EXPRESSION OF ROD AND CONE VISUAL PIGMENTS IN GOLDFISH AND ZEBRAFISH - A RHODOPSIN-LIKE GENE IS EXPRESSED IN CONES

The primary purpose of the present study was to determine whether a rh odopsin-like gene, which has been postulated to represent the green co ne pigment in several species, is in fact expressed in cone photorecep tors instead of rods. The expression patterns of rod opsin and blue an d red cone opsins were also examined in both goldfish and zebrafish re tinas using colorimetric in situ hybridization. The results demonstrat e that the rhodopsin-like gene is expressed in green cones, as predict ed. A subset of small cones that do not hybridize with these cRNA prob es are tentatively identified as ultraviolet receptors. The results al so demonstrate that opsin message in cones is restricted to the perinu clear region, whereas in rods, it is both perinuclear and adjacent to the ellipsoid.