Mercury and selenium interaction in vivo: Effects on thioredoxin reductase and glutathione peroxidase

Shannon Entropy in a European Seabass (Dicentrarchus labrax) System during the Initial Recovery Period after a Short-Term Exposure to Methylmercury

“…In consequence, during the 11-day period of this study, we expected recuperation from stressful conditions in both tanks-in C 1 , from suboptimal water quality; in C 2 , from suboptimal water quality and from MeHg poisoning. Although we did not expect any mortality in any of the groups [15], the observed mortality in the treated group in our study may be, at least partially, due to the small size of the fish combined with the exposure to the contaminant.…”

“…The two experimental cases of European seabass were C1 (control system, not exposed to MeHg) and C2 (exposed system, treated with 4 μg MeHg/L during the previous 14 days, according to Branco et al [15]). MeHg (CH3ClHg, was Sigma-Aldrich product number 33368) was added to the water to ensure that all fish were exposed to the same concentration of the contaminant.…”

Mercury and Selenium in Muscle and Target Organs of Scalloped Hammerhead Sharks Sphyrna lewini of the SE Gulf of California: Dietary Intake, Molar Ratios, Loads, and Human Health Risks

“…These results are more likely related to the high metabolic activity of these sharks, which require large and constant food rations (Lowe 2001). Accordingly, the higher metabolic activity of liver, in which protein synthesis and degradation can be much more rapid than in skeletal muscle tissue, might be an explanation for the highest levels of Hg found in muscle; also the detoxification processes occurring in liver could lead to elimination of toxic forms of Hg, as it has proved for other shark species like blue shark (Branco et al 2007(Branco et al , 2012 indicating that accumulation in this organ does not proceed necessarily with age. In this context, the increase in length and mass are much higher for immature than mature individuals in most elasmobranch species, especially during the first year of life, and elasmobranchs are generally capable of converting energy to growth as efficiently as teleosts.…”

“…Hg is likely sequestered by metallothioneins and other protective proteins, such as selenium proteins (Nam et al 2011). From in vivo assay studies, proposed Hg and Se toxicokinetics when fishes are exposed to MeHg and Se, accumulation is much lower in all organs than when fishes are exposed solely to MeHg, this may result from (Yang et al 2008;Branco et al 2012): (i) excess Se induce an increased production of selenoprotein, with the selenocysteine in this protein acting as a trap for MeHg keeping it in circulation and preventing its entry to the different organs; (ii) selenium preventing MeHg interactions with proteins by competing for the binding sites (SeH and SH groups); and (iii) Se binding MeHg during coexposure enhancing its excretion.…”

“…Like Hg, Se can biomagnify through food webs (Luoma and Rainbow 2008). Other studies have shown that Se and Hg behave antagonistically so their co-occurrence reduce their toxic effects, but the outcome depends strongly on their chemical forms as well as on the molar ratio of these two elements (Parizek and Ostadalova 1967;Wang et al 2001;Ralston et al 2007;Berry and Ralston 2008;Branco et al 2012Branco et al , 2014. Interactions between Hg and Se are essential factors in evaluating risks associated with dietary exposure to Hg, because it appears that Se has a protective effect against Hg toxicity.…”