Control of cell division in yeast using the ionophore, A23187 with calcium and magnesium.

Abstract

A23187 is an ionophore which exhibits specificity for divalent cations and promotes their passive transport across biological membranes1. It therefore effects equilibration of divalent ions between the cell sap and the surrounding medium and counteracts any active accumulation of ions within the cell. Evidence, mainly from studies on sea urchin eggs, supports the hypothesis that calcium ions play an important part in bringing about cell division2–4. We have found that division in the fission yeast, Schizosaccharomyces pombe, is associated with a doubling in magnesium concentration within the cells5. It, therefore, seems likely that, if accumulation of divalent ions within the cell were an essential prerequisite of cell division, this should be inhibited by A23187 and cell division should not take place, and so we have investigated this possibility.