Differential Cell Metabolic Pathways in Gills and Liver of Fish (White Seabream Diplodus sargus) Coping with Dietary Methylmercury Exposure

Abstract

Mercury (Hg) is a dangerous and persistent trace element. Its organic and highly toxic form, methylmercury (MeHg), easily crosses biological membranes and accumulates in biota. Nevertheless, understanding the mechanisms of dietary MeHg toxicity in fish remains a challenge. A time-course experiment was conducted with juvenile white seabreams, Diplodus sargus (Linnaeus, 1758), exposed to realistic levels of MeHg in feed (8.7 μg g−1, dry weight), comprising exposure (E; 7 and 14 days) and post-exposure (PE; 28 days) periods. Total Hg levels increased with time in gills and liver during E and decreased significantly in PE (though levels of control fish were reached only for gills), with liver exhibiting higher levels (2.7 times) than gills. Nuclear magnetic resonance (NMR)-based metabolomics revealed multiple and often differential metabolic changes between fish organs. Gills exhibited protein catabolism, disturbances in cholinergic neurotransmission, and changes in osmoregulation and lipid and energy metabolism. However, dietary MeHg exposure provoked altered protein metabolism in the liver with decreased amino acids, likely for activation of defensive strategies. PE allowed for the partial recovery of both organs, even if with occurrence of oxidative stress and changes of energy metabolism. Overall, these findings support organ-specific responses according to their sensitivity to Hg exposure, pointing out that indications obtained in biomonitoring studies may depend also on the selected organ.

Polystyrene Micro- and Nanoplastics (PS MNPs): A Review of Recent Advances in the Use of -Omics in PS MNP Toxicity Studies on Aquatic Organisms

“…On the contrary, MS is a highly sensitive technique able to detect thousands of metabolites, prior to separation using liquid or gas chromatography (LC or GC, respectively) [102]. Overall, both of the two metabolomics platforms, in combination with powerful chemometric software for multivariate data analysis, which is necessary to deconvolute the huge amount of data produced following a metabolomic experiment [100,103], allow the simultaneous determination and comparison of a wide range of metabolites, offering numerous advantages to clarify the organism-environment interactions [35,36,43,[104][105][106][107][108][109][110][111][112][113]. A description of the effects of PS MNPs at metabolomic level in fishes and aquatic invertebrates is reported in Table 3.…”