Confocal imaging of inhibitory synapses across development (P7, P10, and P21). Top row: example images of Geph-FingR-tdT puncta (red) co-stained with antibody against Bassoon (white) and example images of synapses co-stained for vGAT (white) and Bassoon (red). Bottom row: example images of synapse stained for vGAT (white) and Rim 1/2 (red). Bar graphs (far right) indicate proportions of synapses that showed clear co-localization between the two markers for each row across different postnatal days. Only a minority of GEPH-FingR-tdTom puncta were colocalized with bassoon at P7 (37%,n= 99, SEM = 0.05%), but this colocalization was 90% at P10 (n= 132, SEM = 0.03%) and 95% at P21 (n= 160, SEM = 0.02%). Similarly, at P7, the majority of vGAT-positive synapses did not colocalize with the AZ markers bassoon (43%,n= 99, SEM = 0.05%) or RIM1/2 (37%,n= 100, SEM = 0.05%). At P10, the majority of vGAT puncta colocalized with bassoon (92%,n= 100, SEM = 0.03%) and RIM1/2 (88%,n= 100, SEM = 0.03%), which was also the case at P21 (bassoon 86%,n= 100, SEM = 0.03; RIM1/2 93%,n= 100, SEM = 0.03%). Filled yellow arrows represent GEPH-FingR-tdt puncta that are colocalized with a presynaptic marker, while unfilled yellow arrows represent GEPH- FingR-tdt puncta that are not colocalized with a presynaptic marker.
