Comparative study of transcriptome profiles in the eyes and brain of the tiger puffer Takifugu rubripes brooder under red light filtered LED

Light spectrum is an important environmental factor affecting fish activities. However, the existing studies on spectrum are usually conducted under monochromatic light, which are multiple variables compared to the natural light conditions and increase uncertainty. The results may be caused by the absence of all other chromatic lights. The tiger puffer Takifugu rubripes is an important commercial marine fish in China, Japan, and Korea. In this study, the effects of red light on the eyes and brain of T. rubripes brooder, including histological changes in retina and optic tectum, the levels of oxidative stress indicators in serum, and changes in gene expression at transcriptome level were examined, after the treatment of full spectrum LED (Fs) and red light filtered LED (Rf) for 52 days. The results showed that the growth and histological structure of retina and optic tectum were not significantly altered. While, Rf significantly decreased the activity of superoxide dismutase and catalase, and increased the content of cortisol (P < 0.05), but had no effect on the levels of glutathione peroxidase and malondialdehyde. Transcriptome data revealed that there were 147 differentially expressed genes (DEGs) in the eyes of Rf vs Fs. Many DEGs related to vision changed significantly. KEGG enrichment and GSEA analyses showed that the significantly enriched arachidonic acid pathway down-regulated in the Rf group, in which genes related to sexual maturation and ovulation presented significant changes, suggesting that Rf may affect the ovulation process through this pathway. In the brain, the number of DEGs was only 20, which are most correlated with circadian rhythm. The present study displayed for the first time the role of red light in promoting ovulation in mature fish by filtering it, which may provide more supports to highlight the function of red light in fish culture.