title: Ultrastructural and functional fate of recycled vesicles in hippocampal synapses.
abstract: Efficient recycling of synaptic vesicles is thought to be critical for sustained information transfer at central terminals. However, the specific contribution that retrieved vesicles make to future transmission events remains unclear. Here we exploit fluorescence and time-stamped electron microscopy to track the functional and positional fate of vesicles endocytosed after readily releasable pool (RRP) stimulation in rat hippocampal synapses. We show that most vesicles are recovered near the active zone but subsequently take up random positions in the cluster, without preferential bias for future use. These vesicles non-selectively queue, advancing towards the release site with further stimulation in an actin-dependent manner. Nonetheless, the small subset of vesicles retrieved recently in the stimulus train persist nearer the active zone and exhibit more privileged use in the next RRP. Our findings reveal heterogeneity in vesicle fate based on nanoscale position and timing rules, providing new insights into the origins of future pool constitution.
authors: School of Life Sciences, University of Sussex, Brighton BN1 9QG, UK.
authors: Stephanie A
authors: SA
authors: Rey
authors: School of Life Sciences, University of Sussex, Brighton BN1 9QG, UK.
authors: Catherine A
authors: CA
authors: Smith
authors: School of Life Sciences, University of Sussex, Brighton BN1 9QG, UK.
authors: Milena W
authors: MW
authors: Fowler
authors: School of Life Sciences, University of Sussex, Brighton BN1 9QG, UK.
authors: Freya
authors: F
authors: Crawford
authors: Medical Research Council Laboratory for Molecular Cell Biology, University College London, Gower Street, London WC1E 6BT, UK.
authors: Jemima J
authors: http://orcid.org/0000-0001-5894-7043
authors: JJ
authors: Burden
authors: School of Life Sciences, University of Sussex, Brighton BN1 9QG, UK.
authors: Kevin
authors: K
authors: Staras
mesh_terms: D000818:Animals; D004705:Endocytosis / Q000502:physiology; D006624:Hippocampus / Q000166:cytology*; D009474:Neurons / Q000502:physiology* / Q000648:ultrastructure*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013572:Synaptic Vesicles / Q000502:physiology* / Q000648:ultrastructure*