Laura Tallandini

The use of bird feathers for the monitoring of cadmium pollution

The cadmium contamination mechanism in bird feathers was investigated using starlings fed with diets containing 10 and 50 ppm Cd for five months. The experiment started about two months before the beginning of the annual complete feather molt and lasted until most of the birds completed the molt of the primaries. Concentrations of Cd in liver, kidney, and uropygial gland were highly correlated, but uropygial gland concentration was about 100 times lower. Cadmium was found both in old and new feathers, in a dose-related manner. Old. feathers showed higher metal concentrations than new ones and primaries higher than secondaries. Feather Cd concentration correlated with Cd concentration in liver, kidney, and the uropygial gland. The use of bird feathers are, therefore, a reliable method for monitoring cadmium pollution, but differences between feather type and age must be considered to correctly interpret data collected in the field.

Effects of copper and cadmium on growth, superoxide dismutase and catalase activities in different yeast strains.

1. Three strains of Saccharomyces cerevisiae have been adapted in vitro upon treatment with copper or cadmium. Growth rate, cellular size, metal uptake, superoxide dismutase and catalase activities were measured. 2. Growth rate and metal uptake are quite different among the yeast strains and also for copper and cadmium treatment. At the employed concentrations, only cadmium chiefly affects the cellular volume. 3. Cu, ZnSOD activity is stimulated in the presence of copper, while it is lightly inhibited in the presence of cadmium. Catalase level remains almost unchanged in the conditions tested. This lack of correlation is then discussed.

Haemocytes and blastogenetic cycle in the colonial ascidian Botryllus schlosseri: a matter of life and death

A recurrent blastogenetic cycle characterizes colonies of the ascidian Botryllus schlosseri. This cycle starts when a new zooid generation opens its siphons and ends with take-over, when adult zooids cease filtering and are progressively resorbed and replaced by a new generation of buds, reaching functional maturity. During the generation change, massive apoptosis occurs in the colony, mainly in the tissues of old zooids. In the present study, we have investigated the behaviour of haemocytes during the colonial blastogenetic cycle, in terms of the occurrence of cell death and the expression of molecules involved in the induction of apoptosis. Our results indicate that, during take-over, caspase-3 activity in haemocyte lysates increases. In addition, about 20%–30% of haemocytes express phosphatidylserine on the outer leaflet of their plasma membrane, show DNA fragmentation and are immunopositive for caspase-3. Senescent cells are quickly ingested by circulating phagocytes that frequently, having once engulfed effete cells, in turn enter apoptosis. Dying cells and corpses are replaced by a new generation of cells that appear in the circulation during the generation change.

The hemocyanin of Aplysia limacina: Chemical and functional characterization

1. 1. The Hcy of a mediterranean opisthobranch gastropod, Aplysia limacina, has been characterized. Amino acid composition, sedimentation coefficients, the reaction with oxygen and the ultrastructure have been studied. 2. 2. This Hcy is very similar to other gastropod Hey, as are amino acid composition and general structure. 3. 3. Differences are observed both in the ability to form supramolecular aggregates and in the size and shape of the subunits observed by electron microscopy.

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.

Biochemical and functional characterization of Rapana thomasiana hemocyanin

Abstract 1. 1. The hemocyanin (Hc) of the marine gastropod mollusc Rapana thomasiana was collected from animals living on the west coast of the Black Sea and characterized for its biochemical and functional properties. 2. 2. This Hc is very similar to other gastropod Hcs as far as amino acid composition, general structure and reactivity of the binuclear copper active site are concerned. 3. 3. Some peculiarities in the dissociation-reassociation pattern are observed in comparison to other gastropod Hcs, in particular with respect to the ability to form sopramolecular aggregates. 4. 4. Changes in pH disclose a strong reverse Bohr effect. Different R and T states are required to describe the oxygen binding curves at the different pHs.

The reaction between cyanide and the hemocyanin of Carcinus Maenas. A kinetic study

Abstract The kinetics of the reaction between Carcinus maenas hemocyanin and cyanide has been studied at various KCN concentrations and a different temperatures (21° and 4°C) by following the decrease of the copper-peroxide absorption band, centered at 337 nm, of the copper still bound to the protein and the intrinsic fluorescence changes as functions of time. In all conditions used, the absorption band completely disappears and KCN concentration affects only the rate of the process. The reaction is kinetically homogeneous indicating no site-site interaction. The apparent rate constant increases with the square of cyanide concentration and the inverse of O 2 concentration. The copper still bound decreases at a rate slower than the 337 nm absorption and the process is not kinetically homogeneous. The fluorescence of the protein increases after an induction period showing an inflection point at about 50% of the total effect. A kinetic model has been proposed on the assumption that the two metal ions are removed sequentially from the active site. The experimental data are in agreement with the theoretical equations derived from the model. The equilibrium constants for the formation of the complex between the first and the second copper ion with cyanide and the rate constants of their decomposition have been calculated. The rate-limiting process for the removal of the second copper ion is the formation of the complex with cyanide.

Simple and effective gas chromatographic mass spectrometric procedure for the speciation analysis of organotin compounds in specimens of marine mussels. An evaluation of the organotin pollution of the Lagoon of Venice

This paper describes a simple, effective analytical procedure, based on a gas chromatographic mass spectrometric technique, for the speciation analysis of organotin compounds (OTC) in mussel samples. The direct alkylation reaction of the organotin chlorides in the aqueous digestion solution by NaBEt(4) allowed a short analysis time and a good recovery. The evaluation of the yield of each step constituting the analytical procedure indicated that the alkylation step is the most critical one. The proposed method was advantageously utilised to monitor the level of OTC pollution of the Lagoon of Venice. All the sites examined, both near to and far from anthropogenic activities, revealed significant levels of OTC pollution.

Effects and fate of sediment-sorbed linear alkylbenzene sulphonate (LAS) on the bivalve mollusc mytilus galloprovincialis Lmk

Abstract The toxicity of LAS on aquatic animals has been evaluated in particular relation to its concentration in water, although it is well known that sediments play an important role as repositories and sources of many contaminants, including surfactants. The aim of this study was to evaluate the effects of sediment-sorbed LAS on the marine mussel Mytilus galloprovincialis exposed to sediments drugged with 132 mg/kg dry weight of LAS mixtures. Four experiments were performed and some physiological parameters (filtration, oxygen uptake, nitrogen excretion) were measured on control and treated animals. In order to study uptake and release of sediment-sorbed LAS by mussels, quantification of weight, percentage of organic matter, LAS concentration and LAS homologue distribution on faeces were determined. Results showed no significant differences in physiological responses of treated mussels compared to controls, and the absence of a toxic action of LAS contaminated sediments. Moreover one notable aspect was that higher LAS concentrations were found in faeces than in uningested sediments recovered from water. This fact is tentatively explained either as the result of decreased desorption in the mussel intestinal tract with respect to circulating water, or as enrichment in fine particles by mussel filter feeding activity.

The role of copper and quaternary structure on the conformational properties of Octopus vulgaris hemocyanin

Some structural properties of Octopus vulgaris hemocyanin have been investigated by fluorescence spectroscopy. The three-dimensional structure of Octopus hemocyanin is remarkably tight, resulting in a deep burial of almost all the tryptophyl residues of the protein. The hemocyanin conformation has been studied in the two main aggregation states (11 S, 50 S) of the protein, and with respect to the presence or absence of copper in the active site. Upon changing the pH of the solution, Octopus hemocyanin in the 50 S aggregation state can assume at least three different conformations. During the transition between each conformation the fluorescence quantum yield changes, but the environment of tryptophans does not change. Dissociation of the protein from 50 S to 11 S strongly enhances its susceptibility toward denaturating agents such as pH or temperature, and modifies the effects of fluorescence quenchers such as acrylamide. Moreover, these effects are more pronounced when copper is removed from the active site. A comparative analysis of the results shows that the subunit-subunit interactions exerted within the 50 S species are more important in the maintenance of the conformational stability than the copper ions present in the active sites. This behavior can be accounted for by the large amount of Ca(II) ions linked to 50 S hemocyanin.