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Aquatic animals are vulnerable to arsenic (As) toxicity. However, rarely does a contaminant occur alone in the aquatic environment. For this reason, this study was conducted to evaluate whether titanium dioxide nanoparticles (nTiO2) can interfere with the effects induced by As in Litopenaeus vannamei. Arsenic accumulation and metabolic capacity; expression and enzymatic activity of GSTΩ (glutathione-S-transferase omega isoform); antioxidant responses such as GSH, GR, and GST (reduced glutathione levels, glutathione reductase, and glutathione-S-transferase activity, respectively); and lipid peroxidation in the gills and hepatopancreas of shrimp were evaluated. The results are summarized as follows: (1) higher accumulation of As occurred in both tissues after exposure to As alone; (2) co-exposure to nTiO2 affected the capacity to metabolize As; (3) GSTΩ gene expression was not modified, but its activity was decreased by co-exposure to both contaminants; (4) As alone increased the GSH levels in the hepatopancreas, and co-exposure to nTiO2 reduced these levels in both tissues; (5) a decrease in the GST activity in the gills occurred with all treatments; (6) in the gills, GR activity was increased by As, and nTiO2 reversed this increase, whereas in the hepatopancreas co-exposure inhibited enzyme activity; (7) only in the hepatopancreas lipid damage was observed when animals were exposed to As or nTiO2 but not in co-exposure. The results showed that the As induces toxic effects in both tissues of shrimp and that co-exposure to nTiO2 can potentiate these effects and decrease the capacity to metabolize As, favoring the accumulation of more toxic compounds.

Oxidative challenge is an important factor affecting the adaptive strategies of Antarctic fish, but data on antioxidant defences in these organisms remain scarce. In this investigation, individual antioxidants and the total oxyradical scavenging capacity (TOSC) were characterised in three notothenioid species, Trematomus bernacchii, Trematomus hansoni and Trematomus newnesi; seasonal fluctuations were further analysed in T. bernacchii sampled during different periods of the reproductive cycle, ice melting and phytoplanktonic blooms. The overall results revealed only limited differences between the three notothenioids, with greater TOSC values in T. hansoni and T. newnesi. The capacity for decomposing hydrogen peroxide via catalase was not particularly enhanced in these fish, in contrast to the prominent role of the enzyme in Antarctic invertebrates. An alternative antioxidant strategy, based on the efficiency of low molecular mass scavengers was suggested, especially for T. bernacchii which had higher lev...

Arsenic is a widely distributed element which occurs in several chemical forms in the marine environment. Inorganic arsenic mediates the most toxic effects and predominates in sea water and sediments, while organisms generally accumulate non-toxic organic forms to concentrations probably reflecting species-specific characteristics in arsenic metabolism. This work represents an additional contribution to our knowledge on natural levels and chemical speciation of arsenic in marine organisms; basal concentrations were characterized in several species (bivalves, crustaceans, and fishes) from different environments (polar, temperate, and tropical latitudes), and results revealed an elevated variability with values ranging from less than 5 to about 200 μg g−1. No significant effects were observed as a function of the geographical area, with the only exception of crustaceans always showing more elevated arsenic concentrations in Mediterranean species (about 45–110 μg g−1) compared with tropical species (lower th...

Formation of reactive oxygen species (ROS) is a natural event for aerobic organisms, but it can be exacerbated by both biological and environmental factors. Cellular oxidative damage is well documented in aquatic organisms, and variations of antioxidants can be sensitive in revealing a pro-oxidant condition. Nonetheless, such effects are difficult to predict according to chemicals, kind of exposure, and species sensitivity. Measuring the overall efficiency of cellular antioxidants toward oxyradicals provides a more integrated assessment of susceptibility of a tissue to oxidative stress. Among the methods for analyzing total antioxidant capacity, the total oxyradical scavenging capacity (TOSC) assay offers the possibility to discriminate different oxyradicals, indicating the roles of these species or their metabolic pathways of formation, in the onset of oxidative disease. The TOSC assay has been widely used on marine organisms under natural and disturbed condition suggesting temporal and causal relationsh...

The European eel (Anguilla anguilla) is a euryaline fish suitable for investigating exposure, accumulation patterns and biological effects of lipophilic pollutants such as polychlorinated biphenyls (PCBs). Eels were collected from the Orbetello Lagoon (Tyrrhenian coast of Italy) and injected with increasing doses of Aroclor 1254 to better characterise EROD activity as biomarker in eels from Mediterranean brackish environments. Fish muscle was analysed for PCB content and EROD activity was measured in liver microsomiaI fraction. Significant differences of PCB levels were observed in exposed fish (p < 0.05) while EROD activity increased significantly reaching the highest values at the maximum dose of 50mg/Kg (p < 0.001). Highly positive correlation (r = 0.82; p < 0.01) was found between PCB content and EROD activity. Isomer profiles showed decreases in hexa-CBs. The European eel is confirmed to be a useful sentinel species for assessing pollution in brackish environments whereas EROD activity is characteris...