PROTECT: Predicting teleost fish species' sensitivity at molecular initiating events

我们正在以惊人的速度丧失生物多样性，以至于我们现在正处于第六次大规模灭绝事件中。造成这一现象的原因是多方面的，包括栖息地丧失、气候变化和化学污染。恢复栖息地有可能增加生物多样性，但如果不解决化学污染问题，并保持在对野生动物有害的水平，积极的结果将是有限的。为了指导哪些资源优先用于有益的污染缓解和栖息地恢复战略的政策，有必要确定那些对污染物最敏感并面临灭绝威胁的物种。化学物质通过与蛋白质相互作用发挥其毒性，称为分子启动事件。如果有机体不能对这种有毒的侮辱做出反应，那么个体的健康可能会受到影响，导致在种群水平上的影响。了解决定化学物质在分子启动事件中如何相互作用的因素是在单个物种水平上预测毒理学的关键组成部分。突变可以改变蛋白质的结构和功能。我们知道，人类基因的单一突变会改变蛋白质功能，导致疾病。随着数以百万计的物种、数以千计的蛋白质和数以千计的化学物质排放到环境中，物种对污染物的敏感性范围很大也就不足为奇了。物种敏感度分布曲线证实了这一点，并表明这些巨大的差异可能发生在密切相关的物种之间。物种敏感性来自毒性试验。人们认识到，继续杀死生物是不道德的，人们正在推动寻找替代策略，如体外方法(不使用动物获得的数据)和电子方法(使用计算机程序)，以生成制定保护所有物种的标准所需的数据，一种名为新方法方法学的新方法。对许多物种基因组进行排序的全球倡议有可能在不进行进一步毒性测试的情况下，对预测毒理学产生革命性的影响。基因组资源使我们能够识别物种之间的蛋白质突变。然而，并不是所有的突变都会改变蛋白质的功能，有些突变是中性的，因此需要额外的功能数据来确定分子启动事件中涉及的蛋白质的变化是否会导致单个物种的敏感性。该项目的目的是开发一种基于计算机的方法，通过专注于鱼类应激受体来预测个体物种的敏感性，这种受体被称为皮质醇受体，它包括糖皮质激素受体和盐皮质激素受体。这是因为：1.有可用的分析方法来评估受体的功能，从而评估分子启动事件对人造化学物质的敏感性。有证据表明，在少数物种中，受体对类固醇的敏感性存在差异，但在其他物种中则没有。有一套基于计算机的工具来识别受体中的关键序列基序，这些基序赋予了对化学物质的敏感性。皮质类固醇受体的功能改变对健康有害，人造皮质类固醇正日益成为环境问题。该项目将产生关于9种天然和人造类固醇与来自14目18种鱼类的53种皮质类固醇受体蛋白相互作用的功能信息。这些信息将被用来将受体分类为对皮质类固醇低敏感或高敏感的受体，并与另一类类固醇孕激素相互作用。这些功能数据将与计算分析一起被用来识别分类受体类型的常见氨基酸序列。该项目的成果将是仅根据受体氨基酸序列识别对人造皮质类固醇、其他皮质类固醇内分泌干扰化学品、孕激素和应激反应敏感的鱼类物种。

We are losing biodiversity at an alarming rate, so much so that we are now in a 6th mass extinction event. The reasons for this are varied and include habitat loss, climate change and chemical pollution. Restoration of habitats has the potential to increase biodiversity, but a positive outcome will be limited if chemical pollution is not tackled and remains at a level that is detrimental to wildlife. To guide policy on where to prioritise resources for beneficial pollution mitigation and habitat restoration strategies, it is necessary to identify those species that are the most sensitive to a pollutant and are under threat of extinction.Chemicals exert their toxicity via interacting with proteins, termed the molecular initiating event. If the organism is unable to respond to this toxic insult, then the individual's health may be impacted, leading to effects at a population level. Understanding the factors that determine how a chemical interacts at the molecular initiating event is a key component for predictive toxicology at the individual species level.Mutations can alter a protein's structure and function. We know that single mutations in human genes can alter protein function and lead to disease. With millions of species, thousands of proteins and thousands of chemicals released into the environment it is not surprising that there is a large range of species sensitivities to pollutants. Species sensitivity distribution curves confirm this and show these large differences can occur between closely related species. Species sensitivity is derived from toxicity tests. There is recognition that it is unethical to continue killing organisms, and there is a push to find alternative strategies such as in vitro methods (data derived without the use of animals) and in-silico approaches (the use of computer programmes) to generate the data necessary to set standards to protect all species, a novel approach called New Approach Methodology.Global initiatives to sequence the genomes of many species has the potential to revolutionise predictive toxicology without further toxicity testing. The genomic resource allows us to identify protein mutations between species. However, not all mutations alter protein function, some are neutral and thus additional functional data is required to identify if changes in proteins involved in the molecular initiating event account for an individual species sensitivity. The aim of the project is to develop a computer-based approach to predict individual species sensitivity by focusing on fish stress receptors, called the corticosteroid receptors which comprise the glucocorticoid and mineralocorticoid receptors. This is because: 1. There are assays available to assess receptor functionality and thus the sensitivity of the molecular initiating event to man-made chemicals.2. There is evidence of differences in the sensitivity of the receptors to steroids in a few species, but not others.3. There is a suite of computer-based tools to identity the key sequence motifs in receptors that confer sensitivity to a chemical.4. Altered corticosteroid receptors' function is detrimental to health and man-made corticosteroids are a growing environmental concern. The project will generate functional information on the interaction of 9 natural and man-made steroids with 53 corticosteroid receptors proteins from 18 fish species representing 14 orders. This information will be used to classify the receptors into those that are hypo or hypersensitive to corticosteroids and interact with another class of steroids progestins. This functional data along with computational analysis will be used to identify common amino acid sequences that classify receptor type. The deliverable of the project will be the ability to identify fish species that are sensitive to man-made corticosteroids, other corticosteroid endocrine disrupting chemicals, progestins and stress based on receptor amino acid sequence alone.