Figure 9. Syt7 mutants have a larger releasable pool of SVs and normal endocytosis.

(A) Representative mean eEJC quantal content determined by mEJC charge during 1000 stimuli at 10 Hz in 2 mM Ca²⁺ in control (black) and Syt7^M1 (blue). The inset shows representative eEJC traces in control (black) and Syt7^M1 (blue). (B) Quantification of average cumulative quanta released during the 1000 stimuli at 10 Hz tetanic stimulation in control (black, 19.21K ± 2.88K, n = 7) and Syt7^M1 (blue, 36.18K ± 5.67K, n = 8). (C) Quantification of average quantal content at steady-state release at the end of the 10 Hz stimulation in control (black, 131.54 ± 10.71, n = 7) and Syt7^M1 (blue, 123.05 ± 10.47, n = 8). Statistical significance for B and C was determined with a Mann-Whitney unpaired t-test. (D) FM1-43 loading in control and Syt7^M1 larvae at muscle 6/7 NMJs in 2 mM Ca²⁺ following 150, 300 or 600 stimuli delivered at 0.5 Hz. (E) FM1-43 loading with 500 stimuli at 10 Hz in 2 mM Ca²⁺ and FM1-43 unloading with high K⁺ (90 mM) in control and Syt7^M1 larvae at muscle 6/7 NMJs. (F) Quantification of FM1-43 loading following 150, 300 or 600 stimuli delivered at 0.5 Hz. (G) Quantification of FM1-43 loading after 500 stimulati at 10 Hz. (H) Quantification of FM1-43 unloading with high K⁺ (90 mM). Statistical significance was determined with Student’s t-test for F-H. Scale bar = 5 µm.