FIG. 7.

Alterations in DNA methylation at 28 5′-CG-3′ sites in the p3–p4 segment (Fig. 6) of the IAPI retrotransposon sequence in the Ad12-transformed hamster cell line T637 and in two λ DNA-transgenic BHK21 hamster cell lines, BHK21-λ7 and -λ10. Experimental details are described in the text. The numbering of the 5′-CG-3′ dinucleotides corresponds to that in Fig. 6. During the genomic sequencing experiments, 123 DNA clones from the reference BHK21 cell line, 79 DNA clones from the Ad12-transformed T637 cell line, 58 DNA clones from the BHK21-λ7 cell line, and 73 DNA clones from the BHK21-λ10 cell line were sequenced. The percentage values represent the average of methylated 5′-CG-3′ dinucleotides at each site for DNA from each of the cell lines. In many of the clones, 5′-CG-3′ positions 23 to 27 were in a deleted segment as part of a naturally occurring polymorphism in this region compared to the published nucleotide sequence (25). Furthermore, 5′-CG-3′ positions 19 and 35 were altered to 5′-TG-3′ in many clones and were therefore omitted from this analysis.