Topographic arrangement of S-cone photoreceptors in the retina of the diurnal Nile grass rat (Arvicanthis niloticus).
OBJECTIVE
The retina of Arvicanthis niloticus, a diurnal murine rodent closely related to Rattus (rats) and Mus (mice), contains approximately 30% to 35% cones and has several cone-driven functional characteristics found in humans. In this study the organization of these cone photoreceptors was examined, with emphasis on those expressing the S-opsin photopigment (S-cones).


METHODS
Cones were labeled with antibodies against M- and S-opsins. Their topographic arrangement was examined on images of retinal flatmounts using density measures, nearest-neighbor distance, and Voronoi domain analysis. Partial sequencing of the S-opsin DNA was also performed to determine whether this visual pigment was blue/violet or UV sensitive.


RESULTS
Cone photoreceptors (estimated total population approximately 1.450 million) came in two distinct types that express either M/L- or S-opsin. Both types were present across the retinal surface. S-cones (approximately 7-8% of the total cone population) achieved a higher density in a discrete temporodorsal sector of the retina. The S-cone mosaic was irregular. Finally, S-cones were likely to be UV sensitive, according to genetic analysis.


CONCLUSIONS
The topographic arrangement of cone photoreceptors in the retina of the diurnal Nile grass rat A. niloticus represents a highly pertinent model to improve understanding of the pathologic course of and related therapy for retinal disease involving cones.
Gaillard
Frédéric
F
Institut de Physiologie et Biologie Cellulaires, Université de Poitiers, UMR 6187, Centre National de la Recherche Scientifique, Poitiers, France.
Kuny
Sharee
S
Sauvé
Yves
Y
D000818:Animals; D015153:Blotting, Western; D002452:Cell Count; D002940:Circadian Rhythm / Q000502:physiology*; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect; D008297:Male; D051381:Rats; D017949:Retinal Cone Photoreceptor Cells / Q000166:cytology* / Q000378:metabolism*; D017299:Rod Opsins / Q000378:metabolism*; D015293:Transducin / Q000378:metabolism
D017299:Rod Opsins; C095853:short-wavelength opsin; D015293:Transducin