Fig. 2. Methylation status of individual DNA strands in (A) the H19 upstream differentially methylated domain (DMD) (paternal strands shown) and (B) Snrpn promoter-exon 1 region (maternal strands shown) in cultured blastocysts as determined by bisulfite mutagenesis analysis. Unmethylated CpGs are represented as empty circles, while methylated CpGs are depicted as filled circles. Each line denotes an individual strand of DNA with the number of strands showing a given pattern indicated to the left. Bar height indicates the percentage of strands that have a methylated CpG at each specific site. Paternal and maternal alleles are depicted by black and gray bars, respectively. For H19, a base pair change in the paternal B6 allele eliminates CpG dinucleotide 8, while for Snrpn, CpG dinucleotide 1 is not present in the maternal CAST allele.