Figure 4

HSPC300 controls synaptogenesis at NMJs. (a-f) Anti-Disc Large immunolabeling of muscle 4 synaptic terminals of third instar larvae of the following genotypes: (a-c) wild type; (d-f)HSPC300. Compared to the wild type (WT), HSPC300 NMJs are shorter and display supernumerary buds. Insets in (a,d) show high magnifications of marked regions; (c,f) represent high magnifications of marked regions in (b,e), respectively. Arrows indicate buds. Scale bar: 20 μm (a,d); 14 μm (b,e); 8 μm (c,f). (g,h) Statistical evaluation of the NMJ phenotype of the following genotypes: wild type (WT); HSPC300 (HSPC300^Δ54.3); HSPC300 heterozygous (HSPC300^Δ54.3/+); Revertant, precise excision event (HSPC300^86.1); and Rescue (elav-Gal4; UAS-HSPC300, HSPC300^Δ54.3). (g) Length of synaptic terminals (μm) normalized over respective muscle surface area (μm²). (h) Number of buds per synapse. The sample size (number of muscle 4 junctions scored) was 25 per genotype. Error bars indicate SEM. Statistical significance (p) was calculated using ANOVA and post hoc analysis (see Materials and methods). Asterisks indicate p-value; *p < 0.05; ***p < 0.0001. (i-n) Wild type (i-k) and HSPC300 (l-n) NMJs labeled with anti-Disc Large (DLG; green) and active zone-specific marker NC82 antibody (red). Arrows indicate the region of low NC82 accumulation located between boutons, and arrowheads the supernumerary buds in the mutant synapse. Scale bar: 20 μm (i,j,l,m); 4 μm (k,n).