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Neuron. 1994 Jun;12(6):1257-67.

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

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Department of Physiology, Hebrew University-Hadassah Medical School, Jerusalem, Israel.


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.

[Indexed for MEDLINE]

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