title: Fast calcium signals in Drosophila motor neuron terminals.
abstract: Drosophila is a powerful model for neuroscientists, but physiological techniques have not kept pace with advances in molecular genetics. We introduce a reliable assay for intracellular calcium dynamics in Drosophila larval motor neuron terminals, and a new physiological solution that improves the longevity of the larval preparation. By loading calcium indicators into motor neuron terminals through cut axons, we obtained a high signal-to-noise ratio with confocal microscopy, and good temporal resolution of calcium-dependent fluorescence changes. We provide an estimate for the resting intracellular calcium concentration, the first description of calcium kinetics for a single action potential (AP), and improved resolution of calcium kinetics during AP trains. The very rapid decay of the calcium signal following a single AP (tau ~60 ms) indicates a previously unreported fast calcium extrusion mechanism in Drosophila motor neuron terminals well suited for sustaining physiological processes during the high rates of impulse activity which drive locomotor activity.
authors.affiliation: Department of Physiology, University of Toronto, Toronto, Ontario M5S 1A8, Canada. greg@spine.med.utoronto.ca
authors.forename: G T
authors.initials: GT
authors.lastname: Macleod
authors.forename: M
authors.initials: M
authors.lastname: Hegström-Wojtowicz
authors.forename: M P
authors.initials: MP
authors.lastname: Charlton
authors.forename: H L
authors.initials: HL
authors.lastname: Atwood
mesh_terms: D000818:Animals; D001369:Axons / Q000502:physiology; D020013:Calcium Signaling / Q000502:physiology*; D004330:Drosophila / Q000502:physiology*; D004594:Electrophysiology; D005456:Fluorescent Dyes; D016257:Fura-2; D006706:Homeostasis / Q000502:physiology; D007700:Kinetics; D008839:Microelectrodes; D009045:Motor Endplate / Q000502:physiology; D009046:Motor Neurons / Q000502:physiology*; D009132:Muscles / Q000166:cytology / Q000294:innervation / Q000502:physiology; D009154:Mutation / Q000502:physiology; D010641:Phenotype; D017729:Presynaptic Terminals / Q000502:physiology*; D009435:Synaptic Transmission / Q000502:physiology
chemical_list: D005456:Fluorescent Dyes; D016257:Fura-2