Schumann Peter G, Meade Emma B, Zhi Hui, LeFevre Gregory H, Kolpin Dana W, Meppelink Shannon M, Iwanowicz Luke R, Lane Rachael F, Schmoldt Angela, Mueller Olaf, Klaper Rebecca D
University of Wisconsin-Milwaukee, Milwaukee, Wisconsin, USA.
University of Iowa, Iowa City, Iowa, USA.
Environ Sci Process Impacts. 2022 Oct 19;24(10):1708-1724. doi: 10.1039/d2em00222a.
Discharged wastewater treatment plant (WWTP) effluent greatly contributes to the generation of complex mixtures of contaminants of emerging concern (CECs) in aquatic environments which often contain neuropharmaceuticals and other emerging contaminants that may impact neurological function. However, there is a paucity of knowledge on the neurological impacts of these exposures to aquatic organisms. In this study, caged fathead minnows () were exposed in a temperate-region effluent-dominated stream (, Muddy Creek) in Coralville, Iowa, USA upstream and downstream of a WWTP effluent outfall. The pharmaceutical composition of Muddy Creek was recently characterized by our team and revealed many compounds there were at a low microgram to high nanogram per liter concentration. Total RNA sequencing analysis on brain tissues revealed 280 gene isoforms that were significantly differentially expressed in male fish and 293 gene isoforms in female fish between the upstream and downstream site. Only 66 (13%) of such gene isoforms overlapped amongst male and female fish, demonstrating sex-dependent impacts on neuronal gene expression. By using a systems biology approach paired with functional enrichment analyses, we identified several potential novel gene biomarkers for treated effluent exposure that could be used to expand monitoring of environmental effects with respect to complex CEC mixtures. Lastly, when comparing the results of this study to those that relied on a single-compound approach, there was relatively little overlap in terms of gene-specific effects. This discovery brings into question the application of single-compound exposures in accurately characterizing environmental risks of complex mixtures and for gene biomarker identification.
污水处理厂排放的废水对水生环境中新型关注污染物（CECs）复杂混合物的产生有很大影响，这些混合物通常含有神经药物和其他可能影响神经功能的新型污染物。然而，对于这些暴露对水生生物的神经影响，我们知之甚少。在本研究中，将圈养的黑头呆鱼（Pimephales promelas）暴露于美国爱荷华州珊瑚维尔一条以温带地区污水处理厂排放废水为主的溪流（泥泞溪）中污水处理厂废水排放口的上游和下游。我们团队最近对泥泞溪的药物成分进行了表征，发现其中许多化合物的浓度在每升低微克到高纳克之间。对脑组织进行的全RNA测序分析显示，在上游和下游位点之间，雄性鱼中有280个基因异构体显著差异表达，雌性鱼中有293个基因异构体显著差异表达。这些基因异构体中只有66个（13%）在雄性和雌性鱼中重叠，表明对神经元基因表达存在性别依赖性影响。通过使用系统生物学方法并结合功能富集分析，我们确定了几种潜在的新型基因生物标志物，用于监测经处理废水的暴露情况，这些标志物可用于扩大对复杂CEC混合物环境影响的监测。最后，将本研究结果与那些采用单一化合物方法的研究结果进行比较时，在基因特异性效应方面的重叠相对较少。这一发现使人们对单一化合物暴露在准确表征复杂混合物的环境风险和基因生物标志物识别中的应用产生了质疑。
