Rhodopsin 5- and Rhodopsin 6-mediated clock synchronization in Drosophila melanogaster is independent of retinal phospholipase C-β signaling.
Circadian clocks of most organisms are synchronized with the 24-hour solar day by the changes of light and dark. In Drosophila, both the visual photoreceptors in the compound eyes as well as the blue-light photoreceptor Cryptochrome expressed within the brain clock neurons contribute to this clock synchronization. A specialized photoreceptive structure located between the retina and the optic lobes, the Hofbauer-Buchner (H-B) eyelet, projects to the clock neurons in the brain and also participates in light synchronization. The compound eye photoreceptors and the H-B eyelet contain Rhodopsin photopigments, which activate the canonical invertebrate phototransduction cascade after being excited by light. We show here that 2 of the photopigments present in these photoreceptors, Rhodopsin 5 (Rh5) and Rhodopsin 6 (Rh6), contribute to light synchronization in a mutant (norpA(P41)               ) that disrupts canonical phototransduction due to the absence of Phospholipase C-β (PLC-β). We reveal that norpA(P41)                is a true loss-of-function allele, resulting in a truncated PLC-β protein that lacks the catalytic domain. Light reception mediated by Rh5 and Rh6 must therefore utilize either a different (nonretinal) PLC-β enzyme or alternative signaling mechanisms, at least in terms of clock-relevant photoreception. This novel signaling mode may distinguish Rhodopsin-mediated irradiance detection from image-forming vision in Drosophila.
School of Biological and Chemical Sciences, Queen Mary, University of London, London, United Kingdom.
Joanna
J
Szular
Hana
H
Sehadova
Carla
C
Gentile
Gisela
G
Szabo
Wen-Hai
WH
Chou
Steven G
SG
Britt
Ralf
R
Stanewsky
D000818:Animals; D001683:Biological Clocks / Q000502:physiology*; D056931:Cryptochromes / Q000502:physiology; D029721:Drosophila Proteins / Q000502:physiology*; D004331:Drosophila melanogaster; D008297:Male; D054799:Phospholipase C beta / Q000502:physiology*; D012243:Rhodopsin / Q000502:physiology*
D056931:Cryptochromes; D029721:Drosophila Proteins; C523885:Rh5 protein, Drosophila; C105578:Rh6 protein, Drosophila; D012243:Rhodopsin; D054799:Phospholipase C beta