[Determination of pyrimidine nucleotide sequences of DNA]

A modification of the Burton method for determination of pyrimidine nucleotide blocks (isopliths) of DNA, providing a higher yield of large-sized nucleotide isopliths, is described. The amount of side products (interisopliths) does not exceed their amount upon DNA hydrolysis according to the Burton method. Another advantage of the technique recommended is a considerable shortening of hudrolysis time (20 min instead of 18 hours). The modification described has been successfully used to determine the pyrimidine nucleotide blocks of some warm-blooded animals DNAs. It has been found that the DNA of animals with higher sensitivity to ionised irradiation contains more oligothymidylic sequences as compared to the DNA of animals, less sensitive to irradiation.