[Comparative analysis of the kinetics of renaturation of newly synthetized and total DNA of eukaryotes as a means of demonstrating selective genome synthesis].

A simple and sensitive method for determining the selective eucaryotic DNA synthesis (amplification, ordered replication) amounting up to 10(-6)% of genome has been proposed. The essence of the method is measuring of the combined renaturation of total and in vivo labelled newly synthesized DNA. By means of a special computer program a theoretical investigation of amplification (from 50 to 2-fold) was accomplished, based on the experimentally found renaturation curve of rat liver DNA. A new method of graphical analysis of experimental results is also proposed based on the changes in the specific activities against Cot values. Some advantages of the new graphical method, i. e. greater sensitivity and reliability, simplicity of calculation of the amplification level and of the proportion of radioactivity in the amplified sequences are shown. The major patterns of the changes in the specific activities in different examples of amplification were revealed. Evidence is presented that the amplification necessarily brings about essential changes in the specific activities of denatured and renatured DNA fraction at high Cot values. On the basis of the method developed, the mode of liver DNA synthesis in normal and hormone-induced rats was established. Both in the normal and hydrocortison-induced rat livers no selectivity of DNA synthesis was found in the sense that hormonal induction of RNA synthesis is not a consequence of additional synthesis of DNA templates.