1H NMR-based metabolomic observation of a two-phased toxic mode of action in Eisenia fetida after sub-lethal phenanthrene exposure

Abstract

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 1 H 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.1 H NMR-based metabolomics was used to examine the response of the earthworm Eisenia fetida to sublethal phenanthrene exposure. E. fetida were exposed via contact tests to six sub-lethal (below the measured LC 50 of 1.6 mg cm À2) concentrations of phenanthrene (0.8-0.025 mg cm À2 ) for 48 h. Multivariate statistical analysis of the 1 H NMR spectra of earthworm tissue extracts revealed a two-phased mode of action (MOA). At exposures below 1/16th of the LC 50 , the MOA was characterised by a linear correlation between the metabolic response and exposure concentration. At exposures !1/16th of the LC 50 , 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 concentrationdependent relationships in addition to elucidating the MOA of sub-lethal contaminant-exposure.

Metabolomic Differentiation of Nutritional Stress in an Aquatic Invertebrate

“…A1 for pipeline schematic; figs. A1-A3 are available online) statistics tool (Bundy et al 2004;Lankadurai et al 2011a). The region of 4.70-4.85 ppm was excluded to eliminate small residual H 2 O/HOD signals.…”

Analysis of Eisenia fetida earthworm responses to sub-lethal C60 nanoparticle exposure using 1H-NMR based metabolomics

“…3 and 4;Beckwith-Hall et al, 1998;Ekman et al, 2008;Lankadurai et al, 2011b). In contact tests, leucine, valine, isoleucine, phenylalanine, arginine and lysine did not change significantly (at α¼0.05) after 2 days of exposure.…”

“…Difference class 1 H NMR spectra were constructed to identify metabolites that had significantly increased or decreased relative to the control (Ekman et al, 2008(Ekman et al, , 2009Lankadurai et al, 2011b). The buckets generated by AMIX 3.9.7 statistics tool, which represents the binned 1 H NMR spectra of E. fetida extracts were then imported into Microsoft Excel.…”

“…They showed that only cocoon production was significantly hindered and this was also only at the highest exposure concentration of 50,000 mg/kg, which is markedly higher than any reported environmental concentrations. Therefore, their conclusions that C 60 nanoparticles are not acutely toxic to E. fetida need to be further explored at lower concentrations as studies with other environmental contaminants have reported significant metabolite fluctuations with sub-lethal exposure (Brown et al, 2010;Lankadurai et al, 2011b;McKelvie et al, 2011;Mosleh et al, 2003;Neuhauser and Callahan, 1990;Yuk et al, 2011). Metabolomic methods can also aid in elucidating the biochemical mode of action (MOA) of contaminant exposure.…”

Water-mediated NOE: a promising tool for interrogating interfacial clay–xenobiotic interactions

“…Although the acute health effects of these xenobiotics are well documented, the effect of chronic exposure remains an open question [1-3, 5, 6]. The intrinsic interactions between these xenobiotics and soils hold the key to understanding both their environmental accumulation and their bioavailability [7][8][9][10][11]. Therefore, a better understanding as to how xenobiotics are sequestered into complex rock, soil, and sediments is required [12][13][14].…”