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微量金属的摄取，代谢和毒性的生理过程及其在水生生物，特别是鱼类中的相互作用。在自然环境中，由于人为活动，水生生物经常暴露于微量金属水平升高的环境中。其中一些微量金属，如铜、锌和硒，是生命所必需的，但当它们的浓度超过体内阈值时，就会造成不良影响。其他微量金属如镉、铅和砷没有已知的生物学功能，即使在低浓度接触下也容易在体内积聚并引起毒性。迄今为止，在描述金属接触水生生物的毒性后果的研究中，大部分重点都集中在单一金属上。然而，在受污染的水生生态系统中，生物几乎总是暴露于多种金属。然而，在混合物中存在的微量金属可能通过共享的摄取和/或代谢串扰途径相互作用，导致鱼类的拮抗或协同毒性。本提案中概述的研究有两个主要目标。首先，我将研究鱼类对痕量金属和金属混合物的物种和生命阶段特异性敏感性的分子和生理机制，使用三种生态上不同的加拿大淡水物种（虹鳟鱼，白鲟和黑头鲦鱼）。这些鱼类对微量金属的敏感性不同，同一物种的不同生命阶段也不同，但造成这些差异的机制在很大程度上是未知的。鲟鱼在这方面特别令人感兴趣，因为它们是濒危物种，对微量金属极其敏感，尤其是在它们生命的早期阶段。其次，我将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性能，使用模型金属敏感物种虹鳟鱼。本研究还将侧重于了解这些代谢相互作用是如何通过暴露水平（低到高）和微量金属的化学形式（无机和有机）来调节的。总的来说，这项研究将产生关于鱼在不同生命阶段暴露于金属混合物的生理后果的基本知识。这些知识最终将有助于制定更有效的方法来保护加拿大的淡水生态系统。

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.