Licht-im-Terrarium: Literaturdatenbank
Licht-im-Terrarium: Literaturdatenbank |
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Underwood, H., & Menaker, M. (1976). Extraretinal photoreception in lizards. Photochemistry and Photobiology, 23(4), 227–243. Added by: Sarina (2010-01-09 12:48:41) |
| Resource type: Journal Article DOI: 10.1111/j.1751-1097.1976.tb07247.x BibTeX citation key: Underwood1976 View all bibliographic details  |
Categories: Englisch = English Keywords: Chronobiologie = Chronobiology, Echsen = Lizards Creators: Menaker, Underwood Collection: Photochemistry and Photobiology |
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| Abstract |
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Abstract—In lizards both photoperiodic photoreception and entrainment (synchronization) of the biological clock by environmental light cycles can be accomplished by extraretinal photoreceptors. Testicular size and spermatogenic activity in the green anole, Anolis carolinensis, is maintained under long (14 h) photoperiods in the summer in both sighted and blinded lizards whereas short days (6h) cause testicular regression. In the fall, long photoperiods cause testicular recrudescence and maturation in blinded and blinded-parietalectomized anoles as well as in sighted anoles. Extraretinal photoreceptors can mediate entrainment of the circadian locomotor rhythm in every lizard species examined to date (8 species). The photosensory pineal complex in lizards (pineal organ and parietal eye) may not be involved in entrainment; in any case, its removal does not prevent entrainment of blinded lizards. Localization experiments have shown that the brain is the site of the extraretinal receptors mediating entrainment. The lateral eyes can also contribute to entrainment. In some species, but not all, blinding alters the pattern of the entrained activity rhythm. The free-running activity rhythms of two species of lizards exposed to continuous illumination respond very differently to blinding; these experiments yield insight into the mechanisms of entrainment in the two species as well as showing that caution must be observed when generalizing about the role of retinal and extraretinal receptors not only among different vertebrate classes but also among species of the same class. Added by: Sarina |