Browsing by Author "Marques, C."
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- 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.
- Identification of DNA markers linked to an induced mutated gene conferring resistance to powdery mildew in pea (Pisum sativum L.)Publication . Pereira, G.; Marques, C.; Ribeiro, R.; Formiga, S.; Damaso, M.; Sousa, M. T.; Farinho, M.; Leitão, J. M.We have recently induced two powdery mildew (Erysiphe pisi Syd) resistant mutants in Pisum sativum L. via ethylnitrosourea (ENU) mutagenesis. Both mutations (er1mut1 and er1mut2) affected the same locus er1 that determines most of the identified natural sources of powdery mildew resistance (PMR) in this crop. The mutated gene er1mut2 was mapped to a linkage group of 16 DNA markers combining three main strategies: near isogenic lines (NILs) analysis, bulked segregant analysis and genetic mapping of randomly identified polymorphic markers, together with three DNA-markers techniques: ISSR, RAPDs and AFLPs. Markers located closer to the PMR locus, OPO06(1100y) (0.5 cM), OPT06(480) (3.3 cM) and AGG/CAA(125) (5.5 cM), were cloned and converted into SCAR markers. Markers AH1R(850) and AHR(920y) were found to be allelic and converted into the co-dominant marker ScAH1 (16.3 cM). Two previously known DNA markers, ScOPE16(1600) and A5(420y,) were mapped at 9.6 and 23.0 cM from the PMR locus, respectively. The novel markers identified in this study are currently being transferred to a new F2 mapping population derived from a cross between the induced PMR mutant line F(er1mut2) and a more genetically distant susceptible line of Pisum sativum var. arvense.
- Identification of DNA markers linked to an induced mutated gene conferring resistance to powdery mildew in pea (Pisum sativum L.)Publication . Pereira, G.; Marques, C.; Ribeiro, R.; Formiga, S.; Damâso, M.; Tavares Sousa, M.; Farinhó, M.; Leitão, J. M.We have recently induced two powdery mildew (Erysiphe pisi Syd) resistant mutants in Pisum sativum L. via ethylnitrosourea (ENU) mutagenesis. Both mutations (er1mut1 and er1mut2) affected the same locus er1 that determines most of the identified natural sources of powdery mildew resistance (PMR) in this crop. The mutated gene er1mut2 was mapped to a linkage group of 16 DNA markers combining three main strategies: near isogenic lines (NILs) analysis, bulked segregant analysis and genetic mapping of randomly identified polymorphic markers, together with three DNA-markers techniques: ISSR, RAPDs and AFLPs. Markers located closer to the PMR locus, OPO061100y (0.5 cM), OPT06480 (3.3 cM) and AGG/CAA125 (5.5 cM), were cloned and converted into SCAR markers. Markers AH1R850 and AHR920y were found to be allelic and converted into the co-dominant marker ScAH1 (16.3 cM). Two previously known DNA markers, ScOPE161600 and A5420y, were mapped at 9.6 and 23.0 cM from the PMR locus, respectively. The novel markers identified in this study are currently being transferred to a new F2 mapping population derived from a cross between the induced PMR mutant line F(er1mut2) and a more genetically distant susceptible line of Pisum sativum var. arvense. © Springer Science+Business Media B.V. 2009.
- Is agricultural policy promoting a new role for farmers?: a case studyPublication . Freitas, Maria de Belém; Marques, C.European Agenda 2000 considers the integration of environment in CAP and the role farmers can play on natural resources management. Alternative tillage technologies to seed cereals play an important economic and environmental role on the development of a sustainable agriculture and its adoption may depend on the agricultural policy, particularly policies on income support. The results obtained clearly show that the use of alternative soil tillage technologies would be promoted by the change of supports from the first to the second pillar of CAP and we can conclude that, in general, this change will encourage a faster technological adoption. (c) 2006 Society for Policy Modeling. Published by Elsevier Inc. All rights reserved.
- Methodological aspects of a mathematical programming model to evaluate soil tillage technologies in a risky environmentPublication . Freitas, Maria de Belém; Marques, C.In this work we develop a methodology for the economic evaluation of soil tillage technologies, in a risky environment, and to capture the influence of farmer behaviour on his technology choice. The model has short-term activities, that change with the type of year, and long-term activities, in which sets of traction investment activities are included. Although these activities do not change with the type of year, they lead to different availability of resources for each type of year, since the same tractor has different available fieldwork days under different weather conditions. We prove that the model is sensitive to the greater income variability resulting from the use of alternative technologies and to the balance between income and risk, accounting for the probability of occurrence of each state of nature and giving an investment solution that considers the best production plan for each type of year. (c) 2005 Elsevier B.V. All rights reserved.
- Tetragonia tetragonioides - a potential salt removing species. Response to the combined effects of salts and calciumPublication . Neves, Alcinda; Miguel, Maria Graça; Marques, C.; Panagopoulos, ThomasThe best way to control the salination process and to maintain the sustainability of landscape is the use of environmentally safe and clean techniques. One of these new techniques is the use of salt removing species. In order to study the potential capacity to remove soil salts, several wild halophytic species were being studied. Two experiments with Tetragonia tetragonioides were carried out involving 1) the effects of salts, 2) and the combined effects of salts and calcium. It is shown that T. tetragonioides, besides its high salt removal potential, has other interests, as follows: 1) high biomass production potential; 2) several harvests during the year (summer and winter); 3) high content of minerals; 4) horticultural importance, as a leaf vegetable crop; 6) easy multiplication (seed propagation) and easy crop management; 7) tolerance to drought and hot conditions; 8) soil erosion control due to its excellent soil covering. The obtained results suggest that plants supplemented with the high calcium level had longer internodes than plants in the low calcium level, at high salinity levels.
- The combined effects of salts and calcium on growth and mineral accumulation of Tetragonia tetragonioides - A salt removing speciesPublication . Neves, Alcinda; Miguel, Maria Graça; Marques, C.; Panagopoulos, Thomas; Beltrão, JoséHigh soil salinity levels have drastic effects on the growth and yield of horticultural crops. Salination may be controlled by environmentally safe and clean techniques as the use of salt removing species. Tetragonia tetragonioides, a wild halophytic species has been studied for this purpose. It was studied the effect of high salt concentrations on growth and mineral composition and the influence of high calcium concentration on plant response. Plants were grown in 5 litters in randomized pots and were daily irrigated. The NaCl concentration of the irrigation solution ranged from 0 up to 200 mM. Additionally, the irrigation solution provided plants with two calcium concentrations: 2 and 10 mM of CaCl2. T. tetragonioides present high ability for sodium and chloride leaf accumulation. Besides that, the species provide more advantages: 1) high biomass production potential; 2) several harvests during the year (summer and winter); 3) high content of minerals; 4) horticultural importance, as a leaf vegetable crop; 6) easy multiplication (seed propagation) and easy crop management; 7) tolerance to drought and warm conditions; 8) soil erosion control due to its excellent soil covering. The obtained results suggest that plants supplemented with the high calcium level had longer stems than plants in the low calcium level, accumulated greater amounts of calcium at high salinity levels and present similar leaves dry matter.
- The economic effects of common agricultural policy on Mediterranean montado/dehesa ecosystemPublication . Fragoso, R.; Marques, C.; Lucas, M. R.; Freitas, Maria de Belém; Jorge, R.The decoupling of CAP payments leads production decisions and resources allocation to be more dependent on market prices and competitive advantages. The objective of this paper is to assess the effects of CAP trends on the montado/dehesa traditional ecosystem of Mediterranean regions in terms of farm income, land, labour and capital. A positive mathematical supply model disaggregated by the montado agro-forestry production systems of the Alentejo region in southern Portugal is developed. The results show that decoupling payments of CAP have negative economic effects on agricultural activities and resource use. Agricultural income increases with single farm payments but the foreseen increases in prices do not compensate the loss of the Agenda 2000 area payments in terms of competitiveness. These results reinforce the need to promote alternative agricultural and non-agricultural activities and policies in Mediterranean rural European areas and regions. (C) 2011 Society for Policy Modeling. Published by Elsevier Inc. All rights reserved.