Elementary and macroscopic light-induced currents and their Ca(2+)-dependence in the photoreceptors of Periplaneta americana

Research output: Contribution to journalArticle

Abstract

In a microvillar photoreceptor, absorption of an incident photon initiates a phototransduction reaction that generates a depolarizing light-induced current (LIC) in the microvillus. Although in-depth knowledge about these processes in photoreceptors of the fruitfly Drosophila is available, not much is known about their nature in other insect species. Here, we present description of some basic properties of both elementary and macroscopic LICs and their Ca(2+)-dependence in the photoreceptors of a dark-active species, the cockroach Periplaneta americana. Cockroach photoreceptors respond to single photon absorptions by generating quantum bumps with about 5-fold larger amplitudes than in Drosophila. At the macroscopic current level, cockroach photoreceptors responded to light with variable sensitivity and current waveform. This variability could be partially attributed to differences in whole-cell capacitance. Transient LICs, both elementary and macroscopic, showed only moderate dependence on extracellular Ca(2+). However, with long light pulses, response inactivation was largely abolished and the overall size of LICs increased when extracellular Ca(2+) was omitted. Finally, by determining relative ionic permeabilities from reversals of LICs, we demonstrate that when compared to Drosophila, cockroach light-gated channels are only moderately Ca(2+)-selective.

Details

Authors
  • Esa-Ville Immonen
  • S. Krause
  • Y. Krause
  • R. Frolov
  • M. T. Vahasoyrinki
  • M. Weckstrom
External organisations
  • External Organization - Unknown
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Zoology
Original languageEnglish
Pages (from-to)153-153
JournalFrontiers in Physiology
Volume5
Publication statusPublished - 2014
Publication categoryResearch
Peer-reviewedYes
Externally publishedYes