1-D and 2-D NMR metabolomics of earthworm responses to sub-lethal trifluralin and endosulfan exposure

Abstract

Environmental contextEnvironmental metabolomics is an emerging field that examines the metabolic changes in organisms in response to potential environmental stressors. In this study, nuclear magnetic resonance spectroscopy is used to investigate earthworm metabolic responses to sub-lethal exposure of environmentally persistent pesticides. The study identifies two toxic modes of action elicited by the pesticides, and highlights the potential of metabolomics for the chemical assessment of persistent environmental contaminants. Abstract1-D and 2-D nuclear magnetic resonance (NMR) spectroscopy is used to examine the metabolic response of the earthworm (Eisenia fetida) after contact test exposure to an organofluorine pesticide, trifluralin, and an organochlorine pesticide, endosulfan. Three sub-lethal concentrations were used for each pesticide (0.1, 0.5 and 1.0 mg cm–2 for trifluralin and 0.5, 1.0 and 2.0 μg cm–2 for endosulfan). Principal component analysis of the trifluralin and endosulfan NMR datasets showed separation between the unexposed and the exposed earthworm groups. Alanine, glycine, maltose and ATP were significant in the highest concentration (1.0 mg cm–2) for trifluralin-exposed earthworms and may result from a non-polar narcosis toxic mode of action (MOA). Leucine, phenylalanine, tryptophan, lysine, glutamate, valine, glycine, isoleucine, methionine, glutamine, alanine, maltose, glucose, meibiose, malate, fumarate and ATP were detected as significant for the two highest concentrations (1.0 and 2.0 μg cm–2) for endosulfan-exposed earthworms and a neurotoxic MOA is postulated. This study highlights the use of 1-D and 2-D metabolomics for understanding the biochemical response of environmental contaminants to model organisms such as earthworms.