Figure 3.
Electron Tomographic Analysis of Vesicle Pools in Munc13-Deficient and Control MF-CA3 Synapses
(A–D) Electron tomographic subvolumes of control (CTRL; A) and Munc13-1/2 (M13) DKO (C) MF synapses. (B and D) 3D models of CTRL (B) and M13 DKO (D) MF synapses.
(E) Vesicle distribution within 100 nm of the AZ membrane (N = 2 cultures; n = 15 tomograms).
(F) Mean number of docked clear-cored vesicles (SVs and GVs) in M13 CTRL and DKO MF synapses normalized to the AZ area.
(G) Mean number of vesicles within bins of 5 and 10 nm from the AZ normalized to the AZ area.
(H) Mean number of vesicles within 40 nm of the AZ membrane normalized to the AZ area.
(I) Diameters of all vesicles analyzed, and their distance to the AZ membrane.
(J) Mean number of SVs within 100 nm of the AZ membrane normalized to the AZ area.
(K) Mean number of GVs within 100 nm of the AZ membrane normalized to the AZ area.
(L) Mean number of DCVs within 100 nm of the AZ membrane normalized to the AZ area.
(M) Tomographic slice in which a docked GV is centrally localized at the AZ membrane.
(N–S) Effects of DCG-IV on mEPSCs recorded from CA3 pyramidal cells in slice cultures (N = 2 cultures; n = 28 cells).
(N) Representative traces of mEPSC events recorded from CA3 pyramidal cells in the presence of 1 μM TTX and 10 μM bicuculline (BIC) before and after the application of 2 μM DCG-IV.
(O) Histogram for mEPSC event amplitudes (≥8 pA; 2 pA bins and last bin for all events ≥ 100 pA) before (black, TTX/BIC) and after (gray, TTX/BIC/DCG-IV) application of DCG-IV. Bars represent the number of mEPSC events recorded for an indicated amplitude range in a 5 min interval (mean events per cell + SEM).
(P) Cumulative Pr plot of mEPSC amplitudes. The subtracted cumulative frequency distribution of mEPSCs removed by DCG-IV application is indicated in purple, and the dotted line marks an mEPSC amplitude of 30 pA (see STAR Methods).
(Q) Mean frequency of mEPSCs before and after application of DCG-IV.
(R) Median amplitudes of mEPSCs before and after application of DCG-IV.
(S) Relative changes in the mean amplitude and frequency after the application of DCG-IV normalized to the control condition (TTX/BIC only).
Scale bars: (A–D) and (M), 100 nm. Values indicate mean ± SEM; ∗p < 0.05; ∗∗p < 0.01; ∗∗∗p < 0.001.