Comparative Epigenomic Profiling and Gene Expression Patterns of Zebrafish, Danio rerio, Administrated by Dietary Agrimos

The different aspects of using dietary supplements such as prebiotics in aquaculture and their effects on innate immune response, and especially their vertical transmission, are of a grave importance. To address such issues in both horizontal and vertical transmission of boosting immune system, the present study was designed to investigate the effect of different levels of dietary Agrimos® on the innate immune-related gene expression [Lysozyme (Lyz) and Tumor Necrosis Factor alpha (TNFα)], DNA methylation, and three Histone MethylTransferase [HMTs (H3K4, H3K9, H3K27)] activities as well as growth performance in zebrafish (Danio rerio). Three hundred and sixty healthy 24-days-old zebrafish were randomly distributed in twelve aquaria assigned to four groups. Zebrafish were fed with either control diet or a diet supplemented by different levels (0.2, 0.4, and 0.8%) of Agrimos® for 90 days. The offspring of each treatment was assessed to find the potential of vertical transmission of immunity by using this dietary prebiotic. At the end of the experiment, gene expression studies revealed significant up-regulation (P˂ 0.05) of TNFα and Lyz genes in 0.2 and 0.4% Agrimos® fed fish compared with the control group. Although our findings showed that supplemented diet reduced DNA methylation (P˂ 0.05) in Agrimos® treatments compared with the control, there was no significant change in all three HMTs’ activities among experimental groups (P> 0.05). The result shows the successful transmission of Lyz gene expression as an innate immune response to the offspring of the treated adults and supports a direct role of DNA demethylation in the regulation of these candidate gene expressions, suggesting possible role of diet on regulating the epigenetic processes.