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Tornabene BJ, Hossack BR, Halstead BJ, Eagles-Smith CA, Adams MJ, Backlin AR, Brand AB, Emery CS, Fisher RN, Fleming J, Glorioso BM, Grear DA, Grant EHC, Kleeman PM, Miller DAW, Muths E, Pearl CA, Rowe JC, Rumrill CT, Waddle JH, Winzeler ME, Smalling KL. Broad-Scale Assessment of Methylmercury in Adult Amphibians. Environ Sci Technol 2023; 57:17511-17521. [PMID: 37902062 PMCID: PMC10653216 DOI: 10.1021/acs.est.3c05549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Revised: 09/27/2023] [Accepted: 09/28/2023] [Indexed: 10/31/2023]
Abstract
Mercury (Hg) is a toxic contaminant that has been mobilized and distributed worldwide and is a threat to many wildlife species. Amphibians are facing unprecedented global declines due to many threats including contaminants. While the biphasic life history of many amphibians creates a potential nexus for methylmercury (MeHg) exposure in aquatic habitats and subsequent health effects, the broad-scale distribution of MeHg exposure in amphibians remains unknown. We used nonlethal sampling to assess MeHg bioaccumulation in 3,241 juvenile and adult amphibians during 2017-2021. We sampled 26 populations (14 species) across 11 states in the United States, including several imperiled species that could not have been sampled by traditional lethal methods. We examined whether life history traits of species and whether the concentration of total mercury in sediment or dragonflies could be used as indicators of MeHg bioaccumulation in amphibians. Methylmercury contamination was widespread, with a 33-fold difference in concentrations across sites. Variation among years and clustered subsites was less than variation across sites. Life history characteristics such as size, sex, and whether the amphibian was a frog, toad, newt, or other salamander were the factors most strongly associated with bioaccumulation. Total Hg in dragonflies was a reliable indicator of bioaccumulation of MeHg in amphibians (R2 ≥ 0.67), whereas total Hg in sediment was not (R2 ≤ 0.04). Our study, the largest broad-scale assessment of MeHg bioaccumulation in amphibians, highlights methodological advances that allow for nonlethal sampling of rare species and reveals immense variation among species, life histories, and sites. Our findings can help identify sensitive populations and provide environmentally relevant concentrations for future studies to better quantify the potential threats of MeHg to amphibians.
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Affiliation(s)
- Brian J. Tornabene
- U.S.
Geological Survey, Northern Rocky Mountain
Science Center, Missoula, Montana 59801, United States
| | - Blake R. Hossack
- U.S.
Geological Survey, Northern Rocky Mountain
Science Center, Missoula, Montana 59801, United States
- Wildlife
Biology Program, W. A. Franke College of Forestry & Conservation, University of Montana, Missoula, Montana 59812, United States
| | - Brian J. Halstead
- U.S.
Geological Survey, Western Ecological Research
Center, Dixon, California 95620, United States
| | - Collin A. Eagles-Smith
- U.S.
Geological Survey, Forest and Rangeland
Ecosystem Science Center, Corvallis, Oregon 97331 United States
| | - Michael J. Adams
- U.S.
Geological Survey, Forest and Rangeland
Ecosystem Science Center, Corvallis, Oregon 97331 United States
| | - Adam R. Backlin
- U.S.
Geological Survey, Western Ecological Research
Center, San Diego, California 92101, United States
| | - Adrianne B. Brand
- U.S. Geological
Survey, Eastern Ecological Science Center
(Patuxent Wildlife Research Center), Turners Falls, Massachusetts 01376, United States
| | - Colleen S. Emery
- U.S.
Geological Survey, Forest and Rangeland
Ecosystem Science Center, Corvallis, Oregon 97331 United States
| | - Robert N. Fisher
- U.S.
Geological Survey, Western Ecological Research
Center, San Diego, California 92101, United States
| | - Jill Fleming
- U.S. Geological
Survey, Eastern Ecological Science Center
(Patuxent Wildlife Research Center), Turners Falls, Massachusetts 01376, United States
| | - Brad M. Glorioso
- U.S.
Geological
Survey, Wetland and Aquatic Research Center, Lafayette, Louisiana 70506, United States
| | - Daniel A. Grear
- U.S.
Geological
Survey, National Wildlife Health Center, Madison, Wisconsin 53711, United States
| | - Evan H. Campbell Grant
- U.S. Geological
Survey, Eastern Ecological Science Center
(Patuxent Wildlife Research Center), Turners Falls, Massachusetts 01376, United States
| | - Patrick M. Kleeman
- U.S.
Geological
Survey, Western Ecological Research Center, Point Reyes Station, California 94956, United States
| | - David A. W. Miller
- Department
of Ecosystem Science and Management, Pennsylvania
State University, University Park, Pennsylvania 16802, United States
| | - Erin Muths
- U.S. Geological
Survey, Fort Collins Science Center, Fort Collins, Colorado 80526, United States
| | - Christopher A. Pearl
- U.S.
Geological Survey, Forest and Rangeland
Ecosystem Science Center, Corvallis, Oregon 97331 United States
| | - Jennifer C. Rowe
- U.S.
Geological Survey, Forest and Rangeland
Ecosystem Science Center, Corvallis, Oregon 97331 United States
| | - Caitlin T. Rumrill
- U.S.
Geological Survey, Forest and Rangeland
Ecosystem Science Center, Corvallis, Oregon 97331 United States
| | - J. Hardin Waddle
- U.S. Geological
Survey, Wetland and Aquatic Research Center, Gainesville, Florida 32653, United States
| | - Megan E. Winzeler
- U.S.
Geological
Survey, National Wildlife Health Center, Madison, Wisconsin 53711, United States
| | - Kelly L. Smalling
- U.S. Geological
Survey, New Jersey Water Science Center, Lawrenceville, New Jersey 08648, United States
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Ramel MC, Emery CM, Emery CS, Foulger R, Goberdhan DCI, van den Heuvel M, Wilson C. Drosophila SnoN modulates growth and patterning by antagonizing TGF-beta signalling. Mech Dev 2006; 124:304-17. [PMID: 17289352 DOI: 10.1016/j.mod.2006.12.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2006] [Revised: 12/18/2006] [Accepted: 12/20/2006] [Indexed: 11/22/2022]
Abstract
Signalling by TGF-beta ligands through the Smad family of transcription factors is critical for developmental patterning and growth. Disruption of this pathway has been observed in various cancers. In vertebrates, members of the Ski/Sno protein family can act as negative regulators of TGF-beta signalling, interfering with the Smad machinery to inhibit the transcriptional output of this pathway. In some contexts ski/sno genes function as tumour suppressors, but they were originally identified as oncogenes, whose expression is up-regulated in many tumours. These growth regulatory effects and the normal physiological functions of Ski/Sno proteins have been proposed to result from changes in TGF-beta signalling. However, this model is controversial and may be over-simplified, because recent findings indicate that Ski/Sno proteins can affect other signalling pathways. To address this issue in an in vivo context, we have analyzed the function of the Drosophila Ski/Sno orthologue, SnoN. We found that SnoN inhibits growth when overexpressed, indicating a tumour suppressor role in flies. It can act in multiple tissues to selectively and cell autonomously antagonise signalling by TGF-beta ligands from both the BMP and Activin sub-families. By contrast, analysis of a snoN mutant indicates that the gene does not play a global role in TGF-beta-mediated functions, but specifically inhibits TGF-beta-induced wing vein formation. We propose that SnoN normally functions redundantly with other TGF-beta pathway antagonists to finely adjust signalling levels, but that it can behave as an extremely potent inhibitor of TGF-beta signalling when highly expressed, highlighting the significance of its deregulation in cancer cells.
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Affiliation(s)
- M-C Ramel
- Department of Physiology, Anatomy and Genetics, University of Oxford, Le Gros Clark Building, South Parks Road, Oxford OX1 3QX, UK.
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