Figure 3.

Target-specific reductions in both active zone density and intensity at hyper-innervated NMJs. (A) Schematic illustrating a reduction in the number and intensity of active zones at individual boutons on hyper-innervated muscle 6. (B) Representative images of muscle 6/7 NMJs in the indicated genotypes (wild type: cac^sfGFP-N; M6 >FasII: cac^sfGFP-N; UAS-FasII/+; H94-Gal4/+) immunostained with antibodies against the active zone scaffold bruchpilot (BRP) and GFP to label endogenously tagged Ca²⁺ channels (CAC). (C) Individual boutons from selected areas (white rectangles) of NMJs stained with BRP and CAC in the indicated genotypes and muscles. Note the reduction in the number and intensity of BRP and CAC puncta specifically on muscle 6 in M6 >FasII, while no change is observed on muscle 7 relative to wild type controls. Quantification of BRP and CAC puncta number (D) and density (E) on muscle 6 in M6 >FasII normalized as a percentage of wild type muscle 6 values reveals a small but significant increase in BRP puncta number, while BRP and CAC puncta density is significantly reduced on muscle 6 in M6 >FasII. Quantification of BRP and CAC intensity (F) shows a significant reduction in muscle 6 in M6 >FasII, while the total fluorescence intensity of all BRP and CAC puncta summed across the entire muscle 6 NMJ (G) is unchanged compared to wild type muscle 6. Error bars indicate ±SEM (n ≥ 13; one-way ANOVA; Supplementary Table S2). *p < 0.05; **p < 0.01; ns, not significant.