(B) Hippocampal neurons electroporated at the time of plating with pZOff/VAMP2-HRP or pZOff/VAMP2-HRP/Pclo28 and immunostained at 6 DIV with HRP (green) and Piccolo (red) antibodies. Note the lack of Piccolo immunoreactivity in Pclo28-expressing axons. (C) Transmission EM micrograph of a VAMP2-HRP–positive bouton containing both clear-centered (unlabeled SV) and dark-centered SVs (labeled SV). HRP-labeled vesicles are easily distinguished from 80-nm DCVs and other labeled structures. (D) Synaptic boutons from VAMP2-HRP–expressing (labeled bouton) and untransfected (unlabeled bouton) neurons. Arrowheads denote synaptic junctions, identified based on electron-dense PSDs. (E) An excitatory synapse formed between a pZOff/VAMP2-HRP/Pclo28 (Pclo28)-transfected presynaptic bouton and a postsynaptic spine. (F) An excitatory synapse formed between a pZOff/VAMP2-HRP (control) transfected presynaptic bouton and a postsynaptic spine.Copyright information:Taken from "Piccolo modulation of Synapsin1a dynamics regulates synaptic vesicle exocytosis"The Journal of Cell Biology 2008;181(5):831-846.Published online 2 Jun 2008PMCID:PMC2396795.