Pattern of polar extension of the cell wall in the fission yeast Schizosaccharomyces pombe

The indirect fluorescent-antibody technique has been used to establish the pattern of polar extension in the fission yeast Schizosaccharomyces pombe 160 over a complete cell cycle in liquid medium, thus avoiding the possibility of perturbations being introduced by growth on an agar pad, which is the technique used in most other investigations. Nearly all of the cells (about 98%) showed more growth at the old end than at the new end that was formed by cleavage of the septum at the previous division. Importantly, there was no evidence of the abnormal growth pattern (i.e., the significant contribution of new ends to extension) in cells of S. pombe growing on agar pads reported by Miyata et al. (H. Miyata, M. Miyata, and B.F. Johnson. 1986. Can. J. Microbiol. 32: 528–530 and 1990. Can. J. Microbiol. 36: 390–394). In addition, extension over the cycle was inversely related to birth length (cells shorter than the mean at birth tended to produce daughter cells longer than themselves and vice versa), there was a small but significant asymmetry in the position of the septum, and the time of initiation of extension at the new end was estimated at about 0.24 of the cycle.Key words: Schizosaccharomyces pombe, fission yeast, cell-wall extension, end growth, cell cycle.