Expansion of the Candida albicans cell envelope in different morphological forms of the fungus

Abstract

Modes of cell envelope expansion were monitored in developing cells of Candida albicuns 731055 to which polystyrene beads were attached. Eight different conditions of culture medium, pH and temperature were used to promote growth in a variety of morphological forms. The cells were observed microscopically during growth in Sykes-Moore perfusion chambers, and sequential measurements of distances between the bead and the parent cell, and the bead and the apical tip were used to distinguish apical envelope expansion from general envelope expansion. Morphology index (Mi) was determined at each time point as an estimate of each cell's morphology. Calculations based on the measurements showed that general envelope expansion was inversely proportional to Mi, but that general expansion greater than 20% occurred only in cells with a final Mi < 2.0, indicating that regulation of apical and general envelope expansion alone may be insufficient to determine the different morphologies seen in cells with higher Mi. The rate of expansion of the perimeter of cells was linearly proportional to the final Mi. This observation suggests that commitment to morphological development in C. al6icans may in part involve commitment to a rate of envelope expansion, which itself helps determine the final morphology of a cell.

Mapping the Growth of Fungal Hyphae: Orthogonal Cell Wall Expansion during Tip Growth and the Role of Turgor

“…The photographic images, taken at 15-min intervals, clearly defined the topography of the apical growth zone of the sporangiophore. Other external markers, such as carbon particles (Grove et al, 1970) and polylysinecoated beads (Staebell and Soll, 1985;Merson-Davies and Odds, 1992) have been successfully employed to map growth zones of fungal hyphae. In the present study, we have extended the potential of this methodology by introducing computer-enhanced videomicroscopy to record images and image analysis to make measurements.…”

Image analysis of the morphology of filamentous micro-organisms

“…Although this method did not exploit the full potential of image analysis, being essentially manual, measurements of main hyphal length (longest connected path), total length and hyphal diameter and derived values such as hyphal growth unit could be generated. A similar method using drawn lines on a monitor was used by Merson-Davies & Odds (1992) to study the morphology of Candida albicans. Martin & Bushel1 (1996) used a simple but elegant method to relate antibiotic production to sites of synthesis at known distances from the extending tip in Saccharopolyspora erythraea.…”

“…This would increase its value in studies of dimorphism in yeasts. It might also be useful to characterize dimorphism using the ' morphological index' of Merson-Davies & Odds (1992). Although Merson-Davies & Odds (1992) used very simple image analysis techniques, the concept of defining with a single number a cell shape in the continuous range of morphologies from spherical cells to true hyphae has clear potential.…”

FcStuA from Fusarium culmorum Controls Wheat Foot and Root Rot in a Toxin Dispensable Manner

“…cerevisiae and in C . albicans Phd1p, Sok2p, Efg1p, and Efh1p regulate genetic physiological and biochemical mechanisms responsible for dimorphic transition [7], [9], [10]. Asm-1 controls sexual and asexual reproduction.…”