An electron microscopic study of bud development in Saccharomycodes ludwigii and Saccharomyces cerevisiae

Ruptured fission yeast walls. Structural discontinuities related to the cell cycle

Distributions of rupture sites of fission yeast cells ruptured by glass beads have been related to a new morphometric analysis. As shown previously (Johnson et al., Cell Biophysics, 1995), ruptures were not randomly distributed nor was their distribution dictated by geometry, rather, ruptures at the extensile end were related to cell length just as the rate of extension is related to cell length. The extension patterns of early log, mid-log, late log, and stationary phase cells from suspension cultures were found to approximate the linear growth patterns of Kubitschek and Clay (1986). The median length of cells was found to decline through the log phase in an unbalanced manner.

Method for immobilizing microbial cells on gel surface for dynamic AFM studies

The processes of cell growth and budding of the yeast cells Saccharomyces cerevisiae, which were gently immobilized on 3% agar and submerged in culture medium, were successfully imaged with an atomic force microscope for 6-7 h. Similar experiments on chemically fixed cells did not detect any appreciable change in their appearance except in a few scannings at the very beginning, indicating that the dissolution of agar and/or scraping of its surface by the scanning tip, if any, did not significantly interfere with the images taken thereafter. The increment in the height of many of the untreated cells, accompanied by their lateral enlargement, was taken as an indication of successful imaging of the growth process of yeast cells, together with an image of a growing daughter cell attached to its mother cell.

The fine structure of Hortaea werneckii

Hortaea werneckii (strain CBS 107.67) was examined by light and transmission electron microscopy (TEM). Special attention was paid to the wall architecture, the septum with a simple pore apparatus, the annellidic type of collar and the nuclei. Two-celled organisms showed signs of distoseptation; nuclear events appeared to be rather synchronous in both cells. The fine structural results provided evidence of endogenous conidia development.

The chitin-glucan complex of Saccharomyces cerevisiae. III. Electron-microscopic study of the prebudding stage

Differentiation of the cell wall of Saccharomyces cerevisiae at the site of the future bud was followed. A lentil-like structure originates on the inner side of the cell wall during the first phase. At the same time, an electron-dense layer occurs at the boundary between the inner layer of the cell wall and the lentil-like structure. During the second phase granular material is accumulated at the lower side of the lentil-like structure. During the third phase the lentil-like structure is split apart due to proliferation of the granular material resulting in formation of the base of the encircling region. The marked electron-dense layer observed from the first phase is attached to the surface of the encircling region during differentiation of the latter. During the budding proper the outer layers of the cell wall protrude and the end of the encircling region, together with the adjacent electron-dense layer, acquire their definitive appearance of rings, observed as marked electron-transparent and electron-dense tears on ultrathin sections.

Budding in the dimorphic fungus Phialophora dermatitidis

Ultrastructural comparisons of yeast and hyphal bud formation in Phialophora dermatitidis reveal that bud initiation is characterized by a blastic rupture of the outer portion of the yeast or hyphal wall and the emergence of a bud protuberance through the resulting opening. The wall of the emerging bud is continuous, with only an inner wall layer of the parental yeast or hypha. The outer, ruptured portion of the parental wall typically forms a collar around the constricted emergence region of the developing bud. The cytoplasm within the very young emerging bud invariably contains a small number of membrane-bound vesicles. The septum formed between the daughter bud and the parental yeast or hypha is a complete septum devoid of a septal pore, septal pore plug, or any associated Woronin bodies characteristic of simple septa of the moniliform or true hyphae. These observations suggest that yeast bud formation and lateral hyphal bud formation in the dimorphic fungus P. dermatitidis involve a growth process which occurs identically in both the yeast and mold phase of this human pathogenic organism.