Combination of HPLC with organic and inorganic mass spectrometry to study the metabolic response of the clam Scrobicularia plana to arsenic exposure

Arsenic is a toxic element extensively studied in the marine environment due to differential toxicological effects of inorganic and organic species. In the present work, the bivalve Scrobicularia plana was exposed to AsV (10 and 100 μg/L) for 14 days to evaluate the metabolic perturbations caused by this element. Arsenic speciation and metabolomic analysis were performed in the digestive gland of the bivalve using two complementary analytical platforms based on inorganic and organic mass spectrometry. It has been observed the greater presence of the innocuous specie arsenobetaine produced in this organism as defense mechanism against arsenic toxicity, although significant concentrations of methylated and inorganic arsenic were also present, depending on the level of arsenic in aqueous media. Complementarily, a metabolomic study based on mass spectrometry and statistical discriminant analysis allows a good classification of samples associated to low and high As(V) exposure in relation to controls. About 15 metabolites suffer significant changes of expression by the presence of As(V): amino acids, nucleotides, energy-related metabolites, free fatty acids, phospholipids and triacylglycerides, which can be related to membrane structural and functional damage. In addition, perturbation of the methylation cycle, associated with the increase of homocysteine and methionine was observed, which enhance the methylation of toxic inorganic arsenic to less toxic dimethylarsenic.

This work was supported by the projects CTM2015-67902- C2-1-P and CTM2012-38720-C03-03 from the Spanish Ministry of Economy and Competitiveness, P12-FQM- 0442 from the Regional Ministry of Economy, Innovation, Science and Employment (Andalusian, Government, Spain). Gema Rodríguez Moro and Chiara Trombini thanks to Ministry of Economy and Competitiveness for PhD scholarships (BES-2013-064501 and BES-2013-063426). Finally, authors are grateful to FEDER (European Community) for financial support, grant number UNHU13-1E-1611 and UNHU15-CE-3140.

Peer reviewed