PDF(Pubmed)
Abstract：
Mutagenesis is responsive to many environmental factors. Evolution therefore depends on the environment not only for selection but also in determining the variation available in a population. One such environmental dependency is the inverse relationship between mutation rates and population density in many microbial species. Here, we determine the mechanism responsible for this mutation rate plasticity. Using dynamical computational modelling and in culture mutation rate estimation, we show that the negative relationship between mutation rate and population density arises from the collective ability of microbial populations to control concentrations of hydrogen peroxide. We demonstrate a loss of this density-associated mutation rate plasticity (DAMP) when Escherichia coli populations are deficient in the degradation of hydrogen peroxide. We further show that the reduction in mutation rate in denser populations is restored in peroxide degradation-deficient cells by the presence of wild-type cells in a mixed population. Together, these model-guided experiments provide a mechanistic explanation for DAMP, applicable across all domains of life, and frames mutation rate as a dynamic trait shaped by microbial community composition.
摘要：
诱变对许多环境因素有反应。因此，进化不仅取决于选择的环境，还取决于确定种群中可用的变异的环境。一种这样的环境依赖性是许多微生物物种中突变率和种群密度之间的反比关系。这里,我们确定了这种突变率可塑性的机制。使用动态计算模型和培养突变率估计，我们发现突变率与种群密度之间的负向关系源于微生物种群控制过氧化氢浓度的集体能力。我们证明了当大肠杆菌种群缺乏过氧化氢降解时，这种与密度相关的突变率可塑性（DAMP）的丧失。我们进一步表明，通过混合种群中野生型细胞的存在，在过氧化物降解缺陷型细胞中恢复了较密集种群中突变率的降低。一起,这些模型引导实验为DAMP提供了机械解释，适用于生活的所有领域，帧突变率是由微生物群落组成形成的动态性状。
