DNA methylation status of the promoter regions of Cdkn1a and Ihh in the liver of mice exposed to different doses of TCE (0, 100, 500 and 1000 mg/kg b.w.) (n = 3).

A, D) Nucleotide sequences of Cdkn1a and Ihh promoter region fragments (upper strands) and the corresponding bisulphite-converted sequences (lower strands). CpG dinucleotides are numbered and marked in bold. The restriction enzyme cut sites are marked in italic. Primer sequences are underlined. B, E) Bisulfite sequencing of the Cdkn1a and Ihh promoter regions. Open and closed circles indicate unmethylated and methylated CpG sites respectively. Percent methylation is shown in parentheses. C) COBRA result of the promoter region of Cdkn1a at CpG4-5(CGCG) by BstUI 184 bp (84/100); L: Tiangen DNA ladder II; P, positive control by treating mouse genomic DNA with M.SssI. C, liver samples from mice exposed to corn oil; T, liver samples from mice exposed to TCE at 1000 mg/kg b.w. M, methylation; UM, unmethylation.