Environnement et Changement Climatique Canada, 105 Rue McGill, Montréal, QC, H2Y 2E7, Canada.
Institut de Biologie intégrative et des Systèmes (IBIS), Université Laval, Québec, QC, G1V 0A6, Canada.
Aquat Toxicol. 2018 Sep;202:26-35. doi: 10.1016/j.aquatox.2018.06.007. Epub 2018 Jun 9.
The objective of this study was to determine if temporal variations in tissue metal concentrations are related to biomarkers of retinoid metabolism and oxidative stress responses in juvenile yellow perch (Perca flavescens). To this end, kidney metal (Cd, Cu and Zn) concentrations were measured in fish sampled in spring and fall 2012 in four lakes representing a wide range of water and sediment metal contamination in the Rouyn-Noranda (Quebec) region. Lakes Opasatica and Hélène were considered as reference lakes while lakes Dufault and Marlon were metal-contaminated. Kidney concentrations of Cd, Cu and Zn varied widely between spring and fall in fish from both clean and metal-contaminated lakes. An inter-lake difference in renal metal concentrations was only observed for Cd, with fish from Lake Marlon consistently displaying higher concentrations. In the spring, the concentrations of liver dehydroretinol, dehydroretinyl palmitate and total vitamin A esters were higher in fish sampled in the most contaminated lake. Strong temporal variations in the concentrations of these metabolites, as well as in the percentage of liver free dehydroretinol and the epidermal retinol dehydrogenase 2 transcription levels, were observed in fish living in the most metal-impacted lake, with generally higher values in the spring. In contrast to liver, in muscle, no clear seasonal variations in the concentrations of dehydroretinol, dehydroretinyl stearate or in the percentage of free dehydroretinol were observed in fish captured in the most contaminated lake. Temporal variations of traditional biomarkers of oxidative stress response were also observed in the most metal-impacted lake. For example, the transcription level of the gene encoding Cu/Zn superoxide dismutase-1 in liver and muscle catalase activity of perch sampled in the most contaminated lake were higher in spring than in fall. Positive relationships were found between kidney Cd concentrations and the transcription level of the gene encoding glucose 6-phosphate dehydrogenase, and all forms of retinoid concentrations in liver in spring, except with the percentage of free dehydroretinol where the correlation was negative. Our results translate to a state of stress caused by Cd and illustrate that temporal variations in tissue metal concentrations affect retinoid metabolism and antioxidant capacities in juvenile wild yellow perch. Overall this study contributes to highlight the importance of considering temporal variations when investigating the consequences of metal contamination on the physiology of wild fish.
本研究旨在确定组织金属浓度的时间变化是否与少年黄鲈（Perca flavescens）视黄醇代谢和氧化应激反应的生物标志物有关。为此，在 2012 年春季和秋季，在罗扬诺兰达（魁北克）地区的四个湖泊中采集了鱼类样本，测量了肾脏中的金属（Cd、Cu 和 Zn）浓度，这些湖泊代表了广泛的水和沉积物金属污染。奥帕斯蒂卡湖和海伦湖被认为是参考湖泊，而杜法尔特湖和马龙湖则受到金属污染。无论是在清洁湖泊还是在金属污染湖泊中，春季和秋季采集的鱼类肾脏中的 Cd、Cu 和 Zn 浓度差异很大。仅在 Cd 方面观察到湖泊间肾脏金属浓度的差异，马龙湖的鱼类始终显示出较高的浓度。在春季，从受污染最严重的湖泊中采集的鱼类肝脏中脱氢视黄醇、脱氢视黄醇棕榈酸酯和总维生素 A 酯的浓度较高。在受金属影响最大的湖泊中，这些代谢物的浓度以及肝脏游离脱氢视黄醇的百分比和表皮视黄醇脱氢酶 2 的转录水平均呈现出强烈的季节性变化，春季的数值通常较高。与肝脏不同，在肌肉中，从受污染最严重的湖泊中捕获的鱼类中，脱氢视黄醇、脱氢视黄醇硬脂酸酯或游离脱氢视黄醇的百分比没有明显的季节性变化。在受金属影响最大的湖泊中也观察到了传统氧化应激反应生物标志物的时间变化。例如，肝脏和肌肉中编码 Cu/Zn 超氧化物歧化酶-1 的基因的转录水平以及在最受污染的湖泊中采样的鲈鱼的肝和肌肉过氧化氢酶活性在春季均高于秋季。在春季，肾脏 Cd 浓度与编码葡萄糖 6-磷酸脱氢酶的基因的转录水平以及肝脏中所有形式的视黄醇浓度之间存在正相关关系，除了游离脱氢视黄醇百分比外，相关性为负。我们的研究结果表明 Cd 会导致压力状态，并说明组织金属浓度的时间变化会影响少年野生黄鲈的视黄醇代谢和抗氧化能力。总的来说，这项研究有助于强调在研究金属污染对野生鱼类生理影响时考虑时间变化的重要性。
