Impairment of central pattern generation in Drosophila cysteine string protein mutants.
The cysteine string proteins are integral synaptic vesicle proteins, critical for fast, Ca2+ -regulated exocytosis. Drosophila larvae with null mutations for the cysteine string protein (csp) gene have temperature-sensitive impairments of neurotransmission and presynaptic calcium removal at the neuromuscular junction. Using the larval Drosophila preparation to examine central pattern generation, we characterized the temperature sensitivity of locomotor patterns in wildtype and csp mutant larvae. Intraburst frequency of motoneuronal activity reached 100 Hz and was sufficiently high to rescue the temperature-sensitive synaptic failure in the mutant. Nevertheless, we show that deletion of the csp gene resulted in a severe deficiency in the generation of coordinated larval motor rhythms. Csp mutants that could generate patterned motor activity had slower, poorly coordinated rhythms with altered temperature sensitivity. We conclude that the temperature-sensitive paralysis characteristic of csp mutants is not a direct result of synaptic failure at neuromuscular junctions, as might be expected, but is the result of a failure of locomotor circuit operation at a higher integrative level.
Barclay
Jeff W
JW
Department of Biology, Queen's University, Kingston, Ontario, Canada K7L 3N6.
Atwood
Harold L
HL
Robertson
R Meldrum
RM
D000200:Action Potentials / Q000502:physiology; D000818:Animals; D004330:Drosophila / Q000235:genetics* / Q000502:physiology; D004576:Electromyography / Q000379:methods; D017353:Gene Deletion; D017344:Genes, Insect / Q000502:physiology*; D050956:HSP40 Heat-Shock Proteins; D008124:Locomotion / Q000502:physiology*; D008565:Membrane Proteins / Q000235:genetics*; D009043:Motor Activity; D009046:Motor Neurons / Q000502:physiology*; D009132:Muscles / Q000502:physiology*; D009154:Mutation; D009469:Neuromuscular Junction / Q000502:physiology; D012680:Sensitivity and Specificity; D013696:Temperature
D050956:HSP40 Heat-Shock Proteins; D008565:Membrane Proteins; C088460:cysteine string protein