[Determination of structural differences in DNA by pyrimidine isopliths ratios]

Using a modified Burton procedure, twelve pyrimidine nucleotide isopliths of DNA from five mammalian species (human, rabbit, guinea pig, rat and cattle) were determined. A method is proposed for mathematical estimation of DNA block analysis data, revealing a correlation between the specific DNA primary structure, the systemic status of the organism under investigation and the organism's radiosensitivity. In some cases DNA structural differences as determined by pyrimidine isoplith ratios help to distinguish between families of the same mammalian order. Quantitative isoplith ratios demonstrate that ionizing radiation treatment brings about certain changes in DNA primary structure. Their direction is quite the opposite to the main trend in the changes of DNA structure in the course of biological evolution.