Hill Lucy, Guyot Stéphane, Bertheau Lucie, Davey Hazel
Department of Life Sciences, Aberystwyth University, Penglais, Aberystwyth SY23 3DA, UK.
Université Bourgogne Franche-Comté, L'Institut Agro, Université de Bourgogne, INRAE, UMR PAM 1517, 21000 Dijon, France.
Microorganisms. 2024 Sep 5;12(9):1838. doi: 10.3390/microorganisms12091838.
Experiments exposing to glucose limitation (calorie restriction) are widely used to determine impacts on cell health as a model for aging. Using growth on plates and in liquid culture, we demonstrated that calorie restriction reduces fitness in subsequent nutrient-limited environments. Yeast grown in a calorie-restricted environment took longer to emerge from the lag phase, had an extended doubling time and had a lower percentage of culturability. Cells grown under moderate calorie restriction were able to withstand a gradual heat stress in a similar manner to cells grown without calorie restriction but fared less well with a sudden heat shock. Yeast grown under extreme calorie restriction were less fit when exposed to gradual heating or heat shock. Using RNAseq analysis, we provide novel insight into the mechanisms underlying this response, showing that in the absence of calorie restriction, genes whose products are involved in energy metabolism (glycolysis/gluconeogenesis and the citrate cycle) are predominantly overexpressed when yeasts were exposed to gradual heating, whereas this was not the case when they were exposed to shock. We show that both the culture history and the current environment must be considered when assaying physiological responses, and this has wider implications when developing strategies for the propagation, preservation or destruction of microbial cells.
将细胞暴露于葡萄糖限制（热量限制）的实验被广泛用于确定其对细胞健康的影响，以此作为衰老模型。通过平板培养和液体培养，我们证明热量限制会降低细胞在后续营养限制环境中的适应性。在热量限制环境中生长的酵母从延迟期进入对数期所需的时间更长，倍增时间延长，可培养性百分比更低。在适度热量限制条件下生长的细胞能够以与未进行热量限制的细胞类似的方式承受逐渐升温的热应激，但在突然热休克时表现较差。在极端热量限制条件下生长的酵母在逐渐升温或热休克时适应性更差。通过RNA测序分析，我们对这种反应的潜在机制有了新的认识，结果表明，在没有热量限制的情况下，当酵母暴露于逐渐升温环境时，其产物参与能量代谢（糖酵解/糖异生和柠檬酸循环）的基因主要过表达，而在暴露于热休克时则不然。我们表明，在分析生理反应时必须同时考虑培养历史和当前环境，这在制定微生物细胞的繁殖、保存或破坏策略时具有更广泛的意义。
