Can roach, Rutilus rutilus, adapt to the harmful effects of oestrogen exposure from waste water treatment work effluents?

世界范围内的主要关注集中在观察到野生动物和人类种群的生殖中断，这可能是由于接触干扰人体激素信号系统的化学品(所谓的内分泌干扰性化学品；EDCs)影响生殖健康。我们发现，生活在许多英国河流的鱼类(蟑螂，鲤鱼家族的常见成员)的繁殖力因暴露于污水处理厂(WWTW)污水中的EDCs而受到损害，导致这些影响的化学物质包括避孕药中的天然雌激素激素和药用雌激素。雌性化的蟑螂在竞争的繁殖条件下繁殖能力降低，我们有证据(迄今尚未发表)表明野生蟑螂的繁殖种群规模减少，这些蟑螂生活在污水含量较高的河流中。繁殖个体数量较少的种群会在多个世代中丢失遗传变异，灭绝的风险更大。然而，我们发现，在这些河流的一些高雌激素暴露范围内，蟑螂种群似乎具有自我维持的生殖能力。确定鱼类(这里是蟑螂)是否已经适应了雌激素污染物，它们如何做到这一点(机制)以及这些适应的可能的适应成本对于了解生活在这些污染环境中的鱼类种群的弹性(从而可持续性)是至关重要的。我们将研究蟑螂种群在多个世代暴露于雌激素废水中是否导致了遗传选择，以及选择对雄性鱼类产生雌激素诱导的与负面适应后果相关的影响的影响。我们将通过确定它们的基因组成在功能上的显著变化来检查选择。具体地说，我们将在以下两个方面寻找遗传多态(所谓的单核苷酸多态-SNPs)的差异：(1)我们知道在生殖(和其他生命)过程中雌激素信号重要的特定(候选)基因，以及(2)使用允许我们扫描整个基因组以寻找这些基因变化的方法(使用一种称为RAD-Tag基因分型的技术)。通过采用这些方法，我们希望在生活在高雌激素流出物含量的河流中的鱼类中找到选择的“足迹”，这应该能够识别新的适应过程，并提出在流出物丰富的环境中毒性或生存的重要机制。独一无二的是，我们之所以能够做这项工作，是因为我们对我们计划研究的选定英国河流中的蟑螂野生种群有深入的了解(15年的研究)。我们将通过比较受控暴露于避孕雌激素--雌二醇的反应，来确定历代暴露于高水平雌激素流出物中的蟑螂种群是否已经适应了对环境雌激素的不太敏感，从而现在不太容易受到其相关不良影响的影响。我们将使用从上述相同清洁和污水处理厂污水污染场地收集的蟑螂进行上述种群遗传分析，鱼类将暴露在1年内，并量化对雄性鱼类(包括卵巢)具有负面适应后果的反应的影响。这项工作旨在极大地提高对鱼类适应环境污染物(这里是雌激素)暴露的能力以及它们如何做到这一点的了解，进而帮助了解英国河流中接收污水处理厂污水排放的鱼类种群的弹性。这项工作将对更好地保护我们的水产资源和生物多样性的排放监管具有重要意义，并引起政府监管机构、环境保护团体、工业界和广大公众的广泛关注。

Major worldwide attention has focused on the observations of disruptions of reproduction in both wildlife and human populations that can result from exposure to chemicals that interfere with the body's hormone signalling systems (so-called endocrine disrupting chemicals; EDCs) impacting on reproductive health. We have shown that reproduction in fish (roach, a common member of the carp family of fish) living in many UK Rivers has been damaged by exposure to EDCs contained in the wastewater treatment works (WwTW) effluents and the chemicals responsible for these effects include natural oestrogen hormones and pharmaceutical oestrogens in the contraceptive pill. Feminised roach have a reduced capability to breed under competitive breeding conditions and we have evidence (as yet, unpublished) for reduced breeding population sizes in wild roach living in rivers with a high effluent content. Populations with low numbers of breeding individuals lose genetic variation over multiple generations with a greater risk of extinction. Nevertheless, we find that in some stretches of these rivers with high oestrogenic exposure roach populations appear to be reproductively self-sustaining. Establishing whether fish (here roach) have adapted to oestrogenic contaminants, how they do this (the mechanisms) and the possible fitness costs of these adaptations are essential in understanding resilience (and thus sustainability) of fish populations living in these polluted environments.We will examine whether exposure of roach populations to oestrogenic WwTW effluents over multiple generations has resulted in genetic selection and the impacts of selection on the susceptibility in male fish to develop oestrogen-induced effects associated with negative fitness consequences. We will examine for selection by identifying functionally significant changes in their genetic make up. Specifically we will look for differences in genetic poylmorphisms (so called single nucleotide polymorphisms -SNPs) in (1) specific (candidate) genes that we know are important in oestrogen signalling of reproductive (and other life) processes and (2) by using methods that allow us to scan the whole genome for these genetic alterations (using a technique called RAD-tag genotyping). Adopting these methods we expect to find 'footprints' of selection in fish living in rivers with a high oestrogenic effluent content, which should allow identification of novel adaptive processes and suggest important mechanisms of toxicity or survival in effluent rich environments. Uniquely, we are able to do this work because we have in depth knowledge (15 years of study) of the wild populations of roach in the selected UK Rivers that we propose to study.We will establish whether roach populations exposed to high levels of oestrogenic effluent over many generations have adapted to become less responsive to environmental oestrogens and thus are now less susceptible to their associated adverse effects by comparing responses to a controlled exposure to the contraceptive oestrogen, ethinyloestradiol. We will use roach collected from the same clean and WwTW effluent contaminated sites as for the population genetic analyses described above and fish will be exposed for a period of 1 year and effects quantified on responses that have negative fitness consequences in male fish, including ovotestis. This work is intended to greatly improve understanding of the ability of fish to adapt to exposure to environmental pollutants (here oestrogen) and how they do so, in turn helping to inform on fish population resilience in UK rivers receiving WwTW effluent discharges. The work will have importance in the regulation of discharges for the better protection of our aquatic resources and biodiversity and is of very wide interest to the government regulatory bodies, environment protection groups, industry and the wider public.