Distinguishing pollutant-induced stresses from spatial and temporal environmental heterogeneity - a metabolomic approach to stress ecology

如果蛋白质构成细胞的机器，那么小分子代谢物就是细胞的货币，形成信息流（信号），能量和营养物质，调节许多最重要的生物功能。对这些代谢物的计算--以无偏的方式列出生物样品中存在的所有代谢物--被称为代谢组学。由于代谢在生理控制中的中心性质，存在于细胞和生物体中的代谢物对环境变化（例如土壤化学、气候等的差异）非常敏感。近年来，鉴定细胞中存在的代谢物的大子集的分析方法的发展已经承诺，这种分析可以用来确定哪些环境影响正在影响生物体的健康。这一点很重要，因为人类活动现在意味着，在许多发达国家，以及越来越多的发展中国家，环境条件已经改变，这意味着物种生活在不再是“原始”的生态系统中。人类对环境影响的一个例子是，在许多发达国家，以及越来越多的发展中国家，家庭和工业污染造成了污染的“灰色面纱”。迄今为止，代谢组学方法主要用于实验室研究，以确定一系列物种对环境压力的反应。这些压力包括污染，以及极端温度和疾病等“自然”因素。虽然这些结果非常有希望，但一个潜在的批评是，它在真实的世界中可能不像在实验室中那样成功。这主要是因为在自然环境中，环境因素（例如气候，土壤/水化学，与其他生物体的相互作用）存在很大差异，这些因素也会影响代谢物水平。这可能使得很难，如果不是不可能的话，将正在研究的因素（例如环境污染）的影响与所有其他不同环境因素的影响所产生的“代谢噪音”分开。在这个项目中，我们的目标是专门测试如何可靠的代谢组学可以研究土壤污染对自然种群的影响。我们将研究一种常见的英国蚯蚓物种：蚯蚓是土壤污染的良好“哨兵”物种，因为它们对污染敏感，并在大多数土壤中发挥重要的生态作用。最初，我们将在一年中的几个不同时间从全国范围内的清洁场所采集蠕虫样本。这将告诉我们在相对未受污染的条件下生活的蠕虫中可以发现的各种代谢反应。接下来，我们将进行一系列实验室实验，以了解一系列环境因素（例如不同的土壤酸度，湿度水平，土壤类型，温度）对蠕虫代谢生理学的影响。这将有助于我们解释我们在野外收集的个体中看到的变化：他们处于什么样的自然压力之下？最后，我们将测量一年中不同时间从一组已知污染场地（被有毒重金属和/或有机化学品污染）收集的蠕虫中的代谢物。这将使我们能够回答一个基本问题，即我们能否可靠地将蠕虫从清洁和污染的地点区分开来，即使这些地点本身和采集时的气候条件差异很大？完成后，我们的研究将提供一个广泛和高质量的数据集，可用作未来研究的基线。此外，我们将获得的结果将是相当大的学术兴趣，生理学家和环境科学家。最后，从长远来看，我们的研究结果可能会导致监测和评估我们环境变化状态的方法的发展。

If proteins form the machinery of a cell, then small molecule metabolites are the cell's currency, forming the flows of information (signalling), energy and nutrients that regulate many of the most important biological functions. The accounting of these metabolites - by listing in an unbiased fashion all the metabolites present in a biological sample - is called metabolomics. Because of the central nature of metabolism in the control of physiology, the metabolites that are present in cells and organisms are very sensitive to environmental variation (e.g. differences in soil chemistry, climate, etc.). In recent years, the development of analytical methods to identify a large sub-set of the metabolites present in cells has held promise that such analyses could be used to establish which environmental influences were affecting an organism's health. This is important because human activity now means that in much of the developed, and increasingly the developing, world, the condition of the environment has been changed meaning that species are living within ecosystems that are no longer 'pristine'. One example of the effects of man on the environment is the presence in much of the developed and, increasingly, developing world, of a 'grey veil' of contamination resulting from domestic and industrial pollution. To date the metabolomics approach has been used mostly in laboratory-based studies to identify the responses of a range of species to environmental stresses. These stresses include pollution, as well as 'natural' factors like temperature extremes and disease. While these results have been extremely promising, a potential criticism is that it may not be as successful in the real world as it is in the lab. This is primarily because in the natural environment there are large variations in environmental factors (e.g. climate, soil/ water chemistry, interactions with other organisms), which will all also affect metabolite levels. This may make it difficult, if not impossible, to separate the effects of the factor being studied (e.g. environmental pollution) from the 'metabolic noise' created by the effects of all the other varying environmental factors. In this project we are aiming to specifically to test how reliable metabolomics can be to study the effects of soil pollution on natural populations. We will study a common British earthworm species: earthworms are good 'sentinel' species for soil contamination, as they .are both sensitive to pollution, and play an important ecological role in most soils. Initially, we will sample worms at several different times throughout the year from a wide range of clean sites across the country. This will tell us about the variety of metabolic responses that can be found in worms living under comparatively unpolluted conditions. Next we will conduct a series of laboratory experiments to understand the effects of a range of environmental factors (e.g. different soil acidity, moisture levels, soil type, temperature) on worm metabolic physiology. This will help us interpret the variations we see in our field-collected individuals: what kind of natural stresses were they under? Finally we will measure metabolites in worms collected from a set of known polluted sites (contaminated with toxic heavy metals and/or organic chemicals) at different times through the year. This will allow us to answer the fundamental question, can we reliably distinguish worms from clean and polluted sites, even though the sites themselves and the climatic condition at the time of collections are highly varied? On completion, our study will provide an extensive and high-quality dataset that could be used as a baseline for future research. Further, the results we will obtain will be of considerable academic interest to both physiologist and environmental scientists. Finally our results may, in the long run, lead to the development of methods to monitor and assess the changing state of our environment.