A stochastic, molecular model of the fission yeast cell cycle: role of thenucleocytoplasmic ratio in cycle time regulation

We propose a stochastic version of a recently published, deterministic mode l of the molecular mechanism regulating the mitotic cell cycle of fission y east, Schizosaccharomyces pombe. Stochasticity is introduced in two ways: ( i) by considering the known asymmetry of cell division, which produces daug hter cells of slightly different sizes; and (ii) by assuming that the nucle ar volumes of the two newborn cells may also differ. In this model, the acc umulation of cyclins in the nucleus is proportional to the ratio of cytopla smic to nuclear volumes. We have simulated the cell-cycle statistics of pop ulations of wild-type cells and of wee1(-) mutant cells. Our results are co nsistent with well known experimental observations. (C) 2001 Elsevier Scien ce B.V. All rights reserved.