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- Adaptation of the antioxidant defence system in hydrothermal-vent mussels (Bathymodiolus azoricus) transplanted between two Mid-Atlantic Ridge sitesPublication . Company, Rui; Serafim, Angela; Cosson, Richard; Fiala-Medioni, Aline; Dixon, David R.; Bebianno, Maria JoãoThe vent mussel Bathymodiolus azoricus is the dominant member of the Northern Mid-Atlantic Ridge (MAR) hydrothermal megafauna, and lives in an environment characterized by temporal and spatial variations in the levels of heavy metals, methane and hydrogen sulphide, substances which are known to increase reactive oxygen species levels in the tissues of exposed organisms. To evaluate the effects of two contrasting hydrothermal environments on the antioxidant defence system of this vent mussel species, a 2-week transplant experiment was carried out involving mussels collected from the relatively deep (2300 m), and chemical rich, Rainbow vent field. These were transplanted to the shallower (1700 m), and relatively less toxic, Lucky Strike vent field. To achieve this objective, levels of superoxide dismutase, catalase (CAT), total glutathione peroxidase (GPx), selenium-dependent glutathione peroxidase and lipid peroxidation (LPO) were measured in the gills and mantle tissues of resident and transplant mussels before and after the transplant experiment. With the exception of CAT, the gills of the transplanted mussels had significantly higher antioxidant enzyme activity compared with the basal levels in the donor (Rainbow) and recipient (Lucky Strike) populations; whereas the antioxidant enzyme levels in the mantle tissues of the transplants reflected the baseline levels of activity in the native Lucky Strike mussels after 2 weeks. In contrast, LPO levels were significantly higher in both tissue types in the transplants than in either the source or the recipient populations, which suggested a response to hydrostatic pressure change (note, the transplant animals were brought to the surface for transportation between the two vent fields). The fact that the Rainbow mussels survived the transplant experience indicates that B. azoricus has a very robust constitution, which enables it to cope behaviourally, physiologically and genetically with the extreme conditions found in its naturally contaminated deep-sea environment.
- Adaptation to metal toxicity: a comparison of hydrothermal vent and coastal shrimpsPublication . Gonzalez-Rey, Maria; Serafim, Angela; Company, Rui; Bebianno, Maria JoãoRainbow vent field is one of the most metal-contaminated hydrothermal sites on the Mid-Atlantic Ridge near the Azores region. Two hydrothermal shrimp species dominate the fauna at the Rainbow site along with the mussel Bathymodiolus azoricus. Although the levels of essential and non-essential metals in these shrimps have been studied, the biological consequences of a metal-rich environment are still largely unknown. Therefore, the aim of this study was to determine the levels of metal-binding proteins - metallothioneins (MT) and the activities of antioxidant enzymes - superoxide dismutase, catalase, total glutathione peroxidase and selenium-dependent glutathione peroxidase in two hydrothermal vent shrimps (Mirocaris fortunata and Rimicaris exoculata) collected from the Rainbow site and to compare them with two coastal shrimps (Palaemon elegans and Palaemonetes varians) from a south Portugal lagoon (Ria Formosa) to evaluate their different adaptation strategies towards metals in their environment. Results show significant differences in MT levels and antioxidant enzymatic activities between vent and coastal shrimps and also between shrimp species collected from the same site. This suggests that biochemical responses in both vent and coastal shrimps are affected not only by the environmental characteristics but also by inter-specific differences. Nevertheless, these responses apparently confer successful adaptation for survival in a metal-extreme environment.
- Modeling fish biological responses to contaminants and natural variability in estuariesPublication . Fonseca, V.F.; Vasconcelos, R.P.; França, S.; Serafim, M.A.; Lopes, Belisandra; Company, Rui; Bebianno, Maria João; Costa, M.J.; Cabral, H.N.Understanding the factors that influence biological responses to contaminants has long been a major goal in marine environmental research. Seven estuarine sites along the Portuguese coast were sampled over a year, and different biological responses of Pomatoschistus microps and Atherina presbyter were determined: superoxide dismutase, catalase, ethoxyresorufin O-deethylase, glutathione S-transferase, metallothioneins, lipid peroxidation, RNA:DNA ratio and condition factor K. Generalized linear models (GLM) were developed for each biological variable per species in relation to sediment chemical characterization (metals and polycyclic aromatic hydrocarbons concentration) and environmental conditions (month, site, water temperature, salinity, depth and mud percentage in the sediment). GLM varied in explanatory power and in the set of predictor variables included in the models. Environmental factors were frequently selected as predictor variables. Individual metals concentration and sediment quality guidelines (integrating all metals) were the major contaminants explaining biological variability. Accordingly, models for metallothioneins and lipid peroxidation had highest explanatory power. Species-specific responses and dataset size were the basis of observed differences between GLM for the two species.