Environmentally controlled dimorphic cycle in a fission yeast

Abstract

The fission yeastSchizosaccharomyces pombeshows bipolar growth and is a convenient model for studying cell polarity and polar growth. This paper shows that the relatedSchiz. japonicusvar.japonicuscan switch to unipolar growth and can exist in both yeast and mycelial phases. On solid media, the yeast phase is unstable and prone to switch to the mycelial form, which shows unipolar growth by tip elongation. The hyphae can colonize the body of the substrate (true mycelium) or just its surface (pseudo-mycelium). The yeast-to-mycelium transition and the growth of the mycelium are regulated by a nutritional gradient and are associated with extensive vacuolation. The mycelium can convert into arthroconidia or return to the yeast phase in response to environmental changes. These environmentally controlled morphological transitions makeSchiz. japonicusvar.japonicusan attractive model for the investigation of cell polarity and morphogenesis.