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Knockdown of Cone-Specific Kinase GRK7 in Larval Zebrafish Leads to Impaired Cone Response Recovery and Delayed Dark Adaptation

Authors
Journal
Neuron
0896-6273
Publisher
Elsevier
Publication Date
Volume
47
Issue
2
Identifiers
DOI: 10.1016/j.neuron.2005.06.010

Abstract

Summary Phosphorylation of rhodopsin by rhodopsin kinase GRK1 is an important desensitization mechanism in scotopic vision. For cone vision GRK1 is not essential. However, cone opsin is phosphorylated following light stimulation. In cone-dominant animals as well as in humans, but not in rodents, GRK7, a cone-specific homolog of GRK1, has been identified in cone outer segments. To investigate the function of GRK7 in vivo, we cloned two orthologs of grk7 in zebrafish and knocked down gene expression of grk7a in zebrafish larvae by morpholino antisense nucleotides. Photoresponse recovery in Grk7a-deficient larvae was delayed in electroretinographic measurements, and temporal contrast sensitivity was reduced, particularly under bright-light conditions. These results show that function of a cone-specific kinase is essential for cone vision in the zebrafish retina and argue that pigment bleaching and spontaneous decay alone are not sufficient for light adaptation and rapid cone response inactivation.

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