We assessed, by light and electron microscopy, the influence of deuterium oxide on the dynamics of mitosis and on the morphology of the mitotic apparatus in HeLa cells grown in vitro. A 2-h incubation of HeLa monolayers with low concentrations of D2O (1%-25%) in the medium increased the frequency of multipolar divisions up to 20 times the control level. Substitution of 10% and 25% D2O for H2O induced changes in the proportions of mitotic phases. These changes could be fully reversed to the control pattern after 1 h of recovery in non-deuterated medium. Fifty % D2O strongly inhibited, and 75% D2O blocked the cell cycle before prophase and at (pro-)metaphase. In cells treated with 50% D2O conspicuous morphological changes of the interphase chromatin as well as ultrastructural abnormalities of all mitotic phases were regularly observed. Overall, these results confirmed the antimitotic activity of deuterium oxide and revealed that it could also influence the cell cycle before mitosis. It is suggested that interference with diverse cellular constituents rather than a specific influence on microtubule turnover could be responsible for the disorganization of the cell cycle in HeLa cells by D2O.
Chromatin Chromosomes