title: Overexpressing temperature-sensitive dynamin decelerates phototransduction and bundles microtubules in Drosophila photoreceptors.
abstract: shibire(ts1), a temperature-sensitive mutation of the Drosophila gene encoding a Dynamin orthologue, blocks vesicle endocytosis and thus synaptic transmission, at elevated, or restrictive temperatures. By targeted Gal4 expression, UAS-shibire(ts1) has been used to dissect neuronal circuits. We investigated the effects of UAS-shibire(ts1) overexpression in Drosophila photoreceptors at permissive (19 degrees C) and restrictive (31 degrees C) temperatures. At 19 degrees C, overexpression of UAS-shi(ts1) causes decelerated phototransduction and reduced neurotransmitter release. This phenotype is exacerbated with dark adaptation, age and in white mutants. Photoreceptors overexpressing UAS-shibire(ts1) contain terminals with widespread vacuolated mitochondria, reduced numbers of vesicles and bundled microtubules. Immuno-electron microscopy reveals that the latter are dynamin coated. Further, the microtubule phenotype is not restricted to photoreceptors, as UAS-shibire(ts1) overexpression in lamina cells also bundles microtubules. We conclude that dynamin has multiple functions that are interrupted by UAS-shibire(ts1) overexpression in Drosophila photoreceptors, destabilizing their neural communication irreversibly at previously reported permissive temperatures.
authors.affiliation: Department of Biomedical Science, University of Sheffield, Sheffield S10 2TN, UK.
authors.forename: Paloma T
authors.initials: PT
authors.lastname: Gonzalez-Bellido
authors.forename: Trevor J
authors.initials: TJ
authors.lastname: Wardill
authors.forename: Ripsik
authors.initials: R
authors.lastname: Kostyleva
authors.forename: Ian A
authors.initials: IA
authors.lastname: Meinertzhagen
authors.forename: Mikko
authors.initials: M
authors.lastname: Juusola
mesh_terms: D000221:Adaptation, Ocular / Q000502:physiology; D000818:Animals; D030801:Animals, Genetically Modified; D004330:Drosophila; D029721:Drosophila Proteins / Q000378:metabolism*; D034281:Dynamins / Q000378:metabolism*; D005260:Female; D006358:Hot Temperature; D055537:Light Signal Transduction / Q000502:physiology*; D008564:Membrane Potentials / Q000502:physiology; D008870:Microtubules / Q000502:physiology*; D008928:Mitochondria / Q000502:physiology / Q000648:ultrastructure; D018377:Neurotransmitter Agents / Q000378:metabolism; D010641:Phenotype; D010775:Photic Stimulation; D017956:Photoreceptor Cells, Invertebrate / Q000502:physiology* / Q000648:ultrastructure; D009435:Synaptic Transmission / Q000502:physiology; D013572:Synaptic Vesicles / Q000502:physiology / Q000648:ultrastructure
chemical_list: D029721:Drosophila Proteins; D018377:Neurotransmitter Agents; D034281:Dynamins; C439628:shi protein, Drosophila