Figure 6. Syt7 is absolutely required for transient docking, while docked vesicles recover more quickly without Doc2α.

(A–D) Example transmission electron micrographs of syt7^WT (A), syt7^KO (B), Doc2α^WT (C), and Doc2α^KO (D) synapses frozen at the indicated time points after an action potential (AP) or without stimulation (no stim). Arrows indicate docked vesicles (synaptic vesicles with no visible distance between their membrane and the plasma membrane). (E) The number of docked vesicles per synaptic profile (part of the synapse captured in a 2D section) in syt7 wild-type littermate controls and knockouts. Error bars indicate 95% confidence interval of the mean for all data pooled together; each dot indicates the mean from a single biological replicate. p-Values are from comparisons between wild-type controls (no stim, n = 217; 5 ms, n = 216; 11 ms, n = 217; 14 ms, n = 230 synaptic profiles) and knockouts (no stim, n = 193; 5 ms, n = 215; 11 ms, n = 230; 14 ms, n = 212 synaptic profiles) frozen at the same time point. (F) same as (E), but for Doc2α wild-type controls (no stim, n = 327; 5 ms, n = 229; 11 ms, n = 336; 14 ms, n = 192 synaptic profiles) and knockouts (no stim, n = 330; 5 ms, n = 231; 11 ms, n = 352; 14 ms, n = 321 synaptic profiles). Number of biological replicates (from separate cultures frozen on different days and analyzed in separate randomized batches): 2 for each of the syt7 time points, 2 for 5 ms and 14 ms Doc2 WT, 2 for 5 ms and 11ms Doc2 KO, 3 for Doc2 WT no stim and 11 ms, and 3 for Doc2 KO no stim and 14 ms. The numbers of pits between wild type and knockout were compared using Brown–Forsythe ANOVAs with post hoc Games–Howell’s multiple-comparisons tests. In pairwise tests, the same time point for wild type vs. knockout as well as each time point within each genotype were compared against each other. Only comparisons between the same time point for wild type vs. knockout are shown. See Figure 6—source data 2 for all pairwise comparisons, summary statistics, and test statistics. See Figure 5—figure supplement 2A for active zone sizes from each condition, Figure 5—figure supplement 2C for docked vesicle data normalized to the size of active zones, and Figure 5—figure supplement 2D for distribution of undocked vesicles. See Figure 5—figure supplement 1 for more example micrographs. See Figure 6—source data 1 for all data used to generate the figures.