Direct visualization of site-specific and strand-specific DNA methylation patterns in automated DNA sequencing data.

We report here a simple method of directly visualizing in automated DNA sequencing chromatograms DNA methylations of different types including cytosine methylations in Hpa II and dcm sites as well as adenine methylations in dam sites. This is made possible by the observation that the extent of incorporation of fluorescently labeled dideoxynucleotides is influenced by the methylated bases in template DNA. This simple approach involves routine automated DNA sequencing without any prior treatment of DNA specific for detecting DNA methylation.