title: Copper and hypoxia modulate transcriptional and mitochondrial functional-biochemical responses in warm acclimated rainbow trout (Oncorhynchus mykiss).
abstract: To survive in changing environments fish utilize a wide range of biological responses that require energy. We examined the effect of warm acclimation on the electron transport system (ETS) enzymes and transcriptional responses to hypoxia and copper (Cu) exposure in fish. Rainbow trout (Oncorhynchus mykiss) were acclimated to cold (11 °C; control) and warm (20 °C) temperatures for 3 weeks followed by exposure to Cu, hypoxia or both for 24 h. Activities of ETS enzyme complexes I-IV (CI-CIV) were measured in liver and gill mitochondria. Analyses of transcripts encoding for proteins involved in mitochondrial respiration (cytochrome c oxidase subunits 4-1 and 2: COX4-1 and COX4-2), metal detoxification/stress response (metallothioneins A and B: MT-A and MT-B) and energy sensing (AMP-activated protein kinase α1: AMPKα1) were done in liver mitochondria, and in whole liver and gill tissues by RT-qPCR. Warm acclimation inhibited activities of ETS enzymes while effects of Cu and hypoxia depended on the enzyme and thermal acclimation status. The genes encoding for COX4-1, COX4-2, MT-A, MT-B and AMPKα1 were strongly and tissue-dependently altered by warm acclimation. While Cu and hypoxia clearly increased MT-A and MT-B transcript levels in all tissues, their effects on COX4-1, COX4-2 and AMPKα1 mRNA levels were less pronounced. Importantly, warm acclimation differentially altered COX4-2/COX4-1 ratio in liver mitochondria and gill tissue. The three stressors showed both independent and joint actions on activities of ETS enzymes and transcription of genes involved in energy metabolism, stress response and metals homeostasis. Overall, we unveiled novel interactive effects that should not be overlooked in real world situations wherein fish normally encounter multiple stress factors.
authors.affiliation: Department of Pathology and Microbiology, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PE C1A 4P3, Canada; Department of Biomedical Sciences, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PE 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, PE C1A 4P3, Canada.
authors.forename: Mark
authors.initials: M
authors.lastname: Fast
authors.affiliation: Department of Pathology and Microbiology, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PE C1A 4P3, Canada.
authors.forename: Sara
authors.initials: S
authors.lastname: Purcell
authors.affiliation: Department of Biomedical Sciences, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PE C1A 4P3, Canada.
authors.forename: Nicole
authors.initials: N
authors.lastname: MacDonald
authors.affiliation: Department of Biomedical Sciences, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PE 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, PE 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, BC 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, PE C1A 4P3, Canada. Electronic address: ckamunde@upei.ca.
authors.forename: Collins
authors.initials: C
authors.lastname: Kamunde
mesh_terms: D000064:Acclimatization / Q000187:drug effects; D000818:Animals; D003080:Cold Temperature; D003300:Copper / Q000378:metabolism*; D004579:Electron Transport; D003576:Electron Transport Complex IV; D004734:Energy Metabolism / Q000187:drug effects; D005880:Gills / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D008668:Metallothionein / Q000378:metabolism; D008928:Mitochondria / Q000502:physiology*; D008930:Mitochondria, Liver / Q000378:metabolism; D017686:Oncorhynchus mykiss / Q000378:metabolism / Q000502:physiology*; D013696:Temperature
chemical_list: D003300:Copper; D008668:Metallothionein; D003576:Electron Transport Complex IV
keywords: AMPKα1; Copper; ETS enzymes; Hypoxia; Metallothionein; Warm acclimation