[Cell population structure and nuclear macromolecular synthesis at different stages of the cell cycle in Guerin's carcinoma according to the data from the sedimentation fractionation of isolated nuclei].

For separating isolated nuclei of the Geren carcinoma, according to phases of the cell cycle, the sedimentation fractionation technique in steep gradients of sucrose at 1 g was used. Four peaks were displayed on a sedimentogram, corresponding to the four bands of sedimentating nuclei. From the results of DNA determination and of thymidine-3H incorporation in "pulse chase" experiments, the three peaks of the sedimentogram are identified as those corresponding to nuclei being in G1- and G2-periods of cycles of diploid and tetraploid tumour subpopulations, and ranges between the peaks are identified as nuclear fractions corresponding to S-periods of cycles of both the subpopulations. Data on synthesis of nuclear macromolecules allow us to suppose, that one of the peaks on the sedimentogram may correspond to nuclei of diploid cells being in the late G1-period of the cell cycle.