Figure 3. Reduction of Scaffold Proteins BRP and Syd-1 Results in Isoform-Specific Downregulation of Unc13s in the Adult Drosophila Brain.

(A and B) Confocal images of ALs stained against BRP^Nc82, Unc13A, and Unc13B. All scale bars, 20 μm. Flies with a pan-neuronal brp knockdown (KD; elav-GAL4 > UAS-brp-RNAi) in comparison to a control group (elav-GAL4/+); staining against Unc13A (A). syd-1^null mutant flies (syd^ex1.2/syd^ex3.4) in comparison to w¹¹¹⁸ controls; staining against Unc13B (B).

(C) Average staining intensities of BRP, Unc13A, and Unc13B in the KD or deletion situation normalized to controls show a significant downregulation of average intensity levels of Unc13A (p = 0.0016 for the brp KD). Syd-1 deletion results in downregulation of Unc13B (p = 0.000008). Average intensities of BRP and Syd-1 in unc13A and unc13B deletion mutants, respectively, normalized to controls (unc13B deletion: pacdel100B; unc13^P84200; unc13A deletion: ems7.5/unc13^P84200). The intensity levels of scaffold proteins were not altered in the mutants.

(D and E) Confocal images of calyces stained against BRP^Nc82, Unc13A, and Unc13B. All scale bars, 20 μm. Flies with a pan-neuronal brp KD in comparison to controls; staining against Unc13A (D). Syd-1^null mutants in comparison to controls; staining against Unc13B (E).

(F) Average staining intensities of BRP, Unc13A, and Unc13B in the KD or deletion situation normalized to controls show a significant downregulation of average intensity levels of Unc13A (p = 0.000018) and a significant upregulation of Unc13B (p = 0.0049) in the brp KD animals. Deletion of syd-1 results in downregulation of Unc13B (p = 0.000002). Association tests were conducted using linear mixed models with imaging batch and animal as nested random effects. Bonferroni-corrected significance thresholds α = 0.0167 for the brp KD and the syd-1 deletion and α = 0.025 for the unc13A/B deletions. Graphs as explained for Figure 1.

See also Figure S3.