Proteomic and metabolomic analysis of earthworm Eisenia fetida exposed to different concentrations of 2,2',4,4'-tetrabromodiphenyl ether.

Unlabelled: As a class of brominated flame-retardants (BFRs), polybrominated diphenyl ethers (PBDEs) are widely used in industrial products. PBDEs have been detected in local terrestrial biota from the Laizhou Bay in China. They can induce various toxicities, such as hepatotoxicity, neurotoxicity, cytotoxicity, genotoxicity and endocrine disrupting effects in animals. In this work, we characterized the dose-responsive effects of 2,2',4,4'-tetrabromodiphenyl ether (BDE 47) in earthworm Eisenia fetida using an integrated proteomic and metabolomic approach. Metabolic responses indicated that BDE 47 mainly caused disturbance in osmotic regulation and energy metabolism marked by differentially altered betaine, amino acids, ATP, glucose, maltose and succinate in E. fetida. Proteomic responses revealed that BDE 47 induced cell apoptosis (or injury), oxidative stress, disturbance in protein biosynthesis and energy metabolism in E. fetida in terms of differential proteomic biomarkers. Especially, the increased ATP was confirmed by up-regulated nucleoside diphosphate kinase A and ATP synthase in 1 and 100μg/L of BDE 47-treated groups, respectively. In addition, several metabolic biomarkers including betaine, glycine and 2-hexyl-5-ethyl-3-furansulfonate were relatively stable in all BDE 47-exposed groups. This work demonstrated that proteomics and metabolomics could partially validate one another and their combination could better understand toxicological effects of environmental pollutants.

Biological Significance: As a class of brominated flame-retardants (BFRs), polybrominated diphenyl ethers (PBDEs) are widely used in industrial products and have been detected in local terrestrial biota from the Laizhou Bay in China. Therefore a study on PBDE-induced toxicological effects is necessary. The earthworm E. fetida, a terrestrial sentinel animal, is the most frequently used bioindicator for terrestrial environmental contaminants. To our knowledge, however, very few studies have focused on the dose-dependent responses induced by PBDEs, in terrestrial sentinel animal at protein and metabolite levels. In the present study, an integrated metabolomic and proteomic approach was used to elucidate the dose-dependent toxicological effects of BDE 47 in E. fetida.