Comparative transcriptome analyses reveal changes of gene expression in turbot (Scophthalmus maximus) embryos exposed to different LED light spectra and potential photosensitive function of non-visual opsins

This study describes the transcriptome profiles of turbot (Scophthalmus maximus) embryos exposed to various light spectra, helping to better understand the importance of light spectrum on the development of fish embryo. When exposed to red, orange, green or blue light, up-regulated genes were significantly enriched into lipid, carbohydrate metabolism, indicating enhanced energy consumption compared with full-spectrum light. Molecular functions related to signal transduction, such as supramolecular polymers/complexes/fibers, protein dimerization, were down-regulated in red, orange, and blue groups, while calcium ion binding was up-regulated under green light, indicating that turbot embryo might be more sensitive to green light. The transcription regulator activity and DNA binding transcription factor activity related to retina and nervous system development were down-regulated in orange, green and blue groups, suggesting full light spectrum could be more conducive to the development of nervous system. Moreover, orange light could be advantageous for enhancing the antioxidant capacity, while green light caused abnormal expression of some development related genes. The non-visual photoreceptors with vertebrate ancient opsin and exorhodopsin expression in hypothalamus, hindbrain and pineal area played mainly photosensitive roles. This study provides new insights into the molecular mechanisms underlying photosensitive-phototransduction-physiological-development process in fish embryos and further confirmed the feasibility of utilizing orange light and full spectrum light to establish optimized developmental light spectrum environment in turbot embryo incubation systems.