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The retina visual cycle is driven by cis retinol oxidation in the outer segments of cones
- Source :
- Visual neuroscience. 34
- Publication Year :
- 2017
-
Abstract
- Vertebrate rod and cone photoreceptors require continuous supply of chromophore for regenerating their visual pigments after photoactivation. Cones, which mediate our daytime vision, demand a particularly rapid supply of 11-cis retinal chromophore in order to maintain their function in bright light. An important contribution to this process is thought to be the chromophore precursor 11-cis retinol, which is supplied to cones from Müller cells in the retina and subsequently oxidized to 11-cis retinal as part of the retina visual cycle. However, the molecular identity of the cis retinol oxidase in cones remains unclear. Here, as a first step in characterizing this enzymatic reaction, we sought to determine the subcellular localization of this activity in salamander red cones. We found that the onset of dark adaptation of isolated salamander red cones was substantially faster when exposing directly their outer vs. their inner segment to 9-cis retinol, an analogue of 11-cis retinol. In contrast, this difference was not observed when treating the outer vs. inner segment with 9-cis retinal, a chromophore analogue which can directly support pigment regeneration. These results suggest, surprisingly, that the cis-retinol oxidation occurs in the outer segments of cone photoreceptors. Confirming this notion, pigment regeneration with exogenously added 9-cis retinol was directly observed in the truncated outer segments of cones, but not in rods. We conclude that the enzymatic machinery required for the oxidation of recycled cis retinol as part of the retina visual cycle is present in the outer segments of cones.
- Subjects :
- 0301 basic medicine
genetic structures
Physiology
Adaptation (eye)
Dark Adaptation
Retinol dehydrogenase
Ambystoma
Article
03 medical and health sciences
chemistry.chemical_compound
0302 clinical medicine
medicine
Animals
Vitamin A
Vision, Ocular
Oxidase test
Retina
Retinol
Retinal
Anatomy
Chromophore
Retinal Photoreceptor Cell Outer Segment
Sensory Systems
030104 developmental biology
medicine.anatomical_structure
chemistry
Microspectrophotometry
Biophysics
Retinal Cone Photoreceptor Cells
Retinaldehyde
sense organs
Diterpenes
Oxidation-Reduction
Retinal Pigments
030217 neurology & neurosurgery
Photic Stimulation
Visual phototransduction
Subjects
Details
- ISSN :
- 14698714
- Volume :
- 34
- Database :
- OpenAIRE
- Journal :
- Visual neuroscience
- Accession number :
- edsair.doi.dedup.....5096a1af50dfd2dbe849b5250c97d45c