Ecotoxicology and Wildlife Health Division, Environment and Climate Change Canada, National Wildlife Research Centre, Carleton University, Ottawa, Ontario, Canada.
Environ Toxicol Chem. 2019 Apr;38(4):811-819. doi: 10.1002/etc.4364. Epub 2019 Feb 27.
Double-crested cormorants are piscivorous birds that breed in variably contaminated colonies across the Laurentian Great Lakes of North America. Collection and preparation of environmentally relevant extracts from eggs that contain variable concentrations of organohalogen contaminants represents a minimally invasive approach to characterize potential effects of exposure using in vitro bioassays. In the present study, a rapid, efficient lipid freeze-filtration extraction method was used to prepare extracts from double-crested cormorant eggs collected from 5 breeding colonies that had variable organohalogen contaminant burdens. Extracts, solubilized in dimethyl sulfoxide, were administered to chicken embryonic hepatocytes (CEHs) to determine effects on cell viability, 7-ethoxyresorufin-O-deethylase (EROD) activity, and messenger RNA expression using a chicken ToxChip polymerase chain reaction (PCR) array. The EROD median effect concentration (EC50) values were lower for extracts with greater organohalogen contaminant burdens and thus permitted an initial ranking of colonies based on the efficacy of eliciting an aryl hydrocarbon receptor-mediated response. The ToxChip PCR array data provided a more exhaustive, pathway-based evaluation of extract effects; variability in the transcriptomic profiles was associated with organohalogen contaminant burdens. For example, extracts from Mud Island (Detroit River, MI, USA) had among the highest organohalogen contaminant burdens and elicited a greater biochemical (EROD EC50 = 0.005) and transcriptomic response (22/43 genes altered on the array) in CEHs compared with the least contaminated site, which was Mandarte Island (BC, Canada; EROD EC50 = 0.172; 8/43 genes altered). Avian eggs represent a useful biomonitoring tool for determining complex mixture effects, and the combination of a rapid extraction method, an in vitro bioassay, and targeted endpoint evaluation (biochemical and transcriptomic) shows great promise as an environmental effects monitoring approach. Environ Toxicol Chem 2019;38:811-819. © 2019 Crown in the right of Canada. Published by Wiley Periodicals Inc. on behalf of SETAC.
双冠鸬鹚是一种以鱼为食的鸟类，它们在北美大洛矶山脉的各个受污染的繁殖地繁殖。从含有不同浓度有机卤污染物的卵中收集和制备与环境相关的提取物代表了一种微创方法，可以使用体外生物测定法来描述暴露的潜在影响。在本研究中，使用快速、高效的脂质冷冻过滤提取方法从 5 个繁殖地收集的双冠鸬鹚卵中提取提取物，这些繁殖地的有机卤污染物负担各不相同。用二甲基亚砜溶解提取物，然后用其处理鸡胚肝细胞（CEH），以确定其对细胞活力、7-乙氧基resorufin-O-脱乙基酶（EROD）活性和信使 RNA 表达的影响，采用鸡 ToxChip 聚合酶链反应（PCR）阵列。具有较高有机卤污染物负担的提取物的 EROD 中值效应浓度（EC50）值较低，因此可以根据引发芳基烃受体介导反应的功效对繁殖地进行初步排序。ToxChip PCR 阵列数据提供了更详尽、基于途径的提取物效应评估；转录组谱的变异性与有机卤污染物负担有关。例如，来自 Mud Island（底特律河，MI，美国）的提取物具有最高的有机卤污染物负担之一，与最清洁的位点 Mandarte Island（BC，加拿大； EROD EC50=0.172； 43 个基因中有 8 个发生改变）相比，在 CEH 中引起更大的生化（EROD EC50=0.005）和转录组反应（43 个基因中有 22 个发生改变）。鸟类卵是确定复杂混合物效应的有用生物监测工具，快速提取方法、体外生物测定和靶向终点评估（生化和转录组学）的结合显示出作为环境影响监测方法的巨大潜力。环境毒物化学 2019；38:811-819。©2019 加拿大王室。由 Wiley Periodicals Inc. 代表 SETAC 出版。
