title: Selective replenishment of two vesicle pools depends on the source of Ca2+ at the Drosophila synapse.
abstract: After synaptic vesicles (SVs) undergo exocytosis, SV pools are replenished by recycling SVs at nerve terminals. At Drosophila neuromuscular synapses, there are two distinct SV pools (i.e., the exo/endo cycling pool (ECP), which primarily maintains synaptic transmission, and the reserve pool (RP), which participates in synaptic transmission only during tetanic stimulation). Labeling endocytosed vesicular structures with a fluorescent styryl dye, FM1-43, and measuring intracellular Ca2+ concentrations with a Ca2+ indicator, rhod-2, we show here that the ECP is replenished by SVs endocytosed during stimulation, and this process depends on external Ca2+. In contrast, the RP is refilled after cessation of tetanus by a process mediated by Ca2+ released from internal stores.
authors.affiliation: Institute for Behavioral Sciences, Gunma University School of Medicine, 3-39-22 Showa-machi, Maebashi, Japan. kuromi@med.gunma-u.ac.jp
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kuromi
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Kidokoro
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism / Q000494:pharmacology; D020013:Calcium Signaling / Q000502:physiology*; D002614:Chelating Agents / Q000494:pharmacology; D004331:Drosophila melanogaster / Q000378:metabolism* / Q000648:ultrastructure; D004558:Electric Stimulation; D004705:Endocytosis / Q000502:physiology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005089:Exocytosis / Q000502:physiology; D005456:Fluorescent Dyes; D009469:Neuromuscular Junction / Q000378:metabolism* / Q000648:ultrastructure; D011188:Potassium / Q000378:metabolism / Q000494:pharmacology; D017729:Presynaptic Terminals / Q000378:metabolism* / Q000648:ultrastructure; D021381:Protein Transport / Q000502:physiology; D009435:Synaptic Transmission / Q000502:physiology*; D013572:Synaptic Vesicles / Q000378:metabolism* / Q000648:ultrastructure; D019284:Thapsigargin / Q000494:pharmacology; D014701:Veratridine / Q000494:pharmacology
chemical_list: D002614:Chelating Agents; D004791:Enzyme Inhibitors; D005456:Fluorescent Dyes; D019284:Thapsigargin; D014701:Veratridine; D011188:Potassium; D002118:Calcium