Accumulation of organic and inorganic mercury from food in the tissues of Carcinus maenas: effect of waterborne selenium

Abstract

Accumulation of organic and inorganic mercury from contaminated food into the tissues of selenium-and non-selenium-exposed shore crabs Carcinus maenas were investigated in the laboratory. Crabs fed homogenates of Cardiurn edule collected in the mercury-contaminated Nissum Bredning, Jutland, Denmark, assimilated 50 to 60 % of ingested inorganic and organic mercury. Muscle and midgut gland contained approxin~ately 50 to 60 % and 40 % respectively of both asslmilated mercury species. Simultaneous exposure to selenite augmented accumulation of organic mercury in muscle and increased assimilation of organic mercury from the food. Accumulation of inorganic mercury was not affected by exposure to selenite. When the mercury concentration of the food was increased 10-fold (by the addition of HgClz and CH3HgCl directly to the cockle homogenate), a higher percentage of the ingested inorganic mercury was assimilated by the crabs, 95 % of the inorganic mercury being accumulated in the rnidgut gland. Percent assimilation and tissue distribution of organic mercury was less affected by increasing the concentration in the diet. The subcellular distribution of the 2 mercury species was almost identical. In the soluble fraction both mercury species were bound predominantly to proteins with a molecular weight (MW) of ca 12 000 Da. In the soluble fraction, exposure to selenite diverted mercury from the 12 000 Da region to high (MW > 70 000 Da) or very low (MW c 4000 Da) molecular weight proteins. Injected organic mercury was cleared from the haemolymph more rapidly than inorganic mercury, and clearance of both mercury species from the haemolymph proceeded faster in selenite-exposed crabs.

Retention and distribution of methylmercury administered in the food in marine invertebrates: Effect of dietary selenium

“…maenas, exposure to selenium results in a higher proportion of the whole body mercury being accumulated in the muscle tissue and less in the midgut gland or rest. For C. maenas this is in accordance with previous observations (Bjerregaard and Christensen, 1993;Larsen and Bjerregaard, 1995) and it is also in accordance with observations in the brown shrimp C. crangon (Bjerregaard and Christensen, 2012). A. rubens exposed to 10 µg L -1 inorganic mercury in the water accumulated much lower concentrations of mercury in the pyloric caeca when simultaneously exposed to 75 µg Se-SeO 3 2-L -1 and more in body wall, tube feet and coelomic fluid (Sorensen and Bjerregaard, 1991), comparable to the effect of orally administered selenium on the distribution of methylmercury in the present investigation.…”

Bioenhancement of cadmium transfer along a multi-level food chain

“…Models designed to predict metal trophic transfer should, therefore, consider interspecific differences in internal metal distributions between trophic levels in addition to multiple routes of exposure and abiotic factors (Reinfelder et al, 1998;Thomann, 1981;Wang & Fisher, 1999). Previous studies have also shown that metal bioavailability in prey and assimilation by predators may be influenced by the interactive effects of mixed-metal exposure (Amiard-Triquet & Amirad, 1998;Bjerregaard & Christensen, 1993;Seebaugh & Wallace, 2004). The influence of detoxification mechanisms (e.g., glutathione) other than MT induction and MRG on metal partitioning to the TAM compartment also deserves consideration (Canesi, Viarengo, Leonzio, Filippelli, & Gallo, 1999;Freedman, Ciriolo, & Peisach, 1989;Nieboer & Richardson, 1980).…”

The effect of selenium on mercury assimilation by freshwater organisms

“…A report by PaÍízek and Oštádalová (1967) was one of the first to identify the protective effect of Se on laboratory rats from kidney intoxication by Hg. Since then, many studies have reported interactions or relationships between Se and Hg in various types of organisms in the laboratory using terrestrial (e.g., Gailer et al 2000) or aquatic species (e.g., Bjerregaard and Christensen 1993) or even cells or bacteria (e.g., Frisk et al 2003) and in the field (e.g., Dietz et al 2000;Chen et al 2001). A literature review by Cuvin-Aralar and Furness (1991) presented several possible mechanisms of protection, including a redistribution or excretion of Hg in the presence of Se, a competition for binding sites between both elements, the formation of Hg-Se complexes, the conversion of toxic forms to less toxic forms of Hg, and the prevention of oxidative damage from Hg by Se through an increased activity of glutathione peroxidase.…”