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Adaptation to environmental stress by evolution of non-genotypic heterogeneity within microbial populations

通过微生物种群内非基因型异质性的进化来适应环境压力

基本信息

批准号：
NE/L006553/1
负责人：
Simon Avery
金额：
$ 45.87万
依托单位：
University of Nottingham
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2014
资助国家：
英国
起止时间：
2014 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FL006553%2F1
关键词：
Adaptation environmental stress evolution non

项目摘要

In order to survive in the natural environment, microorganisms must be able to cope with stresses arising from environmental change and perturbation. Sources of environmental stress include natural environmental pressures stemming from climate fluctuations and occasional exposure to harmful elements. In addition, pollution arising from human activities releases potentially-toxic contaminants. It is generally accepted that one key factor which helps species to survive such environmental stresses is the presence of 'genetic variation' within populations, arising from differences in DNA sequence among individual organisms of the same species. This variation means that individuals will have some slightly different characteristics, making it likely that some of the population will be better adapted to withstand particular stressful conditions and allow the species to survive. While such genetic variation is clearly very important, scientific advances over recent years have indicated that there is an additional factor important for the survival of environmental stresses. Experiments with single-cell microorganisms have shown that individual cells within a population have markedly different abilities to survive environmental stresses, despite having the same DNA composition (i.e. being genetically-uniform). This discovery has suggested that this new source of variation, known as 'non-genotypic heterogeneity', may be a major factor allowing microorganisms to survive and overcome environmental stress in nature. However, nearly all of the research into this topic has so far been performed only under model conditions with laboratory organisms. Our recent NERC-funded work has been the first to examine the importance of non-genotypic heterogeneity for microorganisms living in the natural environment, with extremely promising results. Our studies to date have indicated that wild yeasts with high levels of non-genotypic heterogeneity have a competitive advantage over yeasts with lower heterogeneity in polluted habitats. Furthermore, these yeasts evolve the property of increased non-genotypic heterogeneity over time when subject to environmental stress. These important breakthroughs for microbial ecology underpin our new proposal. The objective now is to describe the wider importance of these exciting findings and, for the first time in wild cell populations selected by environmental stress, to uncover the mechanisms that underlie increased non-genotypic heterogeneity. We have three particular aims, as follows. (1) To determine how applicable our findings-to-date are more broadly. This will involve testing non-genotypic heterogeneity at environmental sites subject to quite diverse selection pressures as well as interrogation of a wide range of organisms, including bacteria. (2) To characterise the changes in DNA sequence that allow organisms to adapt to environmental stress by evolving increased non-genotypic heterogeneity. (3) To elucidate how these DNA sequence changes cause increased heterogeneity. We will adopt cutting-edge new techniques to achieve these objectives. The work could also have important applications, for example through the development of heterogeneity "markers" as novel biological reporters of pollutants in the natural environment. The results of the proposed project are anticipated to provide major new insights into non-genotypic heterogeneity as a survival strategy for species during environmental change. This will help greatly in our understanding of how microorganisms persist in the natural environment, and how they may react to harmful changes caused by humans through pollution.

为了在自然环境中生存，微生物必须能够科普环境变化和干扰引起的压力。环境压力的来源包括气候波动和偶尔接触有害元素所产生的自然环境压力。此外，人类活动造成的污染释放出潜在的有毒污染物。人们普遍认为，帮助物种在这种环境压力下生存的一个关键因素是种群内存在的“遗传变异”，这是由同一物种的个体生物体之间的DNA序列差异引起的。这种变异意味着个体将具有一些略微不同的特征，使得一些种群可能更好地适应特定的压力条件，并使该物种得以生存。虽然这种遗传变异显然非常重要，但近年来的科学进展表明，还有一个重要因素对环境压力的生存很重要。单细胞微生物的实验表明，尽管具有相同的DNA组成（即遗传上均匀），但群体中的单个细胞具有明显不同的生存环境压力的能力。这一发现表明，这种新的变异来源，称为“非基因型异质性”，可能是微生物在自然界中生存和克服环境压力的主要因素。然而，迄今为止，几乎所有关于这一主题的研究都是在实验室生物的模型条件下进行的。我们最近的NERC资助的工作是第一个研究生活在自然环境中的微生物的非基因型异质性的重要性，结果非常有希望。迄今为止，我们的研究表明，野生酵母与高水平的非基因型异质性有一个竞争优势，在受污染的栖息地与低异质性的酵母。此外，这些酵母在受到环境胁迫时，随着时间的推移进化出非基因型异质性增加的特性。微生物生态学的这些重要突破支持了我们的新提议。现在的目标是描述这些令人兴奋的发现的更广泛的重要性，并首次在通过环境压力选择的野生细胞群体中，揭示增加非基因型异质性的机制。我们有以下三个具体目标。(1)以确定我们迄今为止的发现在多大程度上适用于更广泛的领域。这将涉及测试非基因型异质性的环境网站受到相当不同的选择压力，以及询问范围广泛的生物体，包括细菌。(2)研究DNA序列的变化，这些变化使生物体通过进化增加非基因型异质性来适应环境胁迫。(3)阐明这些DNA序列变化如何导致异质性增加。我们将采用先进的新技术来实现这些目标。这项工作也可能有重要的应用，例如通过开发异质性“标记”作为自然环境中污染物的新型生物报告。拟议项目的结果预计将提供重大的新见解非基因型异质性作为一种生存策略的物种在环境变化。这将大大有助于我们了解微生物如何在自然环境中生存，以及它们如何对人类通过污染造成的有害变化作出反应。