Interactive effects of trace metals in freshwater fish

我的研究计划的愿景是更好地了解控制痕量金属在水生生物中的吸收、代谢和毒性及其相互作用的生理过程，特别是鱼类。在自然环境中，由于人为活动，水生生物经常暴露在痕量金属水平升高的环境中。其中一些微量金属，如铜、锌和硒，对生命是必不可少的，但当它们的浓度超过人体内的阈值水平时，可能会造成不良影响。其他痕量金属，如镉、铅和砷，没有已知的生物功能，即使在低暴露浓度下，也往往会在体内积累并造成毒性。到目前为止，对金属暴露于水生生物的毒性后果的研究主要集中在单一金属上。然而，在被污染的水生生态系统中，生物几乎总是暴露在多种金属中。然而，当痕量金属以混合物形式存在时，可能会通过共同的吸收和/或代谢串扰途径相互作用，导致对鱼类的拮抗或协同毒性。这项提案中概述的研究有两个主要目标。首先，我将使用三种不同的加拿大淡水物种(彩虹鲑鱼、白鲟鱼和肥头鱼)，研究鱼类对痕量金属和金属混合物的物种和生命阶段特定敏感性的分子和生理机制。对痕量金属的敏感性在这些鱼种之间以及同一物种的不同生命阶段之间也不同，然而导致这些差异的机制在很大程度上是未知的。鲟鱼是濒危物种，对微量金属特别敏感，特别是在其早期生命阶段，因此在这方面特别有兴趣。其次，我将使用对金属敏感的模式物种彩虹鲑鱼，研究必需和非必需金属(硒与镉/砷)之间的代谢相互作用如何影响幼鱼的生理表现。这项研究还将侧重于了解这些代谢相互作用如何受到接触水平(从低到高)和痕量金属(无机和有机)的化学形态的调节。总体而言，这项研究将产生关于鱼类在不同生命阶段暴露于金属混合物的生理后果的基础知识。这些知识最终将有助于制定更有效的方法来保护加拿大淡水生态系统。

The vision of my research program is to better understand the physiological processes that govern the uptake, metabolism and toxicity of trace metals and their interactions in aquatic organisms, particularly fish. In natural environments, aquatic organisms are often exposed to elevated levels of trace metals due to anthropogenic activities. Some of these trace metals such as copper, zinc and selenium are essential for life, but can cause adverse effects when their concentrations exceed the threshold levels in the body. Other trace metals such as cadmium, lead and arsenic have no known biological functions, and tend to accumulate in the body and cause toxicity even at low exposure concentrations. To date, much of the emphasis in research characterizing the toxic consequences of metal exposure to aquatic organisms has been focused on single metals. However, in the contaminated aquatic ecosystems, organisms are almost always exposed to multiple metals. Trace metals when present in mixture may, however, interact with each other via shared routes of uptake and/or metabolic cross-talk, leading to antagonistic or synergistic toxicity in fish. The research outlined in this proposal has two major objectives. First, I will investigate the molecular and physiological mechanisms responsible for species- and life stage-specific sensitivity to trace metals and metal-mixtures in fish, using three ecologically distinct Canadian freshwater species (rainbow trout, white sturgeon and fathead minnow). Sensitivity to trace metals differs among these fish species and also among life stages of the same species, however the mechanisms responsible for these differences are largely unknown. Sturgeons are of especial interest in this context as they are endangered species and extremely sensitive to trace metals, especially at their early life stages. Second, I will examine how the metabolic interactions between essential and non-essential metals (selenium vs. cadmium/arsenic) affect the physiological performance of juvenile fish, using a model metal-sensitive species, rainbow trout. This study will also focus on understanding how these metabolic interactions are modulated by the exposure level (low to high) and chemical forms of trace metals (inorganic and organic). Overall, this research will generate fundamental knowledge on the physiological consequences of exposure to metal-mixtures in fish, at various life stages. Such knowledge will ultimately help to develop more effective approaches for the protection of Canadian freshwater ecosystems.