Research into Yeasts Focusing on its Cell Wall Formation

Abstract

This paper is a historical review of the fixation methods and techniques, for closer and more detailed observation of the ultrastructure of budding yeast Saccharomyces cerevisiae, which we developed with the use of transmission electron microscopy. In our study “Low-Voltage Scanning Electron Microscopy” (LVSEM) was used for uncoated biological specimens and “High-Pressure Freezing · Ultra-Low Temperature/LVSEM” for multi-purpose observation. These methods and techniques enabled us to observe more closely, and analyze with greater precision, the fine structures of yeast cells. This led to studies of cell wall formation from the reverting protoplast of the fission yeast Schizosaccharomyces pombe and its cell division; and of the correlation between cell wall formation and actin cytoskeleton. Further, we present some of the most recent achievements in the use of a new technique for visualizing the molecular structure of yeast cell wall components, using focused ion beam and micro-sampling which were applied to biological specimens. Our success in the visualization of the arrowhead structure of the F-actin in the fission yeast cell, by using myosin S1 decoration, enabled us to clarify the role of actin cytoskeleton during cell division and cell wall formation. Finally we discuss potential future studies of the yeast.