Browsing by Author "Rodrigues, M."
Now showing 1 - 5 of 5
Results Per Page
Sort Options
- Dynamics of CO2, CH4, and N2O in Ria Formosa coastal lagoon (southwestern Iberia) and export to the Gulf of CadizPublication . Sierra, A.; Ortega, T.; Forja, J.; Rodrigues, M.; Cravo, Alexandra; Correia, CátiaA first characterization of greenhouse gases had been carried out to study their role and impact in a productive transitional coastal system of the southern Portugal – Ria Formosa lagoon. To this purpose, the partial pressure of CO2 (pCO2) and the concentration of dissolved CH4 and N2O have been measured. Two surveys were carried out during 2020, at low tide under typical conditions of Spring (March) and end of Summer (October). The samplings sites were distributed along the costal lagoon covering: i) inner areas with strong human impact (influence of different flows of treated wastewater discharges); and ii) main channels in connection with the main inlets to study the exchanges with the ocean. In general, the highest values of the three greenhouse gases were found at the inner studied areas, especially affected by the disposal of treated effluents from wastewater treatment plans, in October. The mean water - atmosphere fluxes of the CO2, CH4 and N2O are positive, showing that the study
- Exploring saccharinate-tetrazoles as selective Cu(II) ligands: structure, magnetic properties and cytotoxicity of copper(II) complexes based on 5-(3-aminosaccharyl)-tetrazolesPublication . Ismael, Amin; Henriques, M. S. C.; Marques, C.; Rodrigues, M.; Barreira, Luísa; Paixao, J. A.; Fausto, R.; Cristiano, M. Lurdes S.The role of copper in the proliferation of cancer cells is under investigation and has been explored in the context of cancer chemotherapy. The evidence that proliferation of cancer cells requires a higher abundance of Cu(II) than their normal counterparts has prompted the development of new copper chelators that can avidly bind copper ions, forming redox active metal complexes that ultimately lead to harmful reactive oxygen species (ROS) in neoplasms. In this context, the mandatory properties of the chelators for medical applications are safety (neglectable cytotoxicity), high binding affinity and selectivity towards Cu(II). We report the synthesis, structure (calculations and single crystal X-ray diffraction), spectroscopic (IR; UV-Vis) and magnetic properties of two novel copper(II) complexes based on 5-(3-aminosaccharyl)-tetrazoles (TS and 2MTS), as well as their in vitro cytotoxicity against the human hepatic carcinoma cell line HepG2. Quite interestingly, we found that the saccharinate-tetrazoles tested exhibit strong binding selectivity to Cu(II), over Fe(II) and Ca(II). Additionally, the corresponding copper complexes have shown a huge increase in the in vitro cytotoxicity against tumoral cells, compared to the corresponding nontoxic ligands. Thus, the new ligands may be viewed as potential precursors of selective cytotoxic agents, acting as non-cytotoxic pro-drugs that can be activated inside neoplastic cells, known to be richer in Cu(II) than the corresponding normal cells.
- Molecular and functional characterization of a cDNA encoding 4-hydroxy-3-methylbut-2-enyl diphosphate reductase from Dunaliella salinaPublication . Ramos, Ana; Marques, A. R.; Rodrigues, M.; Henriques, Nuno; Baumgartner, Alexandra; Castilho, Rita; Brenig, Bertram; Varela, J.In green algae,the final step of the plastidial methylerythritol phosphate (MEP) pathway is catalyzed by 4-hydroxy-3-methylbut-2-enyldiphosphate reductase(HDR; EC: 1.17.1.2),an enzyme proposed to play a keyrole in the regulation of isoprenoid biosynthesis. Here we report the isolation and functional characterization of a 1959- bp Dunaliella salina HDR (DsHDR) cDNA encoding a deduced polypeptide of 474 amino acid residues. Phylogenetic analysis implied a cyanobacterial origin for plant and algal HDR genes. Steady-state DsHDR transcript levels were higher in D. salina cells submitted to nutritional depletion, high salt and/or high light, suggesting that DsHDR may respond to the same environmental cues as genes involved in carotenoid biosynthesis.
- Shear-induced defect formation in a nonionic lamellar phasePublication . Medronho, B.; Rodrigues, M.; Miguel, M. G.; Olsson, U.; Schmidt, C.(2)H NMR experiments on a nonionic oriented lamellar phase demonstrate that shear flow induces structural defects in the lamellar structure. These substantial structural changes give rise to a transition from a viscous to a solidlike behavior; the elastic modulus of presheared samples was found to increase, reversibly, with the applied preshear rate. A similar behavior was found when step-cycling the temperature toward the layer-to-multilamellar-vesicle transition and back at constant shear rate. However, while shear rate controls the defect density, the temperature is found to control the defect rigidity. The lamellar phase exhibits a shear-thinning behavior under steady shear conditions, following the power law eta similar to gamma(n), with n approximate to -0.4. Both the shear thinning and the elastic behavior are in agreement with the available theoretical models. The observed shear-induced structural defects are reversible and can be regarded as a pretransition prior to the shear-induced formation of multilamellar vesicles.
- Structure of beta-cinnamomin, a protein toxic to some plant speciesPublication . Rodrigues, M.; Archer, Margarida; Martel, P.; Jacquet, Alain; Cravador, A.; Carrondo, Maria A.Phytophthora and Pythium species are among the most aggressive plant pathogens, as they invade many economically important crops and forest trees. They secrete large amounts of 10 kDa proteins called elicitins that can act as elicitors of plant defence mechanisms. These proteins may also induce a hypersensitive response (HR) including plant cell necrosis, with different levels of toxicity depending on their pI. Recent studies showed that elicitins function as sterol carrier proteins. The crystallographic structure of the highly necrotic recombinant beta-cinnamomin (beta-CIN) from Phytophthora cinnamomi has been determined at 1.8 Angstrom resolution using the molecular-replacement method. beta-CIN has the same overall structure as beta-cryptogein (beta-CRY), an elicitin secreted by Phytophthora cryptogea, although it shows a different surface electrostatic potential distribution. The protein was expressed in Pichia pastoris and crystallized in the triclinic space group with two monomers in the asymmetric unit. The interface formed by these two monomers resembles that from beta-CRY dimer, although with fewer interactions.