On the Ultrastructure of Yeast Cells

Abstract

Summary: The ultrastructure of yeast cells was first studied in 1957 and the techniques used since then have advanced greatly; an overview of the methods is first presented in this minireview. We achieved high-pressure freezing(HPF)fixation for yeast and developed HPF at ultra-low temperature which required using low voltage SEM(ULT-LVSEM)and immunoelectron microscopy. The cell wall biogenesis of the fission yeast Schizosaccharomyces pombe was defined using this technique. The high quality image of HPF. EULT-LVSEM showed an ultrastructure corresponding to a thin sectioned cell and could be observed three dimensionally from the outside and inside of the cell, allowing the initial septum formation to be seen. Using the antibodies of glucans from this yeast, the cells displayed in situ localization of glucans in the cell wall and Golgi apparatus, and their behavior during septum formation. Highly branched. β-1, 6-glucan was not detected in the first step, but all other glucans, . β-1, 3-and.a-1, 6-glucan, appeared throughout the septum until the secondary septum was formed. Accompanying septum formation the actin was located at the tip of the invaginated cell membrane and also accumulated at the contracted ring in the cell. From these facts it is concluded that the actin cytoskeleton governs septum formation during cell division.