Characterization of Saccharomyces Cerevisiae Pseudohyphal Growth

Abstract

Diploid Saccharomyces cerevisiae strains undergo a dimorphic transition that involves changes in cell shape and the pattern of cell division and results in invasive filamentous growth in response to nitrogen starvation. Cells become long and thin and form pseudohyphae that grow away from the colony and invade the agar medium. Our data strongly suggest that pseudohyphae are initiated when yeast cells bud pseudohyphal cells in an asymmetric cell division. As pseudohyphae elongate, they become covered with yeast cells. Pseudohyphal cells may be vectors to deliver assimilative yeast cells to new substrates thereby allowing S. cerevisiae to forage for nutrients. Pseudohyphal growth requires the polar budding pattern of a/$α$ diploid cells; haploid axially budding cells of identical genotype cannot undergo this dimorphic transition. Mutation of SHR3, a gene required for amino acid uptake, enhances the pseudohyphal phenotype.