(A) Illustration of the steps involved in determining the methylation status of cytosines in a known DNA sequence by the bisulfite conversion method. (B) In vivo methylation of CpG dinucleotides of rho promoter in 5-day and adult chicken erythroid cells using bisulfite conversion technique. Arrows indicate methylated cytosines and are only seen in adult erythroid cells. Positions indicated are relative to the transcription start site. Cytosines that are not associated with CpG dinucleotides (sequence shown in [C]) have all been converted to thymidines in both 5-day and adult erythroid cells. (C) Graphic representation of the in vivo methylation of CpG dinucleotides of rho promoter in 5-day and adult chicken erythroid cells using bisulfite conversion technique. Arrows indicate methylated cytosines and are clearly seen in (A) (data not shown for CpG dinucleotide at position −15). Primers R and F indicate the sequence of rho globin promoter used for designating internal primers and for sequencing.