The quick and the dead: microbial demography at the yeast thermal limit

Abstract

The niche of microorganisms is determined by where their populations can expand. Populations can fail to grow because of high death or low birth rates, but these are challenging to measure in microorganisms. We developed a novel technique that enables single-cell measurement of age-structured birth and death rates in the budding yeast, Saccharomyces cerevisiae, and used this method to study responses to heat stress in a genetically diverse panel of strains. We find that individual cells show significant heterogeneity in their rates of birth and death during heat stress. Genotype-by-environment effects on processes that regulate asymmetric cell division contribute to this heterogeneity. These lead to either premature senescence or early life mortality during heat stress, and we find that a mitochondrial inheritance defect explains the early life mortality phenotype of one of the strains we studied. This study demonstrates how the interplay of physiology, genetic variation and environmental variables influence where microbial populations survive and flourish.

A role for cell polarity in lifespan and mitochondrial quality control in the budding yeast Saccharomyces cerevisiae

“…To assess the fidelity of axial budding, bud scars were visualized using wheat germ agglutinin (WGA), a chitin-binding agent. Inspired by TrackScar (Maxwell and Magwene, 2017), we sequentially stained yeast bud scars with WGA conjugated to different fluorescent dyes to distinguish new from old bud scars. Cells were first stained with Alexa 488-WGA to label all bud scars.…”

Enrichment of aging yeast cells and budding polarity assay in Saccharomyces cerevisiae

“…Here, we describe a method to determine the polarity of bud site selection during the yeast aging process by staining bud scars generated during consecutive rounds of cell division with two colors of AlexaFluor-conjugated WGA. This method is inspired by the TrackScar labeling technique ( Maxwell and Magwene, 2017 ).…”

A Role for Cell Polarity in Lifespan and Mitochondrial Quality Control in the Budding Yeast Saccharomyces cerevisiae

“…In order to assess the fidelity of axial budding, whereby new buds form adjacent to the previous bud site, bud scars were visualized using wheat germ agglutinin (WGA), a chitin-binding agent. Inspired by TrackScar (Maxwell and Magwene, 2017), we sequentially stained yeast bud scars with WGA conjugated to different fluorescent dyes to distinguish new from old bud scars.…”