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  Genetic dissection of light-induced Ca2+ influx into Drosophila photoreceptors

Peretz, A., Sandler, C., Kirschfeld, K., Hardie, R., & Minke, B. (1994). Genetic dissection of light-induced Ca2+ influx into Drosophila photoreceptors. Journal of General Physiology, 104(6), 1057-1077. doi:10.1085/jgp.104.6.1057.

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 Creators:
Peretz, A1, 2, Author              
Sandler, C1, 2, Author              
Kirschfeld, K1, 2, Author              
Hardie, RC, Author              
Minke, B, Author              
Affiliations:
1Former Department Comparative Neurobiology, Max Planck Institute for Biological Cybernetics, Max Planck Society, ou_1497800              
2Max Planck Institute for Biological Cybernetics, Max Planck Society, Spemannstrasse 38, 72076 Tübingen, DE, ou_1497794              

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 Abstract: Invertebrate photoreceptors use the inositol-lipid signaling cascade for phototransduction. A useful approach to dissect this pathway and its regulation has been provided by the isolation of Drosophila visual mutants. We measured extracellular changes of Ca2+ [delta Ca2+]o in Drosophila retina using Ca(2+)-selective microelectrodes in both the transient receptor potential (trp) mutant, in which the calcium permeability of the light-sensitive channels is greatly diminished and in the inactivation-but-no-afterpotential C (inaC) mutant which lacks photoreceptor-specific protein kinase C (PKC). Illumination induced a decrease in extracellular [Ca2+] with kinetics and magnitude that changed with light intensity. Compared to wild-type, the light-induced decrease in [Ca2+]o (the Ca2+ signal) was diminished in trp but significantly enhanced in inaC. The enhanced Ca2+ signal was diminished in the double mutant inaC;trp indicating that the effect of the trp mutation overrides the enhancement observed in the absence of eye-PKC. We suggest that the decrease in [Ca2+]o reflects light-induced Ca2+ influx into the photoreceptors and that the trp mutation blocks a large fraction of this Ca2+ influx, while the absence of eye specific PKC leads to enhancement of light-induced Ca2+ influx. This suggestion was supported by Ca2+ measurements in isolated ommatidia loaded with the fluorescent Ca2+ indicator, Ca Green-5N, which indicated an approximately threefold larger light-induced increase in cellular Ca2+ in inaC relative to WT. Our observations are consistent with the hypothesis that TRP is a light activated Ca2+ channel and that the increased Ca2+ influx observed in the absence of PKC is mediated mainly via the TRP channel.

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 Dates: 1994-12
 Publication Status: Published in print
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 Identifiers: DOI: 10.1085/jgp.104.6.1057
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Title: Journal of General Physiology
  Other : J. Gen. Physiol.
  Abbreviation : JGP
Source Genre: Journal
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Publ. Info: Rockefeller University Press
Pages: - Volume / Issue: 104 (6) Sequence Number: - Start / End Page: 1057 - 1077 Identifier: ISSN: 0022-1295
CoNE: https://pure.mpg.de/cone/journals/resource/954925413895