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. 2008 Jun 11;19(3):511–523. doi: 10.1093/cercor/bhn101

Figure 3.

Figure 3.

Synapsin Ia/IIa/IIIa panspecific labeling in MF and AC terminals from perfusion-fixed WT and synapsin DKO mice. (A) Electron micrograph from a WT MF terminal immunolabeled with synapsin G304 antibodies. A synapse is indicated by its postsynaptic density (arrowheads), spine (s), and vesicles (v). Gold particles were quantified within an RRP and RP zone, morphologically defined according to distances from the presynaptic membrane, 0–100 nm and 100–400 nm, respectively, and laterally limited by a line drawn perpendicularly to the synaptic cleft (see Fig. 1). EZs were defined to be 150 × 250 nm lateral to the RRP or less for smaller synapses. Averages for whole terminals where also acquired (T). Scale bar: 0.1 μm. (B) As in (A), but the electron micrograph is from an AC terminal in a WT mouse. (C, D) As in (A) and (B), but the electron micrographs are from a synapsin DKO mouse. Notice that the only prominent labeling is in the RRP of MF, probably representing synapsin III. (E, F) Histograms showing a comparison between quantified data obtained from 5 WT and 5 DKO mice, in MF, (E), and AC, (F). In DKO, the RRP was significantly different from all other areas, and by several orders of magnitude, indicative of the presence of synapsin III. Also, this could explain the unexpectedly dense labeling in the WT RRP. (G) As in (E) and (F), but average gold particle density is combined with average vesicle density from Figure 1 to correct for error due to variations in vesicle density. In (E) and (F), labeling is artificially high in the RRP due to high vesicle density. Still, a difference between RRP and RP in DKO MF terminals can be seen. Twenty images where analyzed in each of 5 mice (n = 5) per genotype and type of synapse (containing 17–21 synapses). The columns represent mean + standard error of the mean of gold particles/μm2 in the specified areas and in the rest of the terminal (T). Densities were compared between the areas using an analysis of variance test with a Scheffe's post hoc test (#P < 0.01) and between DKO and WT using the t-test (§P < 0.04). A Kruskal–Wallis and Mann–Whitney tests gave similar results (P < 0.05).