Cytosolic calcium transients: Spatial localization and role in drosophila photoreceptor cell function

Rama Ranganathan, Brian J. Bacskai, Roger Y. Tsien, Charles S. Zuker

Research output: Contribution to journalArticle

120 Citations (Scopus)

Abstract

Drosophila phototransduction is a phosphoinositide-mediated and Ca2+-regulated signaling cascade ideal for the dissection of feedback regulatory mechanisms. To study the roles of intracellular Ca2+ ([Ca2+]i) in this process, we developed novel techniques for the measurement of [Ca2+]i in intact photoreceptors. We genetically engineered flies that express a UV-specific rhodopsin in place of the normal rhodopsin, so that long wavelength light can be used to image [Ca2+]i changes while minimally exciting the photoreceptor cells. We show that activation with UV generates [Ca2+]i increases that are spatially localized to the rhabdomeres and that are entirely dependent on the influx of extracellular Ca2+. Application of intracellular Ca2+ chelators of varying affinities demonstrates that the Ca2+ influx initially generates a large-amplitude transient that is crucial for negative regulation. Internal Ca2+ stores were revealed by discharging them with thapsigargin. But, in contrast to proposals that IP3-sensitive stores mediate phototransduction, thapsigargin does not mimic or acutely interfere with photoexcitation. Finally, we identify a photoreceptor-specific PKC as essential for normal kinetics of [Ca2+]i recovery.

Original languageEnglish (US)
Pages (from-to)837-848
Number of pages12
JournalNeuron
Volume13
Issue number4
DOIs
StatePublished - 1994

Fingerprint

Light Signal Transduction
Photoreceptor Cells
Thapsigargin
Rhodopsin
Drosophila
Calcium
Chelating Agents
Phosphatidylinositols
Diptera
Dissection
Light

ASJC Scopus subject areas

  • Neuroscience(all)

Cite this

Cytosolic calcium transients : Spatial localization and role in drosophila photoreceptor cell function. / Ranganathan, Rama; Bacskai, Brian J.; Tsien, Roger Y.; Zuker, Charles S.

In: Neuron, Vol. 13, No. 4, 1994, p. 837-848.

Research output: Contribution to journalArticle

Ranganathan, Rama ; Bacskai, Brian J. ; Tsien, Roger Y. ; Zuker, Charles S. / Cytosolic calcium transients : Spatial localization and role in drosophila photoreceptor cell function. In: Neuron. 1994 ; Vol. 13, No. 4. pp. 837-848.
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