC phenotype. (A) A stretch of synaptic boutons at the NMJ costained with antibodies against GluRIIC (green in upper panel, gray in 2nd panel) and Brp (magenta in upper panel, gray in 3rd panel). (B–F) Quantifications of percentage Brp⁻ synapses (B) and Brp content per Brp⁺ AZ (in a.u.; C) reveal that the percentage of Brp⁻ synapses decreases upon Rab3 expression and the size of each Brp puncta remains unchanged. Brp content per NMJ (in a.u.; D) as well as the Brp density (in a.u.; Brp content normalized by HRP area) (E) increase following Rab3 expression. Expression of Rab3 fully rescues GluRIIC levels (in a.u.) at postsynaptic density (PSD) of unc-104^bris mutant NMJs to control levels (F). (G,H) Representative confocal images from larval VNC stained with antibodies against HRP (G) and Brp (H). (H) Abnormal accumulation of Brp in the cell CB of the VNC in unc-104^bris mutant compared to the control. Overexpression of Rab3 in unc-104^bris background does not reduce accumulation of Brp at the CB region (indicated by yellow arrowheads). Scale bar in (A): 5 μm, (G): 15 μm. Genotypes: control (elavX-Gal4/+;;), unc-104^bris (elavX-Gal4/+;unc-104^bris/unc-104^d11024;), unc-104^bri;Rab3-OE (elavX-Gal4/+;unc-104^bris/unc-104^d11024;UAS-Rab3/+). Experiments were performed at 29°C. Statistical test: one-way ANOVA followed by Tukey’s Multiple Comparison Test. *p < 0.05; **p < 0.01; ***p < 0.001; n.s., p > 0.05. Error bars indicate the SEM.