Endogenous and exogenous biomarker analysis in terrestrial phase amphibians (Lithobates sphenocephala) following dermal exposure to pesticide mixtures
Donna A. Glinski
A B C F , S. Thomas Purucker D , Robin J. Van Meter E , Marsha C. Black B and W. Matthew Henderson D
+ Author Affiliations
- Author Affiliations
A Grantee to U.S. Environmental Protection Agency via Oak Ridge Institute of Science and Education, Athens, GA 30605, USA.
B Department of Environmental Health Science, Interdisciplinary Toxicology Program, University of Georgia, Athens, GA 30602, USA.
C Present address: School of Chemical Sciences, Dublin City University, Dublin D09 W6Y4, Ireland.
D U.S. Environmental Protection Agency, Office of Research and Development, National Exposure Research Laboratory, Athens, GA 30605, USA.
E Departments of Biology and Environmental Science/Studies, Washington College, Chestertown, MD 21620, USA.
F Corresponding author. Email: donna.glinski@dcu.ie
Environmental Chemistry 16(1) 55-67 https://doi.org/10.1071/EN18163
Submitted: 2 August 2018 Accepted: 7 November 2018 Published: 28 November 2018
Environmental context. Metabolomics can be used to provide a snapshot of an organism’s physiology as the organism is exposed to varying environmental conditions. In this study, laboratory-reared amphibians were exposed to multiple pesticides, analogous to field exposures, resulting in an impact to both pesticide body concentrations and the amphibians’ hepatic metabolome. These data can be used in the environmental and ecological risk assessment of multiple pesticides in non-target species.
Abstract. Pesticide mixtures are frequently co-applied throughout an agricultural growing season to maximise crop yield. Therefore, non-target ecological species (e.g. amphibians) may be exposed to several pesticides at any given time on these agricultural landscapes. The objectives of this study were to quantify body burdens in terrestrial phase amphibians and translate perturbed metabolites to their corresponding biochemical pathways affected by exposure to pesticides as both singlets and in combination. Southern leopard frogs (Lithobates sphenocephala) were exposed either at the maximum or 1/10th maximum application rate to single, double or triple pesticide mixtures of bifenthrin (insecticide), metolachlor (herbicide) and triadimefon (fungicide). Tissue concentrations demonstrated both facilitated and competitive uptake of pesticides when in mixtures. Metabolomic profiling of amphibian livers identified metabolites of interest for both application rates; however, the magnitude of changes varied for the two exposure rates. Exposure to lower concentrations demonstrated downregulation in amino acids, potentially owing to their usage for glutathione metabolism and/or increased energy demands. Amphibians exposed to the maximum application rate resulted in upregulation of amino acids and other key metabolites likely owing to depleted energy resources. Coupling endogenous and exogenous biomarkers of pesticide exposure can be used to form vital links in an ecological risk assessment by relating internal dose to pathophysiological outcomes in non-target species.
Additional keywords: application rate, body burden, frog, metabolomics.
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