Selenium prevents downregulation of antioxidant selenoprotein genes by methylmercury |
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| Institution: | 1. National Institute of Nutrition and Seafood Research, NO-5817 Bergen, Norway;2. Department of Biology, University of Bergen, 5020 Bergen, Norway;1. Pontifícia Universidade Católica—Rio de Janeiro (PUC-Rio), Chemistry Department, Rua Marquês de São Vicente, 225, Gávea, CEP, 22453-900 Rio de Janeiro, RJ, Brazil;2. Universidade Federal do Estado do Rio de Janeiro (UNIRIO), Programa de Pós-Graduação em Ciências Biológicas—Biodiversidade Neotropical, Av. Pasteur, 458-Urca, CEP, 22290-240 Rio de Janeiro, RJ, Brazil;3. Instituto de Química, Departamento de Química Analítica, Universidade Estadual de Campinas—UNICAMP, Grupo de Espectrometria, Preparo de amostras e Mecanização-GEPAM, Cx. Postal 6154, 13084-971Campinas, SP, Brazil;4. Instituto Nacional de Ciência e Tecnologia em Bioanalítica—INCTBio, Instituto de Química, Universidade Estadual de Campinas—UNICAMP, Cx. Postal 6154, 13084-971 Campinas, SP, Brazil;1. College of Animal Science and Technology, Shanxi Agricultural University, Taigu 030801, PR China;2. Lab of Animal Reproductive biotechnology, Shanxi Agricultural University, Taigu 030801, PR China;1. Canadian Rivers Institute and Department of Biology, University of New Brunswick, Saint John, New Brunswick, Canada;2. Department of Biological Sciences, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia, Canada;3. Nautilus Environmental Company Inc., 8664 Commerce Court, Burnaby, British Columbia V5A 4N71, Canada;4. Golder Associates Ltd., 2920 Virtual Way, Vancouver, British Columbia, Canada;1. College of Animal Science and Technology, Shanxi Agricultural University, Taigu, PR China;2. Lab of Animal Reproduction, Shanxi Agricultural University, Taigu, PR China;1. Department of Analytical Chemistry, Faculty of Chemistry, Complutense University of Madrid, Ciudad Universitaria, 28040, Madrid, Spain;2. Food Research Division, AZTI, Parque Tecnológico de Bizkaia, Astondo Bidea 609, 48160, Derio, Spain |
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| Abstract: | Selenium (Se) is an essential nutrient required by Se-dependent proteins, termed selenoproteins. The selenoprotein family is small but diverse and includes key proteins in antioxidant, redox signaling, thyroid hormone metabolism, and protein folding pathways. Methylmercury (MeHg) is a toxic environmental contaminant that affects seafood safety. Selenium can reduce MeHg toxicity, but it is unclear how selenoproteins are affected in this interaction. In this study we explored how Se and MeHg interact to affect the mRNA expression of selenoprotein genes in whole zebrafish (Danio rerio) embryos. Embryos were obtained from adult zebrafish fed MeHg with or without elevated Se in a 2×2 factorial design. The embryo mRNA levels of 30 selenoprotein genes were then measured. These genes cover most of the selenoprotein families, including members of the glutathione peroxidase (GPX), thioredoxin reductase, iodothyronine deiodinase, and methionine sulfoxide reductase families, along with selenophosphate synthetase 2 and selenoproteins H, J-P, T, W, sep15, fep15, and fam213aa. GPX enzyme activity and larval locomotor activity were also measured. We found that around one-quarter of the selenoprotein genes were downregulated by elevated MeHg. These downregulated genes were dominated by selenoproteins from antioxidant pathways that are also susceptible to Se-deficiency-induced downregulation. MeHg also decreased GPX activity and induced larval hypoactivity. Elevated Se partially prevented MeHg-induced disruption of selenoprotein gene mRNA levels, GPX activity, and larval locomotor activity. Overall, the MeHg-induced downregulation and subsequent rescue by elevated Se levels of selenogenes regulated by Se status suggest that Se deficiency is a contributing factor to MeHg toxicity. |
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| Keywords: | Selenium Methylmercury Selenoprotein Zebrafish Toxicity Free radicals |
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