in all dnas studied 5-methylcytosine is unevenly distributed in pyrimidine isopliths : the degree of cytosine methylation [ m5c ( c+m5c ) ] is decreased with an increase in the length of isopliths , irrespective of the ratio of thymine and cytosine residues .
C0049308
5-methylcytosine
C0010843
cytosine