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- Metallothionein induction inMytilus edulis exposed to cadmiumPublication . Bebianno, Maria João; Langston, W. J.The exposure of mussels,Mytilus edulis, collected from Whitsand Bay, southwest England, in August 1988, to sublethal concentrations of cadmium (400µg l−1) for 65 d resulted in the induction of metallothionein (MT) synthesis in the soft tissues. In cadmium-exposed mussels, metallothionein concentrations, measured by differential pulse polarography, increased by a factor of three, from 2 to 3 mg g−1 to a maximum of 9 mg g−1 after 30 d. No significant changes could be detected in controls. Cadmium accumulated in the soft tissues of mussels correlated significantly with metallothionein concentrations and can be described by the relationship: MT (mg g−1)=0.045 Cd (µg g−1)+3.03 (r=0.803,P<0.001). Gel chromatography of heat-treated cytosolic extracts showed that the accumulated cadmium is bound principally to the newly formed metallothioneins. Copper and zinc were also analysed in the whole soft-tissues and in subcellular fractions of cadmium-exposed mussels. Although copper concentrations were not affected by cadmium-exposure, zinc levels were significantly reduced. The results demonstrate that the induction of metallothioneins inM. edulis is a quantifiable biological response to sublethal levels of cadmium exposure.
- Fish ultrasonography characterization of cardiac morphology and blood flowPublication . Coucelo, Josefina; Joaquim, N.; Aníbal, J.; Coucelo, JosefinaNon invasive identification and characterization of cardiac morphology and flow of Lophius s.p. and Halobactrachius s.p. was performed using color echo doppler. We used an ALOKA echo camera SSD 830 with a 5 MHZ transducer. Fishes were kept alive with water circulation device. The transducer was applied in the ventral middle line over heart chambers. Bidimensional images were obtained from long and short axis incidences at various levels of cardiac chambers. During each cardiac cycle and for every specimen it was possible to identify the relationship between each structure, measure longitudinal and transversal diameters, identify blood ?uxes and quantify their velocities. Conclusion: In live specimens it is possible, applying non invasive techniques, to observe the cardiac structures and to study the kinetic of the ventricle and bulbus, to identify blood ?ow and to measure his velocity. This can be used as an experimental model for cardiac function.
- Turnover rate of metallothionein and cadmium in Mytilus edulisPublication . Bebianno, Maria João; Langston, W. J.The results demonstrate the first attempt to determine metallothionein turnover in the whole soft tissues of mussels Mytilus edulis exposed to cadmium. Half-lives for metallothionein and cadmium are 25 and 300 days, respectively. As metallothionein degrades the released cadmium induces further synthesis of the protein, to which the metal becomes resequestered. The slow metallothionein turnover rates (compared with mammals) and the lack of significant cadmium excretion testify to the relatively stable nature of the cadmium-metallothionein complex in these invertebrates and supports the view of a detoxifying role for metallothionein in the mussels.
- Involvement of metallothionein in cadmium accumulation and elimination in the clam ruditapes decussataPublication . Bebianno, Maria João; Serafim, Angela; Rita, M. F.Cadmium is one of the most toxic pollutants in seawater because of its persistence, toxicity and potential for bioaecumulation. It is included on the "black list" of several international agreements established to regulate the input of pollutants into the marine environment (Yeasts and Bewers 1987).
- Ludo Formation-a new lithostratigraphic unit in Quaternary of Central AlgarvePublication . Moura, Delminda; Boski, T.A new lithostratigraphic unit (Ludo Formation) is proposed aiming a more objective approach to mapping the Quaternary sedimentary series in the central Algarve.
- Effects of pollutants in the Ria Formosa Lagoon, PortugalPublication . Bebianno, Maria JoãoThe Ria Formosa is a most significant area from the point of view of fisheries, particularly with respect to the culture of molluscean shellfish. Eighty percent of the bivalves (e.g. cross-cut carpet shell, Venerupis decussata) harvested in Portugal come from this area. There are in this coastal lagoon rapidly increasing levels of anthropogenic releases of contaminants transported by untreated sewage and industrial and agriculture effluents. High levels of bacteria, nutrients, metals and organochlorine compounds were detected in the water column as well as suspended solids and sediments in several areas of the lagoon, mainly in the areas surrounding the main cities. Some of these pollutants have been accumulating in the tissues of several bivalve species. The accumulation of these pollutants along with the increase in temperature over the summer resulted in deleterious effects on these species some of which became unsafe for human consumption. These anthropogenic releases together with an ineffective clam harvest practice resulted in a massive clam mortality. This mortality generally occurs after summer and bivalve production has shown a significant decrease in the past 5 years with a negative impact on the economy of the region. Along with held experiments, laboratory studies have been carried out to investigate the biological effects of sublethal concentrations of some of these pollutants in the most commercially important species harvested in the region
- The DNA/RNA ratio as a useful indicator of the nutritional condition in juveniles of Ruditapes decussatusPublication . Chícharo, Luís; Teodosio, MariaCondition indices have been widely used to assess how healthy individuals are under certain circumstances. It has been shown that the RNA/DNA ratio is a good indicator of the nutritional condition of severa1 marine organisms. A very sensitive fluorometric method for RNA/DNA quantification (Clemmesen, 1990) was applied to fed and starved post-larvae laboratory-reared clam, Ruditapes decussatus. The presented study shows that the RNA/DNA ratio is a useful indicator of nutritional stress for bivalve spat. The decrease in RNA/DNA ratio recorded here, under starved conditions was lower than in similar experiments on fish. A lower metabolic rate in clams may result in a slower response with respect to RNA/DNA ratios than that observed in vertebrates.
- O efeito de nitritos na actividade da redutase da metahemoglobina em Halobatrachus didactylus e Sparus aurataPublication . Aníbal, J.No presente estudo determinou-se a actividade In Vitro da redutase da metahemoglobina, na ausência e presença de nitritos, em duas espécies de teleósteos marinhos de habitats e comportamentos diferentes
- Cartografia e estimativa da biomassa de macrófitas aquáticas nas lagoas da Vela e das Baças (Centro Litoral de Portugal) utilizando a técnica de detecçäo remotaPublication . Alface, Isabel Cristina; Boski, T.As zonas húmidas constituem ecossistemas de grande importância em termos de biodiversidade e produtividade, podendo a vegetação aquática, que normalmente lhes está associada, contribuir, de forma significativa, para a sua caracterização como unidade de paisagem.
- The activity of methaemoglobin reductase in toadfish (Halobatrachus didactylus) and gilt head sea bream (Sparus aurata)Publication . Aníbal, J.; Bicho, M.The erythrocytes intracellular oxidative stress oxidizes the haemoglobin forming methaemoglobin, which is nonfunctional. To oppose this formation fishes have an enzyme that reverses the process called methaemoglobin reductase. In vitro activity of the methaemoglobin reductase was determined in two marine fishes with different habitats and behaviours (Halobatrachus didactylus and Sparus aurata). The KM and Vmax, were determined through the Eisenthal and Cornish-Bowden Plot. The basis for this study is that the methaemoglobin reductase system has very active ferricyanide reductase activity, using NADH as the electrons donor. Halobatrachus didactylus showed higher values of methaemoglobin reductase activity (38.9 mmol NAD+/min/gHb) than Sparus aurata (27.8 mmol NAD+/min/gHb). The reductase of Halobatrachus didactylus had, for both substrates, higher values of KM (potassium ferricyanide: 0.133 mM, NADH: 0.067 mM) and lower values of Vmax (potassium ferricyanide: 0.097 min-1; NADH: 0.025 min-1), than Sparus aurata (potassium ferricyanide: KM=0.092 mM, Vmax=0.176 min-1, NADH: KM=0.032 mM, Vmax=0.062 min-1). The results indicated that Halobatrachus didactylus’s methaemoglobin reductase had high antioxidant efficiency, although that one of the Sparus aurata had more sensitivity to the presence of low concentrations of methaemoglobin. The meaning of this different behaviour, at the moment can not be envisaged.