Figure 3.

Candida albicans is polymorphic, displaying a range of cellular growth forms. C. albicans yeast cells can undergo phenotypic switching between white, grey and opaque growth forms that present with different shapes and cell surface characteristics (Gow, Brown and Odds 2002; Sudbery, Gow and Berman 2004; Xu et al. 2008; Huang et al. 2009; Mayer, Wilson and Hube 2013; Tao et al. 2014; Sun et al. 2015). These forms are induced in response to different environmental inputs, and hence are associated with different types of infection (Gow, Brown and Odds 2002). Significantly, the opaque form is associated with efficient mating in C. albicans (Miller and Johnson 2002), with grey cells displaying an intermediate mating competence between opaque and white cells (Tao et al. 2014). The gastrointestinally induced transition (GUT) phenotype is observed in C. albicans cells that ectopically express WOR1 (Pande, Chen and Noble 2013), a key regulator of commensalism. The transition from (white) yeast cells to pseudohyphae or hyphae is stimulated by a wide variety of environmental inputs, which include elevated temperatures, pH and peptidoglycan. Pseudohyphae can be distinguished from hyphae on the basis of the position of the septal junction between a mother yeast cell and its filamentous daughter, and by the presence of invaginations at these septal junctions in pseudohyphae, but not hyphae (Merson-Davies and Odds 1989; Sudbery 2001; Sudbery, Gow and Berman 2004). Candida albicans can be induced to form chlamydospores under specific environmental conditions (Jansons and Nickerson 1970), but the biological significance of this growth form remains obscure (Staib and Morschhäuser 2007). See text.