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.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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Calcium / metabolism
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Calcium / pharmacology
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Calcium Signaling / physiology*
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Chelating Agents / pharmacology
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Drosophila melanogaster / metabolism*
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Drosophila melanogaster / ultrastructure
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Electric Stimulation
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Endocytosis / physiology*
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Enzyme Inhibitors / pharmacology
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Exocytosis / physiology
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Fluorescent Dyes
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Neuromuscular Junction / metabolism*
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Neuromuscular Junction / ultrastructure
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Potassium / metabolism
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Potassium / pharmacology
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Presynaptic Terminals / metabolism*
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Presynaptic Terminals / ultrastructure
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Protein Transport / physiology
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Synaptic Transmission / physiology*
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Synaptic Vesicles / metabolism*
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Synaptic Vesicles / ultrastructure
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Thapsigargin / pharmacology
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Veratridine / pharmacology
Substances
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Chelating Agents
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Enzyme Inhibitors
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Fluorescent Dyes
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Thapsigargin
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Veratridine
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Potassium
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Calcium