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Highlights: [•] Selenium accumulation in tissues can be reverted after a Se withdrawal period. [•] Selenium concentration decreased slower in muscle than in liver and kidney. [•] Selenium induced changes in levels of antioxidant markers in liver and kidney. [•] Changes of biochemical markers persisted even after the withdrawal period. [Copyright &y& Elsevier]

Highlights: [•] Growth was faster, but not statistically significant in Se exposed crayfish after 8 weeks. [•] High Se levels were measured in exoskeleton and hepatopancreas of both Se exposed sexes. [•] Lower values of the health indicator HI were recorded in both Se exposed sexes. [•] Selenium can deplete the hepatopancreas energy reserves, mainly in male crayfish. [ABSTRACT FROM AUTHOR]

Abstract: The effects of a selenium (Se) diet (1.0mg Sekg−1) were investigated on growth, accumulation and antioxidant response in juvenile Tinca tinca at three endpoints (0, 4 and 8 weeks). Growth and condition factor (K >1.5) for both control (0.25mg Sekg−1) and Se tench were not significantly affected. Se exposed fish exhibited the highest Se level in the kidney and the liver after 4 weeks. By feeding more Se the accumulation capacity of tench did not increase and a plateau, mainly for the liver, was thus reached. Se level remained almost constant in the muscle if compared to own control and for each endpoint. Superoxide dismutase activity in both tissues was not affected by Se supplementation and the higher catalase level in the kidney might support the hypothesis that the enzyme was adequate to remove the hydrogen peroxide production following Se exposure. However, supplemented diet with higher Se level could be critical for tench, as it may cause a lowering of glutathione peroxidase and glutathione reductase activities facilitating the onset of oxidative damage. The enhancement of thiol level and glutathione S-transferase activity, mainly in the liver, could be the signals of the only protection against the oxidative damage induced by Se. [Copyright &y& Elsevier]

Highlights: [•] Sturgeon accumulated selenium in tissues with a dose-response relationship. [•] The highest Se concentration was recorded in liver. [•] A dose-response relationship for antioxidant markers was recorded in liver. [•] GPx activity provided to sturgeon a great defense ability against selenium. [ABSTRACT FROM AUTHOR]

Many diets employed in aquaculture are enriched with selenium to improve the diet quality and its conservation. The aim of the study was to investigate the effects of a diet enriched in selenium (1.21mgkg−1) on the antioxidant response of Procambarus clarkii (Girard, 1852). Crayfish fed a diet with lower selenium content (0.30mgkg−1) were the control. Selenium accumulation, enzymatic activities, and total glutathione were evaluated in hepatopancreas of adults of both sexes fed with both diets for 50 days at two experimental times (T 30, T 50 days). Treated females exhibited the highest selenium bioaccumulation during both experimental times, while treated males displayed the highest selenium concentration after 30 days, compared to control crayfish. A sex-related difference was found for the response of the analyzed enzymes in the selenium diet-treated specimens. In fact, superoxide dismutase, glutathione peroxidase and glyoxalase I activities in males were more sensitive compared with females, showing depleted activities in both experimental times. Catalase activity was induced in females (T 50), while glutathione S-transferase activity was the highest in treated females and the lowest in treated males, compared with own controls. Only glutathione reductase activity and glutathione content showed the same trend in both sexes, which were both lowered in treated specimens, when compared with control crayfish. This result might be due to the effect of selenium toxicity on this freshwater species. Males and females of P. clarkii showed a different susceptibility to the prooxidant effects in a Se-enriched diet. [Copyright &y& Elsevier]

This study aimed at investigating the extent of accumulation of selenium in the hepatopancreas of the crayfish Procambarus clarkii and its effects on the enzymatic activities of catalase, glutathione peroxidase, and glutathione reductase. Crayfish were fed for 15 days either a diet enriched in Se, ED (1.21 mg kg-1) or a standard diet, SD (0.30 mg kg-1). Results showed that Se accumulation is higher in the sample subject to ED rather than to SD. A sexual difference was found for the response of the analyzed enzymes in the ED sample only. Catalase activity and glutathione peroxidase activity decreased in females and males, respectively, whereas glutathione reductase activity showed significant reductions in both sexes. These preliminary data might provide information about prooxidant effects of Se on P. clarkii when fed a Se enriched diet. [ABSTRACT FROM AUTHOR]