title: Enhancement of presynaptic performance in transgenic Drosophila overexpressing heat shock protein Hsp70.
abstract: Prior heat shock confers protection to Drosophila synapses during subsequent heat stress by stabilizing quantal size and reducing the decline of quantal emission at individual synaptic boutons. The major heat shock protein Hsp70, which is strongly induced by high temperatures in Drosophila, may be responsible for this synaptic protection. To test this hypothesis, we investigated synaptic protection and stabilization at larval neuromuscular junctions of transgenic Drosophila which produce more than the normal amount of Hsp70 in response to heat shock. Overexpression of Hsp70 coincides with enhanced protection of presynaptic performance, assayed by measuring mean quantal content and percentage success of transmission. Quantal size was not selectively altered, indicating no effects of overexpression on postsynaptic performance. Thus, presynaptic mechanisms can be protected by manipulating levels of Hsp70, which would provide stability to neural circuits otherwise susceptible to heat stress.
authors.affiliation: Department of Physiology, Medical Sciences Building, University of Toronto, Toronto, Ontario, M5S 1A8, Canada. s.karunanithi@utoronto.ca
authors.forename: Shanker
authors.initials: S
authors.lastname: Karunanithi
authors.forename: Jeffrey W
authors.initials: JW
authors.lastname: Barclay
authors.forename: Ian R
authors.initials: IR
authors.lastname: Brown
authors.forename: R Meldrum
authors.initials: RM
authors.lastname: Robertson
authors.forename: Harold L
authors.initials: HL
authors.lastname: Atwood
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D001831:Body Temperature / Q000235:genetics; D004331:Drosophila melanogaster / Q000235:genetics / Q000378:metabolism*; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D018882:Heat Stress Disorders / Q000235:genetics / Q000378:metabolism* / Q000503:physiopathology; D018869:Heat-Shock Response / Q000502:physiology*; D007814:Larva; D009420:Nervous System / Q000254:growth & development / Q000378:metabolism*; D009469:Neuromuscular Junction / Q000235:genetics* / Q000378:metabolism*; D018377:Neurotransmitter Agents / Q000235:genetics / Q000378:metabolism; D009435:Synaptic Transmission / Q000235:genetics*; D013572:Synaptic Vesicles / Q000235:genetics / Q000378:metabolism
chemical_list: D018840:HSP70 Heat-Shock Proteins; D018377:Neurotransmitter Agents