The primordial, blue-cone color system of the mouse retina.
Humans and old world primates have trichromatic color vision based on three spectral types of cone [long-wavelength (L-), middle-wavelength (M-), and short-wavelength (S-) cones]. All other placental mammals are dichromats, and their color vision depends on the comparison of L- and S-cone signals; however, their cone-selective retinal circuitry is still unknown. Here, we identified the S-cone-selective (blue cone) bipolar cells of the mouse retina. They were labeled in a transgenic mouse expressing Clomeleon, a chloride-sensitive fluorescent protein, under the control of the thy1 promoter. Blue-cone bipolar cells comprise only 1-2% of the bipolar cell population, and their dendrites selectively contact S-opsin-expressing cones. In the dorsal half of the mouse retina, only 3-5% of the cones express S-opsin, and they are all contacted by blue-cone bipolar cells, whereas all L-opsin-expressing cones (approximately 95%) are avoided. In the ventral mouse retina, the great majority of cones express both S- and L-opsin. They are not contacted by blue-cone bipolar cells. A minority of ventral cones express S-opsin only, and they are selectively contacted by blue-cone bipolar cells. We suggest that these are genuine S-cones. In contrast to the other cones, their pedicles contain only low amounts of cone arrestin. The blue-cone bipolar cells of the mouse retina and their cone selectivity are closely similar to primate blue-cone bipolars, and we suggest that they both represent the phylogenetically ancient color system of the mammalian retina.
Haverkamp
Silke
S
Department of Neuroanatomy, Max-Planck-Institute for Brain Research, D-60528 Frankfurt/Main, Germany.
Wässle
Heinz
H
Duebel
Jens
J
Kuner
Thomas
T
Augustine
George J
GJ
Feng
Guoping
G
Euler
Thomas
T
D000818:Animals; D019393:Arrestin / Q000378:metabolism; D016764:Cell Polarity; D003118:Color Perception; D066298:In Vitro Techniques; D008164:Luminescent Proteins / Q000235:genetics; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D011993:Recombinant Fusion Proteins / Q000235:genetics; D017949:Retinal Cone Photoreceptor Cells / Q000166:cytology* / Q000378:metabolism; D017299:Rod Opsins / Q000378:metabolism
D019393:Arrestin; D008164:Luminescent Proteins; D011993:Recombinant Fusion Proteins; D017299:Rod Opsins; C415371:clomeleon