Effect of divalent cations and chelators on metaphase to telophase progression and nuclear envelope formation in Chinese hamster cells.

Chinese hamster DON cells in log phase were treated with Colcemid in the G2 period with or without divalent cation chelating agents. The metaphase cells were isolated and incubated in two ways: 1) without Colcemid but with chelating agents or La3+ and observed for metaphase to telophase progression, and 2) with Colcemid, with or without chelating agents and the rate of micronuclei formation in the absence of anaphase monitored. The effect of the chelating agents on cellular 45Ca2+ during metaphase to telophase progression was also studied. The results indicate that Ca2+ and possibly Mg2+ ions are involved in the regulation of certain segments of mitosis. The reduction of environmental and plasma membrane associated Ca2+ with the chelators and La3+ promoted the metaphase to telophase progression as well as nuclear envelope and micronuclei formation.