Developmental changes of opsin gene expression in ray-finned fishes (Actinopterygii)

Abstract

Fish often change their habitat and trophic preferences during development. Dramatic functional differences between embryos, larvae, juveniles and adults also concern sensory systems, including vision. Here we focus on the photoreceptors (rod and cone cells) in the retina and their gene expression profiles during the development. Using comparative transcriptomics on 63 species, belonging to 23 actinopterygian orders, we report general developmental patterns of opsin expression, mostly suggesting an increased importance of the rod opsin (RH1) gene and the long-wavelength sensitive (LWS) cone opsin, and a decreasing importance of the shorter wavelength sensitive cone opsin throughout development. Furthermore, we investigate in detail ontogenetic changes in 14 selected species (from Polypteriformes, Acipenseriformes, Cypriniformes, Aulopiformes and Cichliformes), and we report examples of expanded cone opsin repertoires, cone opsin switches (mostly within RH2) and increasing rod:cone ratio as evidenced by the opsin and phototransduction cascade genes. Our findings provide molecular support for developmental stage-specific visual palettes of rayfinned fishes and shifts between, which most likely arose in response to ecological, behavioural and physiological factors.

Retinal development and the expression profiles of opsin genes during larval development in Takifugu rubripes

“…Thus, each replicated opsin gene maintains the cell-type specificity and acquires different spectral sensitivities. As reported in other fishes, the expression of opsin genes showed developmental stagedependent patterns (Carleton et al, 2008;Lupše et al, 2021Lupše et al, , 2022, therefore the spectral properties (and whether they are longer-or shorter-shifted) of the RH2-1 and RH2-2 and their expression patterns in the development stage in T. rubripes should be further examined in the future. The short wavelength sensitive opsins consist of SWS1 and SWS2.…”