Accumulation, loss and molecular distribution of cadmium inMytilus edulis

Abstract

In Mytilus edulis, accumulation and loss of Cd were analyzed under experimental conditions. Cd uptake by the whole soft body is linear, increasing significantly with increasing Cd concentrations in the uptake medium. Until 100 #g Cd 1-1, neither limitation of uptake nor any saturation process can be observed. Loss of Cd, measured after transfer of experimentally contaminated mussels to natural sea water, is exponential; biological half lives vary between 14 and 29 days. Gills are the primary sites of Cd uptake from the water, whereas in mid-gut gland, kidney, and mantle the uptake is retarded during the first few days. The mid-gut gland not only bears the main body load of Cd, but also shows the highest Cd concentrations. Gel chromatographic studies of midgut gland proteins reveal that Cd is eluated over the whole molecular weight range. Three metallothionein-like proteins with molecular weights of 6,600, 13,200, and 21,000 Dalton could be established. However, they cannot be taken as effective detoxification proteins, because more than 50 % of the accumulated metal is bound to high molecular weight proteins.

Cadmium-Binding Proteins in the Mussel, Mytilus edulis

“…Soon after the Noel-Lambot report, Talbot and Magee (2) demonstrated that similar proteins were present in mussels exposed to contaminating metals in the natural environment. More recent studies have verified the presence of BPs in Mytilus edulis following exposure to cadmium (3)(4)(5) and mercury (6). In a related species, Mytilus galloprovincialis, BPs have also been demonstrated following exposure to both cadmium (7) and copper (8)(9)(10).…”

Physiological responses of estuarine animals to cadmium pollution

“…In addition, the difference in half times of vertebrates and invertebrates raises the question whether there are fundamental differences in the mechanism of heavy-metal detoxication in both systematic groups. This point is dealt with in detail by Scholz (1979Scholz ( , 1980. Scholz (1980) SOME METABOLIC RESPONSES I should like to add a few remarks on some recently observed influences of sublethal Cd contamination on metabolic processes of adult invertebrates.…”

“…This point is dealt with in detail by Scholz (1979Scholz ( , 1980. Scholz (1980) SOME METABOLIC RESPONSES I should like to add a few remarks on some recently observed influences of sublethal Cd contamination on metabolic processes of adult invertebrates. In decapod crustaceans it has been observed that Cd uptake rate decreases in the order: Eupagurus bernhardus > Carcinus maenas > Hriocheir sinensis.…”

“…The high capacity of mussels for accumulating heavy metals is one reason for considering these animals as suitable o r g a n i s m s f o r m o n i t o r i n g heavy-metal pollution (Phillips, 1976a;b). Schulz-Baldes (1973) and Scholz (1980) found a partial linear relation between heavy-metal content of sea water and that of mussels. However, these animals absorb heavy metals not only from the water and their organic food but also from inorganic particulate matter.…”

“…However, according to Peden et al (1973) there was almost no elimination of this metal within 3 to 7 weeks, when Carcinus maenas, Patella vulgata and Nucella lapillus individuals, which had accumulated cadmium under contaminated field conditions (Cd content of sea water 0.01 mg 1-1) were transferred to an uncontaminated estuary (0.0002 mg Cd 1-1). The ranges of the half times found indicate that the metal may be bound within different compartments (Coombs & George, 1979;Janssen & Scholz, 1979;Scholz, 1980), from which it will be released at different rates. In addition, the difference in half times of vertebrates and invertebrates raises the question whether there are fundamental differences in the mechanism of heavy-metal detoxication in both systematic groups.…”