Because it is highly reactive, ROS may oxidize the most cellular

Because it is highly reactive, ROS may oxidize the most cellular compounds. Malondialdehyde is an end product of lipid peroxidation that is extensively used as an indirect marker

of oxidative stress [65]. IP injection of silicon-based QDs induced an increase of the MDA level by 66% Buparlisib and 143% in the liver tissue after 1 and 3 days, followed by a slight decrease after 7 days (Figure 3). The observed MDA pattern can be explained by taking into account the various factors. Firstly, as thermoconformers, fish present acclimatory adaptations that include the enrichment of membrane lipid composition Figure 2 Liver histology of Carassius gibelio . (A) Control (non-injected) animals. (B) Liver histopathology 24 h after IP injection indicates accumulation of melanomacrophage centers (arrow). (C) Fibrosis EPZ-6438 purchase (arrow) 72 h after IP injection. (D) Hepatolysis micro centers (arrow) at 7 days after IP injection. H&E staining. with polyunsaturated fatty acids (PUFA) of the ω-3 and/or ω-6 types for preserving membrane fluidity at lower temperatures. A typical reaction during ROS-induced damage is the peroxidation of unsaturated fatty acids [66]. Since the

relative oxidation reaction speed generally increases with increasing unsaturation [65], fish phospholipid membranes are more sensitive to oxidative reactions by ROS than those of the mammals [67]. Hence, the highest level of MDA registered 3 days after QDs exposure might suggest strong on-going lipid peroxidation processes propagated by lipid radicals that may also affect Histamine H2 receptor the Figure 3 Effects of silicon-based QDs on lipid peroxidation in Carassius gibelio liver. Results are expressed as percent (%) from controls ± RSD (n = 6); * P < 0.05; *** P < 0.001. proteins (Table 1). Secondly, due to its propagative nature, lipid peroxidation of unsaturated fatty acids is less dependent on the initial level of free radicals; once initiated, it generates more reactive radicals that sustain the oxidative reaction [65]. The decreased MDA level noticed in

the seventh day might be explained by the action of liver antioxidant mechanisms which are able to gradually quench the spread of lipid peroxidation that is accomplished by the activation of GPX specific activity (Figure 4). Proteins are sensitive to direct ROS attack and also to oxidative damage by lipid peroxidation products [68]. Lipid radical transfer has been demonstrated for reactive N group side chain aminoacids tryptophan, arginine, histidine, and lysine. Tyrosine and methionine degradation by oxidizing lipids has also been demonstrated [69]. Due to their reactivity, lipid peroxidation end products such asmalondialdehyde or other lipid-derived aldehydes do not accumulate and they form Schiff bases in the reaction of carbonyl groups with the amino groups of proteins. The effects of the silicon-based QDs exposure on protein oxidation in the liver tissue of C. gibelio are summarized in Table 1.

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