Memory and fitness optimization of bacteria under fluctuating environments.
Memory and fitness optimization of bacteria under fluctuating environments.
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DOI：
10.1371/journal.pgen.1004556
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发表时间：
2014-09
期刊：
影响因子：
4.5
通讯作者：
Kussell E
中科院分区：
文献类型：
--
作者：
Lambert G;Kussell E
细菌通过感知特定营养物质的可用性、表达代谢所需的基因以及在特定代谢物耗尽后抑制它们来谨慎地调节其代谢表型。然而，目前尚不清楚遗传网络如何在快速波动的环境下在代际之间维持和传递表型状态。通过使用微流体使细菌承受波动的碳源（葡萄糖和乳糖），我们发现了大肠杆菌中的两种非遗传记忆并分析了它们的好处。首先，稳定的细胞内 lac 蛋白的传递所赋予的表型记忆显着减少了中间时间尺度（1-10 代）周期性波动下的滞后期。其次，反应记忆是一种滞后行为，在去除外部诱导物后基因表达仍然存在，当环境在短时间内（<1代）波动时，它会增强适应能力。使用数学模型，我们分析了记忆在环境波动时间尺度上的好处。我们证明，记忆机制提供了生物学中一类重要的生存策略，可以改善波动环境下的长期适应性。这些结果可用于了解生物体如何适应营养物质、抗生素和其他环境压力水平的波动。细菌对新环境的适应通常涉及基因表达的重组，从而暂时降低生长速度。通过使用创新的微流体装置将细胞暴露于波动的条件下，我们发现大肠杆菌细胞可以记住过去的环境，从而加速它们的生理适应。使用建模方法与实验相结合，我们证明了生物体记忆的适应性优势：1）在世代之间传递长寿的细胞内蛋白质或2）以历史依赖的方式对波动做出反应。我们的工作描述了生物体中适应性记忆最简单的例子之一，并为遗传网络在不同波动（包括营养物、抗生素和其他环境压力）下的行为提供了重要的见解。
Bacteria prudently regulate their metabolic phenotypes by sensing the availability of specific nutrients, expressing the required genes for their metabolism, and repressing them after specific metabolites are depleted. It is unclear, however, how genetic networks maintain and transmit phenotypic states between generations under rapidly fluctuating environments. By subjecting bacteria to fluctuating carbon sources (glucose and lactose) using microfluidics, we discover two types of non-genetic memory in Escherichia coli and analyze their benefits. First, phenotypic memory conferred by transmission of stable intracellular lac proteins dramatically reduces lag phases under cyclical fluctuations with intermediate timescales (1–10 generations). Second, response memory, a hysteretic behavior in which gene expression persists after removal of its external inducer, enhances adaptation when environments fluctuate over short timescales (<1 generation). Using a mathematical model we analyze the benefits of memory across environmental fluctuation timescales. We show that memory mechanisms provide an important class of survival strategies in biology that improve long-term fitness under fluctuating environments. These results can be used to understand how organisms adapt to fluctuating levels of nutrients, antibiotics, and other environmental stresses. Bacterial adaptation to new environments typically involves reorganization of gene expression that temporarily decreases growth rates. By exposing cells to fluctuating conditions using an innovative microfluidic device, we discover that E. coli cells can remember past environments, which accelerates their physiological adaptation. Using a modeling approach combined with experiments, we demonstrate the adaptive advantage of memory for organisms that 1) transmit long-lived intracellular proteins between generations or 2) respond to fluctuations in a history-dependent manner. Our work describes one of the simplest examples of adaptive memory in a living organism and provides significant insights into the behavior of genetic networks under diverse fluctuations, including nutrients, antibiotics, and other environmental stresses.
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影响因子：
56.9
作者：
Elf, Johan;Li, Gene-Wei;Xie, X. Sunney
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作者：
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作者：
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