title: Response of oxidative stress transcripts in the brain of wild yellow perch (Perca flavescens) exposed to an environmental gradient of methylmercury.
abstract: Methylmercury (MeHg) exposure and adverse health effects in fishes have been documented, but the molecular mechanisms involved in toxicity have not been fully characterized. The objectives of the current study were to (1) determine whether total Hg (THg) in the muscle was predictive of MeHg concentrations in the brain of wild female yellow perch (Perca flavescens) collected from four lakes in Kejimkujik National Park, a known biological mercury (Hg) hotspot in Nova Scotia, Canada and (2) to determine whether transcripts involved in the oxidative stress response were altered in abundance in fish collected across five lakes representing a MeHg gradient. In female yellow perch, MeHg in whole brain (0.38 to 2.00μg/g wet weight) was positively associated with THg in muscle (0.18 to 2.13μg/g wet weight) (R2=0.61, p<0.01), suggesting that muscle THg may be useful for predicting MeHg concentrations in the brain. Catalase (cat) mRNA levels were significantly lower in brains of perch collected from lakes with high Hg when compared to those individuals from lakes with relatively lower Hg (p=0.02). Other transcripts (cytochrome c oxidase, glutathione peroxidase, glutathione-s-transferase, heat shock protein 70, protein disulfide isomerase, and superoxide dismutase) did not show differential expression in the brain over the gradient. These findings suggest that MeHg may be inversely associated with catalase mRNA abundance in the central nervous system of wild fishes.
authors.affiliation: Department of Biology and Canadian Rivers Institute, University of New Brunswick, Saint John, New Brunswick, E2L 4L5, Canada. Electronic address: s.graves@usask.ca.
authors.forename: Stephanie D
authors.initials: SD
authors.lastname: Graves
authors.affiliation: Department of Biology and Canadian Rivers Institute, University of New Brunswick, Saint John, New Brunswick, E2L 4L5, Canada.
authors.forename: Karen A
authors.initials: KA
authors.lastname: Kidd
authors.affiliation: Department of Biology and Canadian Rivers Institute, University of New Brunswick, Saint John, New Brunswick, E2L 4L5, Canada.
authors.forename: Katharina L
authors.initials: KL
authors.lastname: Batchelar
authors.affiliation: Department of Biology and Canadian Rivers Institute, University of New Brunswick, Saint John, New Brunswick, E2L 4L5, Canada.
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Cowie
authors.affiliation: Department of Earth and Environmental Sciences, Acadia University, Wolfville, Nova Scotia, B4P 2R6, Canada.
authors.forename: Nelson J
authors.initials: NJ
authors.lastname: O'Driscoll
authors.affiliation: Department of Biology and Canadian Rivers Institute, University of New Brunswick, Saint John, New Brunswick, E2L 4L5, Canada; Department of Physiological Sciences and Center for Environmental and Human Toxicology, UF Genetics Institute, College of Veterinary Medicine, University of Florida, Gainesville, FL 32611, USA.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Martyniuk
mesh_terms: D000818:Animals; D001822:Body Burden; D001921:Brain / Q000187:drug effects* / Q000378:metabolism; D002374:Catalase / Q000235:genetics* / Q000378:metabolism; D015536:Down-Regulation; D004784:Environmental Monitoring / Q000379:methods; D005260:Female; D029941:Fish Proteins / Q000235:genetics* / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D005819:Genetic Markers; D008767:Methylmercury Compounds / Q000378:metabolism / Q000633:toxicity*; D018482:Muscle, Skeletal / Q000378:metabolism; D009674:Nova Scotia; D018384:Oxidative Stress / Q000187:drug effects* / Q000235:genetics; D010471:Perches / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics* / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D014874:Water Pollutants, Chemical / Q000378:metabolism / Q000633:toxicity*
chemical_list: D029941:Fish Proteins; D005819:Genetic Markers; D008767:Methylmercury Compounds; D012333:RNA, Messenger; D014874:Water Pollutants, Chemical; D002374:Catalase
keywords: Fish; Gene expression; Metals; Methyl mercury; Oxidative stress