cell cycle in the fission yeast, Schizosaccharomyces pombe. IV. Relationship between cell size and cycle time of non-growing cells due to a nutritional shift-down

To prepare an oversized and synchronized cell sample, exponentially growing cells of Schizosaccharomyces pombe were exposed to 8 mM hydroxyurea for 3 h, then transferred to a poor medium (0.5 % malt medium or nitrogen-free minimal medium). The transferred cells were grown in a small chamber without shaking and observed by time-lapse photomicrography. Cells cultivated in the poor medium divided twice synchronously, but hardly elongated in cell length between the two divisions. Under this condition, the relationship between cell size and cycle duration (the time interval between the divisions) was investigated. Cells smaller than a particular size had a negative correlation between cell size at birth and cycle duration. Cells above the particular cell size had a constant minimum cycle duration. Cells divided regardless of size at division. These results suggest that cycle duration depends on cell size at birth, not at division.