The light response of Drosophila photoreceptors is accompanied by an increase in cellular calcium: effects of specific mutations

Neuron. 1994 Jun;12(6):1257-67. doi: 10.1016/0896-6273(94)90442-1.


Photoreceptors of dissociated Drosophila retinae were loaded with the fluorescent Ca2+ indicators, fluo-3 and Calcium Green-5N. In fluo-3-loaded, wild-type photoreceptors, a rapid increase in fluorescence (Ca2+ signal) accompanied the light-evoked inward current. Removal of extracellular Ca2+ greatly reduced the Ca2+ signal, indicating Ca2+ influx as its major cause. In Calcium Green-5N-loaded trp mutants, which lack a large fraction of the Ca2+ permeability underlying the light-evoked inward current, the Ca2+ signal was smaller relative to wild-type photoreceptors. Fluo-3-loaded norpA mutant photoreceptors, which lack a light-activated phospholipase C, generated no light-evoked inward current and no Ca2+ signal. The phosphoinositide pathway therefore appears necessary for both excitation and changes in cytosolic free Ca2+ concentration.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Aniline Compounds
  • Animals
  • Calcium / metabolism*
  • Calcium Channels / physiology
  • Drosophila melanogaster / genetics
  • Drosophila melanogaster / physiology*
  • Electrophysiology
  • Fluorescent Dyes
  • In Vitro Techniques
  • Light
  • Membrane Potentials / radiation effects
  • Mutation*
  • Photoreceptor Cells, Invertebrate / physiology*
  • Photoreceptor Cells, Invertebrate / radiation effects
  • Pupa
  • Retina / physiology
  • Spectrometry, Fluorescence
  • Xanthenes


  • Aniline Compounds
  • Calcium Channels
  • Fluorescent Dyes
  • Xanthenes
  • Fluo-3
  • Calcium