Gene Duplication and Spectral Diversification of Cone Visual Pigments of Zebrafish

Abstract

Zebrafish is becoming a powerful animal model for the study of vision but the genomic organization and variation of its visual opsins have not been fully characterized. We show here that zebrafish has two red (LWS-1 and LWS-2), four green (RH2-1, RH2-2, RH2-3, and RH2-4), and single blue (SWS2) and ultraviolet (SWS1) opsin genes in the genome, among which LWS-2, RH2-2, and RH2-3 are novel. SWS2, LWS-1, and LWS-2 are located in tandem and RH2-1, RH2-2, RH2-3, and RH2-4 form another tandem gene cluster. The peak absorption spectra (λmax) of the reconstituted photopigments from the opsin cDNAs differed markedly among them: 558 nm (LWS-1), 548 nm (LWS-2), 467 nm (RH2-1), 476 nm (RH2-2), 488 nm (RH2-3), 505 nm (RH2-4), 355 nm (SWS1), 416 nm (SWS2), and 501 nm (RH1, rod opsin). The quantitative RT-PCR revealed a considerable difference among the opsin genes in the expression level in the retina. The expression of the two red opsin genes and of three green opsin genes, RH2-1, RH2-3, and RH2-4, is significantly lower than that of RH2-2, SWS1, and SWS2. These findings must contribute to our comprehensive understanding of visual capabilities of zebrafish and the evolution of the fish visual system and should become a basis of further studies on expression and developmental regulation of the opsin genes.

Whole-genome resequencing of three Coilia nasus population reveals genetic variations in genes related to immune, vision, migration, and osmoregulation

“…Moreover, OPNLW was selected, and its expression in AP and SP were significantly lower than in LP. OPNLW is red-sensitive opsin and light-absorbing molecules that mediate vision [ 30 ]. Suspended particles in freshwater can cause short-wavelength light scattering, which may cause the visual image of fish to fade.…”

Use of Zebrafish Models to Boost Research in Rare Genetic Diseases

“…Photoreceptor cells are grouped into rods and cones, arranged in a mosaic pattern in the ONL and specialized for phototransduction. Zebrafish photoreceptor cells have two major subtypes, namely, rods, which are sensitive to light and permit for dim light vision, and cones, subdivided into four classes that include blue-sensitive cones (407-417 nm), green-sensitive cones (473-480 nm), red-sensitive cones (556-564 nm) and UV-sensitive cones (360-361 nm) [55,56]. The latter are involved in vision during bright light as well as color vision.…”

Behavioural red-light sensitivity in fish according to the optomotor response

“…Open Sci. 8: 210415 zebrafish [13] provoked an OMR is quite interesting. Although the expressed LWS opsin was present in a slight amount overall in the retina, this low amount appears to be enough to cause a behavioural response in zebrafish.…”

“…In trout, cichlid and anemonefish, some photoreceptor cells co-express spectrally distinct opsins [4][5][6][7][8]. Most fish species have more than one spectral cone type [9][10][11][12][13][14][15][16][17].…”