Vacuolar dynamics during the morphogenetic transition in Candida albicans

Morphogenetic transitions between the yeast, pseudohyphal and true hyphal forms of the fungal pathogen Candida albicans are coordinated with the cell cycle. In true hyphae, large vacuoles are formed in subapical compartments that influence compartment size and hence cell cycle progression and branching frequency. Here, live-cell imaging techniques were applied to study the dynamic process of vacuolar segregation in the three different morphological forms of C. albicans. We show the presence of a filamentous vacuole segregation structure in pseudohyphae and true hyphae that differs from that of a stream of vacuole vesicles typical of vacuole inheritance in yeast cells. In growing hyphae, retrograde transport of the vacuoles led to apparent capture and adhesion of vacuoles to supapical septa, and septation events sometimes led to the bisection of large vacuoles that occupied sites of cytokinesis. Inhibitor studies also demonstrated that vacuole motility in C. albicans was actin dependent and microtubule independent.