Browsing by Author "Ribeiro, C."
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- Alpha cinnamomin elicits a defence response against Phytophthora cinnamomi in Castanea sativaPublication . Medeira, C.; Maia, I.; Ribeiro, C.; Candeias, I.; Melo, Eduardo P.; Sousa, N.; Cravador, A.Phytophthora cinnamomi and P. cambivora are considered as the causal agents of Castanea sativa ink disease. These soil-borne plant pathogens invade and destroy the root system leading to the death of the trees. Most Phytophthora species secrete elicitins, a group of unique highly conserved proteins that are able to enhance plant defence responses in a systemic acquired resistance manner against infection by several pathogens. A cluster of four elicitin genes was identified in P. cinnamomi. In previous works one of these elicitins, α- cinnamomin was shown to restrict the invasion of root cortical tissues by P. cinnamomi preventing vascular colonization in cork and holm oak. In the present work, roots of chestnut plantlets grown in vitro were allowed to absorb α-cinnamomin at 100 μg/ml for two days before being inoculated with P. cinnamomi. The effects of this elicitin on host-pathogen interaction were studied at histological and ultrastructural levels. P. cinnamomi was restricted to the outer cortex of 65% of the roots pre-treated with α-cinnamomin. In these roots, the vascular cylinders were free of pathogen. On the contrary, the pathogen reached the vascular cylinder, penetrating the phloem and xylem vessels in all non-treated assayed roots. The signs of pathogen degradation in the cortical parenchyma, mainly in the intercellular spaces, and the increase of a physical barrier in epidermal and sub-epidermal cell wall-media lamella and intercellular spaces by impregnation with phenol-like compounds strongly suggest that α-cinnamomin induced in chestnut defence reactions against P. cinnamomi.
- A Bacia do Algarve: estratigrafia, paleogeografia e tectónicaPublication . Terrinha, P.; Rocha, R.; Rey, J.; Cachão, M.; Moura, Delminda; Roque, C.; Martins, L.; Valadares, V.; Cabral, J.; Azevedo, M. R.; Barbero, L.; Clavijo, E.; Dias, R. P.; Gafeira, J.; Matias, H.; Matias, L.; Madeira, C. M. S; Munhã, J.; Rebelo, Luis; Ribeiro, C.; Vicente, J.; Noiva, J.; Youbi, N.; Bensalah, M. K.A “Bacia do Algarve” corresponde, segundo a literatura científica tradicional, aos terrenos mesocenozóicos que orlam o Sul de Portugal, desde o Cabo de São Vicente ao rio Guadiana (~140km), penetrando irregularmente para o interior entre 3 km a 25 km, sobre terrenos de idade carbónica da Zona Sul Portuguesa. O hiato, de aproximadamente 70 milhões de anos, materializado pela discordância angular entre as rochas sedimentares de tipo flysch do Carbónico, metamorfizadas e deformadas durante a orogenia varisca, e as rochas sedimentares continentais do Triásico inferior provável, separa dois ciclos de Wilson. Os sedimentos carbónicos metamorfizados resultam do empilhamento orogénico de um possível prisma de acrecção associado à orogenia varisca e ao fecho de um oceano paleozóico e formação da Pangeia, enquanto que os sedimentos continentais triásicos resultam do fim do colapso e do arrasamento do orógeno varisco e início do estiramento continental que viriam a culminar com a separação das placas litosféricas África, Eurásia e América.Os sedimentos mais recentes do Mesozóico e os mais antigos bem datados do Cenozóico encontram-se separados por um outro hiato que ultrapassa ligeiramente os 70 milhões de anos na área emersa. Este hiato resulta duma alteração tectónica radical no contexto onde nessa época geológica se inseria a Bacia do Algarve. Esta mudança, que ocorreu no fim do Cenomaniano, resultou da rotação do vector de deslocamento da trajectória de África em relação à Eurásia, de aproximadamente NW-SE para SW-NE (segundo as coordenadas actuais, e.g. Dewey et al, 1989), poria termo ao regime distensivo e de bacia de tipo rifte na Bacia do Algarve, com o fim do regime transtensivo entre a região noroeste da placa África e sudoeste da placa Eurásia e início da colisão.
- Electromechanical actuators based on poly(vinylidene fluoride) with [N-1 (1) (1) (2(OH))][NTf2] and [C(2)mim] [C2SO4]Publication . Dias, J. C.; Martins, Marcos; Ribeiro, S.; Silva, M. M.; Esperança, J. M. S. S.; Ribeiro, C.; Botelho, G.; Costa, C. M.; Lanceros-Mendez, S.Actuators based on electroactive polymers are increasingly used in applications including microelectronic devices and artificial muscles, demanding low voltage operation and controllable switching response. This work reports on the preparation of electroactive actuators based on poly(vinylidene fluoride) (PVDF) composites with 10, 25, and 40 wt% N,N,N-trimethyl-N-(2-hydroxyethyl) ammonium bis(trifluoromethylsulfonyl)imide ([N-1 1 1 2(OH)][NTf2]) and 1-Ethyl-3-methylimidazolium Ethylsulfate ([C(2)mim][C2SO4]) ionic liquids (ILs) prepared by solvent casting. Independent of the IL type, its presence leads to the crystallization of PVDF in the piezoelectric beta-phase. The degree of crystallinity and electrical conductivity of the samples strongly depends on ILs type and content. The highest electrical conductivity was found for PVDF/IL composites with 40 wt% of [N-1 1 1 2(OH)][NTf2]. The strain displacement and bending of the PVDF/IL composites were evaluated as a function of IL type and content under applied peak voltages of 2.0, 5.0, and 10.0 V at a frequency of 10 mHz. Strain displacement of the actuators depends more on IL content than on IL type, and the best strain bending response was found for the PVDF/IL composite with 25 wt% of [N-1 1 1 2(OH)][NTf2] at 5.0 V. Further, it is shown that [C(2)mim] [C2SO4]/PVDF composites do not show cytotoxic behavior, being suitable for biomedical applications.
- Polyarthritis due to metastatic calcinosis in a patient with new WT1 gene mutation resolution after renal transplantationPublication . Martins, F. Rajão; Gonçalves, Francisco; Guedes, A.; Sequeira, G.; Ribeiro, C.Metastatic calcinosis is an uncommon condition characterized by diffuse soft tissue calcification, which may occur with advanced chronic kidney disease (CKD), typically in those undergoing kidney replacement therapy (1, 2). Deposits usually appear around large joints such as the elbow, hip, and shoulder. Periarticular deposits may lead to arthralgia, reduced joint mobility, and neurovascular symptoms. Sustained elevation of serum phosphate levels is the main contributor in CKD patients.