Strong contrast of hypermethylation in females and hypomethylation in males within the sex determination region (SDR) of channel catfish during early sex differentiation of 9, 12, and 16 days post fertilization (dpf). Red color indicates hypermethylation, green color indicates intermediate methylation, and blue color indicate hypomethylation. Samples included females at 9 dpf (F9), females at 12 dpf (F12), and females at 16 dpf (F16), males at 9 dpf (M9), males at 12 dpf (M12), and males at 16 dpf (M16). The SDR and epigenetically marked locus are indicated. Numbers at the lower border are nucleotide positions of the differentially methylated CpG sites along the sex chromosome. Figure was adopted from Yang et al. (2022)