Patterns of extension growth of the fission yeast, Schizosaccharomyces pombe

The growth of sausage-shaped cells of the fission yeast, Schizosaccharomyces pombe (strain NCYC 132), was followed in the second or third cycle by time-lapse photomicrography. Experimental cells were harvested from glucose-limited (0.2% glucose EMM3) chemostat culture (dilution rate, 0.125/h) and were plated onto a slide with EMM3 agar (2% glucose). By observing their extension patterns, we found some rules of extension growth. Thus, (1) all sibs with walls newly formed in the previous cycle, whose progenitor cells grew at the old end (followed Mitchison's rule), grow at the old end (also follow Mitchison's rule). (2) Sibs with old walls whose progenitor cell followed Mitchison's rule behave in one of three ways: (i) growth at the old end (follow Mitchison's rule); (ii) growth at the new end (violate Mitchison's rule); or (iii) growth at both ends (bipolar). (3) Both sibs whose progenitor grew at both ends (bipolar) always grow at the old end (follow Mitchison's rule).