  High hydrostatic pressure is commonly encountered in many environments, but
the effects of high pressure on eukaryotic cells have been understudied. To
understand the effects of hydrostatic pressure in the model eukaryote,
Saccharomyces cerevisiae, we have performed quantitative experiments of cell
division, cell morphology, and cell death under a wide range of pressures. We
developed an automated image analysis method for quantification of the yeast
budding index - a measure of cell cycle state - as well as a continuum model of
budding to investigate the effect of pressure on cell division and cell
morphology. We find that the budding index, the average cell size, and the
eccentricity - a measure of how much the cell morphology varies from the being
elliptical - of the cells decrease with increasing pressure. Furthermore, high
hydrostatic pressure led to the small but finite probability of cell death via
both apoptosis and necrosis. Our experiments suggest that decrease of budding
index arises from cellular arrest or death at the cell cycle checkpoints during
different stages of cell division.
