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Short-term mercury exposure disrupts muscular and hepatic lipid metabolism in a migrant songbird. Sci Rep 2022; 12:11470. [PMID: 35794224 PMCID: PMC9259677 DOI: 10.1038/s41598-022-15680-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Accepted: 06/28/2022] [Indexed: 11/18/2022] Open
Abstract
Methylmercury (MeHg) is a global pollutant that can cause metabolic disruptions in animals and thereby potentially compromise the energetic capacity of birds for long-distance migration, but its effects on avian lipid metabolism pathways that support endurance flight and stopover refueling have never been studied. We tested the effects of short-term (14-d), environmentally relevant (0.5 ppm) dietary MeHg exposure on lipid metabolism markers in the pectoralis and livers of yellow-rumped warblers (Setophaga coronata) that were found in a previous study to have poorer flight endurance in a wind tunnel than untreated conspecifics. Compared to controls, MeHg-exposed birds displayed lower muscle aerobic and fatty acid oxidation capacity, but similar muscle glycolytic capacity, fatty acid transporter expression, and PPAR expression. Livers of exposed birds indicated elevated energy costs, lower fatty acid uptake capacity, and lower PPAR-γ expression. The lower muscle oxidative enzyme capacity of exposed birds likely contributed to their weaker endurance in the prior study, while the metabolic changes observed in the liver have potential to inhibit lipogenesis and stopover refueling. Our findings provide concerning evidence that fatty acid catabolism, synthesis, and storage pathways in birds can be dysregulated by only brief exposure to MeHg, with potentially significant consequences for migratory performance.
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Li L, Li H, Wu L, Qi H. Sulfur dioxide improves drought tolerance through activating Ca 2+ signaling pathways in wheat seedlings. ECOTOXICOLOGY (LONDON, ENGLAND) 2022; 31:852-859. [PMID: 35538264 DOI: 10.1007/s10646-022-02547-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 04/07/2022] [Indexed: 06/14/2023]
Abstract
Sulfur dioxide (SO2) and drought are two important co-occurring abiotic stresses affecting the growth and productivity of plants. Here, we will investigate the role of Ca2+ in regulating antioxidant defense during drought or SO2/drought stress, and the effect of SO2 pretreatment on the physiological response of wheat seedlings to drought stress. The results showed that exogenous Ca2+ increased the activities of SOD, CAT and POD, and reduced the contents of H2O2 and MDA in drought-treated wheat seedlings, suggesting Ca2+ could improve drought tolerance by promoting antioxidant defense in plants. Moreover, exogenous Ca2+ up-regulated the expression of two stress-responsive transcription factor (TF) genes, ERF1 and MYB30, to cope with drought stress. Exposure of wheat seedlings to 10 mg m-3 SO2 significantly enhanced the activities of SOD, CAT and POD. The contents of H2O2 and MDA remained at control levels, showing that SO2 at this concentration led to an activation of the antioxidant defense system and did not cause oxidative damage to the seedlings. Furthermore, 10 mg m-3 SO2 pretreatment increased the expression of CCaMK and CPK10, enhanced the activities of SOD and POD, and reduced the accumulation of H2O2 and MDA in drought-treated wheat seedlings, showing a role of SO2 in protection of plants against drought stress. However, with removal of Ca2+ by spraying EGTA on the SO2-pretreated wheat seedlings, the expression of transcription factor genes and activities of antioxidant enzymes were decreased, and the contents of H2O2 and MDA enhanced to the level of drought treatment alone, suggesting a role of Ca2+ in the SO2-induced alleviation of drought stress. Together, these results indicated that exogenous Ca2+ increased defense-related gene expression and enzyme activity in response to drought stress, and that pre-exposure to appropriate levels of SO2 could improve drought tolerance through activation of Ca2+ signaling pathways in plants. This study would provide new strategy for enhancing plant resistance to environmental stress.
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Affiliation(s)
- Lihong Li
- Department of Chemistry and Chemical Engineering, JinzhongUniversity, Yuci, China
| | - Haiyan Li
- Department of Biology, Taiyuan Normal University, Yuci, China
| | - Lihua Wu
- Department of Biology, Taiyuan Normal University, Yuci, China
| | - Hongxue Qi
- Department of Chemistry and Chemical Engineering, JinzhongUniversity, Yuci, China.
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Le Croizier G, Point D, Renedo M, Munaron JM, Espinoza P, Amezcua-Martinez F, Lanco Bertrand S, Lorrain A. Mercury concentrations, biomagnification and isotopic discrimination factors in two seabird species from the Humboldt Current ecosystem. MARINE POLLUTION BULLETIN 2022; 177:113481. [PMID: 35245770 DOI: 10.1016/j.marpolbul.2022.113481] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Revised: 02/15/2022] [Accepted: 02/17/2022] [Indexed: 06/14/2023]
Abstract
Assessing mercury (Hg) biomagnification requires the description of prey-predator relationships, for each species and ecosystem, usually based on carbon and nitrogen isotope analyses. Here, we analyzed two seabirds from the Humboldt Current ecosystem, the Guanay cormorant (Phalacrocorax bougainvillii) and the Peruvian booby (Sula variegata), as well as their main prey, the Peruvian anchovy (Engraulis ringens). We reported Hg concentrations, Hg biomagnification (BMF) and isotopic discrimination factors (Δ13C and Δ15N) in seabird whole blood. BMFs and Δ13C in our study (on wild birds where diet was not controlled) were similar to other piscivorous seabirds previously studied in captive settings, but Δ15N were lower than most captive experiments. We observed lower Hg concentrations in Humboldt seabirds compared to other oligotrophic ecosystems, possibly due to Hg biodilution in the high biomass of the first trophic levels. This work calls for a better characterization of Hg trophic dynamics in productive upwelling ecosystems.
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Affiliation(s)
- Gaël Le Croizier
- Instituto de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México, Av. Joel Montes Camarena S/N, Mazatlán, Sin. México 82040, Mexico.
| | - David Point
- UMR Géosciences Environnement Toulouse (GET), Observatoire Midi Pyrénées (OMP), 14 avenue Edouard Belin, 31400 Toulouse, France
| | - Marina Renedo
- UMR Géosciences Environnement Toulouse (GET), Observatoire Midi Pyrénées (OMP), 14 avenue Edouard Belin, 31400 Toulouse, France
| | | | - Pepe Espinoza
- Laboratorio de Ecología Trófica, Instituto del Mar del Perú, Esquina Gamarra y General Valle S/N Chucuito Callao, Lima, Peru; Carrera de Biología Marina, Facultad de Ciencias Veterinarias y Biológicas, Universidad Científica del Sur, Lima, Peru
| | - Felipe Amezcua-Martinez
- Instituto de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México, Av. Joel Montes Camarena S/N, Mazatlán, Sin. México 82040, Mexico
| | - Sophie Lanco Bertrand
- Institut de Recherche pour le Développement (IRD), MARBEC (Univ. Montpellier, Ifremer, CNRS, IRD), Avenue Jean Monnet, 34200 Sète, France
| | - Anne Lorrain
- Univ Brest, CNRS, IRD, Ifremer, LEMAR, F-29280 Plouzané, France
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Grieves LA, Bottini CLJ, Branfireun BA, Bernards MA, MacDougall-Shackleton SA, MacDougall-Shackleton EA. Food stress, but not experimental exposure to mercury, affects songbird preen oil composition. ECOTOXICOLOGY (LONDON, ENGLAND) 2020; 29:275-285. [PMID: 32036507 DOI: 10.1007/s10646-020-02171-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 01/28/2020] [Indexed: 06/10/2023]
Abstract
Mercury is a global pollutant and potent neurotoxic metal. Its most toxic and bioavailable form, methylmercury, can have both lethal and sublethal effects on wildlife. In birds, methylmercury exposure can disrupt behavior, hormones, the neuroendocrine system, and feather integrity. Lipid-rich tissues and secretions may be particularly susceptible to disruption by lipophilic contaminants such as methylmercury. One such substance is feather preen oil, a waxy secretion of the uropygial gland that serves multiple functions including feather maintenance, anti-parasitic defense, and chemical signaling. If methylmercury exposure alters preen oil composition, it could have cascading effects on feather quality, susceptibility to ectoparasites, and mate choice and other social behaviors. We investigated whether exposure to methylmercury, either alone or in association with other stressors, affects preen oil chemical composition. We used a two-factor design to expose adult song sparrows (Melospiza melodia) to an environmentally relevant dietary dose of methylmercury and/or to another stressor (unpredictable food supply) for eight weeks. The wax ester composition of preen oil changed significantly over the 8-week experimental period. This change was more pronounced in the unpredictable food treatment, regardless of dietary methylmercury. Contrary to our prediction, we found no main effect of methylmercury exposure on preen oil composition, nor did methylmercury interact with unpredictable food supply in predicting the magnitude of chemical shifts in preen oil. While it remains critical to study sublethal effects of methylmercury on wildlife, our findings suggest that the wax ester composition of preen oil is robust to environmentally relevant doses of this contaminant.
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Affiliation(s)
- L A Grieves
- Department of Biology, The University of Western Ontario, 1151 Richmond St., London, ON, N6A 5B7, Canada.
| | - C L J Bottini
- Department of Biology, The University of Western Ontario, 1151 Richmond St., London, ON, N6A 5B7, Canada
| | - B A Branfireun
- Department of Biology, The University of Western Ontario, 1151 Richmond St., London, ON, N6A 5B7, Canada
| | - M A Bernards
- Department of Biology, The University of Western Ontario, 1151 Richmond St., London, ON, N6A 5B7, Canada
| | - S A MacDougall-Shackleton
- Department of Psychology, The University of Western Ontario, 1151 Richmond St., London, ON, N6A 5C2, Canada
| | - E A MacDougall-Shackleton
- Department of Biology, The University of Western Ontario, 1151 Richmond St., London, ON, N6A 5B7, Canada
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Ma Y, Perez CR, Branfireun BA, Guglielmo CG. Dietary exposure to methylmercury affects flight endurance in a migratory songbird. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2018; 234:894-901. [PMID: 29253830 DOI: 10.1016/j.envpol.2017.12.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Revised: 12/01/2017] [Accepted: 12/04/2017] [Indexed: 06/07/2023]
Abstract
Although there has been much speculation in the literature that methylmercury (MeHg) exposure can reduce songbird fitness, little is known about its effects on migration. Migrating songbirds typically make multiple flights, stopping to refuel for short periods between flights. How refueling at MeHg-contaminated stopover sites would contribute to MeHg bioaccumulation, and how such exposure could affect subsequent flight performance during migration has not been determined. In a dosing experiment we show that migratory yellow-rumped warblers (Setophaga coronata) rapidly accumulate dietary MeHg in blood, brain and muscle, liver and kidneys in just 1-2 weeks. We found that exposure to a 0.5 ppm diet did not affect vertical takeoff performance, but in 2-h wind tunnel flights, MeHg-treated warblers had a greater median number of strikes (landing or losing control) in the first 30 min, longer strike duration, and shorter flight duration. The number of strikes in the first 30 min of 0.5 ppm MeHg-exposed warblers was related to mercury concentration in blood in a sigmoid, dose-dependent fashion. Hyperphagic migratory songbirds may potentially bioaccumulate MeHg rapidly, which can lead to decreased migratory endurance flight performance.
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Affiliation(s)
- Yanju Ma
- Department of Biology, University of Western Ontario, London, Ontario, Canada; Advanced Facility for Avian Research, University of Western Ontario, London, Ontario, Canada.
| | - Cristina R Perez
- Department of Agriculture, Nutrition and Veterinary Sciences, University of Nevada, Reno, NV 89557, USA
| | - Brian A Branfireun
- Department of Biology, University of Western Ontario, London, Ontario, Canada; Centre for Environment and Sustainability, University of Western Ontario, London, Ontario, Canada
| | - Christopher G Guglielmo
- Department of Biology, University of Western Ontario, London, Ontario, Canada; Advanced Facility for Avian Research, University of Western Ontario, London, Ontario, Canada
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