[Precise DNA cytometry: investigation of individual variability in animal genome size]

The variability of genome size was studied in animal populations and in cell populations of different animal species by means of DNA flow cytometry with the precision level of several tenths of percent. For populations of frog Rana esculenta and laboratory mouse lines C57B1 and CBA the analysis was made with cells of different tissues: erythrocytes for R. esculenta, splenocytes for mice and haploid cells of testes for both species. The results of DNA cytometry, obtained with cells of different species, were shown to be correlated, which indicates the objectivity of individual intrapopulation differences in the genome size recorded with DNA flow cytometry. The level of variability (expressed as CV) was 0.3-0.4% for the population of frogs, and 0.2-0.3% for mouse lines. The analysis of genome size variability in cell populations of different animal species revealed a relationship between the variability level and the genome size: the coefficient of variance of the peak of DNA histogram was inversely related to the square root of genome size. The latter effect may be explained by fluctuations of a measured multicomponent object, but it is still unclear whether these fluctuations could be related to the genome size or to pecularities of chromatin structure. It is concluded that the method of flow DNA cytometry may be effective for studying individual differences in the genome size.