Microbes in nature frequently experience “boom or bust” cycles of environmental stress. Thus, microbes that can anticipate the onset of stress would have an advantage. One way that microbes anticipate future stress is through acquired stress resistance, where cells exposed to a mild dose of one stress gain the ability to survive an otherwise lethal dose of a subsequent stress. In the budding yeast Saccharomyces cerevisiae, certain stressors can cross protect against high salt concentrations, though the mechanisms governing this acquired stress resistance are not well understood. In this study, we took advantage of wild yeast strains to understand the mechanism underlying ethanol-induced cross protection against high salt concentrations. We found that mild ethanol stress allows cells to resume growth on high salt, which involves a novel role for a well-studied salt transporter. Overall, this discovery highlights how leveraging natural variation can provide new insights into well-studied stress defense mechanisms.

Background Throughout the first year of the COVID-19 pandemic, our research team monitored and documented policy changes in United States (U.S.) prison systems. Data sources included prison websites and official prison social media accounts. Over 2500 data sources relevant to the COVID-19 pandemic in U.S. prisons were located and summarized in to five different categories: 1) prevention, 2) case identification and intervention, 3) movement, 4) social communication and connection, and 5) programming, recreation, and privileges. Results All state prison systems reportedly enacted multiple policies intended to limit the spread of COVID-19 during the pandemic. Document analysis revealed that the most commonly released policies were restrictions on social contacts and privileges, basic preventive measures (e.g., distribution of masks), and basic case identification measures (e.g., verbal screening and temperature checks). Utilization of social media for policy communication varied significantly across states, though relevant data was more often released on Facebook than Twitter. Conclusions Together, our work provides foundational knowledge on the wide breadth of policies that were reportedly enacted in the first year of the pandemic that may be used as a base for quantitative work on policy effectiveness and examinations of implementation.

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27All living organisms must recognize and respond to various environmental stresses 28 throughout their lifetime. In natural environments, cells frequently encounter fluctuating 29 concentrations of different stressors that can occur in combination or sequentially. Thus, the 30 ability to anticipate an impending stress is likely ecologically relevant. One possible mechanism 31 for anticipating future stress is acquired stress resistance, where cells pre-exposed to a mild 32 sub-lethal dose of stress gain the ability to survive an otherwise lethal dose of stress. We have 33 been leveraging wild strains of Saccharomyces cerevisiae to investigate natural variation in the 34 yeast ethanol stress response and its role in acquired stress resistance. Here, we report that a 35 wild vineyard isolate possesses ethanol-induced cross-protection against severe concentrations 36 of salt. Because this phenotype correlates with ethanol-dependent induction of the ENA genes, 37 which encode sodium efflux pumps already associated with salt resistance, we hypothesized 38 that variation in ENA expression was responsible for differences in acquired salt tolerance 39 across strains. Surprisingly, we found that the ENA genes were completely dispensable for 40 ethanol-induced survival of high salt concentrations in the wild vineyard strain. Instead, the ENA 41 genes were necessary for the ability to resume growth on high concentrations of salt following a 42 mild ethanol pretreatment. Surprisingly, this growth acclimation phenotype was also shared by 43 the lab yeast strain despite lack of ENA induction under this condition. This study underscores 44 that cross protection can affect both viability and growth through distinct mechanisms, both of 45 which likely confer fitness effects that are ecologically relevant. 46 47 48