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De Marco G, Billè B, Brandão F, Galati M, Pereira P, Cappello T, Pacheco M. Differential Cell Metabolic Pathways in Gills and Liver of Fish (White Seabream Diplodus sargus) Coping with Dietary Methylmercury Exposure. TOXICS 2023; 11:181. [PMID: 36851056 PMCID: PMC9961322 DOI: 10.3390/toxics11020181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Revised: 02/10/2023] [Accepted: 02/12/2023] [Indexed: 06/18/2023]
Abstract
Mercury (Hg) is a dangerous and persistent trace element. Its organic and highly toxic form, methylmercury (MeHg), easily crosses biological membranes and accumulates in biota. Nevertheless, understanding the mechanisms of dietary MeHg toxicity in fish remains a challenge. A time-course experiment was conducted with juvenile white seabreams, Diplodus sargus (Linnaeus, 1758), exposed to realistic levels of MeHg in feed (8.7 μg g-1, dry weight), comprising exposure (E; 7 and 14 days) and post-exposure (PE; 28 days) periods. Total Hg levels increased with time in gills and liver during E and decreased significantly in PE (though levels of control fish were reached only for gills), with liver exhibiting higher levels (2.7 times) than gills. Nuclear magnetic resonance (NMR)-based metabolomics revealed multiple and often differential metabolic changes between fish organs. Gills exhibited protein catabolism, disturbances in cholinergic neurotransmission, and changes in osmoregulation and lipid and energy metabolism. However, dietary MeHg exposure provoked altered protein metabolism in the liver with decreased amino acids, likely for activation of defensive strategies. PE allowed for the partial recovery of both organs, even if with occurrence of oxidative stress and changes of energy metabolism. Overall, these findings support organ-specific responses according to their sensitivity to Hg exposure, pointing out that indications obtained in biomonitoring studies may depend also on the selected organ.
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Affiliation(s)
- Giuseppe De Marco
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, 98166 Messina, Italy
| | - Barbara Billè
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, 98166 Messina, Italy
| | - Fátima Brandão
- Centre for Environmental and Marine Studies (CESAM) and Department of Biology, University of Aveiro, 3810-193 Aveiro, Portugal
| | - Mariachiara Galati
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, 98166 Messina, Italy
| | - Patrícia Pereira
- Centre for Environmental and Marine Studies (CESAM) and Department of Biology, University of Aveiro, 3810-193 Aveiro, Portugal
| | - Tiziana Cappello
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, 98166 Messina, Italy
| | - Mário Pacheco
- Centre for Environmental and Marine Studies (CESAM) and Department of Biology, University of Aveiro, 3810-193 Aveiro, Portugal
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Chastel O, Fort J, Ackerman JT, Albert C, Angelier F, Basu N, Blévin P, Brault-Favrou M, Bustnes JO, Bustamante P, Danielsen J, Descamps S, Dietz R, Erikstad KE, Eulaers I, Ezhov A, Fleishman AB, Gabrielsen GW, Gavrilo M, Gilchrist G, Gilg O, Gíslason S, Golubova E, Goutte A, Grémillet D, Hallgrimsson GT, Hansen ES, Hanssen SA, Hatch S, Huffeldt NP, Jakubas D, Jónsson JE, Kitaysky AS, Kolbeinsson Y, Krasnov Y, Letcher RJ, Linnebjerg JF, Mallory M, Merkel FR, Moe B, Montevecchi WJ, Mosbech A, Olsen B, Orben RA, Provencher JF, Ragnarsdottir SB, Reiertsen TK, Rojek N, Romano M, Søndergaard J, Strøm H, Takahashi A, Tartu S, Thórarinsson TL, Thiebot JB, Will AP, Wilson S, Wojczulanis-Jakubas K, Yannic G. Mercury contamination and potential health risks to Arctic seabirds and shorebirds. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 844:156944. [PMID: 35752241 DOI: 10.1016/j.scitotenv.2022.156944] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 06/20/2022] [Accepted: 06/20/2022] [Indexed: 06/15/2023]
Abstract
Since the last Arctic Monitoring and Assessment Programme (AMAP) effort to review biological effects of mercury (Hg) on Arctic biota in 2011 and 2018, there has been a considerable number of new Arctic bird studies. This review article provides contemporary Hg exposure and potential health risk for 36 Arctic seabird and shorebird species, representing a larger portion of the Arctic than during previous AMAP assessments now also including parts of the Russian Arctic. To assess risk to birds, we used Hg toxicity benchmarks established for blood and converted to egg, liver, and feather tissues. Several Arctic seabird populations showed Hg concentrations that exceeded toxicity benchmarks, with 50 % of individual birds exceeding the "no adverse health effect" level. In particular, 5 % of all studied birds were considered to be at moderate or higher risk to Hg toxicity. However, most seabirds (95 %) were generally at lower risk to Hg toxicity. The highest Hg contamination was observed in seabirds breeding in the western Atlantic and Pacific Oceans. Most Arctic shorebirds exhibited low Hg concentrations, with approximately 45 % of individuals categorized at no risk, 2.5 % at high risk category, and no individual at severe risk. Although the majority Arctic-breeding seabirds and shorebirds appeared at lower risk to Hg toxicity, recent studies have reported deleterious effects of Hg on some pituitary hormones, genotoxicity, and reproductive performance. Adult survival appeared unaffected by Hg exposure, although long-term banding studies incorporating Hg are still limited. Although Hg contamination across the Arctic is considered low for most bird species, Hg in combination with other stressors, including other contaminants, diseases, parasites, and climate change, may still cause adverse effects. Future investigations on the global impact of Hg on Arctic birds should be conducted within a multi-stressor framework. This information helps to address Article 22 (Effectiveness Evaluation) of the Minamata Convention on Mercury as a global pollutant.
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Affiliation(s)
- Olivier Chastel
- Centre d'Etudes Biologiques de Chizé (CEBC), UMR 7372 CNRS- La Rochelle Université, 79360 Villiers-en-Bois, France.
| | - Jérôme Fort
- Littoral Environnement et Sociétés (LIENSs), UMR 7266 CNRS-La Rochelle Université, 17000 La Rochelle, France.
| | - Joshua T Ackerman
- U.S. Geological Survey, Western Ecological Research Center, Dixon Field Station, 800 Business Park Drive, Suite D, Dixon, CA 95620, United States.
| | - Céline Albert
- Littoral Environnement et Sociétés (LIENSs), UMR 7266 CNRS-La Rochelle Université, 17000 La Rochelle, France
| | - Frédéric Angelier
- Centre d'Etudes Biologiques de Chizé (CEBC), UMR 7372 CNRS- La Rochelle Université, 79360 Villiers-en-Bois, France
| | - Niladri Basu
- McGill University, Faculty of Agriculture and Environmental Sciences, Montreal, QC H9X 3V9, Canada
| | | | - Maud Brault-Favrou
- Littoral Environnement et Sociétés (LIENSs), UMR 7266 CNRS-La Rochelle Université, 17000 La Rochelle, France
| | - Jan Ove Bustnes
- Norwegian Institute for Nature Research, FRAM Centre, 9296 Tromsø, Norway
| | - Paco Bustamante
- Littoral Environnement et Sociétés (LIENSs), UMR 7266 CNRS-La Rochelle Université, 17000 La Rochelle, France; Institut Universitaire de France (IUF), 75005 Paris, France
| | | | | | - Rune Dietz
- Department of Ecoscience, Aarhus University, 4000 Roskilde, Denmark
| | | | - Igor Eulaers
- Norwegian Polar Institute, Fram center, 9296 Tromsø, Norway; Department of Ecoscience, Aarhus University, 4000 Roskilde, Denmark
| | - Alexey Ezhov
- Murmansk Marine Biological Institute Russian Academy of Science, 183010 Vladimirskaya str. 17 Murmansk, Russia
| | - Abram B Fleishman
- Conservation Metrics, Inc., Santa Cruz, CA, United States of America
| | | | - Maria Gavrilo
- Arctic and Antarctic Research Institute, 199397 St. Petersburg, Russia
| | - Grant Gilchrist
- Environment and Climate Change Canada, National Wildlife Research Centre, 1125 Colonel By Drive, Raven Road, Carleton University, Ottawa, Ont., Canada K1A 0H3
| | - Olivier Gilg
- Laboratoire Chrono-environnement, UMR 6249, Université de Bourgogne Franche Comté, 25000 Besançon, France; Groupe de Recherche en Ecologie Arctique, 16 rue de Vernot, F-21440 Francheville, France
| | - Sindri Gíslason
- Southwest Iceland Nature Research Centre, Gardvegur 1, 245 Sudurnesjabaer, Iceland
| | - Elena Golubova
- Laboratory of Ornithology, Institute of Biological Problems of the North, RU-685000 Magadan, Portovaya Str., 18, Russia
| | - Aurélie Goutte
- EPHE, PSL Research University, UMR 7619 METIS, F-75005 Paris, France
| | - David Grémillet
- Centre d'Ecologie Fonctionnelle et Evolutive (CEFE), UMR 5175 Univ Montpellier, CNRS, EPHE, IRD, Montpellier, France,; Percy FitzPatrick Institute of African Ornithology, University of Cape Town, Rondebosch, South Africa
| | - Gunnar T Hallgrimsson
- Department of Life and Environmental Sciences, University of Iceland, 102 Reykjavik, Iceland
| | - Erpur S Hansen
- South Iceland Nature Research Centre, Ægisgata 2, 900 Vestmannaeyjar, Iceland
| | | | - Scott Hatch
- Institute for Seabird Research and Conservation, Anchorage, 99516-3185, AK, USA
| | - Nicholas P Huffeldt
- Department of Ecoscience, Aarhus University, 4000 Roskilde, Denmark; Greenland Institute of Natural Resources, 3900 Nuuk, Greenland
| | - Dariusz Jakubas
- Department of Vertebrate Ecology and Zoology, University of Gdansk, 80-308 Gdansk, Poland
| | - Jón Einar Jónsson
- University of Iceland's Research Center at Snæfellsnes, 340 Stykkishólmur, Iceland
| | - Alexander S Kitaysky
- University of Alaska Fairbanks, Institute of Arctic Biology, Department of Biology & Wildlife, Fairbanks, AK 99775-7000, United States of America
| | | | - Yuri Krasnov
- Murmansk Marine Biological Institute Russian Academy of Science, 183010 Vladimirskaya str. 17 Murmansk, Russia
| | - Robert J Letcher
- Environment and Climate Change Canada, National Wildlife Research Centre, 1125 Colonel By Drive, Raven Road, Carleton University, Ottawa, Ont., Canada K1A 0H3
| | | | - Mark Mallory
- Biology, Acadia University Wolfville, Nova Scotia B4P 2R6, Canada
| | - Flemming Ravn Merkel
- Department of Ecoscience, Aarhus University, 4000 Roskilde, Denmark; Greenland Institute of Natural Resources, 3900 Nuuk, Greenland
| | - Børge Moe
- Norwegian Institute for Nature Research, 7485 Trondheim, Norway
| | - William J Montevecchi
- Memorial Univerisity of Newfoundland and Labrador, St. John's, Newoundland A1C 3X9, Canada
| | - Anders Mosbech
- Department of Ecoscience, Aarhus University, 4000 Roskilde, Denmark
| | - Bergur Olsen
- Faroe Marine Reseaqrch Institute, Nóatún 1, FO-110 Tórshavn, Faroe Islands
| | - Rachael A Orben
- Department of Fisheries, Wildlife and Conservation Sciences, Oregon State University, Hatfield Marine Science Center, Newport, OR, USA
| | - Jennifer F Provencher
- Science & Technology Branch, Environment and Climate Change Canada, Ottawa, Ontario, Canada K1A 0H3
| | | | - Tone K Reiertsen
- Norwegian Institute for Nature Research, FRAM Centre, 9296 Tromsø, Norway
| | - Nora Rojek
- U.S. Fish and Wildlife Service, Alaska Maritime Wildlife Refuge, Homer, AK, USA
| | - Marc Romano
- U.S. Fish and Wildlife Service, Alaska Maritime Wildlife Refuge, Homer, AK, USA
| | - Jens Søndergaard
- Department of Ecoscience, Aarhus University, 4000 Roskilde, Denmark
| | - Hallvard Strøm
- Norwegian Polar Institute, Fram center, 9296 Tromsø, Norway
| | - Akinori Takahashi
- National Institute of Polar Research, 10-3 Midori-cho, Tachikawa, Tokyo 190-8518, Japan
| | - Sabrina Tartu
- Centre d'Etudes Biologiques de Chizé (CEBC), UMR 7372 CNRS- La Rochelle Université, 79360 Villiers-en-Bois, France
| | | | - Jean-Baptiste Thiebot
- National Institute of Polar Research, 10-3 Midori-cho, Tachikawa, Tokyo 190-8518, Japan
| | - Alexis P Will
- University of Alaska Fairbanks, Institute of Arctic Biology, Department of Biology & Wildlife, Fairbanks, AK 99775-7000, United States of America; National Institute of Polar Research, 10-3 Midori-cho, Tachikawa, Tokyo 190-8518, Japan
| | - Simon Wilson
- Arctic Monitoring and Assessment Programme (AMAP) Secretariat, The Fram Centre, Box 6606, Stakkevollan, 9296, Tromsø, Norway
| | | | - Glenn Yannic
- Univ. Grenoble Alpes, Univ. Savoie Mont Blanc, CNRS, LECA, 38000 Grenoble, France
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da Silva Júnior FJTM, Ribeiro JDN, da Silva HLA, da Silva Carneiro C, de Jesus EFO, de Araújo UB, Lazzarini SM, Souza AR, Simões JS, Lopes RT, Dos Anjos MJ, da Silva Ferreira M, Mársico ET. Study of inorganic elements in different organs and tissues of Amazonian manatee (Trichechus inunguis) from Brazil. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2022; 29:30486-30495. [PMID: 35000156 DOI: 10.1007/s11356-021-17748-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Accepted: 11/21/2021] [Indexed: 06/14/2023]
Abstract
Multielement concentrations (P, S, Cl, K, Ca, Cr, Mn, Fe, Ni, Cu, Zn, Rb, and Rh) and total mercury (T-Hg) were analyzed in different organs and tissues of Amazonian manatee (Trichechus inunguis). Samples of 27 T. inunguis specimens, maintained in the collection of the Amazonian Center for the Research and Preservation of Aquatic Mammals, were used, situated in an area highly impacted by gold mining in the northern region of the Brazilian Amazon. Samples of aquatic plants used as food by the animals were also analyzed. The elements S, Cl, K, Cr, and Mn accumulated mainly in the musculature, while Fe and Cu were more concentrated in the liver. Trace elements, such as rubidium (Rb) and rhodium (Rh), not previously reported in the organs of animals of the family Trichechidae, were also identified. The averages for T-Hg in the skin, muscle, encephalon, liver, kidney, and lung samples were, respectively, 0.1540 ± 0.1332, 0.0593 ± 0.1044, 0.0517 ± 0.0467, 0.0486 ± 0.0543, 0.0237 ± 0.0336, and 0.0013 ± 0.0032 µg.g-1. The values obtained for the vibrissae samples were below the limit of quantification, which allows for the conclusion that this tissue cannot be used as a contamination marker. It was observed that even when kept in a conservation breeding site, these animals were exposed to non-essential trace elements. Differences in the accumulation of elements were observed between the different organs and tissues analyzed. The presence of contaminants in animals that live in a preservation center, even at low levels, deserves attention.
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Affiliation(s)
| | - Joanna Damazio Nunes Ribeiro
- Department of Food Technology, Fluminense Federal University (UFF), Rua Vital Brazil Filho n° 64, Niterói, RJ, 24230-340, Brazil
| | - Hugo Leandro Azevedo da Silva
- Department of Food Technology, Fluminense Federal University (UFF), Rua Vital Brazil Filho n° 64, Niterói, RJ, 24230-340, Brazil.
| | - Carla da Silva Carneiro
- Health Science Center, Federal University of Rio de Janeiro (UFRJ), Rio de Janeiro, RJ, Brazil
| | | | - Ubiratan Barbosa de Araújo
- Nuclear Instrumentation Laboratory COPPE/UFRJ, Federal University of Rio de Janeiro (UFRJ), Rio de Janeiro, RJ, Brazil
| | - Stella Maris Lazzarini
- Center for Research and Preservation of Aquatic Mammals (CPPMA), ELETRONORTE, Balbina, AM, Brazil
| | - Aline Ramos Souza
- Center for Research and Preservation of Aquatic Mammals (CPPMA), ELETRONORTE, Balbina, AM, Brazil
- Institute of Biological Sciences, Federal University of Amazonas (UFAM), Manaus, AM, Brazil
| | - Julia Siqueira Simões
- Department of Food Technology, Fluminense Federal University (UFF), Rua Vital Brazil Filho n° 64, Niterói, RJ, 24230-340, Brazil
| | - Ricardo Tadeu Lopes
- Nuclear Instrumentation Laboratory COPPE/UFRJ, Federal University of Rio de Janeiro (UFRJ), Rio de Janeiro, RJ, Brazil
| | - Marcelino José Dos Anjos
- Nuclear Instrumentation Laboratory COPPE/UFRJ, Federal University of Rio de Janeiro (UFRJ), Rio de Janeiro, RJ, Brazil
| | - Micheli da Silva Ferreira
- Department of Food Technology, Fluminense Federal University (UFF), Rua Vital Brazil Filho n° 64, Niterói, RJ, 24230-340, Brazil
| | - Eliane Teixeira Mársico
- Department of Food Technology, Fluminense Federal University (UFF), Rua Vital Brazil Filho n° 64, Niterói, RJ, 24230-340, Brazil
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Luz DA, Cartágenes SDC, da Silveira CCSDM, Pinheiro BG, Ferraro KMMM, Fernandes LDMP, Fontes-Júnior EA, Maia CDSF. Methylmercury plus Ethanol Exposure: How Much Does This Combination Affect Emotionality? Int J Mol Sci 2021; 22:ijms222313131. [PMID: 34884935 PMCID: PMC8658096 DOI: 10.3390/ijms222313131] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Revised: 10/26/2021] [Accepted: 10/29/2021] [Indexed: 12/12/2022] Open
Abstract
Mercury is a heavy metal found in organic and inorganic forms that represents an important toxicant with impact on human health. Mercury can be released in the environment by natural phenoms (i.e., volcanic eruptions), industrial products, waste, or anthropogenic actions (i.e., mining activity). Evidence has pointed to mercury exposure inducing neurological damages related to emotional disturbance, such as anxiety, depression, and insomnia. The mechanisms that underlie these emotional disorders remain poorly understood, although an important role of glutamatergic pathways, alterations in HPA axis, and disturbance in activity of monoamines have been suggested. Ethanol (EtOH) is a psychoactive substance consumed worldwide that induces emotional alterations that have been strongly investigated, and shares common pathophysiological mechanisms with mercury. Concomitant mercury and EtOH intoxication occur in several regions of the world, specially by communities that consume seafood and fish as the principal product of nutrition (i.e., Amazon region). Such affront appears to be more deleterious in critical periods of life, such as the prenatal and adolescence period. Thus, this review aimed to discuss the cellular and behavioral changes displayed by the mercury plus EtOH exposure during adolescence, focused on emotional disorders, to answer the question of whether mercury plus EtOH exposure intensifies depression, anxiety, and insomnia observed by the toxicants in isolation.
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Affiliation(s)
- Diandra Araújo Luz
- Laboratório de Farmacologia da Inflamação e do Comportamento, Instituto de Ciências da Saúde, Universidade Federal do Pará, Belém 66075-110, PA, Brazil; (D.A.L.); (S.d.C.C.); (C.C.S.d.M.d.S.); (B.G.P.); (K.M.M.M.F.); (E.A.F.-J.)
| | - Sabrina de Carvalho Cartágenes
- Laboratório de Farmacologia da Inflamação e do Comportamento, Instituto de Ciências da Saúde, Universidade Federal do Pará, Belém 66075-110, PA, Brazil; (D.A.L.); (S.d.C.C.); (C.C.S.d.M.d.S.); (B.G.P.); (K.M.M.M.F.); (E.A.F.-J.)
| | - Cinthia Cristina Sousa de Menezes da Silveira
- Laboratório de Farmacologia da Inflamação e do Comportamento, Instituto de Ciências da Saúde, Universidade Federal do Pará, Belém 66075-110, PA, Brazil; (D.A.L.); (S.d.C.C.); (C.C.S.d.M.d.S.); (B.G.P.); (K.M.M.M.F.); (E.A.F.-J.)
| | - Bruno Gonçalves Pinheiro
- Laboratório de Farmacologia da Inflamação e do Comportamento, Instituto de Ciências da Saúde, Universidade Federal do Pará, Belém 66075-110, PA, Brazil; (D.A.L.); (S.d.C.C.); (C.C.S.d.M.d.S.); (B.G.P.); (K.M.M.M.F.); (E.A.F.-J.)
| | - Kissila Márvia Matias Machado Ferraro
- Laboratório de Farmacologia da Inflamação e do Comportamento, Instituto de Ciências da Saúde, Universidade Federal do Pará, Belém 66075-110, PA, Brazil; (D.A.L.); (S.d.C.C.); (C.C.S.d.M.d.S.); (B.G.P.); (K.M.M.M.F.); (E.A.F.-J.)
| | - Luanna de Melo Pereira Fernandes
- Departamento de Ciências Morfológicas e Fisiológicas, Centro das Ciências Biológicas e da Saúde (CCBS), Universidade Estadual do Pará, Belém 66095-100, PA, Brazil;
| | - Enéas Andrade Fontes-Júnior
- Laboratório de Farmacologia da Inflamação e do Comportamento, Instituto de Ciências da Saúde, Universidade Federal do Pará, Belém 66075-110, PA, Brazil; (D.A.L.); (S.d.C.C.); (C.C.S.d.M.d.S.); (B.G.P.); (K.M.M.M.F.); (E.A.F.-J.)
| | - Cristiane do Socorro Ferraz Maia
- Laboratório de Farmacologia da Inflamação e do Comportamento, Instituto de Ciências da Saúde, Universidade Federal do Pará, Belém 66075-110, PA, Brazil; (D.A.L.); (S.d.C.C.); (C.C.S.d.M.d.S.); (B.G.P.); (K.M.M.M.F.); (E.A.F.-J.)
- Correspondence:
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Dibbern M, Elmeros M, Dietz R, Søndergaard J, Michelsen A, Sonne C. Mercury exposure and risk assessment for Eurasian otters (Lutra lutra) in Denmark. CHEMOSPHERE 2021; 272:129608. [PMID: 33486453 DOI: 10.1016/j.chemosphere.2021.129608] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 01/05/2021] [Accepted: 01/08/2021] [Indexed: 06/12/2023]
Abstract
Mercury (Hg) exposure may cause a wide range of adverse effects in mammals. A piscivorous apex predator, as the Eurasian otters (Lutra lutra) may accumulate and biomagnify heavy metals and pollutants. Here we investigate the Hg burden in 117 otters from Denmark to evaluate Hg concentrations and risks of health effects. Mercury concentrations ranged between 0.02 and 10.1 μg/g wet weight (ww) in liver tissue and 0.30-40.0 μg/g dry weight in fur. Concentrations in liver and fur in individual otters were highly correlated (P < 0.001). Generalized linear modelling showed that mercury concentrations in both liver and fur increased with age (liver: P < 0.002; fur P < 0.05) and with distance to the marine coastline i.e. towards freshwater habitats (P = 0.0526), and δ13C in muscle tissues (P < 0.001). No differences were detected between males and females (P > 0.59) and no correlation were detected between Hg concentration and trophic level (δ15N) (liver: P = 0.35; fur: P = 0.54). Mercury concentrations in the liver exceeded the No Risk threshold in 15% of the otters, and 25% had levels above the lowest observed effect level of 3.4 μg/g ww that may be associated with adverse effects on the central nervous system. The proportion exceeding these thresholds should therefore be monitored to document possible temporal and spatial trends in Hg exposure and the potential risk to the conservation status of the otter population.
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Affiliation(s)
- Miriam Dibbern
- Department of Bioscience, Aarhus University, Frederiksborgvej 399, PO Box 358, DK-4000, Roskilde, Denmark; Department of Bioscience, Aarhus University, Grenåvej 14 Kalø, DK-8410, Rønde, Denmark
| | - Morten Elmeros
- Department of Bioscience, Aarhus University, Grenåvej 14 Kalø, DK-8410, Rønde, Denmark.
| | - Rune Dietz
- Department of Bioscience, Aarhus University, Frederiksborgvej 399, PO Box 358, DK-4000, Roskilde, Denmark
| | - Jens Søndergaard
- Department of Bioscience, Aarhus University, Frederiksborgvej 399, PO Box 358, DK-4000, Roskilde, Denmark
| | - Anders Michelsen
- Terrestrial Ecology Section, Department of Biology, University of Copenhagen, Universitetsparken 15, DK-2100, Copenhagen, Denmark
| | - Christian Sonne
- Department of Bioscience, Aarhus University, Frederiksborgvej 399, PO Box 358, DK-4000, Roskilde, Denmark
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Biswas S, Bellare J. Adaptive mechanisms induced by sparingly soluble mercury sulfide (HgS) in zebrafish: Behavioural and proteomics analysis. CHEMOSPHERE 2021; 270:129438. [PMID: 33429232 DOI: 10.1016/j.chemosphere.2020.129438] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Revised: 12/18/2020] [Accepted: 12/22/2020] [Indexed: 06/12/2023]
Abstract
Mercury (Hg) causes great health concerns due to its extreme neurotoxicity. However, here we show that pretreatment of sparingly soluble mercury compound (HgS) could induce adaptive mechanisms in zebrafish, which can resist the neurotoxic effects of mercury chloride (HgCl2). In this study, zebrafish were treated with HgS (in the form of 99% HgS arising from traditional Ayurvedic medicine Rasasindura (RS), chosen for its particle and crystallite sizes). This work was prompted by the traditional use of this form of HgS to treat nervous and immune-related diseases. Our investigation on zebrafish behaviour showed that RS pretreated fish group (RS-HG) was less severely affected by HgCl2 exposure, as compared to the RS non-treated (VC-HG) group. Further, biochemical tests showed that RS pretreatment prevents alteration of reactive oxygen species (ROS), acetylcholinesterase (AChE), and cortisol as compared to the VC-HG group. Proteomics and bioinformatics studies of zebrafish brain tissues suggested that Rasasindura (RS-HG group) protects alteration of various protein expression related to KEGG pathways, including citrate cycle (TCA cycle) and glutathione metabolism that are directly or indirectly linked to the oxidative stress, against HgCl2 induced neurotoxicity. We found that adaptive mechanisms were initiated by the initiation of response to stress (enrichment of GO:0006950 pathway), due to the accumulation of a small amount of ionic Hg (60 ± 10 ng/g) after 15 days of RS treatment. These adaptive mechanisms avoid further adverse neurotoxicity of HgCl2. Thus, HgS (RS) pretreatment can induce protective effects in zebrafish.
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Affiliation(s)
- Snehasis Biswas
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India
| | - Jayesh Bellare
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India; Wadhwani Research Centre for Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India.
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Lian M, Field CL, van Wijngaarden E, Rios C, Castellini JM, Greig DJ, Rea LD, Coleman DJ, Thomson CE, Gulland FMD, O'Hara TM. Assessment of clinical outcomes associated with mercury concentrations in harbor seal pups (Phoca vitulina richardii) in central California. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 758:143686. [PMID: 33279198 DOI: 10.1016/j.scitotenv.2020.143686] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Accepted: 11/06/2020] [Indexed: 06/12/2023]
Abstract
Monomethyl mercury (MeHg+) from the diet can cause mild to severe neurotoxicosis in fish-eating mammals. Chronic and low-level in utero exposure also can be neurotoxic, as documented in laboratory animal studies and epidemiologic investigations. In free-ranging animals, it is challenging to study low-level exposure related neurotoxicosis, and few studies have investigated the relationship between mercury (Hg) and adverse outcomes in wild populations. Relative to Hg concentrations on admission we evaluated different types of behaviors for 267 Pacific harbor seal (HS; Phoca vitulina richardii) pups at The Marine Mammal Center from 2015 to 2019 during rehabilitation after stranding and maternal separation. Admitted HS pups underwent a clinical exam; including sex and weight determination, and hair (partly lanugo grown in utero) and blood samples were collected for total Hg concentration ([THg]) determination. All pups were monitored weekly (behavior assessments included response to tactile stimulation, movement, swimming, interactions with other seals, hand feeding, and feeding independently), and days in rehabilitation and survival were recorded. There was a significant negative correlation between [THg] and responses to tactile stimulation and movements, measured in both hair and whole blood (p < 0.05). This relationship was found both during the intensive care unit (ICU) stage, and during the pool stage of rehabilitation. Additionally, there was a significant association between greater [THg] and number of days spent in rehabilitation, although there was no relationship between [THg] and survival. There was a significant sex difference, with greater [THg] in female pups, which contrasts with previously published findings in juvenile and adult harbor seals. Our findings support small, but significant associations between gestational THg exposure and clinical effects for tactile sensory response and movement, and longer rehabilitation durations for HS pups, although there was considerable variability among animals.
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Affiliation(s)
- Marianne Lian
- Department of Veterinary Medicine, University of Alaska Fairbanks, 2141 Koyokuk Dr, Fairbanks, AK 99775-7750, USA; Department of Chemistry and Biochemistry, University of Alaska Fairbanks, 900 Yukon Dr Rm. 194, Fairbanks, AK 99775-6160, USA.
| | - Cara L Field
- The Marine Mammal Center, 2000 Bunker Road, Fort Cronkhite, Sausalito, CA 94965, USA
| | - Edwin van Wijngaarden
- University of Rochester School of Medicine and Dentistry, 601 Elmwood Avenue, Rochester, NY 14642, USA
| | - Carlos Rios
- The Marine Mammal Center, 2000 Bunker Road, Fort Cronkhite, Sausalito, CA 94965, USA
| | - J Margaret Castellini
- Department of Veterinary Medicine, University of Alaska Fairbanks, 2141 Koyokuk Dr, Fairbanks, AK 99775-7750, USA
| | - Denise J Greig
- The Marine Mammal Center, 2000 Bunker Road, Fort Cronkhite, Sausalito, CA 94965, USA
| | - Lorrie D Rea
- Water and Environmental Research Center, Institute of Northern Engineering, University of Alaska Fairbanks, 1764 Tanana Loop, Fairbanks, AK 99775, USA
| | - Denver J Coleman
- The Marine Mammal Center, 2000 Bunker Road, Fort Cronkhite, Sausalito, CA 94965, USA
| | - Christine E Thomson
- Department of Veterinary Medicine, University of Alaska Fairbanks, 2141 Koyokuk Dr, Fairbanks, AK 99775-7750, USA; Animal Referral Hospital Brisbane, Sinnamon Park, Brisbane, Queensland, Australia
| | - Frances M D Gulland
- The Marine Mammal Center, 2000 Bunker Road, Fort Cronkhite, Sausalito, CA 94965, USA
| | - Todd M O'Hara
- Department of Veterinary Medicine, University of Alaska Fairbanks, 2141 Koyokuk Dr, Fairbanks, AK 99775-7750, USA; Veterinary Integrative Biosciences, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, TX 77843, USA
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8
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Chételat J, Ackerman JT, Eagles-Smith CA, Hebert CE. Methylmercury exposure in wildlife: A review of the ecological and physiological processes affecting contaminant concentrations and their interpretation. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 711:135117. [PMID: 31831233 DOI: 10.1016/j.scitotenv.2019.135117] [Citation(s) in RCA: 74] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 10/15/2019] [Accepted: 10/21/2019] [Indexed: 05/12/2023]
Abstract
Exposure to methylmercury (MeHg) can result in detrimental health effects in wildlife. With advances in ecological indicators and analytical techniques for measurement of MeHg in a variety of tissues, numerous processes have been identified that can influence MeHg concentrations in wildlife. This review presents a synthesis of theoretical principals and applied information for measuring MeHg exposure and interpreting MeHg concentrations in wildlife. Mercury concentrations in wildlife are the net result of ecological processes influencing dietary exposure combined with physiological processes that regulate assimilation, transformation, and elimination. Therefore, consideration of both physiological and ecological processes should be integrated when formulating biomonitoring strategies. Ecological indicators, particularly stable isotopes of carbon, nitrogen, and sulfur, compound-specific stable isotopes, and fatty acids, can be effective tools to evaluate dietary MeHg exposure. Animal species differ in their physiological capacity for MeHg elimination, and animal tissues can be inert or physiologically active, act as sites of storage, transformation, or excretion of MeHg, and vary in the timing of MeHg exposure they represent. Biological influences such as age, sex, maternal transfer, and growth or fasting are also relevant for interpretation of tissue MeHg concentrations. Wildlife tissues that represent current or near-term bioaccumulation and in which MeHg is the predominant mercury species (such as blood and eggs) are most effective for biomonitoring ecosystems and understanding landscape drivers of MeHg exposure. Further research is suggested to critically evaluate the use of keratinized external tissues to measure MeHg bioaccumulation, particularly for less-well studied wildlife such as reptiles and terrestrial mammals. Suggested methods are provided to effectively use wildlife for quantifying patterns and drivers of MeHg bioaccumulation over time and space, as well as for assessing the potential risk and toxicological effects of MeHg on wildlife.
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Affiliation(s)
- John Chételat
- Environment and Climate Change Canada, National Wildlife Research Centre, 1125 Colonel By Drive, Ottawa, ON K1A 0H3, Canada.
| | - Joshua T Ackerman
- U.S. Geological Survey, Western Ecological Research Center, Dixon Field Station, 800 Business Park Drive, Suite D, Dixon, CA 95620, United States
| | - Collin A Eagles-Smith
- U.S. Geological Survey, Forest and Rangeland Ecosystem Science Center, 3200 SW Jefferson Way, Corvallis, Oregon, 97331, United States
| | - Craig E Hebert
- Environment and Climate Change Canada, National Wildlife Research Centre, 1125 Colonel By Drive, Ottawa, ON K1A 0H3, Canada
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9
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Li M, Juang CA, Ewald JD, Yin R, Mikkelsen B, Krabbenhoft DP, Balcom PH, Dassuncao C, Sunderland EM. Selenium and stable mercury isotopes provide new insights into mercury toxicokinetics in pilot whales. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 710:136325. [PMID: 31927288 DOI: 10.1016/j.scitotenv.2019.136325] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 12/16/2019] [Accepted: 12/23/2019] [Indexed: 05/12/2023]
Abstract
High exposures of mammalian species to inorganic mercury (HgII) and methylmercury (MeHg) have been associated with adverse effects on behavior and reproduction. Different mammalian species exhibit varying responses to similar external exposure levels, reflecting potential differences in Hg toxicokinetics. Here, we use Hg stable isotopes, total Hg, MeHg and selenium (Se) concentrations measured in multiple tissues of North Atlantic pilot whales (Globicephala melas) to investigate processes affecting the distribution and accumulation of HgII and MeHg. We find that simple mixing of two distinct isotopic end-members: MeHg (1.4‰) and HgII (-1.6‰) can explain the observed variability of δ202Hg in brain tissue. A similar isotopic composition for the MeHg end-member in the brain, muscle, heart, and kidney suggests efficient exchange of MeHg in blood throughout the body. By contrast, the Hg isotopic composition of the liver of adult whales is different from younger whales and other tissues that follow the two-end member mixing model. Measured Se:Hg ratios are lowest in adult whales with the highest levels of MeHg exposure. In these individuals, Se availability is likely reduced by complexation with demethylated HgII. We speculate that this results in a higher fraction of labile HgII eliminated from the liver of adult whales compared to young whales and subsequent redistribution to other tissues, potentially affecting toxicity.
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Affiliation(s)
- Miling Li
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, United States; Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, MA 02115, United States.
| | - C Alicia Juang
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, United States
| | - Jessica D Ewald
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, United States; Faculty of Agricultural and Environmental Sciences, Macdonald Campus, McGill University Ste-Anne-de-Bellevue, Quebec H9X 3V9, Canada
| | - Runsheng Yin
- Department of Civil and Environmental Engineering, University of Wisconsin, Madison, WI, United States
| | - Bjarni Mikkelsen
- The Faroese Museum of Natural History, V. U. Hammershaimbsgøta 13, FO-100 Tórshavn, Faroe Islands
| | | | - Prentiss H Balcom
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, United States
| | - Clifton Dassuncao
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, United States; Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, MA 02115, United States
| | - Elsie M Sunderland
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, United States; Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, MA 02115, United States
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Li P, Du B, Chan HM, Feng X, Li B. Mercury bioaccumulation and its toxic effects in rats fed with methylmercury polluted rice. THE SCIENCE OF THE TOTAL ENVIRONMENT 2018; 633:93-99. [PMID: 29573695 DOI: 10.1016/j.scitotenv.2018.03.185] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2018] [Revised: 03/16/2018] [Accepted: 03/16/2018] [Indexed: 06/08/2023]
Abstract
Recent evidence indicated that methylmercury (MeHg) contaminated rice can be a significant source of MeHg human exposure, but the health implications are not known. The objective of this study was to study the kinetics, speciation, and effects of MeHg contaminated rice using a rat model. Five groups of adult Sprague-Dawley rats (n=10 in each group) were fed control rice, low (10ng/g MeHg) and high (25ng/g MeHg) MeHg contaminated rice. Two groups of the positive control were fed control rice spiked with the same levels of MeHgCl. Short-term exposure to low level of spiked MeHgCl stimulated the growth of male rats while long-term exposure to spiked MeHgCl inhibited the growth in female rats. There was no temporal variation of total mercury (THg) concentrations in the rat fecal samples from each group, and the THg concentrations significantly correlated with the inorganic Hg concentrations in the feeding rice. There were significant differences in the accumulation of THg and MeHg among different groups and different organs. THg and MeHg concentrations in the kidney were the highest among the organs examined. The blood and brain had high percentages of THg as MeHg, which indicates that MeHg can easily pass through the blood-brain barrier and has a high affinity for brain tissue. Exposure to rice containing 25ng/g MeHg decreased antioxidant function and damaged the nervous system in rats, but no significant effects were found in the group fed with rice containing 10ng/g MeHg. MeHgCys in rice is less toxic than spiked MeHgCl to rats. The toxicity of MeHg both decided by its concentration and speciation.
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Affiliation(s)
- Ping Li
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Buyun Du
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Hing Man Chan
- Centre for Advanced Research in Environmental Genomics, University of Ottawa, Ottawa K1N 6N5, Canada
| | - Xinbin Feng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China.
| | - Baixiang Li
- Department of Toxicology, Public Health College, Harbin Medical University, Harbin 150081, China.
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11
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Ma L, Evans RD, Wang W, Georg RB. In vivo fractionation of mercury isotopes in tissues of a mammalian carnivore (Neovison vison). THE SCIENCE OF THE TOTAL ENVIRONMENT 2018; 627:1228-1233. [PMID: 30857087 DOI: 10.1016/j.scitotenv.2018.01.296] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Revised: 01/13/2018] [Accepted: 01/28/2018] [Indexed: 06/09/2023]
Abstract
The use of isotope ratios to trace Hg contamination sources in environmental compartments is now generally accepted. However, for biota and especially for mammals, it is still unknown if and/or how Hg isotopes fractionate in vivo and which tissue is most representative of the source(s) of contamination. We measured fractionation of Hg in mink (Neovison vison) tissues (fur, brain, blood, liver, kidney) collected during a controlled feeding experiment where captive mink were fed differing amounts of methylmercury. There was no significant effect of dietary MeHg concentrations on Hg fractionation in most tissues. Net fractionation of Hg, i.e., fractionation corrected for diet (δ202Hgtissue-δ202Hgdiet) was observed in all tissues with the greatest net fractionation occurring in the mink liver (-1.39‰) and kidney (-0.95‰). Less net fractionation, occurred in the brain (-0.12‰), blood (0.38‰) and fur (0.30‰). In the absence of brain tissue, fur is a suitable proxy which is readily obtainable and can be non-lethally collected. In these mink, it appears that biochemical processes such as demethylation, contribute to significant fractionation of Hg in the liver and kidney, but not as much in the brain and fur, where transport of Hg via thiol-containing complexes may be more important.
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Affiliation(s)
- Lan Ma
- Environment & Life Sciences Graduate Program, Trent University, 1600 West Bank Drive, Peterborough, ON K9L 0G2, Canada
| | - R Douglas Evans
- School of the Environment, Trent University, 1600 West Bank Drive, Peterborough, ON K9L 0G2, Canada.
| | - Wei Wang
- School of the Environment, Trent University, 1600 West Bank Drive, Peterborough, ON K9L 0G2, Canada
| | - R Bastian Georg
- Water Quality Centre, Trent University, 1600 West Bank Drive, Peterborough, ON K9L 0G2, Canada
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12
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Chételat J, Hickey MBC, Poulain AJ, Dastoor A, Ryjkov A, McAlpine D, Vanderwolf K, Jung TS, Hale L, Cooke ELL, Hobson D, Jonasson K, Kaupas L, McCarthy S, McClelland C, Morningstar D, Norquay KJO, Novy R, Player D, Redford T, Simard A, Stamler S, Webber QMR, Yumvihoze E, Zanuttig M. Spatial variation of mercury bioaccumulation in bats of Canada linked to atmospheric mercury deposition. THE SCIENCE OF THE TOTAL ENVIRONMENT 2018; 626:668-677. [PMID: 29396333 DOI: 10.1016/j.scitotenv.2018.01.044] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Revised: 01/05/2018] [Accepted: 01/06/2018] [Indexed: 06/07/2023]
Abstract
Wildlife are exposed to neurotoxic mercury at locations distant from anthropogenic emission sources because of long-range atmospheric transport of this metal. In this study, mercury bioaccumulation in insectivorous bat species (Mammalia: Chiroptera) was investigated on a broad geographic scale in Canada. Fur was analyzed (n=1178) for total mercury from 43 locations spanning 20° latitude and 77° longitude. Total mercury and methylmercury concentrations in fur were positively correlated with concentrations in internal tissues (brain, liver, kidney) for a small subset (n=21) of little brown bats (Myotis lucifugus) and big brown bats (Eptesicus fuscus), validating the use of fur to indicate internal mercury exposure. Brain methylmercury concentrations were approximately 10% of total mercury concentrations in fur. Three bat species were mainly collected (little brown bats, big brown bats, and northern long-eared bats [M. septentrionalis]), with little brown bats having lower total mercury concentrations in their fur than the other two species at sites where both species were sampled. On average, juvenile bats had lower total mercury concentrations than adults but no differences were found between males and females of a species. Combining our dataset with previously published data for eastern Canada, median total mercury concentrations in fur of little brown bats ranged from 0.88-12.78μg/g among 11 provinces and territories. Highest concentrations were found in eastern Canada where bats are most endangered from introduced disease. Model estimates of atmospheric mercury deposition indicated that eastern Canada was exposed to greater mercury deposition than central and western sites. Further, mean total mercury concentrations in fur of adult little brown bats were positively correlated with site-specific estimates of atmospheric mercury deposition. This study provides the largest geographic coverage of mercury measurements in bats to date and indicates that atmospheric mercury deposition is important in determining spatial patterns of mercury accumulation in a mammalian species.
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Affiliation(s)
- John Chételat
- Environment and Climate Change Canada, National Wildlife Research Centre, Ottawa, Ontario K1A 0H3, Canada.
| | | | - Alexandre J Poulain
- Biology Department, Faculty of Science, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada
| | - Ashu Dastoor
- Air Quality Research Division, Environment and Climate Change Canada, Dorval, Quebec H9P 1J3, Canada
| | - Andrei Ryjkov
- Air Quality Research Division, Environment and Climate Change Canada, Dorval, Quebec H9P 1J3, Canada
| | - Donald McAlpine
- New Brunswick Museum, Saint John, New Brunswick E2K 1E5, Canada
| | - Karen Vanderwolf
- New Brunswick Museum, Saint John, New Brunswick E2K 1E5, Canada; Canadian Wildlife Federation, Kanata, Ontario K2M 2W1, Canada
| | - Thomas S Jung
- Yukon Department of Environment, Whitehorse, Yukon Territory Y1A 2C6, Canada
| | - Lesley Hale
- Ontario Ministry of Natural Resources & Forestry, Peterborough, Ontario K9J 8M5, Canada
| | - Emma L L Cooke
- Environment and Climate Change Canada, National Wildlife Research Centre, Ottawa, Ontario K1A 0H3, Canada
| | - Dave Hobson
- Alberta Environment and Parks, Edson, Alberta T7E 1T2, Canada
| | - Kristin Jonasson
- Department of Biology, Western University, London, Ontario N6A 5B7, Canada
| | - Laura Kaupas
- Department of Biological Sciences, University of Calgary, Calgary, Alberta T2N 1N4, Canada
| | - Sara McCarthy
- Wildlife Division, Fisheries and Land Resources, Goose Bay, Newfoundland and Labrador A0P 1E0, Canada
| | - Christine McClelland
- Environment and Climate Change Canada, National Wildlife Research Centre, Ottawa, Ontario K1A 0H3, Canada
| | | | - Kaleigh J O Norquay
- Department of Biology, University of Winnipeg, Winnipeg, Manitoba R3B 2G3, Canada
| | - Richard Novy
- Golder Associates Ltd., Calgary, Alberta T2A 7W5, Canada
| | | | - Tony Redford
- Animal Health Centre, BC Ministry of Agriculture, Abbotsford, British Columbia V3G 2M3, Canada
| | - Anouk Simard
- Direction de l'expertise sur la faune terrestre, l'herpétofaune et l'avifaune, Ministère des Forêts, de la Faune et des Parcs, Québec, Quebec G1S 4X4, Canada
| | - Samantha Stamler
- Alberta Environment and Parks, Edmonton, Alberta T6H 4P2, Canada
| | - Quinn M R Webber
- Department of Biology, University of Winnipeg, Winnipeg, Manitoba R3B 2G3, Canada
| | - Emmanuel Yumvihoze
- Biology Department, Faculty of Science, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada
| | - Michelle Zanuttig
- Environment and Climate Change Canada, National Wildlife Research Centre, Ottawa, Ontario K1A 0H3, Canada
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13
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Guining W, Shifeng C, Qibiao S, Hua S, Meiyu L, Fei H, Wenjie L, Guoshou L, Zhoufeng H, Xiao T, Xiao L, Xianbiao Z, Baowei W, Naihong C. Antidepressant-like effect of active fraction of Polyrhachisvicina Roger in a rat depression model. J TRADIT CHIN MED 2018. [DOI: 10.1016/j.jtcm.2018.02.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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14
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Nunes B, Vidal D, Barbosa I, Soares AMVM, Freitas R. Pollution effects on biochemical pathways determined in the polychaete Hediste diversicolor collected in three Portuguese estuaries. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2016; 18:1208-1219. [PMID: 27499386 DOI: 10.1039/c6em00297h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Biomonitoring is an important tool for the assessment of the quality and functions of ecosystems, providing information about the pollutants present and the direct effects that they exert on organisms. Biomonitoring relies upon the quantification of variables that can be biochemical, genetic, morphological and physiological changes. Such variables are designated as biomarkers, and multiple biomarkers are usually determined simultaneously in order to have a more integrated analysis and information about sublethal early effects of contaminants. In this work, we quantified biomarkers, associated with oxidative stress (glutathione-S-transferases GSTs, and catalase CAT, activities; levels of peroxidative alterations, by the thiobarbituric acid reactive substances assay, TBARS) and neurotoxicity (acetylcholinesterase activity, AChE) in the polychaete Hediste diversicolor. Organisms were collected at three distinct estuaries, Ria de Aveiro (Laranjo and São Jacinto), Douro River (São Paio, Afurada, and Ribeira da Granja), both impacted by human activities, and Minho River (Seixas), which has been used as a reference site. Obtained data showed the occurrence of anti-oxidant responses, in most samples from contaminated sites, which was not followed however by the occurrence of oxidative damage in organisms from Ria de Aveiro. None of the analyzed organisms had significant impairment of cholinesterasic activity, suggesting the absence of a prior exposure to neurotoxic compounds. In fact, organisms collected at Ria de Aveiro had largely increased AChE activity, suggesting an uncommon paradoxical biological response that is further discussed.
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Affiliation(s)
- B Nunes
- Departamento de Biologia, Centro de Estudos do Ambiente e do Mar, Campus Universitário de Santiago, Universidade de Aveiro, 3810-193 Aveiro, Portugal.
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15
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Romero MB, Polizzi P, Chiodi L, Das K, Gerpe M. The role of metallothioneins, selenium and transfer to offspring in mercury detoxification in Franciscana dolphins (Pontoporia blainvillei). MARINE POLLUTION BULLETIN 2016; 109:650-654. [PMID: 27210558 DOI: 10.1016/j.marpolbul.2016.05.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Revised: 05/03/2016] [Accepted: 05/04/2016] [Indexed: 06/05/2023]
Abstract
The concentrations of mercury (Hg), selenium (Se) and metallothioneins (MT) were evaluated in fetuses, calves, juveniles and adults of the endangered coastal Franciscana dolphin (Pontoporia blainvillei) from Argentina. Mercury concentrations varied among analyzed tissues (liver, kidney, muscle and brain), with liver showing the higher concentrations in all specimens. An age-dependent accumulation was found in liver, kidney and brain. No significant relationship between Hg and MT concentrations was found for all tissues analyzed. Hepatic Hg molar concentrations were positively correlated with those of Se, indicating a great affinity between these two elements. Furthermore, dark granules of HgSe were observed in Kupffer cells in the liver by electron microscopy, suggesting the role of this macrophage in the detoxification of Hg. A transfer of Hg through placenta was proved. The presence of Hg in brain in all age classes did not show concentrations associated with neurotoxicity.
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Affiliation(s)
- M B Romero
- Instituto de Investigaciones Marinas y Costeras (IIMyC), Universidad Nacional de Mar del Plata (UNMDP), Toxicología Ambiental, Dpto. Ciencias Marinas, FCEyN, Funes 3350, 7600 Mar del Plata, Argentina.
| | - P Polizzi
- Instituto de Investigaciones Marinas y Costeras (IIMyC), Universidad Nacional de Mar del Plata (UNMDP), Toxicología Ambiental, Dpto. Ciencias Marinas, FCEyN, Funes 3350, 7600 Mar del Plata, Argentina
| | - L Chiodi
- Instituto de Investigaciones Marinas y Costeras (IIMyC), Universidad Nacional de Mar del Plata (UNMDP), Toxicología Ambiental, Dpto. Ciencias Marinas, FCEyN, Funes 3350, 7600 Mar del Plata, Argentina
| | - K Das
- Laboratory for Oceanology, MARE Center B6c, University of Liege, Liege 4000, Belgium
| | - M Gerpe
- Instituto de Investigaciones Marinas y Costeras (IIMyC), Universidad Nacional de Mar del Plata (UNMDP), Toxicología Ambiental, Dpto. Ciencias Marinas, FCEyN, Funes 3350, 7600 Mar del Plata, Argentina
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16
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Basu N, Scheuhammer AM, Evans RD, O'Brien M, Chan HM. Cholinesterase and monoamine oxidase activity in relation to mercury levels in the cerebral cortex of wild river otters. Hum Exp Toxicol 2016; 26:213-20. [PMID: 17439924 DOI: 10.1177/0960327107070570] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Mercury (Hg) is a global pollutant that is neurotoxic to many mammalian species. The present study was conducted to determine if the bioaccumulation of Hg by wild river otters ( Lontra canadensis) could be related to variations in the activities of key neurochemical enzymes. River otters were collected from Ontario and Nova Scotia (Canada) during the trapping seasons, spanning 2002-2004, and their brains were dissected into the cerebral cortex and cerebellum. The activities of cholinesterase (ChE) and monoamine oxidase (MAO) were measured from each sample and correlated with concentrations of brain Hg from the same animal. Significant negative correlations were found between concentrations of brain Hg and ChE (total Hg: r= -0.42; MeHg: r= -0.33) and MAO (total Hg: r= -0.31; MeHg: r= -0.42) activity in the cerebral cortex. The scatterplots relating concentrations of brain Hg and enzyme activity in the cerebral cortex were wedge-shaped, and could be fitted with quantile regression modeling, suggesting that Hg may act as a limiting factor for ChE and MAO activity. No relationships were found in the cerebellum. These data suggest that environmentally relevant concentrations of Hg may influence the activities of ChE and MAO in the cerebral cortex of river otters, and by extension, other fish-eating mammals.
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Affiliation(s)
- N Basu
- Department of Natural Resource Sciences, McGill University, Ste. Anne de Bellevue, Quebec, Canada
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17
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Evans RD, Hickie B, Rouvinen-Watt K, Wang W. Partitioning and kinetics of methylmercury among organs in captive mink (Neovison vison): A stable isotope tracer study. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2016; 42:163-169. [PMID: 26855415 DOI: 10.1016/j.etap.2016.01.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Revised: 01/08/2016] [Accepted: 01/09/2016] [Indexed: 06/05/2023]
Abstract
Despite the importance of methylmercury (MeHg) as a neurotoxin, we have relatively few good data on partitioning and kinetics of MeHg among organs, particularly across the blood-brain barrier, for mammals that consume large quantities of fish. The objective of this study was to determine the partition coefficients between blood and brain, liver and kidney and fur for MeHg under steady-state conditions and to measure the half-lives for MeHg in these organs. Captive mink (Neovison vison) were fed a diet enriched with two stable isotopes of Hg, Me(199)Hg and Me(201)Hg for a period of 60 days. After a period of 10 days the diet was changed to contain only Me(201)Hg so that, between days 10 and 60, we were able to measure both uptake and elimination rates from blood, brain, liver kidney and fur. Liver and kidney response was very rapid, closely following changes in blood concentrations but there was a small lag time between peak blood concentrations and peak brain concentrations. Half-lives for MeHg were 15.4, 10.2 and 13.4 days for brain, liver and kidney, respectively. There was no measurable conversion of the MeHg to inorganic Hg (IHg) in the brain over the 60 day period, unlike in liver and kidney.
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Affiliation(s)
- R Douglas Evans
- School of the Environment, Trent University, Peterborough, ON K9L 0G2, Canada; Water Quality Centre, Trent University, Peterborough, ON K9L 0G2, Canada.
| | - Brendan Hickie
- School of the Environment, Trent University, Peterborough, ON K9L 0G2, Canada
| | | | - Wei Wang
- School of the Environment, Trent University, Peterborough, ON K9L 0G2, Canada
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Gajdosechova Z, Brownlow A, Cottin NT, Fernandes M, Read FL, Urgast DS, Raab A, Feldmann J, Krupp EM. Possible link between Hg and Cd accumulation in the brain of long-finned pilot whales (Globicephala melas). THE SCIENCE OF THE TOTAL ENVIRONMENT 2016; 545-546:407-413. [PMID: 26748005 DOI: 10.1016/j.scitotenv.2015.12.082] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Revised: 12/18/2015] [Accepted: 12/18/2015] [Indexed: 06/05/2023]
Abstract
The bioaccumulation of metals was investigated by analysis of liver, kidney, muscle and brain tissue of a pod of 21 long-finned pilot whales (Globicephala melas) of all ages stranded in Scotland, UK. The results are the first to report cadmium (Cd) passage through the blood-brain barrier of pilot whales and provide a comprehensive study of the long-term (up to 35 years) mammalian exposure to the environmental pollutants. Additionally, linear accumulation of mercury (Hg) was observed in all studied tissues, whereas for Cd this was only observed in the liver. Total Hg concentration above the upper neurochemical threshold was found in the sub-adult and adult brains and methylmercury (MeHg) of 2.2mg/kg was found in the brain of one individual. Inter-elemental analysis showed significant positive correlations of Hg with selenium (Se) and Cd with Se in all studied tissues. Furthermore, differences in the elemental concentrations in the liver and brain tissues were found between juvenile, sub-adult and adult groups. The highest concentrations of manganese, iron, zinc, Se, Hg and MeHg were noted in the livers, whereas Cd predominantly accumulated in the kidneys. High concentrations of Hg and Cd in the tissues of pilot whales presented in this study reflect ever increasing toxic stress on marine mammals.
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Affiliation(s)
- Zuzana Gajdosechova
- Trace Element Speciation Laboratory, Department of Chemistry, Meston Walk, University of Aberdeen, Aberdeen AB24 3UE, UK
| | | | - Nicolas T Cottin
- Trace Element Speciation Laboratory, Department of Chemistry, Meston Walk, University of Aberdeen, Aberdeen AB24 3UE, UK
| | - Mariana Fernandes
- Trace Element Speciation Laboratory, Department of Chemistry, Meston Walk, University of Aberdeen, Aberdeen AB24 3UE, UK
| | - Fiona L Read
- Oceanlab, University of Aberdeen, Main Street, Newburgh AB41 6AA, UK
| | - Dagmar S Urgast
- Trace Element Speciation Laboratory, Department of Chemistry, Meston Walk, University of Aberdeen, Aberdeen AB24 3UE, UK
| | - Andrea Raab
- Trace Element Speciation Laboratory, Department of Chemistry, Meston Walk, University of Aberdeen, Aberdeen AB24 3UE, UK
| | - Jörg Feldmann
- Trace Element Speciation Laboratory, Department of Chemistry, Meston Walk, University of Aberdeen, Aberdeen AB24 3UE, UK
| | - Eva M Krupp
- Trace Element Speciation Laboratory, Department of Chemistry, Meston Walk, University of Aberdeen, Aberdeen AB24 3UE, UK
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Evans RD, Grochowina NM, Basu N, O'Connor EM, Hickie BE, Rouvinen-Watt K, Evans HE, Chan HM. Uptake of selenium and mercury by captive mink: Results of a controlled feeding experiment. CHEMOSPHERE 2016; 144:1582-1588. [PMID: 26517385 DOI: 10.1016/j.chemosphere.2015.09.096] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Revised: 09/14/2015] [Accepted: 09/26/2015] [Indexed: 06/05/2023]
Abstract
Captive, juvenile, ranch-bred, male mink (Neovison vison) were fed diets containing various concentrations of methyl-mercury (MeHg) and selenium (Se) for a period of 13 weeks and then sacrificed to determine total Hg levels in fur, blood, brain, liver and kidneys and total Se concentrations in brain tissue. As MeHg concentrations in the diet increased, concentrations of total Hg in the tissues also increased with the highest level occurring in the fur > liver = kidney > brain > blood. Concentrations of Hg in the fur were correlated (r(2) > 0.97) with liver, kidney, blood and brain concentrations. The addition of Se to the mink diet did not appear to affect most tissue concentrations of total Hg nor did it affect the partitioning of Hg between the liver:blood, kidney:blood and brain:blood; however, partitioning of Hg between fur and blood was apparently affected.
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Affiliation(s)
- R D Evans
- Environmental and Resource Science, Trent University, 1600 West Bank Drive, Peterborough, ON, K9J 7B8, Canada; Water Quality Centre, Trent University, 1600 West Bank Drive, Peterborough, ON, K9J 7B8, Canada.
| | - N M Grochowina
- Environmental and Resource Science, Trent University, 1600 West Bank Drive, Peterborough, ON, K9J 7B8, Canada
| | - N Basu
- Faculty of Agricultural and Environmental Sciences, MacDonald Stewart Building, McGill University, 21111 Lakeshore Rd., St Anne de Bellevue, QC, H9X 3V9, Canada.
| | - E M O'Connor
- Environmental and Resource Science, Trent University, 1600 West Bank Drive, Peterborough, ON, K9J 7B8, Canada.
| | - B E Hickie
- Environmental and Resource Science, Trent University, 1600 West Bank Drive, Peterborough, ON, K9J 7B8, Canada
| | - K Rouvinen-Watt
- Department of Plant and Animal Sciences, Faculty of Agriculture, Dalhousie University, PO Box 55, Truro, NS, B2N 5E3, Canada.
| | - H E Evans
- Environmental and Resource Science, Trent University, 1600 West Bank Drive, Peterborough, ON, K9J 7B8, Canada; Water Quality Centre, Trent University, 1600 West Bank Drive, Peterborough, ON, K9J 7B8, Canada
| | - H M Chan
- Community Health Program, University of Northern British Columbia, Prince George, BC, Canada.
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Behavior and the cholinergic parameters in olfactory bulbectomized female rodents: Difference between rats and mice. Behav Brain Res 2015; 297:5-14. [PMID: 26431763 DOI: 10.1016/j.bbr.2015.09.033] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Revised: 09/24/2015] [Accepted: 09/25/2015] [Indexed: 12/20/2022]
Abstract
Olfactory bulbectomy (OBX) in rodents induces a wide spectrum of functional disturbances, including behavioral, neurochemical, and neuromorphological alterations. We have examined the effects of OBX on behavior and the parameters of the cholinergic system in female rats and mice. In rats, OBX resulted in the appearance of some depressive-like behavioral marks, such as the decreased sucrose consumption, hyperactivity, impaired short-term memory and anxiety-like behavioral features, such as shortened presence in the center of the open field arena or open arms of the elevated plus-maze and an enhancement of avoidance behavior. These behavioral abnormalities could be associated with disturbances in hippocampal function, this suggestion being supported by the presence of cellular changes in this brain structure. No effect of OBX on the number of cholinergic neurons in the medial septum-diagonal band as well as on the acetylcholine content and acetylcholinesterase activity in the septum, hippocampus, and neocortex could be detected. In contrast, in mice, OBX impaired spontaneous alternation behavior and decreased the number of cholinergic neurons in the medial septum-diagonal band. These data demonstrate that rats and mice differently respond to OBX, in particular, OBX does not significantly affect the cholinergic system in rats.
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Krey A, Ostertag SK, Chan HM. Assessment of neurotoxic effects of mercury in beluga whales (Delphinapterus leucas), ringed seals (Pusa hispida), and polar bears (Ursus maritimus) from the Canadian Arctic. THE SCIENCE OF THE TOTAL ENVIRONMENT 2015; 509-510:237-247. [PMID: 24958011 DOI: 10.1016/j.scitotenv.2014.05.134] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2013] [Revised: 05/19/2014] [Accepted: 05/27/2014] [Indexed: 06/03/2023]
Abstract
Marine mammals are indicator species of the Arctic ecosystem and an integral component of the traditional Inuit diet. The potential neurotoxic effects of increased mercury (Hg) in beluga whales (Delphinapterus leucas), ringed seals (Pusa hispida), and polar bears (Ursus maritimus) are not clear. We assessed the risk of Hg-associated neurotoxicity to these species by comparing their brain Hg concentrations with threshold concentrations for toxic endpoints detected in laboratory animals and field observations: clinical symptoms (>6.75 mg/kg wet weight (ww)), neuropathological signs (>4 mg/kg ww), neurochemical changes (>0.4 mg/kg ww), and neurobehavioral changes (>0.1mg/kg ww). The total Hg (THg) concentrations in the cerebellum and frontal lobe of ringed seals and polar bears were <0.5mg/kg ww, whereas the average concentration in beluga whale brain was >3mg/kg ww. Our results suggest that brain THg levels in polar bears are below levels that induce neurobehavioral effects as reported in the literature, while THg concentrations in ringed seals are within the range that elicit neurobehavioral effects and individual ringed seals exceed the threshold for neurochemical changes. The relatively high THg concentration in beluga whales exceeds all of the neurotoxicity thresholds assessed. High brain selenium (Se):Hg molar ratios were observed in all three species, suggesting that Se could protect the animals from Hg-associated neurotoxicity. This assessment was limited by several factors that influence neurotoxic effects in animals, including: animal species; form of Hg in the brain; and interactions with modifiers of Hg-associated toxicity, such as Se. Comparing brain Hg concentrations in wildlife with concentrations of appropriate laboratory studies can be used as a tool for risk characterization of the neurotoxic effects of Hg in Arctic marine mammals.
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Affiliation(s)
- Anke Krey
- Natural Resources and Environmental Studies, University of Northern British Columbia, 3333 University Way, Prince George, BC V2N 4Z9, Canada.
| | - Sonja K Ostertag
- Natural Resources and Environmental Studies, University of Northern British Columbia, 3333 University Way, Prince George, BC V2N 4Z9, Canada.
| | - Hing Man Chan
- Center for Advanced Research in Environmental Genomics, University of Ottawa, 20 Marie-Curie, Ottawa, ON K1N 6N5, Canada.
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Scheuhammer A, Braune B, Chan HM, Frouin H, Krey A, Letcher R, Loseto L, Noël M, Ostertag S, Ross P, Wayland M. Recent progress on our understanding of the biological effects of mercury in fish and wildlife in the Canadian Arctic. THE SCIENCE OF THE TOTAL ENVIRONMENT 2015; 509-510:91-103. [PMID: 24935263 DOI: 10.1016/j.scitotenv.2014.05.142] [Citation(s) in RCA: 114] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2014] [Revised: 05/29/2014] [Accepted: 05/29/2014] [Indexed: 05/24/2023]
Abstract
This review summarizes our current state of knowledge regarding the potential biological effects of mercury (Hg) exposure on fish and wildlife in the Canadian Arctic. Although Hg in most freshwater fish from northern Canada was not sufficiently elevated to be of concern, a few lakes in the Northwest Territories and Nunavut contained fish of certain species (e.g. northern pike, Arctic char) whose muscle Hg concentrations exceeded an estimated threshold range (0.5-1.0 μg g(-1) wet weight) within which adverse biological effects begin to occur. Marine fish species generally had substantially lower Hg concentrations than freshwater fish; but the Greenland shark, a long-lived predatory species, had mean muscle Hg concentrations exceeding the threshold range for possible effects on health or reproduction. An examination of recent egg Hg concentrations for marine birds from the Canadian Arctic indicated that mean Hg concentration in ivory gulls from Seymour Island fell within the threshold range associated with adverse effects on reproduction in birds. Mercury concentrations in brain tissue of beluga whales and polar bears were generally lower than levels associated with neurotoxicity in mammals, but were sometimes high enough to cause subtle neurochemical changes that can precede overt neurotoxicity. Harbour seals from western Hudson Bay had elevated mean liver Hg concentrations along with comparatively high muscle Hg concentrations indicating potential health effects from methylmercury (MeHg) exposure on this subpopulation. Because current information is generally insufficient to determine with confidence whether Hg exposure is impacting the health of specific fish or wildlife populations in the Canadian Arctic, biological effects studies should comprise a major focus of future Hg research in the Canadian Arctic. Additionally, studies on cellular interactions between Hg and selenium (Se) are required to better account for potential protective effects of Se on Hg toxicity, especially in large predatory Arctic fish, birds, and mammals.
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Affiliation(s)
- Anton Scheuhammer
- Environment Canada, National Wildlife Research Centre, Carleton University, Ottawa, ON K1A 0H3, Canada
| | - Birgit Braune
- Environment Canada, National Wildlife Research Centre, Carleton University, Ottawa, ON K1A 0H3, Canada.
| | - Hing Man Chan
- Centre for Advanced Research in Environmental Genomics, University of Ottawa, Ottawa, ON K1N 6N5, Canada
| | - Héloïse Frouin
- Jasco Research, 4464 Markam St., Victoria, BC V8Z 7X8, Canada
| | - Anke Krey
- Natural Resources and Environmental Studies, University of Northern British Columbia, Prince George, BC V2N 4Z9, Canada
| | - Robert Letcher
- Environment Canada, National Wildlife Research Centre, Carleton University, Ottawa, ON K1A 0H3, Canada
| | - Lisa Loseto
- Fisheries and Oceans Canada, National Centre for Arctic Aquatic Research Excellence, 501 University Crescent, Winnipeg, MB R3T 2N6, Canada
| | - Marie Noël
- School of Earth and Ocean Sciences, University of Victoria, Victoria, BC V8P 5C2, Canada
| | - Sonja Ostertag
- Natural Resources and Environmental Studies, University of Northern British Columbia, Prince George, BC V2N 4Z9, Canada
| | - Peter Ross
- Fisheries and Oceans Canada, Institute of Ocean Sciences, Sidney, BC V8L 4B2, Canada
| | - Mark Wayland
- Environment Canada, Canadian Wildlife Service, 115 Perimeter Rd., Saskatoon, Saskatchewan S7N 0X4, Canada
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Basu N. Applications and implications of neurochemical biomarkers in environmental toxicology. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2015; 34:22-9. [PMID: 25331165 DOI: 10.1002/etc.2783] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2014] [Revised: 10/13/2014] [Accepted: 10/15/2014] [Indexed: 05/20/2023]
Abstract
Thousands of environmental contaminants have neurotoxic properties, but their ecological risk is poorly characterized. Contaminant-associated disruptions to animal behavior and reproduction, both of which are regulated by the nervous system, provide decision makers with compelling evidence of harm, but such apical endpoints are of limited predictive or harm-preventative value. Neurochemical biomarkers, which may be used to indicate subtle changes at the subcellular level, may help overcome these limitations. Neurochemical biomarkers have been used for decades in the human health sciences and are now gaining increased attention in the environmental realm. In the present review, the applications and implications of neurochemical biomarkers to the field of ecotoxicology are discussed. The review provides a brief introduction to neurochemistry, covers neurochemical-based adverse outcome pathways, discusses pertinent strengths and limitations of neurochemical biomarkers, and provides selected examples across invertebrate and vertebrate taxa (worms, bivalves, fish, terrestrial and marine mammals, and birds) to document contaminant-associated neurochemical disruption. With continued research and development, neurochemical biomarkers may increase understanding of the mechanisms that underlie injury to ecological organisms, complement other measures of neurological health, and be integrated into risk assessment practices.
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Affiliation(s)
- Niladri Basu
- Faculty of Agricultural and Environmental Sciences, McGill University, Montreal, Quebec, Canada
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24
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Ostertag SK, Shaw AC, Basu N, Chan HM. Molecular and neurochemical biomarkers in Arctic beluga whales (Delphinapterus leucas) were correlated to brain mercury and selenium concentrations. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2014; 48:11551-11559. [PMID: 25171565 DOI: 10.1021/es501369b] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Mercury (Hg) concentrations have increased in western Arctic beluga whales (Delphinapterus leucas) since the industrial revolution. Methylmercruy (MeHg) is a known neurotoxicant, yet little is known about the risk of exposure for beluga whales. Selenium (Se) has been linked to demethylation of MeHg in cetaceans, but its role in attenuating Hg toxicity in beluga whales is poorly understood. The objective of this study is to explore relationships between Hg and Se concentrations and neurochemical biomarkers in different brain regions of beluga whales in order to assess potential neurotoxicological risk of Hg exposure in this population. Brain tissue was sampled from hunter-harvested beluga whales from the western Canadian Arctic in 2008 and 2010. Neurochemical and molecular biomarkers were measured with radioligand binding assays and quantitative PCR, respectively. Total Hg (HgT) concentration ranged from 2.6-113 mg kg(-1) dw in temporal cortex. Gamma-amminobutyric acid type A receptor (GABAA-R) binding in the cerebellum was negatively associated with HgT, MeHg and total Se (SeT) concentrations (p ≤ 0.05). The expression of mRNA for GABAA-R subunit α2 was negatively associated with HgT and MeHg (p ≤ 0.05). Furthermore, GABAA-R binding was positively correlated to mRNA expression for GABAA-R α2 subunit, and negatively correlated to the expression of mRNA for GABAA-R α4 subunit (p ≤ 0.05). The expression of N-methyl-d-aspartate receptor (NMDA-R) subunit 2b mRNA expression was negatively associated with iHglabile concentration in the cerebellum (p ≤ 0.05). Variation of molecular and/or biochemical components of the GABAergic and glutamatergic signaling pathways were associated with MeHg exposure in beluga whales. Our results show that MeHg exposure is associated with neurochemical variation in the cerebellum of beluga whales and Se may partially protect from MeHg-associated neurotoxicity.
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Affiliation(s)
- Sonja K Ostertag
- Natural Resources and Environmental Studies, University of Northern British Columbia , Prince George, British Columbia Canada , V2N 4Z9
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USE OF CELLULOSE FILTER PAPER TO QUANTIFY WHOLE-BLOOD MERCURY IN TWO MARINE MAMMALS: VALIDATION STUDY. J Wildl Dis 2014; 50:271-8. [DOI: 10.7589/2013-08-214] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Rutkiewicz J, Bradley M, Mittal K, Basu N. Methylmercury egg injections: part 2--pathology, neurochemistry, and behavior in the avian embryo and hatchling. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2013; 93:77-86. [PMID: 23669341 DOI: 10.1016/j.ecoenv.2013.04.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2012] [Revised: 03/30/2013] [Accepted: 04/01/2013] [Indexed: 05/20/2023]
Abstract
Methylmercury (MeHg) is a toxic metal that has been frequently linked to neurochemical alterations, brain lesions, neurobehavioral changes, and reproductive impairments in wild and captive birds. Much less is known about the effects of MeHg on the developing avian brain and resulting effects on hatchling behavior. The objective of this work was to use air cell injection studies to investigate the effect of in ovo MeHg exposure on brain pathology and four neurochemical biomarkers (N-methyl-d-aspartate (NMDA) receptor, γ-aminobutyric acid (GABA) receptor, glutamine synthetase (GS) and glutamic acid decarboxylase (GAD)) that have previously been studied in wild birds, and on hatchling righting response, balance, and startle response. In a series of six studies, we exposed white leghorn chicken and Japanese quail embryos to methylmercury chloride (MeHgCl) (range: 0-6.4μg/g egg) via egg injection on embryonic day (ED) 0 and measured receptor levels and enzyme activity at different stages of embryonic (days 11, 14, and 19 in chicken; day 15 in quail) and hatchling (day 1 and day 7) development, and in whole brain or discrete brain regions (cerebrum, cerebellum, optic lobe). We assessed neurobehaviors on post hatch (PH) days 1 and 7. Despite accumulating relatively high levels of Hg in the brain, embryos and hatchlings did not consistently display neurochemical changes consistent with those seen in wild birds and laboratory mammals. Hatchlings also did not demonstrate behavioral alterations. Pathology did not indicate a difference in occurrence and types of lesions between control and dosed birds. These findings suggest that in ovo MeHg exposure alone may not be responsible for neurological impacts in bird. This work draws attention to factors, such as age and species, that may influence responses to MeHg in birds.
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Affiliation(s)
- Jennifer Rutkiewicz
- Department of Environmental Health Sciences, University of Michigan School of Public Health, 1415 Washington Heights, Ann Arbor, MI 48109, USA
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Rea LD, Castellini JM, Correa L, Fadely BS, O'Hara TM. Maternal Steller sea lion diets elevate fetal mercury concentrations in an area of population decline. THE SCIENCE OF THE TOTAL ENVIRONMENT 2013; 454-455:277-282. [PMID: 23545490 DOI: 10.1016/j.scitotenv.2013.02.095] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Revised: 02/27/2013] [Accepted: 02/27/2013] [Indexed: 06/02/2023]
Abstract
Total mercury concentrations ([THg]) measured in western Aleutian Island Steller sea lion pup hair were the highest maximum [THg] documented in this endangered species to date. Some pups exceeded concentrations at which other fish-eating mammals can exhibit adverse neurological and reproductive effects (21% and 15% pups above 20 and 30 μg/g in hair, respectively). Of particular concern is fetal exposure to mercury during a particularly vulnerable stage of neurological development in late gestation. Hair and blood [THg] were highly correlated and 20% of pups sampled in the western Aleutian Islands of Alaska exceeded mammalian risk thresholds established for each of these tissues. Higher nitrogen isotope ratios suggested that pups accumulated the highest [THg] when their dams fed on higher trophic level prey during late gestation.
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Affiliation(s)
- Lorrie D Rea
- Division of Wildlife Conservation, Alaska Department of Fish and Game, Fairbanks, AK 99701, United States.
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Basu N, Head J, Nam DH, Pilsner JR, Carvan MJ, Chan HM, Goetz FW, Murphy CA, Rouvinen-Watt K, Scheuhammer AM. Effects of methylmercury on epigenetic markers in three model species: mink, chicken and yellow perch. Comp Biochem Physiol C Toxicol Pharmacol 2013; 157:322-7. [PMID: 23481557 PMCID: PMC4346372 DOI: 10.1016/j.cbpc.2013.02.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Revised: 02/17/2013] [Accepted: 02/19/2013] [Indexed: 10/27/2022]
Abstract
We previously reported that methylmercury (MeHg) exposure is associated with DNA hypomethylation in the brain stem of male polar bears. Here, we conveniently use archived tissues obtained from controlled laboratory exposure studies to look for evidence that MeHg can disrupt DNA methylation across taxa. Brain (cerebrum) tissues from MeHg-exposed mink (Neovison vison), chicken (Gallus gallus) and yellow perch (Perca flavescens) were analyzed for total Hg levels and global DNA methylation. Tissues from chicken and mink, but not perch, were also analyzed for DNA methyltransferase (DNMT) activity. In mink we observed significant reductions in global DNA methylation in an environmentally-relevant dietary exposure group (1 ppm MeHg), but not in a higher group (2 ppm MeHg). DNMT activity was significantly reduced in all treatment groups. In chicken or yellow perch, no statistically significant effects of MeHg were observed. Dose-dependent trends were observed in the chicken data but the direction of the change was not consistent between the two endpoints. Our results suggest that MeHg can be epigenetically active in that it has the capacity to affect DNA methylation in mammals. The variability in results across species may suggest inter-taxa differences in epigenetic responses to MeHg, or may be related to differences among the exposure scenarios used as animals were exposed to MeHg through different routes (dietary, egg injection), for different periods of time (19-89 days) and at different life stages (embryonic, juvenile, adult).
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Affiliation(s)
- Niladri Basu
- Department of Environmental Health Sciences, University of Michigan, 1415 Washington Heights, Ann Arbor, MI 48109, USA.
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Dietz R, Sonne C, Basu N, Braune B, O'Hara T, Letcher RJ, Scheuhammer T, Andersen M, Andreasen C, Andriashek D, Asmund G, Aubail A, Baagøe H, Born EW, Chan HM, Derocher AE, Grandjean P, Knott K, Kirkegaard M, Krey A, Lunn N, Messier F, Obbard M, Olsen MT, Ostertag S, Peacock E, Renzoni A, Rigét FF, Skaare JU, Stern G, Stirling I, Taylor M, Wiig Ø, Wilson S, Aars J. What are the toxicological effects of mercury in Arctic biota? THE SCIENCE OF THE TOTAL ENVIRONMENT 2013; 443:775-90. [PMID: 23231888 DOI: 10.1016/j.scitotenv.2012.11.046] [Citation(s) in RCA: 188] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2012] [Revised: 11/07/2012] [Accepted: 11/10/2012] [Indexed: 05/12/2023]
Abstract
This review critically evaluates the available mercury (Hg) data in Arctic marine biota and the Inuit population against toxicity threshold values. In particular marine top predators exhibit concentrations of mercury in their tissues and organs that are believed to exceed thresholds for biological effects. Species whose concentrations exceed threshold values include the polar bears (Ursus maritimus), beluga whale (Delphinapterus leucas), pilot whale (Globicephala melas), hooded seal (Cystophora cristata), a few seabird species, and landlocked Arctic char (Salvelinus alpinus). Toothed whales appear to be one of the most vulnerable groups, with high concentrations of mercury recorded in brain tissue with associated signs of neurochemical effects. Evidence of increasing concentrations in mercury in some biota in Arctic Canada and Greenland is therefore a concern with respect to ecosystem health.
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Affiliation(s)
- Rune Dietz
- Aarhus University, Department for Bioscience, Arctic Research Centre, P.O. Box 358, Roskilde, DK-4000, Denmark.
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Roach KA, Jacobsen NF, Fiorello CV, Stronza A, Winemiller KO. Gold Mining and Mercury Bioaccumulation in a Floodplain Lake and Main Channel of the Tambopata River, Perú. ACTA ACUST UNITED AC 2013. [DOI: 10.4236/jep.2013.41005] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Braune BM, Scheuhammer AM, Crump D, Jones S, Porter E, Bond D. Toxicity of methylmercury injected into eggs of thick-billed murres and arctic terns. ECOTOXICOLOGY (LONDON, ENGLAND) 2012; 21:2143-2152. [PMID: 22760665 DOI: 10.1007/s10646-012-0967-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 06/13/2012] [Indexed: 06/01/2023]
Abstract
Mercury (Hg) has been increasing in some marine birds in the Canadian Arctic over the past several decades. To evaluate the potential reproductive impact of Hg exposure, eggs of two species of arctic-breeding seabirds, the thick-billed murre and arctic tern, were dosed with graded concentrations of methylmercury (MeHg) and artificially incubated in the laboratory to determine species differences in sensitivity. Based on the dose-response curves, the median lethal concentrations (LC(50)) for thick-billed murre and arctic tern embryos were 0.48 and 0.95 μg g(-1) Hg on a wet-weight (ww) basis, respectively. Compared with published LC(50) values for other avian species, the murres and terns had a medium sensitivity to MeHg exposure. LC(50) values were also calculated for the actual Hg concentration measured in the embryos, that is, the maternally-deposited Hg plus the injected MeHg dose. This increased the LC(50) values to 0.56 μg g(-1) Hg ww in the thick-billed murre and to 1.10 μg g(-1) Hg ww in the arctic tern. Although muscarinic acetylcholine and N-methyl-D-aspartic acid glutamate receptor levels have been correlated with increasing Hg concentrations in brains of adult birds, no significant associations were found in brain tissue of the murre or tern embryos. The incidence of gross external anatomical deformities was 4.3 % in the murre embryos and 3.6 % in the tern embryos. However, given that the eggs were taken from wild populations, it is unlikely that the deformities observed in this study were due to MeHg exposure alone.
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Affiliation(s)
- Birgit M Braune
- Environment Canada, National Wildlife Research Centre, Carleton University, Raven Road, Ottawa, ON, K1A 0H3, Canada.
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Depew DC, Basu N, Burgess NM, Campbell LM, Devlin EW, Drevnick PE, Hammerschmidt CR, Murphy CA, Sandheinrich MB, Wiener JG. Toxicity of dietary methylmercury to fish: derivation of ecologically meaningful threshold concentrations. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2012; 31:1536-47. [PMID: 22549893 DOI: 10.1002/etc.1859] [Citation(s) in RCA: 113] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2011] [Revised: 01/20/2012] [Accepted: 02/10/2012] [Indexed: 05/20/2023]
Abstract
Threshold concentrations associated with adverse effects of dietary exposure to methylmercury (MeHg) were derived from published results of laboratory studies on a variety of fish species. Adverse effects related to mortality were uncommon, whereas adverse effects related to growth occurred only at dietary MeHg concentrations exceeding 2.5 µg g(-1) wet weight. Adverse effects on behavior of fish had a wide range of effective dietary concentrations, but generally occurred above 0.5 µg g(-1) wet weight. In contrast, effects on reproduction and other subclinical endpoints occurred at dietary concentrations that were much lower (<0.2 µg g(-1) wet wt). Field studies generally lack information on dietary MeHg exposure, yet available data indicate that comparable adverse effects have been observed in wild fish in environments corresponding to high and low MeHg contamination of food webs and are in agreement with the threshold concentrations derived here from laboratory studies. These thresholds indicate that while differences in species sensitivity to MeHg exposure appear considerable, chronic dietary exposure to low concentrations of MeHg may have significant adverse effects on wild fish populations but remain little studied compared to concentrations in mammals or birds.
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Affiliation(s)
- David C Depew
- Department of Biology and School of Environmental Studies, Queen's University, Kingston, Ontario, Canada.
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Nam DH, Yates D, Ardapple P, Evers DC, Schmerfeld J, Basu N. Elevated mercury exposure and neurochemical alterations in little brown bats (Myotis lucifugus) from a site with historical mercury contamination. ECOTOXICOLOGY (LONDON, ENGLAND) 2012; 21:1094-101. [PMID: 22331394 DOI: 10.1007/s10646-012-0864-9] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 01/31/2012] [Indexed: 05/04/2023]
Abstract
Despite evidence of persistent methylmercury (MeHg) contamination in the South River (Virginia, USA) ecosystem, there is little information concerning MeHg-associated neurological impacts in resident wildlife. Here we determined mercury (Hg) concentrations in tissues of insectivorous little brown bats (Myotis lucifugus) collected from a reference site and a MeHg-contaminated site in the South River ecosystem. We also explored whether neurochemical biomarkers (monoamine oxidase, MAO; acetylcholinesterase, ChE; muscarinic acetylcholine receptor, mAChR; N-methyl-D-aspartate receptor, NMDAR) previously shown to be altered by MeHg in other wildlife were associated with brain Hg levels in these bats. Concentrations of Hg (total and MeHg) in tissues were significantly higher (10-40 fold difference) in South River bats when compared to reference sites. Mean tissue mercury levels (71.9 ppm dw in liver, 7.14 ppm dw in brain, 132 ppm fw in fur) in the South River bats exceed (sub)-clinical thresholds in mammals. When compared to the South River bats, animals from the reference site showed a greater ability to demethylate MeHg in brain (33.1% of total Hg was MeHg vs. 65.5%) and liver (8.9% of total Hg was MeHg vs. 50.8%) thus suggesting differences in their ability to detoxify and eliminate Hg. In terms of Hg-associated neurochemical biomarker responses, interesting biphasic responses were observed with an inflection point between 1 and 5 ppm dw in the brain. In the reference bats Hg-associated decreases in MAO (r = -0.61; p < 0.05) and ChE (r = -0.79; p < 0.01) were found in a manner expected but these were not found in the bats from the contaminated site. Owing to high Hg exposures, differences in Hg metabolism, and the importance of the aforementioned neurochemicals in multiple facets of animal health, altered or perhaps even a lack of expected neurochemical responses in Hg-contaminated bats raise questions about the ecological and physiological impacts of Hg on the bat population as well as the broader ecosystem in the South River.
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Affiliation(s)
- Dong-Ha Nam
- Department of Environmental Health Sciences, University of Michigan School of Public Health, Ann Arbor, MI 48109, USA
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Nam DH, Rutkiewicz J, Basu N. Multiple metals exposure and neurotoxic risk in bald eagles (Haliaeetus leucocephalus) from two Great Lakes states. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2012; 31:623-31. [PMID: 22170515 DOI: 10.1002/etc.1712] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2011] [Revised: 10/02/2011] [Accepted: 10/25/2011] [Indexed: 05/13/2023]
Abstract
In the present study, the authors determined concentrations of several elements (As, Cd, Co, Cu, Cr, Mn, Pb, Sb, Zn) in the brains and livers of 46 bald eagles (Haliaeetus leucocephalus) from two Great Lakes states, Michigan and Minnesota. To explore whether exposures are of neurological concern, the authors assessed their associations with neurochemical receptors (N-methyl-D-aspartate [NMDA] and γ-aminobutyric acid A [GABA(A)]) and enzymes (glutamine synthetase [GS] and glutamic acid decarboxylase [GAD]) that play critical roles in vertebrate neurobehavior and reproduction. For most elements, levels in the livers and brains did not differ between region and gender. Hepatic Pb levels averaged 33.1 ppm (dry wt), 30.4% of all carcasses exceeded proposed avian Pb thresholds (>26.4 ppm), and in 30.8% of the birds examined evidence of Pb pellets or fragments was found. Significant changes in the activities of GS and GAD were related to brain concentrations of several metals (Pb, Cd, Co, Cu, Zn). No relationships were found among any of the nine elements and NMDA or GABA(A) receptor levels. When combined with the authors' previous study on these same eagles that showed Hg-associated alterations in GS, GAD, and NMDA receptor levels, the present research suggests that bald eagles are exposed to various elements, especially Pb and Hg, that are capable of causing changes in GABAergic and glutamatergic neurotransmission. The functional significance of these neurochemical changes warrants attention.
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Affiliation(s)
- Dong-Ha Nam
- Department of Environmental Health Sciences, School of Public Health, University of Michigan, Ann Arbor, Michigan, USA
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Martin PA, McDaniel TV, Hughes KD, Hunter B. Mercury and other heavy metals in free-ranging mink of the lower Great Lakes basin, Canada, 1998-2006. ECOTOXICOLOGY (LONDON, ENGLAND) 2011; 20:1701-1712. [PMID: 21874547 DOI: 10.1007/s10646-011-0763-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 08/05/2011] [Indexed: 05/31/2023]
Abstract
Mercury concentrations were examined in livers of free-ranging mink (Neovison vison) trapped in the lower Great Lakes basin from 1998 to 2006. Significant geographic variation in total mercury levels was found in mink from 13 Great Lakes locations, many of which are within Great Lakes Areas of Concern (AOCs). Total mercury levels in mink from these locations were generally low to moderate, with means (±SE) ranging from 0.99 (±0.36) μg/g dry weight in mink from inland Lake Erie to 7.31 (±1.52) μg/g in mink from Walpole Island in the St. Clair River AOC. Overall, mercury exposure was highest in mink trapped in locations associated with large riverine wetlands. Total mercury concentrations were negatively related to the percentage of mercury present as methylmercury and positively related to selenium concentrations, consistent with increasing demethylation of methylmercury with increasing total mercury concentrations. One-year old mink had significantly higher levels of mercury and selenium than mink under 1 year but similar to mink 2 years of age and older. Mercury levels were below those associated with mercury toxicity. Concentrations of cadmium, lead and arsenic were low and largely associated with environmental background levels. Significant age and sex effects were found for cadmium. Lead levels were significantly lower in mink infected by the lung nematode parasite compared to uninfected animals. Further studies of biomagnification of methylmercury in wetland environments, where top predators such as mink may be an increased risk of exposure, are warranted.
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Hamilton M, Scheuhammer A, Basu N. Mercury, selenium and neurochemical biomarkers in different brain regions of migrating common loons from Lake Erie, Canada. ECOTOXICOLOGY (LONDON, ENGLAND) 2011; 20:1677-1683. [PMID: 21847660 DOI: 10.1007/s10646-011-0754-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 07/21/2011] [Indexed: 05/31/2023]
Abstract
Common loons (Gavia immer) can be exposed to relatively high levels of dietary methylmercury (MeHg) through fish consumption, and several studies have documented MeHg-associated health effects in this species. To further study the neurological risks of MeHg accumulation, migrating loons dying of Type E botulism were collected opportunistically from the Lake Erie shore at Long Point (Ontario, Canada) and relationships between total mercury (THg), selenium (Se), and selected neurochemical receptors and brain enzymes were investigated. THg concentrations were 1-78 μg/g in liver; and 0.3-4 μg/g in the brain (all concentrations reported on a dry weight basis). A significant (p < 0.05) positive correlation was found between THg in liver and THg in 3 subregions of the brain (cerebral cortex: r = 0.433; cerebellum: r = 0.293; brain stem: r = 0.405). THg varied significantly among different brain regions, with the cortex having the highest concentrations. Se levels in the cortex and cerebellum were 1-29 and 1-10 μg/g, respectively, with no significant differences between regions. Se was not measured in brain stem due to insufficient tissue mass. There were molar excesses of Se over mercury (Hg) in both cortex and cerebellum at all Hg concentrations, and a significant positive relationship between THg and the Hg:Se molar ratio (cortex: r = 0.63; cerebellum: r = 0.47). No significant associations were observed between brain THg and the N-methyl-D-aspartic acid (NMDA) receptor concentration, nor between THg and muscarinic cholinergic (mACh) receptor concentration; however, brain THg levels were lower than in previous studies that reported significant Hg-associated changes in neuroreceptor densities. Together with previous studies, the current findings add to our understanding of Hg distribution in the brain of common loons, and the associations between Hg and sub-lethal neurochemical changes in fish-eating wildlife.
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Affiliation(s)
- Melanie Hamilton
- Environment Canada, National Wildlife Research Center, Carleton University, Ottawa, ON, Canada
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Rutkiewicz J, Nam DH, Cooley T, Neumann K, Padilla IB, Route W, Strom S, Basu N. Mercury exposure and neurochemical impacts in bald eagles across several Great Lakes states. ECOTOXICOLOGY (LONDON, ENGLAND) 2011; 20:1669-76. [PMID: 21735125 DOI: 10.1007/s10646-011-0730-1] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 06/22/2011] [Indexed: 05/16/2023]
Abstract
In this study, we assessed mercury (Hg) exposure in several tissues (brain, liver, and breast and primary feathers) in bald eagles (Haliaeetus leucocephalus) collected from across five Great Lakes states (Iowa, Michigan, Minnesota, Ohio, and Wisconsin) between 2002-2010, and assessed relationships between brain Hg and neurochemical receptors (NMDA and GABA(A)) and enzymes (glutamine synthetase (GS) and glutamic acid decarboxylase (GAD)). Brain total Hg (THg) levels (dry weight basis) averaged 2.80 μg/g (range: 0.2-34.01), and levels were highest in Michigan birds. THg levels in liver (r(p) = 0.805) and breast feathers (r(p) = 0.611) significantly correlated with those in brain. Brain Hg was not associated with binding to the GABA(A) receptor. Brain THg and inorganic Hg (IHg) were significantly positively correlated with GS activity (THg r(p) = 0.190; IHg r(p) = 0.188) and negatively correlated with NMDA receptor levels (THg r(p) = -0245; IHg r(p) = -0.282), and IHg was negatively correlated with GAD activity (r(s) = -0.196). We also report upon Hg demethylation and relationships between Hg and Se in brain and liver. These results suggest that bald eagles in the Great Lakes region are exposed to Hg at levels capable of causing subclinical neurological damage, and that when tissue burdens are related to proposed avian thresholds approximately 14-27% of eagles studied here may be at risk.
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Affiliation(s)
- Jennifer Rutkiewicz
- Department of Environmental Health Sciences, University of Michigan School of Public Health, Ann Arbor, MI 48109, USA
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Black P, Niu L, Sachdeva M, Lean D, Poon R, Bowers WJ, Chan HM, Arnason JT, Pelletier G. Modulation of the effects of methylmercury on rat neurodevelopment by co-exposure with Labrador Tea (Rhododendron tomentosum ssp. subarcticum). Food Chem Toxicol 2011; 49:2336-42. [DOI: 10.1016/j.fct.2011.06.035] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2011] [Revised: 06/14/2011] [Accepted: 06/15/2011] [Indexed: 02/07/2023]
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Adams DH, Sonne C, Basu N, Dietz R, Nam DH, Leifsson PS, Jensen AL. Mercury contamination in spotted seatrout, Cynoscion nebulosus: an assessment of liver, kidney, blood, and nervous system health. THE SCIENCE OF THE TOTAL ENVIRONMENT 2010; 408:5808-5816. [PMID: 20850170 DOI: 10.1016/j.scitotenv.2010.08.019] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2010] [Revised: 08/04/2010] [Accepted: 08/09/2010] [Indexed: 05/29/2023]
Abstract
Marine fishes in South Florida (Florida Keys-Florida Bay-Everglades region) accumulate higher concentrations of mercury (Hg) in their tissues than similar fishes from other areas of the southeastern U.S., though it is not known whether these elevated levels affect fish health. In this study, we used quantifiable pathological and biochemical indicators to explore Hg-associated differences in marine fish from South Florida, where Hg contamination is high, and from Indian River Lagoon, Florida, which served as a reference area. Hg concentrations in all tissues of mature spotted seatrout (Cynoscion nebulosus) from South Florida were significantly higher than those from Indian River Lagoon and were within the threshold range of those in studies where effects of Hg exposure have been observed. The distribution of Hg among tissues followed the same trend in both areas, with the greatest concentration in kidney tissue, followed by liver, muscle, brain, gonad, and red blood cells. Blood-plasma biochemistry showed that concentrations of iron, inorganic phosphate, lactate dehydrogenase, and aspartate aminotransferase were significantly less in South Florida. Also, fructosamine and alkaline phosphatase were significantly less in South Florida. Liver histology revealed that pyknosis/necrosis, interstitial inflammation, and bile duct hyperplasia were found only in seatrout from South Florida, and steatosis/glycogen was more frequently found in Indian River Lagoon specimens. In renal tissue, interstitial inflammation, glomerular dilatation and thickening, and tubular degeneration and necrosis were more frequently found in South Florida specimens. Changes in the liver cytoskeleton and morphology may explain some of the differences in blood parameters between study areas. Neurochemical analyses showed that brain N-methyl-d-aspartic acid (NMDA) receptors (but not those of muscarinic cholinergic receptors, monoamine oxidase, or acetylcholinesterase) were significantly less in fish from South Florida than from Indian River Lagoon. These findings provide compelling evidence that elevated Hg could cause quantifiable pathological and biochemical changes that might influence the health of spotted seatrout and could also affect other marine fish species.
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Affiliation(s)
- Douglas H Adams
- Florida Fish and Wildlife Conservation Commission, Fish and Wildlife Research Institute, 1220 Prospect Ave., No. 285, Melbourne, FL 32901, USA.
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Wada H, Yates DE, Evers DC, Taylor RJ, Hopkins WA. Tissue mercury concentrations and adrenocortical responses of female big brown bats (Eptesicus fuscus) near a contaminated river. ECOTOXICOLOGY (LONDON, ENGLAND) 2010; 19:1277-84. [PMID: 20596767 DOI: 10.1007/s10646-010-0513-0] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 06/07/2010] [Indexed: 05/04/2023]
Abstract
Much of the research on mercury (Hg) in wild vertebrates has focused on piscivores and other animals at high trophic levels. However, recent studies indicated that insectivorous terrestrial vertebrates may also be at risk. In the present study, we examined blood and fur Hg concentrations as well as the adrenocortical responses of insectivorous big brown bats (Eptesicus fuscus) near the Hg-contaminated South River, VA and a nearby reference area. Baseline glucocorticoids and adrenocortical responses to handling have been widely used to assess the influence of environmental stressors because plasma glucocorticoids rise in response to various physical, psychological, and physiological challenges. Female bats captured at the contaminated site had 2.6 times higher blood and fur Hg concentrations than those captured at the reference site (blood: 0.11 vs. 0.04 μg/g wet weight; fur: 28.0 vs. 10.9 μg/g fresh weight). Fur Hg concentrations at the contaminated site were higher than most wild omnivorous and carnivorous mammals reported in the literature. Although fur and blood Hg concentrations were tightly correlated, fur Hg concentrations averaged 260 times higher than concentrations in blood. This suggests that fur may be an important depuration route for bats, just as it is in other mammals. Despite the high Hg concentrations in bat tissue, we did not observe any site difference in adrenocortical responses. Our results suggest that the bats at the contaminated site were exposed to Hg concentrations below those causing adverse effects on their adrenal axis.
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Affiliation(s)
- Haruka Wada
- Department of Fisheries and Wildlife Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA.
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Rutkiewicz J, Scheuhammer A, Crump D, Jagla M, Basu N. Investigation of spatial trends and neurochemical impacts of mercury in herring gulls across the Laurentian Great Lakes. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2010; 158:2733-2737. [PMID: 20641170 DOI: 10.1016/j.envpol.2010.04.018] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Herring gulls (Larus argentatus) bioaccumulate mercury (Hg) but it is unknown whether they are exposed at levels of neurological concern. Here we studied brain tissues from gulls at five Great Lakes colonies and one non-Great Lakes colony during spring of 2001 and 2003. Total brain Hg concentrations ranged from 0.14 to 2.0 microg/g (dry weight) with a mean of 0.54 microg/g. Gulls from Scotch Bonnet Island, on the easternmost edge of the Great Lakes, had significantly higher brain Hg than other colonies. No association was found between brain Hg concentration and [3H]-ligand binding to neurochemical receptors (N-methyl-D-aspartate, muscarinic cholinergic, nicotinic cholinergic) or nicotinic receptor alpha-7 relative mRNA expression as previously documented in other wildlife. In conclusion, spatial trends in Hg contamination exist in herring gulls across the Great Lakes basin, and herring gulls accumulate brain Hg but not at levels associated with sub-clinical neurochemical alterations.
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Affiliation(s)
- Jennifer Rutkiewicz
- Department of Environmental Health Sciences, University of Michigan School of Public Health, 109 S. Observatory St, Ann Arbor, MI 48109, USA
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Basu N, Scheuhammer A, Rouvinen-Watt K, Grochowina N, Evans D, Chan HM. Variation of cholinergic biomarkers in brain regions and blood components of captive mink. ENVIRONMENTAL MONITORING AND ASSESSMENT 2010; 162:377-386. [PMID: 19267210 DOI: 10.1007/s10661-009-0803-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2008] [Accepted: 01/27/2009] [Indexed: 05/27/2023]
Abstract
Studies are increasingly using cholinergic parameters as biomarkers of early neurotoxicity, but few have characterized this system in ecologically relevant model organisms. In the present study, key neurochemicals in the cholinergic pathway were measured and analyzed from discrete parts of brain and blood from captive mink (Mustela vison). Similar to other mammals, the regional distribution of cholinergic parameters in the brain could be ranked from highest to lowest as: basal ganglia > occipital cortex > brain stem > cerebellum (F (3,192) = 172.1, p < 0.001). Higher variation in cholinergic parameters was found in the cerebellum (coefficient of variation = 34.9%), and the least variation was measured in the brain stem (19.7%). Variation was also assessed by calculating the difference between the lowest and highest measures among individual animals: choline acetyltransferase (1.6x fold difference), cholinesterase (2.0x), muscarinic receptor levels (2.4x), acetylcholine (3.7x), nicotinic receptor levels (3.9x), and choline transporter (5.0x). In blood samples, activity and inter-individual variation of cholinesterase was highest in whole blood and lowest in plasma and serum. By using captive mink of a common genetic source, age, gender, and rearing conditions, these data help establish normal levels, ranges, and variations of cholinergic biomarkers among brain regions, blood components, and individual animals. Such information may better enable the utility of cholinergic biomarkers in environmental assessments.
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Affiliation(s)
- Niladri Basu
- Department of Environmental Health Sciences, School of Public Health, University of Michigan, Ann Arbor, MI 48109, USA.
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In vitro and whole animal evidence that methylmercury disrupts GABAergic systems in discrete brain regions in captive mink. Comp Biochem Physiol C Toxicol Pharmacol 2010; 151:379-85. [PMID: 20060493 DOI: 10.1016/j.cbpc.2010.01.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/11/2009] [Revised: 01/01/2010] [Accepted: 01/02/2010] [Indexed: 10/20/2022]
Abstract
The effects of mercury (Hg) on key components of the GABAergic system were evaluated in discrete brain regions of captive juvenile male American mink (Neovison vison) using in vitro and in vivo (whole animal) experimental approaches. In vitro studies on cortical brain tissues revealed that inorganic Hg (HgCl(2); IC50=0.5+/-0.2microM) and methyl Hg (MeHgCl; IC50=1.6+/-0.2microM) inhibited glutamic acid decarboxylase (GAD; EC 4.1.1.15) activity. There were no Hg-related effects on [(3)H]-muscimol binding to GABA(A) receptors (IC50s>100microM). HgCl(2) (IC50=0.8+/-0.3microM) but not MeHgCl (IC50>100microM) inhibited GABA-transaminase (GABA-T; EC 2.6.1.19) activity. In a whole animal study, neurochemical indicators of GABAergic function were measured in brain regions (occipital cortex, cerebellum, brain stem, and basal ganglia) of captive mink fed relevant levels of MeHgCl (0 to 2microg/g feed, ppm) daily for 89d. No effects on GAD activity were measured. Concentration-dependent decreases in [(3)H]-muscimol binding to GABA(A) receptors and GABA-T activity were found in several brain regions, with reductions as great as 94% (for GABA(A) receptor levels) and 71% (for GABA-T activity) measured in the brain stem and basal ganglia. These results show that chronic exposure to environmentally relevant levels of MeHg disrupts GABAergic signaling. Given that GABA is the main inhibitory neurotransmitter in the mammalian nervous system, prolonged disruptions of its function may underlie the sub-clinical impacts of MeHg at relevant levels to animal health.
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Mammalian wildlife as complementary models in environmental neurotoxicology. Neurotoxicol Teratol 2010; 32:114-9. [DOI: 10.1016/j.ntt.2008.12.005] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2008] [Revised: 12/12/2008] [Accepted: 12/16/2008] [Indexed: 11/23/2022]
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Haines KJR, Evans RD, O'Brien M, Evans HE. Accumulation of mercury and selenium in the brain of river otters (Lontra canadensis) and wild mink (Mustela vison) from Nova Scotia, Canada. THE SCIENCE OF THE TOTAL ENVIRONMENT 2010; 408:537-542. [PMID: 19880158 DOI: 10.1016/j.scitotenv.2009.09.055] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2009] [Revised: 09/04/2009] [Accepted: 09/30/2009] [Indexed: 05/28/2023]
Abstract
Total Hg, methyl-Hg (MeHg) and Se levels were measured in the brain of river otters (Lontra canadensis) and wild mink (Mustela vison) carcasses collected from Nova Scotia, Canada. Total Hg concentrations in the otters' brain were highly variable, ranging from 0.3 to 18.0 microg/g dw and were significantly higher in animals caught from inland areas of the province versus coastal animals. Similarly, inland otters contained significantly more MeHg in the brain than did coastal otters. MeHg was highly correlated with total Hg in both inland and coastal otters and represented on average approximately 82% of the total Hg. Selenium concentrations in the otter brain ranged from 1.0 to 7.8 microg/g dw but unlike Hg, there was no significant difference in Se levels between inland and coastal otters. There was a significant positive relationship between Se and total Hg concentrations in the otters with the molar ratio of Se:Hg approximately 1:1 for animals having an Hg concentration>18 nmol/g dw. The non-random sampling protocol for the mink precluded extensive statistical analysis of the data. However, unlike otters, virtually all (i.e. 98%) of the total Hg in mink brain was present as MeHg in both inland and coastal mink. Also unlike the otter results, Se concentrations showed no relationship with either total or MeHg in both inland and coastal mink. The data suggest that mink and otters may have different mechanisms for managing high levels of Hg in the brain.
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Affiliation(s)
- Kevin J R Haines
- Watershed Ecosystems Graduate Program, Trent University, 1600 West Bank Drive, Peterborough, ON, Canada K9J 7B8
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Gong P, Basu N, Scheuhammer AM, Perkins EJ. Neurochemical and electrophysiological diagnosis of reversible neurotoxicity in earthworms exposed to sublethal concentrations of CL-20. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2010; 17:181-186. [PMID: 19274471 PMCID: PMC2801850 DOI: 10.1007/s11356-009-0117-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/03/2008] [Accepted: 02/13/2009] [Indexed: 05/27/2023]
Abstract
BACKGROUND, AIM, AND SCOPE Hexanitrohexaazaisowurtzitane (CL-20) is a relatively new energetic compound sharing some degree of structural similarity with hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), a known neurotoxic compound. Previously, we demonstrated using a noninvasive electrophysiological technique that CL-20 was a more potent neurotoxicant than RDX to the earthworm Eisenia fetida. In the present study, we investigated the effect of CL-20 exposure and subsequent recovery on muscarinic acetylcholine receptors (mAChRs) to further define the mechanism of reversible neurotoxicity of CL-20 in E. fetida. MATERIALS AND METHODS We used a noninvasive electrophysiological technique to evaluate neurotoxicity in CL-20-treated worms, and then measured how such exposures altered levels of whole-body mAChR in the same animals. RESULTS AND DISCUSSION A good correlation exists between these two types of endpoints. Effect on mAChR levels was most prominent at day 6 of exposure. After 7 days of recovery, both conduction velocity and mAChR were significantly restored. Our results show that sublethal concentrations of CL-20 significantly reduced mAChR levels in a concentration- and duration-dependent manner, which was accompanied with significant decreases in the conduction velocity of the medial and lateral giant nerve fibers. After 7-day post exposure recovery, worms restored both neurochemical (mAChR) and neurophysiological (conduction velocity) endpoints that were reduced during 6-day exposures to CL-20 concentrations from 0.02 to 0.22 microg/cm(2). CONCLUSIONS AND PERSPECTIVES Our findings support the idea that CL-20 induced neurotoxic effects are reversible, and suggest that CL-20 neurotoxicity may be mediated through the cholinergic system. Future studies will investigate other neurotransmission systems such as GABA, glutamate, and monoamine. Ion channels in the nerve membrane should be examined to further define the precise mechanisms underlying CL-20 neurotoxicity.
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Affiliation(s)
- Ping Gong
- SpecPro Inc., 3909 Halls Ferry Road, Vicksburg, MS 39180, USA.
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Role of N-methyl-D-aspartate receptors in polychlorinated biphenyl mediated neurotoxicity. Toxicol Lett 2009; 184:50-5. [DOI: 10.1016/j.toxlet.2008.10.013] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2008] [Revised: 10/20/2008] [Accepted: 10/21/2008] [Indexed: 12/16/2022]
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Klenavic K, Champoux L, Mike O, Daoust PY, Evans RD, Evans HE. Mercury concentrations in wild mink (Mustela vison) and river otters (Lontra canadensis) collected from eastern and Atlantic Canada: relationship to age and parasitism. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2008; 156:359-366. [PMID: 18367299 DOI: 10.1016/j.envpol.2008.02.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2007] [Revised: 01/30/2008] [Accepted: 02/10/2008] [Indexed: 05/26/2023]
Abstract
Total mercury (Hg) concentrations were measured in the fur, brain and liver of wild mink (Mustela vison) and river otters (Lontra canadensis) collected from eastern and Atlantic Canada. Total Hg concentrations in fur were strongly correlated with levels in the brain and liver. There was no difference in tissue concentrations between male and female mink; however, female otters had significantly higher fur, brain and liver Hg levels than males. Similarly, there was not a significant relationship between Hg concentration and age of mink, whereas in otters, Hg concentrations in all three tissues decreased significantly with age. In both species, only a very small percentage of the variability in Hg concentration was explained by age. After adjusting the data for site-to-site differences in Hg levels, Hg concentrations in the fur of mink infected by the parasite, Dioctophyma renale, were found to be significantly higher than Hg levels in uninfected mink.
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Affiliation(s)
- Katherine Klenavic
- Environmental and Resource Studies, Trent University, 1600 West Bank Drive, Peterborough, ON K9J 7B8, Canada
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Scheuhammer AM, Basu N, Burgess NM, Elliott JE, Campbell GD, Wayland M, Champoux L, Rodrigue J. Relationships among mercury, selenium, and neurochemical parameters in common loons (Gavia immer) and bald eagles (Haliaeetus leucocephalus). ECOTOXICOLOGY (LONDON, ENGLAND) 2008; 17:93-101. [PMID: 17899374 DOI: 10.1007/s10646-007-0170-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2007] [Accepted: 08/23/2007] [Indexed: 05/17/2023]
Abstract
Fish-eating birds can be exposed to levels of dietary methylmercury (MeHg) known or suspected to adversely affect normal behavior and reproduction, but little is known regarding Hg's subtle effects on the avian brain. In the current study, we explored relationships among Hg, Se, and neurochemical receptors and enzymes in two fish-eating birds--common loons (Gavia immer) and bald eagles (Haliaeetus leucocephalus). In liver, both species demonstrated a wide range of total Hg (THg) concentrations, substantial demethylation of MeHg, and a co-accumulation of Hg and Se. In liver, there were molar excesses of Se over Hg up to about 50-60 microg/g THg, above which there was an approximate 1:1 molar ratio of Hg:Se in both species. However, in brain, bald eagles displayed a greater apparent ability to demethylate MeHg than common loons. There were molar excesses of Se over Hg in brains of bald eagles across the full range of THg concentrations, whereas common loons often had extreme molar excesses of Hg in their brains, with a higher proportion of THg remaining as MeHg compared with eagles. There were significant positive correlations between brain THg and muscarinic cholinergic receptor concentrations in both species studied; whereas significant negative correlations were observed between N-methyl-D-aspartic acid (NMDA) receptor levels and brain Hg concentration. There were no significant correlations between brain Se and neurochemical receptors or enzymes (cholinesterase and monoamine oxidase) in either species. Our findings suggest that there are significant differences between common loons and bald eagles with respect to cerebral metabolism and toxicodynamics of MeHg and Se. These interspecies differences may influence relative susceptibility to MeHg toxicity; however, neurochemical responses to Hg in both species were similar.
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Affiliation(s)
- A M Scheuhammer
- National Wildlife Research Centre, Environment Canada, Ottawa, ON, Canada.
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Fischer C, Fredriksson A, Eriksson P. Coexposure of neonatal mice to a flame retardant PBDE 99 (2,2',4,4',5-pentabromodiphenyl ether) and methyl mercury enhances developmental neurotoxic defects. Toxicol Sci 2007; 101:275-85. [PMID: 17982161 DOI: 10.1093/toxsci/kfm271] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Epidemiological studies indicate that exposure to environmental pollutants during early human development can have deleterious effects on cognitive development. The interaction between environmental pollutants is suggested as one reason for the observed defective neurological development in children from the Faeroe Islands as compared to children from the Seychelles. We have previously seen in mice that polychlorinated biphenyls (PCBs) can interact together with methyl mercury (MeHg), as well as PCB together with polybrominated diphenyl ether (PBDE 99) to exacerbate developmental neurotoxic effects when present during a critical period of neonatal brain development. PBDEs are a new class of global environmental contaminants. The present study shows that neonatal coexposure to PBDE 99 (0.8 mg/kg body weight) and MeHg (0.4 or 4.0 mg/kg body weight) can exacerbate developmental neurotoxic effects. These effects are manifested as disrupted spontaneous behavior, reduced habituation, and impaired learning/memory abilities. This is seen in the low dose range, where the sole compounds do no give rise to developmental neurotoxic effects. The effects seen are more than just additive. Furthermore, a significant effect of interaction was seen on the cholinergic nicotinic receptors in the cerebral cortex and hippocampus. This suggests that a mechanism for the observed cognitive defects is via the cholinergic system. Furthermore, PBDE can interact with MeHg causing developmental neurotoxic effects similar to those we previously have observed between PCB 153 + MeHg and PCB 52 + PBDE 99. This is of vital importance, as the levels of PBDEs are increasing in mother's milk and in the environment generally.
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Affiliation(s)
- Celia Fischer
- Department of Environmental Toxicology, Uppsala University, Norbyvägen 18A, S-752 36 Uppsala, Sweden
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