Wu Su-Mei, Tsai Jeng-Wei, Tzeng Wen-Nan, Chen Wei-Yu, Shih Wan-Yu
Department of Aquatic Biosciences, National Chiayi University, No. 300 University Rd., Chiayi 600, Taiwan.
Department of Biological Science and Technology, China Medical University, No. 91, Hsueh-Shih Rd., Taichung 404, Taiwan.
Aquat Toxicol. 2015 Jun;163:51-9. doi: 10.1016/j.aquatox.2015.03.016. Epub 2015 Mar 20.
Branchial Na(＋)-K(＋)-ATPase (NKA) activity has been suggested as a promising biomarker for assessing metal stress in aquatic organisms. However, studies that systematically show the effectiveness of using NKA activity to detect metal exposure and toxicity at the individual level are limited. In this study, we aimed to determine whether branchial NKA activity mechanistically responds to the accumulation of waterborne copper (Cu) and accounts for observed toxicity over time under environmentally-relevant and aquafarming Cu exposure levels (0.2, 1 and 2 mg L(-1)). Temporal trends in Cu accumulation and the corresponding responses of branchial NKA activity resulting from Cu exposure were investigated in laboratory experiments conducted on juvenile tilapia (Oreochromis mossambicus), a freshwater teleost that shows potential as a bioindicator of real-time and historical metal pollution. We used the process-based damage assessment model (DAM) to inspect the time course of Cu toxicity by integrating the compensation process between Cu-induced inhibition and repair of branchial NKA activity. NKA activity acted as a sensitive biomarker for Cu exposure and accumulation in tilapia, which showed induced impairment of osmoregulation and lethality when they were exposed to environmentally relevant levels (0.2 mg L(-1)), but not to higher exposure levels (1 and 2 mg L(-1)) in aquaculture farms or contaminated aquatic ecosystems. This study highlights the benefits and limitations of using branchial NKA activity as a sensitive biomarker to assess the health status of a fish population and its ecosystem.
鳃钠钾ATP酶（NKA）活性被认为是评估水生生物金属应激的一个有前景的生物标志物。然而，系统地表明在个体水平上使用NKA活性检测金属暴露和毒性有效性的研究有限。在本研究中，我们旨在确定鳃NKA活性是否在机制上对水中铜（Cu）的积累做出反应，并解释在环境相关和水产养殖铜暴露水平（0.2、1和2 mg L(-1)）下随时间观察到的毒性。在对莫桑比克罗非鱼（Oreochromis mossambicus）幼鱼进行的实验室实验中，研究了铜积累的时间趋势以及铜暴露导致的鳃NKA活性的相应反应，莫桑比克罗非鱼是一种淡水硬骨鱼，有潜力作为实时和历史金属污染的生物指示物。我们使用基于过程的损伤评估模型（DAM），通过整合铜诱导的鳃NKA活性抑制和修复之间的补偿过程，来检查铜毒性的时间进程。NKA活性是罗非鱼铜暴露和积累的敏感生物标志物，当它们暴露于环境相关水平（0.2 mg L(-1)）时，会出现渗透调节受损和致死现象，但在水产养殖场或受污染的水生生态系统中暴露于较高水平（1和2 mg L(-1)）时则不会。本研究强调了使用鳃NKA活性作为敏感生物标志物来评估鱼类种群及其生态系统健康状况的益处和局限性。
