Abstract
High temperature causes ubiquitous environmental stress to microorganisms, but studies have not fully explained whether and to what extent heat shock would affect genome stability. Hence, this study explored heat-shock-induced genomic alterations in the yeast Saccharomyces cerevisiae. Using genetic screening systems and customized single nucleotide polymorphism (SNP) microarrays, we found that heat shock (52 °C) for several minutes could heighten mitotic recombination by at least one order of magnitude. More than half of heat-shock-induced mitotic recombinations were likely to be initiated by DNA breaks in the S/G2 phase of the cell cycle. Chromosomal aberration, mainly trisomy, was elevated hundreds of times in heat-shock-treated cells than in untreated cells. Distinct chromosomal instability patterns were also observed between heat-treated and carbendazim-treated yeast cells. Finally, we demonstrated that heat shock stimulates fast phenotypic evolutions (such as tolerance to ethanol, vanillin, fluconazole, and tunicamycin) in the yeast population. This study not only provided novel insights into the effect of temperature fluctuations on genomic integrity but also developed a simple protocol to generate an aneuploidy mutant of yeast.
Highlights
The yeast species Saccharomyces cerevisiae, like most cold-blooded organisms, experiences constant environmental change
Our main findings are that (1) heat shock can greatly simulate chromosomal instability in yeast, (2) more than half of the heat-shockinduced loss of heterozygosity (LOH) were initiated by recombinational lesions in the S/G2 phase of the cell cycle, (3) chromosomal aberration was the most frequent genomic alteration in the heat-shock-treated yeast cells, (4) different chromosomal aberration patterns were observed between the heatshock- and carbendazim-treated cells, and (5) heat shock drives phenotypic variations in yeast populations
We found that heat shock (52 °C for 4 min) elevated the crossover rate by about tenfold on the right arm of chr IV in yeast (Fig. 1)
Summary
The yeast species Saccharomyces cerevisiae, like most cold-blooded organisms, experiences constant environmental change. Yeast cells show optimal growth within a short temperature range (25–30 °C). (Morano et al 2012), and temperatures above 36 °C would trigger heat shock response in yeast cells and affect their normal physiological activities (Yamamoto et al 2007; Morano et al 2012; Caspeta et al 2014). Understanding how S. cerevisiae responds to heat shock would enrich our knowledge of cell biology but would provide references for developing robust strains for industrial application (Abdelbanat et al 2010; Huang et al 2018; Morard et al 2019). S. cerevisiae has been widely used to explore heat shock response modulators. High temperature can greatly induce heat shock proteins (HSPs) to prevent the formation of protein aggregates and to help proteins acquire their normal functions (Piper 1995; Morano et al 2012). Heat-shocktreated cells would accumulate trehalose, which stabilizes proteins and membrane (Conlin and Nelson 2007)
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