D 2O induced alterations of mitosis in PtK 1, cells

Abstract

Deuterium oxide (D 2O) was applied to PtK 1 cells to assess its effect on mammalian mitosis. Cells exposed to culture medium containing up to 50% D 2O were able to enter and complete mitosis, but the duration of mitosis was increased proportionally to the concentration of D 2O applied. Cells exposed to 50% D 2O showed increases of more than 300% for the interval between nuclear envelope breakdown and anaphase onset, and approximately 65% for the interval between anaphase onset and initial furrowing. At a concentration of 80%, D 2O acted as an inhibitor of mitosis; after 8 h exposure to this concentration, cultures showed an increase in the proportion of mulinucleate cells and an absence of mitotic figures. When applied early in anaphase, 80% D 2O effectively slowed chromosome separation, prolonging anaphase for more than 60 min. Normal chromosome motion was restored when medium containing D 2O was replaced with control medium. Mitotic chromosomes remained condensed throughout prolonged anaphase intervals. Immunofluoresence examination of spindles stained using a monoclonal anti-tubulin revealed no pronounced increase in microtubule polymerization after exposure of cells to 20–80% D 2O.