Arnaldo Cassini

Cadmium bioaccumulation studies in the freshwater molluscs Anodonta cygnea and Unio elongatulus

Abstract 1. The effects of cadmium exposure have been studied in two freshwater bivalves, A. cygnea and U. elongatulus . 2. Cadium exposure induces an unremarkable cadmium uptake in the tissues of both the organisms. Thus the low metal concentration in the tissues together with the absence of suffering seem to indicate the presence of some kind of regulation. 3. Cadmium exposure has little effect on copper and zinc levels and distribution indicating in these organisms the presence of little interaction between cadmium and divalent essential metals. 4. The percentage distribution of cadmium, copper and zinc between the two main fractions obtained from Sephadex G-75 varies with metal, organism and tissue suggesting that high molecular weight metal chelating compounds are actually present in the organisms. 5. The detoxication capabilities of different organisms are discussed in relation to the differences found in two closely related freshwater animals.

Regulation and subcellular distribution of copper in the freshwater molluscs Anodonta cygnea (L.) and Unio elongatulus (Pf.)

1. The effects of copper exposure have been studied in two freshwater bivalves, Anodonta cygnea and Unio elongatulus. 2. Copper exposure induces a small degree of copper accumulation in both organisms leading to the hypothesis of a regulatory mechanism for copper intake. 3. Copper distribution in the particulate fractions is affected by copper treatments, with an increase in the lysosome-enriched fraction. 4. Copper exposure does not affect zinc levels and distribution. 5. The percentage distribution of copper and zinc among the eytosol fractions obtained from Sephadex G-75 varies with organism, tissue and copper exposure suggesting that high molecular weight chelating compounds are actually present in the two organisms.

Physiological responses to heavy metals and adaptation to increased oxygen partial pressure in Antarctic fish and protozoa

Abstract In the first part of this study, metal bioaccumulation and metallothioneins were investigated in various organs of the red‐blooded teleost, Trematomus bernacchii, and the haemoglobinless Chionodraco hamatus. Hepatic metallothionein correlated positively with Cd, Cu, and Zn concentrations in T. bernacchii, whereas in C. hamatus it showed a positive correlation only with Cd. A metal‐linking protein with characteristics typical of metallothioneins was identified in the liver of C. hamatus as well as of T. bernacchii. In the second part, data on the amino acid sequence of the enzyme Superoxide dismutase (SOD) were analysed and compared with SOD sequences from other animals. In the third part, a low degree of tolerance against the toxic effects of copper was recorded in two cilates, Pleuronema coronatum and Euplotes rariseta, collected from Terra Nova Bay and cultured in the laboratory.

Metallothionein and Glutathione as Stress Indicators in Bivalves in the Lagoon of Venice

Bivalves are often used as indicators of metal pollution, as their digestive glands and gills are important target organs for metal accumulation. With the aim of studying the effects of stress conditions (heavy metal pollution) using metallothionein (MT) and glutathione (GSH) as markers, we studied three species of Bivalvia: Mytilus galloprovincialis, which feeds on suspended matter filtered from sea water by cilia on the gill surfaces, and Tapes philippinarum and Scapharca inequivalvis, which live on sediments. These species were sampled in spring 1998 in two stations with different pollution levels, at Chioggia and Marghera in the Lagoon of Venice. Digestive gland MT contents were significantly different in the same station in the three species: the specimens with the greatest MT contents were T. philippinarum. The same species at Marghera was also the one with the greatest amounts of Mn, Co and Fe in the digestive gland. GSH digestive gland contents and Mn, Co and Fe concentrations were statistically greater in M. galloprovincialis from Chioggia with respect to M. galloprovincialis from Marghera. GSH digestive gland contents of S. inequivalvis were also higher in the species from Chioggia. Comparing digestive gland results of the three species at the same two stations, M. galloprovincialis and S. inequivalvis had significantly greater amounts of GSH than T. philippinarum. As regards gills, M. galloprovincialis from Chioggia had significantly greater amounts of GSH than M. galloprovincialis from Marghera; in the latter station S. inequivalvis had significantly greater amounts of GSH and metals than M. galloprovincialis. We also looked for relationships between different parameters: length or weight with MT or GSH.