title: Effects of copper, hypoxia and acute temperature shifts on mitochondrial oxidation in rainbow trout (Oncorhynchus mykiss) acclimated to warm temperature.
abstract: Temperature fluctuations, hypoxia and metals pollution frequently occur simultaneously or sequentially in aquatic systems and their interactions may confound interpretation of their biological impacts. With a focus on energy homeostasis, the present study examined how warm acclimation influences the responses and interactions of acute temperature shift, hypoxia and copper (Cu) exposure in fish. Rainbow trout (Oncorhynchus mykiss) were acclimated to cold (11°C; control) and warm (20°C) temperature for 3 weeks followed by exposure to environmentally realistic levels of Cu and hypoxia for 24h. Subsequently, mitochondrial electron transport system (ETS) respiratory activity supported by complexes I-IV (CI-IV), plasma metabolites and condition indices were measured. Warm acclimation reduced fish condition, induced aerobic metabolism and altered the responses of fish to acute temperature shift, hypoxia and Cu. Whereas warm acclimation decelerated the ETS and increased the sensitivity of maximal oxidation rates of the proximal (CI and II) complexes to acute temperature shift, it reduced the thermal sensitivity of state 4 (proton leak). Effects of Cu with and without hypoxia were variable depending on the acclimation status and functional index. Notably, Cu stimulated respiratory activity in the proximal ETS segments, while hypoxia was mostly inhibitory and minimized the stimulatory effect of Cu. The effects of Cu and hypoxia were modified by temperature and showed reciprocal antagonistic interaction on the ETS and plasma metabolites, with modest additive actions limited to CII and IV state 4. Overall, our results indicate that warm acclimation came at a cost of reduced ETS efficiency and increased sensitivity to added stressors.
authors.affiliation: Department of Pathology and Microbiology, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, Prince Edward Island C1A 4P3, Canada; Department of Biomedical Sciences, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, Prince Edward Island C1A 4P3, Canada.
authors.forename: Ravinder
authors.initials: R
authors.lastname: Sappal
authors.affiliation: Department of Pathology and Microbiology, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, Prince Edward Island C1A 4P3, Canada.
authors.forename: Mark
authors.initials: M
authors.lastname: Fast
authors.affiliation: Department of Biomedical Sciences, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, Prince Edward Island C1A 4P3, Canada.
authors.forename: Don
authors.initials: D
authors.lastname: Stevens
authors.affiliation: Department of Pathology and Microbiology, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, Prince Edward Island C1A 4P3, Canada.
authors.forename: Fred
authors.initials: F
authors.lastname: Kibenge
authors.affiliation: British Columbia Centre for Aquatic Health Sciences, 871A Island Highway, Campbell River, British Columbia V9W 2C2, Canada.
authors.forename: Ahmed
authors.initials: A
authors.lastname: Siah
authors.affiliation: Department of Biomedical Sciences, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, Prince Edward Island C1A 4P3, Canada. Electronic address: ckamunde@upei.ca.
authors.forename: Collins
authors.initials: C
authors.lastname: Kamunde
mesh_terms: D000064:Acclimatization / Q000187:drug effects* / Q000502:physiology; D000818:Animals; D003080:Cold Temperature; D003300:Copper / Q000633:toxicity*; D004579:Electron Transport; D003576:Electron Transport Complex IV / Q000378:metabolism; D000860:Hypoxia / Q000503:physiopathology*; D008928:Mitochondria / Q000187:drug effects* / Q000378:metabolism; D017686:Oncorhynchus mykiss / Q000378:metabolism / Q000502:physiology*; D010085:Oxidative Phosphorylation; D013696:Temperature; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D014874:Water Pollutants, Chemical; D003300:Copper; D003576:Electron Transport Complex IV
keywords: Copper; Electron transport system; Energy homeostasis; Hypoxia; Interactions; Temperature