title: Analyzing the effectiveness of using branchial NKA activity as a biomarker for assessing waterborne copper toxicity in tilapia (Oreochromis mossambicus): A damage-based modeling approach.
abstract: 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.
authors: Department of Aquatic Biosciences, National Chiayi University, No. 300 University Rd., Chiayi 600, Taiwan.
authors: Su-Mei
authors: SM
authors: Wu
authors: Department of Biological Science and Technology, China Medical University, No. 91, Hsueh-Shih Rd., Taichung 404, Taiwan. Electronic address: tsaijw@mail.cmu.edu.tw.
authors: Jeng-Wei
authors: JW
authors: Tsai
authors: Department of Aquatic Biosciences, National Chiayi University, No. 300 University Rd., Chiayi 600, Taiwan.
authors: Wen-Nan
authors: WN
authors: Tzeng
authors: Department of Biomedical Science and Environmental Biology, Kaohsiung Medical University, No. 100, Shih-Chuan 1st Rd., Kaohsiung 807, Taiwan.
authors: Wei-Yu
authors: WY
authors: Chen
authors: Department of Science Education and Application, National Taichung University of Education, No. 140, Minsheng Rd., Taichung 403, Taiwan.
authors: Wan-Yu
authors: WY
authors: Shih
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D003300:Copper / Q000032:analysis / Q000633:toxicity*; D005880:Gills / Q000187:drug effects* / Q000378:metabolism; D007700:Kinetics; D007928:Lethal Dose 50; D008954:Models, Biological; D012964:Sodium / Q000032:analysis; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*; D013054:Spectrophotometry, Atomic; D017210:Tilapia / Q000378:metabolism*; D023382:Toxicity Tests, Acute; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000633:toxicity*
chemical_list: D015415:Biomarkers; D014874:Water Pollutants, Chemical; D003300:Copper; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase
keywords: Biomarker; Copper; Damage assessment model; Na(+)/K(+)-ATPase; Toxicodynamics; Toxicokinetics