Testosterone and Cholesterol Vasodilation of Rat Aorta Involves L-Type Calcium Channel Inhibition

Testosterone has rapid nongenomic vasodilator effects which could be involved in protective cardiovascular actions. Several authors suggested specific mechanisms to explain this effect, but this matter was not clarified yet. We studied the actions of testosterone and cholesterol on endothelium-denuded rat aorta and their effects on the L-type Ca2+ current (ICa,L) and potassium current (IK). Testosterone (1–100 μM) totally relaxed, in a rapid and concentration-dependent way, the aortic rings contracted by KCl or by (−)-Bay K8644 (BAY). Cholesterol also fully relaxed the contractions induced by KCl. None of the potassium channel antagonists tested (glibenclamide, tetraethylammonium and 4-aminopyridine) modified significantly the relaxant effect of testosterone. The antagonist of classic testosterone receptors, flutamide, did not modify the vasorelaxant effect of testosterone. Furthermore, testosterone and cholesterol inhibited either basal and BAY-stimulated ICa,L in A7r5 cells and they have no effects on IK. In summary, our results demonstrate that cholesterol and testosterone relax rat aorta by inhibiting LTCC. This effect of testosterone is not mediated by the classic hormone receptor or by potassium channel activation. These results suggest that the vasodilator mechanism of cholesterol and testosterone is the same

Phenotypic variation of Fucus ceranoides, F. spiralis and F. vesiculosus in a temperate coast (NW Portugal)

Brown algae includes several species of Fucus, reported both in the tidal and intertidal zones of cold and temperate regions. Environmental parameters induce wide biological variability in intertidal algae, manifested by alterations at several levels, and this has lead to the failure of some reports to discriminate between closely related taxa, particularly Fucus species. As the genus Fucus is widely represented on the Portuguese coast, the biometric parameters of three species (F spiralis, F. vesiculosus and F. ceranoides) collected from several sampling sites in Portugal, were studied over twelve months. Environmental parameters (water temperature, pH, dissolved oxygen, salinity, phosphorous - orthophosphate and total phosphate, nitrate, nitrite and ammonia) were analysed. The objective of this study was to understand how environmental parameters influence and establish morphological variation in the Fucus species. Canonical Correspondence Analysis (CCA), which helps define the relationships between morphological and physicochemical variables, was carried out for each species in order to determine which physicochemical parameter most affects the morphology of Fucus. The variable biometric that strongly separates the three Fucus species is the number of receptacles per thalli, and this parameter was highly correlated with F ceranoides. The two others species were distinguished principally by the height of the bigger receptacle, the midrib height of the holdfast, the height of the smaller receptacle, and the midrib width of the holdfast. The CCA analysis also showed that the dominant factor influencing morphometric parameters was salinity, being always in strict correlation with water temperatures and orthophosphate. For F ceranoides, physicochemical parameters (especially a higher concentration of orthophosphate and lower salinity) seem to influence morphological parameters, mainly in the raised number of receptacles per thalli. Salinity was the most important environmental parameter to distinguishing F spiralis and F vesiculosus in northern Portugal.FCT/CONTROL project - PDCTM/C/MAR/15266/199

Glutathione-S-transferase activity of Fucus spp. as a biomarker of environmental contamination

Coastal zones are important areas from both ecological and economical points of view. However, in the last decades, in several regions of the globe, they have been increasingly impacted by complex discharges of contaminants and by marine traffic accidents. The Portuguese Atlantic coast is particularly exposed to these contaminants due to the proximity of important navigation routes. Several rocky shore organisms have been tested and used as bioindicators of environmental contamination. However, to the best of our knowledge Fucus spp., which are key species in rocky shore communities, have not been used as bioindicators in monitoring studies based on biomarkers. The objective of this study was to investigate the potential of glutathione-S-transferase (GST) activity of several Fucus species (Fucus ceranoides, Fucus spiralis var. platycarpus, Fucus spiralis var. spiralis and Fucus vesiculosus var. vesiculosus) to discriminate sites with different contamination levels along the Portuguese Northwestern coast, between the Minho river estuary and the Aveiro's Lagoon, as an environmental biomarker. With the exception of F spiralis var. spiralis, for which a confusing pattern of activity was found requiring further analysis, all the other species and varieties showed higher GST levels in more contaminated sites than in less contaminated ones, indicating that Fucus spp. are suitable for use as bioindicators and their GSTs as biomarkers of environmental contamination in coastal zones and estuaries. (C) 2004 Elsevier B.V. All rights reserved.FCT/CONTROL project - PDCTM/ C/MAR/15266/199

Expression, purification, crystallization and preliminary diffraction data characterization of Escherichia coli ribonuclease II (RNase II)

Diffraction data from E. coli RNase II crystals of wild type and of an inactive mutant and its SeMet-derivative form were obtained to 2.44 and 2.74 Å resolution, providing a set of preliminary phases. An improved purification protocol allowed higher reproducibility in the crystallization of the mutant form

Fucus spp. as a mercury contamination bioindicator in costal areas (Northwestern Portugal)

Mercury has been considered as one of the most important pollutants in coastal and estuarine areas. Efforts have been made to detect, as early as possible, the effects of this and other metals in several species. Macroalgae, particularly Fucus spp., have been widely used as biomonitors of metal pollution. In this study, three Fucus species (F. spiralis, F. vesiculosus and F. ceranoides) were collected from several sampling sites in Portugal. The concentrations of mercury were determined in three structural parts (holdfast, stipe and receptacles). Two different techniques were used to determine mercury concentrations. Almost all mercury concentrations (in sediments and in water) were below national and international standards. Mercury concentration in the specimens (0.012-0.061 mu g g(-1) for receptacles, 0.028-0.221 mu g g(-1) for stipe and 0.029-0.287 mu g g(-1) for holdfast) was always higher that those obtained for the sediment (0.001-0.112 mu g g(-1)). With few exceptions the contrary was found for receptacles. In general, a good agreement between concentrations of mercury in sediment and Fucus was found. The results indicate that Fucus accumulate mercury and may be a suitable species for use in risk assessment for coast and estuarine areas, by providing valuable information regarding the levels of mercury that will be available for the consumers of Fucus spp.FCTCONTROL project - PDCTM/C/MAR/15266/199

Mercury pollution in Ria de Aveiro (Portugal): a review of the system assessment

The Ria de Aveiro (Portugal) is a coast al lagoon adjacent to the Atlantic Ocean and it has an inner bay (Laranjo bay) that received a highly contaminated effluent discharged by a mercury cell chlor-alkali plant from the 1950s until 1994. The aim of this study is to review in a holistic way several research studies that have been carried out in the Ria de Aveiro, in order to evaluate the remobilization of the mercury accumulated within the system and the recovery of the lagoon. The spatial distribution of the total mercury in the surrounding terrestrial environment has also been considered. Results indicate that the main mercury contamination problems in the Ria de Aveiro are confined to the Laranjo bay. Mercury export to the coastal waters and its impact on the nearshore compartments (water column, sediment and biota) are low. No direct effects of the mercury from nearby industrial activities were detected in Aveiro’s urban soils, although historical mercury contamination is still affecting soil quality in the immediate vicinity of the chlor-alkali plant, located in Estarreja. Moreover, macrophyte harvesting for human direct or indirect use and the consumption of mussels, crabs and the sea bass from the Laranjo bay may constitute a health risk. Further studies focusing on developing skills for the restoration of the ecosystem are presently underway