An integrative approach to understanding soil pollutants' effects on earthworms

保持土壤质量对于保护土壤群落的生物多样性至关重要，并且还具有农业意义，因为污染的土壤可能影响作物生长。蚯蚓在土壤中发挥着关键的生态作用：它们通过土壤和植物材料的物理混合和研磨加速了碳周转的速度。因此，保护蚯蚓免受污染对于保护生物多样性和维持土壤生态功能都是极其重要的。它们也可以作为哨兵物种来了解土壤污染的影响到底有多严重，也就是说，如果蚯蚓的数量受到影响，这表明污染水平是真正的环境问题。我们将研究化学污染物对具有良好特征的附生蚯蚓（Lumbricus rubellus）物种的影响，使用四种代表广泛污染物类别的模型化学品：铜和镉（潜在有毒金属），阿特拉津（杀虫剂）和氟蒽（芳香有机化合物，由自然过程和工业废物产生）。这项工作将基于一个现有研究联盟（NER/T/S/2002/00021，“利用陆地哨兵和模式物种整合对污染的生物反应层级”）产生的样本和数据来完成。该项目已经对其中三种化学品（镉、阿特拉津、氟蒽）进行了与生态有关的亚致死水平的可重复接触；铜暴露的蠕虫也将可用。这些污染物的代谢影响将使用核磁共振（NMR）光谱来评估蚯蚓组织的提取物。核磁共振是一种非靶向的小分子代谢物的通用检测器，因此可以提供蚯蚓代谢的概况或指纹。光谱复杂且信息丰富，因此需要多元模式识别方法来优化分析和解释数据。这种非目标代谢物分析与多变量数据处理的结合被称为代谢组学。代谢组学数据将由转录组微阵列数据（表达可能受到化学物质影响的数千个基因的谱）和种群终点（例如，每只蠕虫产卵的茧数，生长速度）补充。因此，我们提出了一种综合的方法来理解这一重要的生物和环境问题。所谓的“基因组”（综合分析）数据集将使我们能够提出关于不同化学物质如何对蚯蚓产生毒性和发育影响的假设。然而，通常很难使用组学数据生成与实际野外人口有关的任何信息。至关重要的是，我们将能够将基因组数据集与与蚯蚓种群的生态影响直接相关的生命周期模型联系起来。这将使我们有能力以一种对保护蚯蚓免受不同化学污染物真正重要的方式来解释代谢组学观察结果。

Maintaining soil quality is vital for the preservation of biological diversity of soil communities, and also has agricultural implications, as polluted soils may affect crop growth. Earthworms play a key ecological role in soils: they speed up the rate of carbon turnover by physical mixing and grinding of soils and plant material. Thus, it is extremely important to protect earthworms from pollution, in order both to preserve biodiversity, and to maintain soil ecological functioning. They can also serve as sentinel species for understanding how significant the effects of soil pollution really are, i.e. if earthworm populations are impacted it is an indication that contaminant levels are of real environmental concern. We will study the effect of chemical pollutants on the well-characterized epigeic earthworm species Lumbricus rubellus, using four model chemicals that are representative of broad classes of pollutants: copper and cadmium (potentially toxic metals), atrazine (pesticides), and fluoranthene (aromatic organic compounds, produced both by natural processes and as industrial wastes). This will be done by building on samples and data generated by an existing research consortium (NER/T/S/2002/00021, 'Exploiting terrestrial sentinel and model species to integrate tiers of biological response to pollution'). This project has already carried out reproducible exposures at ecologically relevant sub-lethal levels for three of these chemicals (cadmium, atrazine, fluoranthene); copper-exposed worms will be available as well. The metabolic effects of these pollutants will be assessed using nuclear magnetic resonance (NMR) spectroscopy to profile extracts of the earthworm tissue. NMR is a non-targeted universal detector for small-molecule metabolites, and thus can provide a profile or fingerprint of the earthworms' metabolism. The spectra are complex and information-rich, and therefore multivariate pattern-recognition methods are needed for optimum analysis and interpretation of the data. This combination of non-targeted metabolite profiling together with multivariate data handling is known as metabolomics. The metabolomic data will be complemented by transcriptomic microarray data (profiles of thousands of genes whose expression may be affected by the chemicals), and population end-points (e.g. number of cocoons laid by each worm, growth rates). Thus, we are proposing an integrative approach to understanding this important biological and environmental question. The so-called 'omic' (comprehensive profiling) data sets will allow us to develop hypotheses about how the different chemicals cause toxic and developmental effects in earthworms. However, often it is difficult to use omic data to generate any information that is relevant to actual field populations. Critically, we will be able to relate the omic data sets to life-cycle models that have direct relevance to ecological effects on earthworm populations. This will give us the power to interpret the metabolomic observations in a way that is truly significant for protecting earthworms from different chemical pollutants.