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

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.

微生物的生态位（niche）由其种群能够扩张的生境所决定。种群可因死亡率过高或出生率过低而无法增殖，但在微生物中精准测定这两项参数颇具挑战。我们开发了一项全新技术，可对出芽繁殖的酿酒酵母（Saccharomyces cerevisiae）中年龄结构型的出生率与死亡率开展单细胞水平测定（single cell measurement），并利用该方法针对一组遗传多样性菌株的热应激响应展开研究。研究发现，热应激过程中，单个细胞的出生率与死亡率存在显著异质性。调控不对称细胞分裂（asymmetric cell division）过程的基因型-环境互作（Genotype-by-environment）效应是该异质性的重要成因。此类效应会在热应激期间引发细胞过早衰老或早期死亡，我们发现，线粒体遗传缺陷（mitochondrial inheritance defect）可解释所研究菌株中某一株的早期死亡表型（phenotype）。本研究阐明了生理状态、遗传变异与环境变量之间的相互作用如何调控微生物种群的存活与繁衍。