Cell cycle regulation of histone H1O in CHO cells: a flow cytofluorimetric study after double staining of the cells.

The regulation of histone H1O content throughout the cell cycle of non-synchronized Chinese hamster ovary (CHO) cells has been studied using double fluorescent staining and flow cytofluorometry. In exponentially growing cells, the amount of H1O was found to be proportional to the DNA content of the cells, indicating that the protein is synthesized throughout the cell cycle. However, when cells were arrested in G1 at saturation density the amount of H1O was greater than that found in G1 cells of the exponentially growing population. In contrast, the levels of H1-1 were the same for G1 cells of both populations. These results show that the regulation of H1O accumulation differs from that of other histones.