Histone H3 occupancy at the promoters and exon 2 of the ε-, γ-, and β-globin genes in fetal and adult erythroblasts. (A) Histone H3 occupancy at the ε-, γ-, and β-globin gene promoters. The y-axis is the H3 amount relative to the external mouse Aire gene. The ε gene promoter contains the same amount of H3 as the Aire gene. In comparison with the ε promoter, the occupancy of H3 at the γ and β gene promoters is reduced in fetal and adult erythroblasts. (B) H3 occupancy in exon 2 of the ε-, γ-, and β-globin genes in fetal and adult erythroblasts. Exon 2 of the γ and β genes has the same amount of histone H3 as that at ε gene at both stages except β exon 2 in adult erythroblasts. (C,D) Acetylation levels per histone H3 between fetal and adult erythroblasts at the promoters and exons.