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

摘要全世界的注意力主要集中在观察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物质（所谓的内分泌干扰化学物质；EDCs）而影响生殖健康造成的。我们已经证明，生活在英国许多河流中的鱼（蟑螂，鲤鱼家族的一种常见成员）的生殖受到了污水处理厂（WwTW）流出物中含有的EDCs的损害，造成这些影响的化学物质包括天然雌激素激素和避孕药中的药物雌激素。雌性蟑螂在竞争性繁殖条件下繁殖能力下降，我们有证据（尚未发表）表明，生活在高污水含量河流中的野生蟑螂繁殖种群规模减少。繁殖个体数量少的种群在几代之后失去遗传变异，灭绝的风险更大。然而，我们发现，在这些河流的一些延伸高雌激素暴露蟑螂种群似乎是生殖自我维持。确定鱼类（这里是蟑螂）是否已经适应了雌激素污染物，它们是如何适应的（机制），以及这些适应的可能适应性成本，对于理解生活在这些污染环境中的鱼类种群的恢复力（以及由此产生的可持续性）至关重要。我们将研究蟑螂种群在多代暴露于雌性废水中是否导致了遗传选择，以及选择对雄性鱼产生雌性诱导效应的易感性的影响，这些影响与负面适应性后果有关。我们将通过识别基因组成中功能显著的变化来检查选择。具体来说，我们将在以下方面寻找遗传多态性（所谓的单核苷酸多态性-SNPs）的差异：(1)我们知道在生殖（和其他生命）过程中的雌激素信号中很重要的特定（候选）基因；(2)通过使用允许我们扫描整个基因组以寻找这些遗传改变的方法（使用一种称为rad标签基因分型的技术）。采用这些方法，我们期望在生活在具有高雌激素流出物含量的河流中的鱼类中找到选择的“足迹”，这应该允许识别新的适应过程，并提出在富含流出物的环境中毒性或生存的重要机制。独特的是，我们能够做这项工作，因为我们有深入的知识（15年的研究），蟑螂的野生种群在选定的英国河流，我们建议研究。我们将通过比较暴露于避孕雌激素乙炔雌二醇的反应，确定暴露于高水平雌激素流出物的蟑螂种群在许多代中是否已经适应了对环境雌激素的反应减弱，从而现在不太容易受到其相关不利影响。我们将使用与上述种群遗传分析相同的清洁和WwTW污水污染地点收集的蟑螂，鱼将暴露1年，并对雄性鱼（包括卵睾丸）产生负面适应性后果的反应进行量化。这项工作旨在极大地提高对鱼类适应暴露于环境污染物（这里是雌激素）的能力的理解，以及它们是如何做到这一点的，从而有助于了解英国河流中接受WwTW污水排放的鱼类种群的恢复能力。这项工作对监管排放、更好地保护我们的水生资源和生物多样性具有重要意义，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兴趣。

SummaryMajor 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Feminised roach have a reduced capability to breed under competitive breeding conditions and we have evidence (as yet, unpublished) for reduced breeding population sizes in wild roach living in rivers with a high effluent content.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.