Ultrastructure of cell wall of the cps8 actin mutant cell in Schizosaccharomyces pombe

A Schizosaccharomyces pombe cps8 mutant, of which the gene encodes a mutant actin with an amino acid substitution of Asp for Gly(273) [J. Ishiguro and W. Kobayashi (1996) FEES Lett. 392, 237-241], was used to determine the ro le of the actin cytoskeleton in cell wall formation. In the cps8 mutant cel ls, atomic force microscopic and scanning electron microscopic images showe d abnormal depolarized and branched morphology. Fibrous material covered a part of the surface of growing cps8 cells. Transmission electron microscopi c images showed variable thickness of the cell wall due to multilayering of cell wall materials, and aberrant multisepta due to diagonal growth of the primary septum, whereas the normal primary septum grows at a right angle f rom the cortex. This abnormal septum formation may induce abnormality of th e cell with multinuclei and/or multisepta, caused by non-separation of daug hter cells. These results indicate that actin plays an important role in ce ll wall and septum formation. (C) 1999 Federation of European Microbiologic al Societies. Published by Elsevier Science B.V. All rights reserved.