Polarized Morphogenesis of Candida Albicans: Cytology, Induction and Control
There can be few systems of cellular morphogenesis which have attracted such interest, yet have proved to be so recalcitrant to investigation as yeast-mould dimorphism in Candida albicans. Until very recently morphological mutants have not been available and the use of molecular genetics is in this organism still in its infancy. Since genetic techniques have not so far provided the means to explore this fascinating phenomenon, we have attempted instead to produce a cytological and physiological description of the yeast to hyphal transition and some of the early events which are associated with this process. In particular we have been motivated by work with other eukaryotic organisms such as the slime moulds and the true filamentous fungi which has shown that temporal and spatial fluxes of inorganic ions are often tightly coupled to cellular differentiation1,2. Based on this type of approach our studies on C. albicans suggest that germ tube formation occurs in response to nutrient poor conditions, especially when the supply of nitrogen is limiting. The pattern of cell growth reviewed below seems well adapted to these conditions. We find that there is a good correlation between an early rise in the cytoplasmic pH of the cell and the induction of germ tube growth. Our recent work studying the effects of applied electrical fields on germ tube formation and budding in C. albicans suggests that transmembrane fluxes of calcium ions are also of importance to germ tube formation. This article provides a brief description of these studies and their implication to the control of dimorphism in this organism.
KeywordsGerm Tube Germ Tube Formation Germ Tube Growth Exogenous Calcium Proton Efflux
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