CELLULAR RESPONSES TO ENVIRONMENTAL POLLUTION IN MYTILUS GALLOPROVINCIALIS

Environmental metabolomics is a cutting edge approach to assessing the health of aquatic organisms and discover novel metabolic biomarkers as organismal defensive or adaptive responses to various stress, providing an overview of the metabolic status of a biological system. Marine mussels, particularly the genus Mytilus, are widely used as sentinel organisms in biomonitoring studies for assessing the impact of anthropogenic contaminants. The aim of this study was to investigate the metabolic responses of mussels (Mytilus galloprovincialis) to environmental pollution by comparing metabolic profiles of different target organs using a metabolomic approach with pattern recognition methods. Specimens of Mytilus galloprovincialis were caged at two sites, an anthropogenically impacted and a reference area, located along the eastern coastline of Sicily, Italy, and held in situ over a thirty-day period. Mussel digestive gland (DG) and gills (G) samples were collected as organs for xenobiotic bioaccumulation and filter-feeding and respiration, respectively, and the extracts analyzed by nuclear magnetic resonance (NMR) spectroscopy. Organic osmolytes, such as betaine and taurine, were found to dominate the metabolome in both tissue profiles. Principal component analysis applied to both organs clearly distinguished the site receiving pollution inputs from the non-polluted site. These differences were associated to changes in metabolites involved in various biochemical pathways correlated with physiological organ functions. Specifically, increases of amino acids (in DG and G) and osmolytes (in G) suggested disturbance in osmoregulation. Changes in glucose, Krebs cycle intermediates and glycogen indicated perturbation in energy metabolism. Impairment of neurotransmission was also hypothesized in gills. The overall findings demonstrate the effectiveness of metabolomics in ecotoxicological studies in assessing environmental influences on the health status of aquatic organisms.