Evidence for Cytosine Methylation in Ribosomal RNA Genes and in a Family of Dispersed Repetitive DNA Elements in Agaricus bisporus and Selected Other Agaricus Species

Li, A., and Horgen, P. A. 1993. Evidence for cytosine methylation in ribosomal RNA genes and in a family of dispersed repetitive DNA elements in Agaricus bisporus and selected other Agaricus species. Experimental Mycology 17, 356-361. Evidence for the methylation of Agaricus repetitive DNA sequences was demonstrated using restriction enzyme analysis and DNA hybridization. Our results indicate that 5-methylcytosine (^5mC) was the only methylated base detected. The nucleotide was present as the internal cytosine of the CCGG recognition sequence in the ribosomal RNA genes and in a family of dispersed repetitive DNA elements of the commercial mushroom, Agaricus bisporus and selected other Agaricus species. Densitometry analysis revealed more methylation in the rDNA than in the dispersed repetitive elements. No methylation of cytosine residues was detected in mitochondrial ribosomal RNA genes nor in the inverted repeated sequences of the A. bisporus mitochondrial genome.