1H NMR-based metabolomic observation of a two-phased toxic mode of action in Eisenia fetida after sub-lethal phenanthrene exposure
Brian P. Lankadurai A , David M. Wolfe A , André J. Simpson A and Myrna J. Simpson A B
+ Author Affiliations
- Author Affiliations
A Department of Chemistry, University of Toronto, 1265 Military Trail, Toronto, ON, M1C 1A4, Canada.
B Corresponding author. Email: myrna.simpson@utoronto.ca
Environmental Chemistry 8(2) 105-114 https://doi.org/10.1071/EN10094
Submitted: 24 August 2010 Accepted: 2 December 2010 Published: 2 May 2011
Journal Compilation © CSIRO Publishing 2011 Open Access CC BY-NC-ND
Environmental context. Phenanthrene is a persistent soil contaminant, whose toxic mode of action in earthworms has not been fully examined. We adopt a metabolomics approach, using 1H nuclear magnetic resonance (NMR) spectroscopy, to measure the response of earthworms to sub-lethal phenanthrene exposure. The results indicate that NMR-based metabolomics may be used to monitor responses to sub-lethal levels of contaminants and to delineate their toxic mode of action.
Abstract. 1H NMR-based metabolomics was used to examine the response of the earthworm Eisenia fetida to sub-lethal phenanthrene exposure. E. fetida were exposed via contact tests to six sub-lethal (below the measured LC50 of 1.6 mg cm–2) concentrations of phenanthrene (0.8–0.025 mg cm–2) for 48 h. Multivariate statistical analysis of the 1H NMR spectra of earthworm tissue extracts revealed a two-phased mode of action (MOA). At exposures below 1/16th of the LC50, the MOA was characterised by a linear correlation between the metabolic response and exposure concentration. At exposures ≥1/16th of the LC50, the metabolic response to phenanthrene appeared to plateau, indicating a distinct change in the MOA. Further data analysis suggested that alanine, lysine, arginine, isoleucine, maltose, ATP and betaine may be potential indicators for sub-lethal phenanthrene exposure. Metabolite variation was also found to be proportional to the exposure concentration suggesting that NMR-based earthworm metabolomics is capable of elucidating concentration-dependent relationships in addition to elucidating the MOA of sub-lethal contaminant-exposure.
Additional keywords: concentration-dependence, contact tests, LC50, metabonomics.
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