Cadmium and copper metallothioneins in the American lobster, Homarus americanus.

Abstract

Lobsters were fed cadmium-rich oysters for 28 days, and the induction of cadmium metallothionein and its relation to concentrations of cadmium, copper, and zinc in the digestive gland and gills was determined.A portion of the tissues also was retained for determining the cytosolic distribution of these metals by gel filtration and ion-exchange chromatography. The digestive gland contained a majority of the cadmium, copper, and zinc, and both cadmium and zinc were actively accumulated from the oysters. Gel chromatography of the digestive gland cytosol showed that initially cadmium and zinc were bound to macromolecules with molecular weights of > 70,000, -45,000 and < 5000, and for copper > 70,000, 10,000-7,000, and < 5000. Therefore, only copper was bound to a protein with a molecular weight in the range of metallothionein (i.e., 10,000-7,000). However, after feeding on cadmium-laden oysters for 28 days, both cadmium and copper were bound to the metallothioneinlike protein. Further purification ofthe cadmium/copper protein by ion-exchange chromatography showed that a large portion of the copper and all of the cadmium did not bind to DEAE-Sephacel. The induction of cadmium metallothionein in the digestive gland is correlated with tissue cadmium concentration. There is, however, a tissue threshold concentration of cadmium of 80 to 100 1Lg Cd/g wet weight required for induction. Coincident with the induction of the cadmium metallothionein was a cytosolic redistribution of copper. The distribution of zinc was not affected.Crustaceans (1-6) and particularly the American lobster, Hornarus americanus (7,8), concentrate metals, such as cadmium, copper, and zinc in their digestive glands (i.e., hepatopancreas). In addition to being a possible direct hazard to the organism, these metals also may be hazardous to organisms that consume digestive glands of crustaceans, including man. In the case of the lobster, such a situation already has occurred near Belledune Harbor, New Brunswick, Canada (7,9). Here, digestive glands from local animals were shown to contain up to 203.7 ,ug/g wet weight of cadmium (9). These levels were considered a health hazard to the local population, who consumed the digestive gland. A similar situation also has occurred for blue crabs, Callinectes sapidus, (1,2) from the Hudson River, where animals from Foundry Cove had cadmium concentrations in the digestive glands of up to 20 ,ug/g wet weight.Because lobsters can accumulate large quantities of metals in the digestive gland, a physiologically active detoxification system must be present to sequester the accumulated metals, such as cadmium, copper, and zinc. It is, therefore, of interest to determine the chemical forms of these metals in the tissue. In our earlier research, we demonstrated that lobsters accumulate cadmium more efficiently from food than from water (8,10). Also the lobster has m etal-binding proteins in the diges-

Links between estuarine condition and spatial distributions of marine invaders

“…This can result in physiological acclimation as tolerance is gained through exposure to sublethal concentrations, or the evolution of genetically based resistance through natural selection (Klerks & Weis, 1987;Levinton et al, 2003). Some invertebrates also exhibit sequestering mechanisms such as the binding of metals to inducible metallothioneins (Olafson et al, 1979;Suzuki et al, 1980;Thompson et al, 1982;Engel & Brouwer, 1986;Jenkins & Sanders, 1986;Roesijadi, 1986) or in granules and vesicles (Brown, 1977;George & Pirie, 1979;Lowe & Moore, 1979;Mason et al, 1984). Some invertebrates also exhibit sequestering mechanisms such as the binding of metals to inducible metallothioneins (Olafson et al, 1979;Suzuki et al, 1980;Thompson et al, 1982;Engel & Brouwer, 1986;Jenkins & Sanders, 1986;Roesijadi, 1986) or in granules and vesicles (Brown, 1977;George & Pirie, 1979;Lowe & Moore, 1979;Mason et al, 1984).…”

Copper-Metallothioneins in the American Lobster, Homarus americanus: Potential Role as Cu(I) Donors to Apohemocyanin

“…In the digestive gland of the American lobster, Homarus americanus, large amounts of copper and copper-binding proteins had been demonstrated (17)(18)(19), and this organ also had been shown to be the site of hemocyanin biosynthesis (20). Hemocyanin, a Cu(I)-containing protein that serves as an oxygen carrier in crustacea, usually occurs in very high concentrations (up to 100 mg/mL) in the hemolymph.…”

“…and Brouwer(17). Digestive glands were removed from lobsters and used immediately or stored at -60?C.…”

Evaluation of composition and in vitro solubility rate of by-products of the Atlantic shellfish industry as alternative calcium sources

“…On average Cu is found in seawater 0.25 ng/L and can be present as high as 12 ng/L [32]. Crab shell and LS contained approximately 16.25 and 12 mg/kg of copper, respectively, which is higher than the concentration found in the seawater because of their ability to accumulate Cu over their life span [38]. The levels in Ca sources were able to partially meet requirements (Table 1).…”