Vertebrate ancient opsin photopigment spectra and the avian photoperiodic response

In mammals, photoreception is restricted to cones, rods and a subset of retinal ganglion cells. By contrast, non-mammalian vertebrates possess many extraocular photoreceptors but in many cases the role of these photoreceptors and their underlying photopigments is unknown. In birds, deep brain photor...

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Bibliographic Details
Published in:Biology letters (2005) 2012-04, Vol.8 (2), p.291-294
Main Authors: Davies, Wayne I. L., Turton, Michael, Peirson, Stuart N., Follett, Brian K., Halford, Stephanie, Garcia-Fernandez, Jose M., Sharp, Peter J., Hankins, Mark W., Foster, Russell G.
Format: Article
Language:English
Subjects:
Animals
Avian
Blotting, Western
Chickens - physiology
Deep Brain Photoreceptor
HEK293 Cells
Hemoglobins - physiology
Hemoglobins - radiation effects
Humans
Hypothalamus
Hypothalamus - cytology
Hypothalamus - physiology
Immunochromatography
Neurobiology
Opsins - physiology
Opsins - radiation effects
Photic Stimulation
Photoperiod
Photoperiodic Response
Photoreceptor Cells, Vertebrate - chemistry
Photoreceptor Cells, Vertebrate - physiology
Protein Isoforms - physiology
Protein Isoforms - radiation effects
Recombinant Proteins - metabolism
Recombinant Proteins - radiation effects
Reproduction
Retinaldehyde
Seasons
Spectrophotometry
Vertebrate Ancient Opsin
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Summary:In mammals, photoreception is restricted to cones, rods and a subset of retinal ganglion cells. By contrast, non-mammalian vertebrates possess many extraocular photoreceptors but in many cases the role of these photoreceptors and their underlying photopigments is unknown. In birds, deep brain photoreceptors have been shown to sense photic changes in daylength (photoperiod) and mediate seasonal reproduction. Nonetheless, the specific identity of the opsin photopigment ‘sensor’ involved has remained elusive. Previously, we showed that vertebrate ancient (VA) opsin is expressed in avian hypothalamic neurons and forms a photosensitive molecule. However, a direct functional link between VA opsin and the regulation of seasonal biology was absent. Here, we report the in vivo and in vitro absorption spectra (λmax = ∼490 nm) for chicken VA photopigments. Furthermore, the spectral sensitivity of these photopigments match the peak absorbance of the avian photoperiodic response (λmax = 492 nm) and permits maximum photon capture within the restricted light environment of the hypothalamus. Such a correspondence argues strongly that VA opsin plays a key role in regulating seasonal reproduction in birds.
ISSN:1744-9561
1744-957X
DOI:10.1098/rsbl.2011.0864