Methylation pattern of CpG dinucleotides in the chicken α^π-globin gene promoter.

(A) The chicken α^π-globin gene promoter sequence. The bent arrow indicates the transcription start site. CpG dinucleotides are in bold and underlined. (B) Methylation analysis of the chicken α^π-globin gene promoter in primary erythroid cells during development. Arrows indicate cytosine residues at CpG dinucleotides. These cytosines have been completely converted to thymidines (indicating unmethylated cytosines) in DNA from day 5 embryonic erythroid cells. Progressive failure of conversion to thymidines (indicative of methylation) is seen during development, and DNA derived from adult erythroid cells shows methylated cytosines.