Fig. 2.

Actin depolymerization disrupts synaptic vesicle recycling in presynaptic boutons, whereas recycling in axons is unperturbed. Fluorescent (left and middle panels) and bright-field images (right panels) show activity-dependent recycling indicated by activity-dependent FM4–64 dye uptake in left panels (load), and subsequent activity-induced destaining in middle panels (unload). Arrows indicate recycling sites. Most recycling sites in control neurons are larger and associated with somata and dendrites (A), whereas in latrunculin A (latA)-treated neurons they are smaller and mostly associated with axons (B). After treatment with TeNT alone (C) or TeNT and latrunculin A (D, TeNT +lat A), all of the cycling boutons are small and mostly associated with axons that often fasciculate together (C, D).E, Quantitative analysis of the area of recycling puncta shows control puncta to be significantly larger than any of the treatment groups, which are not significantly different from one another. An asterisk indicates a significant difference from control (ANOVA, p < 0.0001; Scheffe'spost hoc analysis). Scale bar, 7.9 μm.