May 2008
Volume 49, Issue 13
Free
ARVO Annual Meeting Abstract  |   May 2008
Zebrafish Cx55.5(c54x) 'Knock Outs' Have Deficits In Cone-Mediated Vision
Author Affiliations & Notes
  • M. Kamermans
    Retinal Signal Processing, Netherlands Institute for Neuroscience, Amsterdam, The Netherlands
  • T. Sjoerdsma
    Retinal Signal Processing, Netherlands Institute for Neuroscience, Amsterdam, The Netherlands
  • J. van Asselt
    Retinal Signal Processing, Netherlands Institute for Neuroscience, Amsterdam, The Netherlands
  • J. Klooster
    Retinal Signal Processing, Netherlands Institute for Neuroscience, Amsterdam, The Netherlands
  • Y. Claassen
    Retinal Signal Processing, Netherlands Institute for Neuroscience, Amsterdam, The Netherlands
  • H. Ripps
    Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, Illinois
  • I. Fahrenfort
    Retinal Signal Processing, Netherlands Institute for Neuroscience, Amsterdam, The Netherlands
  • C. R. Shields
    Retinal Signal Processing, Netherlands Institute for Neuroscience, Amsterdam, The Netherlands
  • Footnotes
    Commercial Relationships  M. Kamermans, None; T. Sjoerdsma, None; J. van Asselt, None; J. Klooster, None; Y. Claassen, None; H. Ripps, None; I. Fahrenfort, None; C.R. Shields, None.
  • Footnotes
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Investigative Ophthalmology & Visual Science May 2008, Vol.49, 2429. doi:https://doi.org/
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      M. Kamermans, T. Sjoerdsma, J. van Asselt, J. Klooster, Y. Claassen, H. Ripps, I. Fahrenfort, C. R. Shields; Zebrafish Cx55.5(c54x) 'Knock Outs' Have Deficits In Cone-Mediated Vision. Invest. Ophthalmol. Vis. Sci. 2008;49(13):2429. doi: https://doi.org/.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose: : Cx55.5 hemichannels in the tips of horizontal cell dendrites may function in horizontal cell negative feedback to cone photoreceptors in the zebrafish retina. To test for a link between Cx55.5 hemichannels and the feedback mechanism we investigated: 1) whether Cx55.5 can form hemichannels that are open under physiological conditions, 2) whether the pharmacological profile of Cx55.5 is similar to that of feedback and 3) whether Cx55.5 knock-out fish have visual defects consistent with loss of feedback from HCs to cones.

Results: : 1) Cx55.5 hemichannels are open at physiological membrane potentials and at physiological Ca-concentrations. 2) Hemichannels and feedback are known to be blocked by carbenoxolone, low dose of Co2+ and intracellular acidification. Here we show that Cx55.5 hemichannels are also inhibited by HEPES, which may account for the reports of feedback inhibition by HEPES. 3) The retina develops normally in zebrafish lacking Cx55.5 protein but relative to wild type zebrafish, these animals have poorer visual performance as measured with the optokinetic response.

Conclusions: : The data presented in this study show that Cx55.5 is involved in the neural processing in the outer retina. Cx55.5 hemichannels play a role in the feedback mechanism from HCs to cones. This study is the first to demonstrate a change in the visually-guided behavior of an intact living animal by altering the retinal horizontal cell network.

Keywords: horizontal cells • photoreceptors • retina 
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