Diurnal rhythm of cone opsin expression in the teleost fish Haplochromis burtoni

• Published in: Visual neuroscience Vol. 22; no. 2; pp. 135 - 141
• Main Authors: HALSTENBERG, SVEN, LINDGREN, KRISTIN M., SAMAGH, SANJUM P. S., NADAL-VICENS, MIREYA, BALT, STEVE, FERNALD, RUSSELL D.
• Format: Journal Article
• Language: English
• Published: New York, USA Cambridge University Press 01.03.2005
• Subjects: Amino acids; Animals; Behavior; Biological and medical sciences; Cichlids - physiology; Circadian Rhythm - physiology; Cone photoreceptor; Diurnal rhythm; Eye and associated structures. Visual pathways and centers. Vision; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation - physiology; Haplochromis (Astatotilapia) burtoni; Laboratory animals; Light; Opsin; Polymerase Chain Reaction; Renewals; Retinal Cone Photoreceptor Cells - physiology; Rhythm; RNA, Messenger - metabolism; Rod Opsins - genetics; Temporal regulation; Vertebrates: nervous system and sense organs; Diurnal rhythm; Opsin; Temporal regulation; Haplochromis (Astatotilapia) burtoni; Cone photoreceptor; Cone; Photoreceptor; Retina; Diurnal variation; Eye; Visual system; Vertebrata; Pisces; Haplochromis burtoni
• ISSN: 0952-5238; 1469-8714
• DOI: 10.1017/S0952523805222022

The biochemical and morphological specializations of rod and cone photoreceptors reflect their roles in sight. The apoprotein opsin, which converts photons into chemical signals, functions at one end of these highly polarized cells, in the outer segment. Previous work has shown that the mRNA of rod opsin, the opsin specific to rods, is renewed in the outer segment with a diurnal rhythm in the retina of the teleost fish Haplochromis burtoni. Here we show that in the same species, all three cone opsin mRNAs (blue, green, and red) also have a diurnal rhythm of expression. Quantitative real-time polymerase chain reaction (PCR) with primer pairs specific for the cone photoreceptor opsin subtypes was used to detect opsin mRNA abundance in animals sacrificed at 3-h intervals around the clock. All three cone opsins were expressed with diurnal rhythms similar to each other but out of phase with the rod opsin rhythm. Specifically, cone opsin expression occurs at a higher level near the onset of the dark period, when cones are not used for vision. Finally, we found that the rhythm of cone opsin expression in fish appears to be light dependent, as prolonged darkness changes normal diurnal expression patterns.