Figure 2.

DNA from A. carterae is highly resistant to digestion by restriction enzymes that are sensitive to CpG methylation. Aliquots (10 μg) of genomic DNA prepared from cells grown under high-light conditions were digested with a 6-fold excess of the restriction enzymes indicated and subjected to electrophoresis on 1% (w/v) agarose, and the gels were stained with ethidium bromide. Control lanes (C) were treated exactly as digests, except that restriction enzymes were not added. Lanes λH and λM correspond to restriction digests of A. carterae DNA to which 3 μg of bacteriophage λDNA was added. C, Methylation sensitivities and recognition specificities of the endonucleases used. “+” indicates that digestion with the restriction endonuclease is inhibited by a 5-MeC at that position. “o” indicates that digestion with the restriction endonuclease was not inhibited by a 5-MeC at that position.