Fig. 3: V57 factors alter synapse morphology and identity.

a Sample images (left) of Ngn2-only vs. NV57 neurons immunostained with pan-synaptic marker Synapsin. Average values (right) of Synapsin puncta density normalized by dendritic MAP2 area, and puncta size. b–d Similar immunostainings as a, except for glutamatergic presynapse marker vGLUT b, and GABAergic presynapse markers GAD65/GAD67 c, or vGAT d. e Representative images of EGFP-labeled dendritic branches from Ctrl (Ngn2-only, top row) vs. V57 neurons (bottom row) co-labeled for vGLUT and vGAT (yellow and cyan arrowheads, respectively); maximum intensity z-projections highlight an intricate distribution of both synapse types, especially in V57 condition. f Super-resolution image (left) of a single optical section from V57 condition depicts minimal co-localization between vGLUT and vGAT signals; grey arrowheads point at partially overlapping signals (cyan crosshair) resolved in x/z or y/z axis; intensity profile shows peak separation between signals from a region-of-interest (yellow dotted line). Mander’s coefficients (right) of co-localization between vGLUT and vGAT were plotted. g, h Same as a, but for glutamatergic (Homer, g) or GABAergic (Gephyrin, h) postsynapse markers. i Same as e, except for co-existence of elaborate Homer and Gephyrin puncta, especially in V57 condition. j Same as f, but for postsynaptic Homer and Gephyrin puncta that similarly illustrate minimal co-localization. Average values on bar-graphs represent means ± SEM for number of field-of-views analyzed/independent batches. Individual data-points are provided as color-coded open circles. Statistical significance was weighed by two-tailed, unpaired, Student’s t-test (for Skewness and Kurtosis values -2 >≈  and ≈ < 2), or two-sided, nonparametric Mann-Whitney U-test (Source Data), with ***P < 0.005; **P < 0.01; *P < 0.05; ns = not significant, P > 0.05.