Kraemer Lisa D, Campbell Peter G C, Hare Landis
Université du Québec, INRS-Eau, Terre et Environnement, 490 de la Couronne, Québec City, QC, Canada G1K 9A9.
Environ Pollut. 2006 Jul;142(2):313-25. doi: 10.1016/j.envpol.2005.10.004. Epub 2005 Dec 9.
Temporal fluctuations in metal (Cd and Cu) concentrations were monitored over four months (May to August) in the liver of juvenile yellow perch (Perca flavescens) sampled from four lakes situated along a metal concentration gradient in northwestern Quebec: Lake Opasatica (reference lake, low metal concentrations), Lake Vaudray (moderate metal concentrations) and lakes Osisko and Dufault (high metal levels). The objectives of this study were to determine if hepatic metal concentrations and metal-handling strategies at the sub-cellular level varied seasonally. Our results showed that Cd and Cu concentrations varied most, in both absolute and relative values, in fish with the highest hepatic metal concentrations, whereas fish sampled from the reference lake did not show any significant variation. To examine the sub-cellular partitioning of these two metals, we used a differential centrifugation technique that allowed the separation of cellular debris, metal detoxified fractions (heat-stable proteins such as metallothionein) and metal sensitive fractions (heat-denaturable proteins (HDP) and organelles). Whereas Cd concentrations in organelle and HDP fractions were maintained at low concentrations in perch from Lakes Opasatica and Vaudray, concentrations in these sensitive fractions were higher and more variable in perch from Lakes Dufault and Osisko, suggesting that there may be some liver dysfunction in these two fish populations. Similarly, Cu concentrations in these sensitive fractions were higher and more variable in perch from the two most Cu-contaminated lakes (Dufault and Osisko) than in perch from the other two lakes, suggesting a breakdown of homeostatic control over this metal. These results suggest not only that metal concentrations vary seasonally, but also that concentrations vary most in fish from contaminated sites. Furthermore, at the sub-cellular level, homeostatic control of metal concentrations in metal-sensitive fractions is difficult to maintain in perch with high hepatic metal concentrations.
在魁北克西北部沿着金属浓度梯度分布的四个湖泊中采集了幼年黄鲈（Perca flavescens）的肝脏样本，对其金属（镉和铜）浓度在四个月（5月至8月）内的时间波动情况进行了监测。这四个湖泊分别是奥帕萨蒂卡湖（参考湖，金属浓度低）、沃德里湖（中等金属浓度）以及奥西斯科湖和迪福尔湖（高金属水平）。本研究的目的是确定肝脏金属浓度以及亚细胞水平的金属处理策略是否随季节变化。我们的结果表明，肝脏金属浓度最高的鱼类中，镉和铜的浓度无论在绝对值还是相对值上变化都最大，而从参考湖采集的鱼类则未显示出任何显著变化。为了研究这两种金属的亚细胞分配情况，我们采用了差速离心技术，该技术能够分离细胞碎片、金属解毒部分（如金属硫蛋白等热稳定蛋白）和金属敏感部分（热变性蛋白（HDP）和细胞器）。在奥帕萨蒂卡湖和沃德里湖的鲈鱼中，细胞器和HDP部分的镉浓度保持在低水平，而在迪福尔湖和奥西斯科湖的鲈鱼中，这些敏感部分的镉浓度更高且变化更大，这表明这两个鱼类种群的肝脏可能存在一些功能障碍。同样，在两个受铜污染最严重的湖泊（迪福尔湖和奥西斯科湖）的鲈鱼中，这些敏感部分的铜浓度比其他两个湖泊的鲈鱼更高且变化更大，这表明对这种金属的稳态控制出现了破坏。这些结果不仅表明金属浓度随季节变化，而且在受污染地点的鱼类中浓度变化最大。此外，在亚细胞水平上，肝脏金属浓度高的鲈鱼难以维持对金属敏感部分中金属浓度的稳态控制。
