CIM2-Artigos (em revistas ou actas indexadas)
Permanent URI for this collection
Conteúdo: Artigos em revistas ou actas de conferências indexadas
a) incluídas na
a) incluídas na
- » Web of Science
- (v. www.webofknowledge.com)
- » ERIH
- (European Research Index for Humanities: erihplus)
- » Latindex
- (Sistema Regional de Información para Revistas Científicas de América Latina, Caribe, España y Portugal: latindex.org)
- » Scielo
- (Scientific Electronic Library Online: www.scielo.org)
- » Scopus SJR
- (SCImago Journal & Country Rank: www.scimagojr.com)
Browse
Browsing CIM2-Artigos (em revistas ou actas indexadas) by Issue Date
Now showing 1 - 10 of 1067
Results Per Page
Sort Options
- 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.
- Influence of oxidative stress produced by nitrite in the activity of methaemoglobin reductase in two different species of fishPublication . Aníbal, J.; Bicho, M.Nitrite induces the oxidation of 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 the presence and absence of nitrite in two marine fishes (toadfish, Halobatrachus didactylus and gilt head sea breams 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. Halobatrachus didactylus showed a significant decrease in its values of methaemoglobin reductase activity with the increase in nitrite concentration (38.9; l6.3; 14.5: l4.0 and 12.3 mmol NAD+/min/gHB respectively to 0; 1; 3; 6 and 9 mM N02). In Sparus aurata, the nitrite didn't induced significant variations in the methaemoglobin reductase activity (27.8; 27.1; 25.3; 22.3 and 18.7 mmol NAD+/min/gHB respectively to 0; 1; 3; 6 and 9 mM N02). This results probably indicate fish to have other paths opposing to the formation of methaemoglobin, rather than the enzymatic system of the methaemoglobin reductase. At the moment the meaning of this of this different behaviour is not known.
- Polimorfismo genético da haptoglobina e grau de gravidade da hipertensão arterial essencialPublication . Monteiro, C.; Lança, H.; Joaquim, N.; Lamy, I.; Aníbal, J.; Coucelo, Josefina; Azevedo, J.; Bicho, M.É conhecida a associação do polimorfismo genético da haptoglobina(Hp)quer com a sensibilidade ao sódio da pressão arterial quer com a gravidade hipertensão arterial (HTA).
- Tidal flushing of ammonium, iron and manganese from inter-tidal sediment pore watersPublication . Caetano, M.; Falcão, M.; Vale, C.; Bebianno, Maria JoãoConcentrations of ammonium, manganese and iron were examined in sediment pore water and near-bottom water of inter-tidal sediments of Ria Formosa, a coastal lagoon in the South of Portugal, during the short period of time that water flooded the area. Short-sediment cores and overlying water retained during the ebb tide were sampled at air-exposed area. Immediately after the inundation sediment cores and flooding water were repeatedly collected over short periods of time: 20 min for ammonium and 60 min for iron and manganese. The pore water composition of the upper 2-cm sediment changed dramatically in NH4+, Mn and Fe during the first minutes of the flood. This decrease was recorded together with an increase of ammonium and manganese in the flooding water. The inundation causes a mixing of freshly tidal water in the interstices of sediment surface, pore water being mixed with sea water and oxygen supplied to anoxic layers of the sediment. Consequently NH: in pore water and weakly bound to sediment is exported to the water column, Mn(II) also escapes from the sediment, but Fe(II) is oxidised rapidly and iron is recycled inside the sediment. These processes occur on a semi-diurnal time scale that implies a continuously re-adjustment of the chemical of inter-tidal sediment surface of Ria Formosa.