Circadian rhythm of nonpineal extraretinal photosensitivity in a teleost fish, the lake chub,Couesius plumbeus
✍ Scribed by Kavaliers, Martin
- Publisher
- John Wiley and Sons
- Year
- 1981
- Tongue
- English
- Weight
- 405 KB
- Volume
- 216
- Category
- Article
- ISSN
- 0022-104X
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✦ Synopsis
Abstract
Lake chub, Couesius plumbeus, displayed a diurnal rhythm of nonpineal extraretinal photosensitivity under laboratory light‐dark cycles. There was a bimodal pattern in the threshold intensity (energy fluence rate) for iniating extraretinally mediated photoresponses. Significantly greater intensitites were required in the scotophase than in the photophase of a 12‐hour‐light:12‐hour‐dark cycle. Maximal sensitivity was at the light‐dark and dark‐light transitions. Under constant darkness this pattern continued as a free‐running circadian rhythm of nonpineal extraretinal photosensitivity. The pineal organ, which is directly photosensitive and involved in the control of circadian rhythms in teleost fishes, is not essential for either the generation or expression of this circadian rhythm.