HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (12) Citing Articles via Google Scholar Google Scholar Articles by Bailey, M. J. Articles by Cassone, V. M. Search for Related Content PubMed PubMed Citation Articles by Bailey, M. J. Articles by Cassone, V. M.

Opsin Photoisomerases in the Chick Retina and Pineal Gland: Characterization, Localization, and Circadian Regulation

¹From the Center For Biological Clocks Research and the ²Department of Biology, Texas A&M University, College Station, Texas.

PURPOSE. The chick retina and pineal gland exhibit circadian oscillations in biochemical and physiological processes in vivo and in vitro, which entrain to 24-hour light–dark cycles. However, the phototransduction mechanisms responsible for entrainment are largely unknown. The present study characterizes two candidate opsinlike genes that may play a role in entrainment of the clocks in these tissues.

METHODS. Bioinformatics, cladistic techniques, and in situ hybridization and Northern blot analyses were conducted to characterize, localize, and determine the circadian expression of the candidate opsinlike genes in the retina and pineal gland.

RESULTS. Two candidate photosensors and/or photoisomerases were predominantly distributed within the pineal gland and retina: the retinal pigmented epithelium-derived rhodopsin homologue (peropsin, gRrh) and retinal G-protein–coupled receptor opsin (RGR opsin, gRgr). Northern blot and in situ analyses revealed mRNA expression for both opsins in the pineal gland, retina, and brain tissue. The mRNA for both genes within the pineal gland and retina is regulated on a circadian basis such that they are highest in late subjective day. Digoxigenin in situ analyses showed retinal gRgr message within the inner nuclear layer (INL) and retinal ganglion cell layer (RGL), whereas gRrh message was distributed predominantly in the RGL. In the pineal gland, gRgr message was sparsely distributed among pinealocytes in follicles, but not within the follicles themselves, whereas gRrh was localized in interstitial areas indicative of astrocytic and/or endothelial origin.

CONCLUSIONS. The presence of two putative photoisomerases within the pineal gland and in retinal layers associated with biological clock function provides two candidate opsinlike genes that may serve in the visual cycle regulation of the circadian clock.

This article has been cited by other articles:

				T. G. Kusakabe, N. Takimoto, M. Jin, and M. Tsuda Evolution and the origin of the visual retinoid cycle in vertebrates Phil Trans R Soc B, October 12, 2009; 364(1531): 2897 - 2910. [Abstract] [Full Text] [PDF]

				D. J. Valdez, P. S. Nieto, E. Garbarino-Pico, L. B. Avalle, H. Diaz-Fajreldines, C. Schurrer, K. M. Cheng, and M. E. Guido A nonmammalian vertebrate model of blindness reveals functional photoreceptors in the inner retina FASEB J, April 1, 2009; 23(4): 1186 - 1195. [Abstract] [Full Text] [PDF]

				D. Trifunovic, M. Karali, D. Camposampiero, D. Ponzin, S. Banfi, and V. Marigo A High-Resolution RNA Expression Atlas of Retinitis Pigmentosa Genes in Human and Mouse Retinas Invest. Ophthalmol. Vis. Sci., June 1, 2008; 49(6): 2330 - 2336. [Abstract] [Full Text] [PDF]

				M. A. Contin, D. M. Verra, and M. E. Guido An invertebrate-like phototransduction cascade mediates light detection in the chicken retinal ganglion cells FASEB J, December 1, 2006; 20(14): 2648 - 2650. [Abstract] [Full Text] [PDF]