Organ‐specific metabolome deciphering cell pathways to cope with mercury in wild fish (golden grey mullet Chelon auratus)

Metabolomics is a powerful approach in evaluating the health status of organisms in eco-toxicological studies. However, metabolomics data reflect metabolic variations that are attributable to factors intrinsic to the environment and organism, and it is thus crucial to accurately evaluate the metabolome of the tissue/organ examined when it is exposed to no stressor. The metabolomes of the liver and gills of wild golden grey mullet (Chelon auratus) from a reference area were analyzed and compared by proton nuclear magnetic resonance (1H NMR)‐based metabolomics. Both organs were characterized by amino acids, carbohydrates, osmolytes, nucleosides and their derivatives, and miscellaneous metabolites. However, similarities and differences were revealed in their metabolite profile and related to organ‐specific functions. Taurine was predominant in both organs due to its involvement in osmoregulation in gills, and detoxification and antioxidant protective processes in liver. Environmental exposure to mercury (Hg) triggered multiple and often differential metabolic alterations in fish organs. Disturbances in ion‐osmoregulatory processes were high-lighted in the gills, whereas differential impairments between fish organs were pointed out in en-ergy‐producing metabolic pathways, protein catabolism, membrane stabilization processes, and an-tioxidant defense system, reflecting the induction of organ‐specific adaptive and defensive strate-gies. Overall, a strict correlation between metabolites and organ‐specific functions of fish gills and liver were discerned in this study, as well as organ‐specific cytotoxicity mechanisms of Hg in fish.