Exploring Tissues-Bias DNA Methylation of Two Sex-Related Genes (Cyp19a1 and Dmrt1) in Correlation with Gene Expression in Japanese Anchovy (Engraulis Japonicus)

Recent epigenetic research suggests that the methylation pattern of several sex-related genes (e.g., dmrt1, cyp19a1, etc.) varies according to fish size, age, sex, and surrounding environment, affecting final maturity and seed quality. Notably, Japanese anchovy (Engraulis japonicus), a small pelagic fish constituting one of Japan's most important fishery resources, has many advantages and is increasingly recognized as an upcoming model organism for marine research. However, there is insufficient research on the epigenetic mechanism of genes involved in this target. This research intends to understand more about the DNA methylation level of two sex-related genes in Japanese anchovy in three different tissues (pituitary, liver, and gonad). We also compared the DNA methylation level with the relative gene expression of both genes in the gonad to better understand the relationship between these mechanisms in Japanese anchovy. We found that there is gonad and sex-biased DNA methylation compared with liver and pituitary. The relative gene expression analysis also confirmed a gender bias and a strong correlation between DNA methylations and gene expressions of both genes. For these two genes, the DNA methylation level of cyp19a1 is higher in females, whereas the gene expression is lower in females, and the results for dmrt1 are opposite. The results of this study confirmed that dmrt1 and cyp19a1 are sex-related genes and their expression has a strong relationship with sex development in Japanese anchovy.