Photopigments and photoentrainment in the Syrian golden hamster.
The Syrian golden hamster (Mesocricetus auratus) is an important model in the study of circadian rhythms. However, as in other mammals, little is known about the photoreceptors that mediate circadian entrainment. Using immunocytochemistry and RNA blot hybridization, we found no evidence for the presence of blue-/UV-sensitive opsin. In contrast, green-sensitive cone opsin was demonstrated in the retina both by immunocytochemistry and reverse-transcription PCR. When used as a probe in RNA blot hybridization, this PCR fragment labelled one transcript (5.8 kb) in hamster retinal RNA. These findings are in accordance with preliminary data from other investigators using electroretinography, which showed one cone-mediated photoreceptive mechanism with a maximum sensitivity of 501 nm, but none at shorter wavelengths. However, we found that non-saturating pulses of ultraviolet radiation (357 nm) caused phase shifts in locomotor behaviour. These results corroborate earlier reports that UV radiation can regulate the photoperiodic response in this animal. Having confirmed these apparently contradictory earlier reports, we discuss the mechanisms that might create a UV-triggered non-visual response in a green cone monochromat. Finally, we propose the use of the Syrian golden hamster as a model for photoreceptor development and function in the absence of S/UV cones.
von Schantz
M
M
Department of Biology, Imperial College of Science, Technology and Medicine, London, UK. m.vonschantz@ic.ac.uk
Argamaso-Hernan
S M
SM
Szél
A
A
Foster
R G
RG
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001522:Behavior, Animal / Q000502:physiology / Q000528:radiation effects; D002940:Circadian Rhythm / Q000502:physiology / Q000528:radiation effects*; D003001:Cloning, Molecular; D006224:Cricetinae; D018076:DNA, Complementary; D004596:Electroretinography; D007150:Immunohistochemistry; D008124:Locomotion / Q000502:physiology / Q000528:radiation effects; D008647:Mesocricetus; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D017949:Retinal Cone Photoreceptor Cells / Q000737:chemistry* / Q000502:physiology / Q000528:radiation effects; D017299:Rod Opsins / Q000032:analysis / Q000235:genetics* / Q000378:metabolism; D017422:Sequence Analysis, DNA; D014466:Ultraviolet Rays
D018076:DNA, Complementary; D017299:Rod Opsins