Cell cycle and growth control in Candida Species

This chapter describes the major Candida albicans morphologies and the current understanding of the cell biological and cell cycle features that distinguish them. It highlights recent insights into how cell cycle regulators influence the formation of hypha-specific cellular features in particular. Since morphogenesis and cell cycle regulation have been studied most extensively in C. albicans, the chapter primarily focuses on work in C. albicans. The important distinction between yeast and pseudohyphae is that pseudohyphae spend more time in G2 phase of the cell cycle than yeast cells , and they continue to elongate during this time. There has long been a controversy as to how pseudohyphae are related to true hyphae. Initial models suggested that yeast cells, pseudohyphae, and true hyphae reside along a continuum. Later, based on differences in cell cycle dynamics and subcellular structures, it was proposed that pseudohyphae and hyphae represent two distinct morphological states, with pseudohyphae being more like yeast form growth with respect to cell cycle progression and cell biological markers. Recent work has shed light on cell biological features associated with cell cycle progression in chlamydospores and is discussed in theis chapter. In the C. albicans genome sequence, there are three G1 cyclins (Ccn1, Cln3, and Hgc1) and two G2 or B-type/mitotic cyclins (Clb2 and Clb4) that are predicted to associate with Cdc28.