977 resultados para Geraz do Lima, Luis do Rego Barreto, visconde de, 1777-1840.


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Authorship attributed to Antonio Manoel do Rego Abranches in: Silva, Innocencio Francisco da. Diccionario bibliographica portuguez, v. 1. Lisboa, 1858.

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The food chain theory predict that presence of omnivory prevent the trophic cascade and could be a strong stabilizing factor over resource and consumer community dynamics, and that the nutrient enrichment destabilize populations dynamics. Most of the freshwater tropical reservoirs are eutrophic, and strategies that seek improve the water quality through the control of phytoplankton biomass and nutrient input, become essential for the improvement and preservation of water quality. The aim of this study was test the zooplanktivory (when larvae) and omnivory (when young and adult) effects of Nile Tilapia over the structure and dynamics of plankton communities, in addition or absence of nutrients enrichment. For this, one field experiment was performed with a factorial design 2x3 resulting in six treatments: control, without fish and nutrient (C); with omnivorous fish (O); with zooplanktivorous fish (Z); without fish and with enrichment of nutrients (NP); with omnivorous fish and nutrients (ONP); and, with zooplanktivorous fish and nutrients (ZNP). The two planktivory types reduced the zooplankton biomass and increased the phytoplankton biomass, but the omnivory of filter-feeding fish attenuated the trophic cascade magnitude. The fertilization by nutrients increases the nutrient concentrations in water and the phytoplankton biomass, but the effect on zooplankton is dependent of the trophic structure. In a general way, the effects of the fish and nutrient addition were addictive, but significant interactions among those factors were observed in the answer of some zooplankton groups. The effects of omnivorous fish over the temporal variability of phytoplankton and zooplankton biomass were very variable, the increase or reduce in variability of the plankton depending of the level of nutrients and of the analyzed variable. With base in this study, we conclude that the planktivory type exercised by the fish and the concentrations of nutrients in the water affects the force of pelagic trophic cascades and probably the success of biomanipulation programs for the handling of water quality in lakes and tropical reservoirs

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SnO2:2 at. %Er xerogel samples were obtained by sol-gel technique from colloidal suspensions with distinct pHs. The evaluation of critical regions inside the nanocrystallite is fundamental for the interpretation of the influence of pH on the emission data. In this way, the nanocrystal depletion layer thickness was obtained with the help of photoluminescence, Raman, X-ray diffraction, and field-emission gun scanning electron microscopy measurements. It was observed that acid suspensions (pH < 7) lead to high surface disorder in which a larger number of cross-linked bonds Sn-O-Sn among nanoparticles are present. For these samples, the nanoparticle depletion layer is larger as compared to samples obtained from other pH. Photoluminescence measurement in the near infrared region indicates that the emission intensity of the transition 4I13/2 → 4I15/2 is also influenced by the pH of the starting colloidal suspension, generating peaks more or less broadened, depending on location of Er3+ ions in the SnO2 lattice (high or low symmetry sites). © 2013 AIP Publishing LLC.

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Os constituintes começaram a modificar o texto apresentado. Foram confirmados 24 itens do capítulo dos direitos e garantias individuais. Não houve acordo em dois pontos: a necessidade de mandado judicial para prisão e a aplicação imediata destas normas, o mandado de injunção será definido só no voto. Há uma preocupação com a constante falta de quórum.

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Objetivando avaliar o comportamento das emissões de CO2 do solo em áreas mineradas do município de Santo Antônio de Pádua-RJ e sua correlação com a rizosfera, este presente estudo utilizou uma câmara fechada com sensor de infravermelho em três diferentes paisagens, a saber: A-1 (área reflorestada há 10 anos), A-2 (área desmatada) e A-3 (área em processo de recuperação). Em cada área foi instalada três cilindros para efeitos de repetição. O monitoramento foi realizado durante os meses representativos de cada estação do ano de 2013, sendo a análise realizada durante dois dias consecutivos. Concomitantemente as coletas de CO2 foram realizadas coletas de dados de temperatura e umidade do solo, sendo também avaliadas informações pedológicas através das análises de granulometria, porosidade, pH, carbono orgânico e matéria orgânica. Informações meteorológicas e microclimatológicas também foram extraídas através de uma estação meteorológica automática e através de sensores portáteis. Os resultados permitem concluir que existe uma variação sazonal dos fluxos de CO2, havendo uma tendência de máximos de emissão durante o verão e de mínimas durante o inverno, sendo o outono e a primavera marcados por valores medianos. A correlação das áreas entre os dois dias monitoramento indicam que as emissões foram semelhantes ao da análise em dia anterior, apresentando uma correlação significativa a 5% para A-1 e A-2 e de 1% para A-3. A-1 e A-2 apresentaram emissões de CO2 mais homogêneas que A-3, havendo, entretanto, um maior fluxo de CO2 durante o verão para todas as áreas. Os dados de MOS, COS e pH demonstraram não haver uma correlação direta com as emissões de CO2. Os dados de porosidade e densidade, porém, apontam para uma possível correlação com as menores emissões de CO2 em A-3 devido a menor porosidade e maior densidade de seus solos. A temperatura do solo foi a variável que mais se correlacionou com as emissões de CO2, havendo um índice igual a r =0,68 para A-1 e de r =0,74 para A-2, sendo que em A-3 esta correlação não foi significativa. A temperatura do ar demonstrou uma correlação somente na área descampada de A-2. No que se refere à correlação da umidade do solo não houve correlações diretas significativas, sendo que somente houve uma correlação negativa (r=-0,50) significativa a 5% em A-3 com a umidade do ar. O diagnóstico ambiental das áreas de monitoramento revela que estas possuem baixos indicadores de qualidade, sendo afetados também pela escassez hídrica da região durante oito meses do ano. A-1 apresenta os melhores indicadores biológicos, químicos e microclimáticos, seguidos por A-2 e A-3 que apresentam diversas deficiências e problemas em termos de estrutura e atividade biológica dos solos. Neste estudo permite-se concluir que áreas próximas, porém com características distintas podem produzir diferentes padrões de emissão de CO2, dificultando, portanto, estimativas globais de emissão de CO2. Os elementos mais associados às emissões de CO2 parecem estar relacionados à temperatura do solo e do ar, umidade do ar e estrutura do solo, havendo, entretanto, outros fatores que podem estar indiretamente relacionados e que exercem diferentes influências de acordo com o ambiente analisado.

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Es un estudio llevado a cabo por un equipo de trabajo de la Escuela de Artes aplicadas y oficios artísticos de Zamora con la colaboración de Directores y exdirectores de las Escuelas de Artes aplicadas de las distintas provincias de la Comunidad Castellano-Leonesa, a raiz de un encuentro-exposición. El objetivo es poder obtener un estudio individual de cada Escuela que refleje la situación actual y sirva de punto de partida a una estructuración coherente de las Enseñanzas de Artes Plásticas y Diseño. Se ha dado una visión general sobre la problemática de las Enseñanzas Artísticas y su situación comparativa en el ámbito europeo y con una Comunidad con trasferencias en Educación. La metodología ha sido: a) La realización de una encuesta a cada Escuela con los siguientes apartados: -Nombre de la Escuela; -Ciudad en la que está ubicada; -Dirección; -Fecha de creación; -Profesorado. b) Documentación gráfica complementaria: fachadas, aulas, talleres, etc. c) Planos de ubicación del edificio y un estudio histórico de cada Centro. Como conclusión se hace necesario contemplar la coexistencia de una fuerte demanda de formación artístico-plástica relacionada con el mundo del Diseño y la Imagen, deben ser tenidas en cuenta a la hora de elaborar la esstructuración de estos Centros y reunir la tradición y los procedimientos artesanales con la modernidad y la investigación. Se acompañan dos anexos con las familias profesionales de la nueva LOGSE. El trabajo no está publicado..

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The design of therapeutic compounds targeting transthyretin (TTR) is challenging due to the low specificity of interaction in the hormone binding site. Such feature is highlighted by the interactions of TTR with diclofenac, a compound with high affinity for TTR, in two dissimilar modes, as evidenced by crystal structure of the complex. We report here structural analysis of the interactions of TTR with two small molecules, 1-amino-5-naphthalene sulfonate (1,5-AmNS) and 1-anilino-8-naphthalene sulfonate (1,8-ANS). Crystal structure of TTR: 1,8-ANS complex reveals a peculiar interaction, through the stacking of the naphthalene ring between the side-chain of Lys15 and Leu17. The sulfonate moiety provides additional interaction with Lys15` and a water-mediated hydrogen bond with Thr119`. The uniqueness of this mode of ligand recognition is corroborated by the crystal structure of TTR in complex with the weak analogue 1,5-AmNS, the binding of which is driven mainly by hydrophobic partition and one electrostatic interaction between the sulfonate group and the Lys15. The ligand binding motif unraveled by 1,8-ANS may open new possibilities to treat TTR amyloid diseases by the elucidation of novel candidates for a more specific pharmacophoric pattern. (C) 2009 Published by Elsevier Ltd.

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Suramin is a hexasulfonated naphthylurea which has been recently characterized as a non-competitive inhibitor of human alpha-thrombin activity over fibrinogen, although its binding site and mode of interaction with the enzyme remain elusive. Here, we determined two X-ray structure of the thrombin: suramin complex, refined at 2.4 angstrom resolution. While a single thrombin: suramin complex was found in the asymmetric unit cell of the crystal, some of the crystallographic contacts with symmetrically related molecules are mediated by both the enzyme and the ligand. Molecular dynamics simulations with the 1:1 complex demonstrate a large rearrangement of suramin in the complex, but with the protein scaffold and the more extensive protein-ligand regions keep unchanged. Small-angle X-ray scattering measurements at high micromolar concentration demonstrate a suramin-induced dimerization of the enzyme. These data indicating a dissimilar binding mode in the monomeric and oligomeric states, with a monomeric, 1:1 complex to be more likely to exist at the thrombin physiological, nanomolar concentration range. Collectively, close understanding on the structural basis for interaction is given which might establish a basis for design of suramin analogues targeting thrombin. Crown Copyright (C) 2009 Published by Elsevier B.V. All rights reserved.

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Transthyretin (TTR) is a tetrameric beta-sheet-rich transporter protein directly involved in human amyloid diseases. Several classes of small molecules can bind to TTR delaying its amyloid fibril formation, thus being promising drug candidates to treat TTR amyloidoses. In the present study, we characterized the interactions of the synthetic triiodo L-thyronine analogs and thyroid hormone nuclear receptor TR beta-selecfive agonists GC-1 and GC-24 with the wild type and V30M variant of human transthyretin (TTR). To achieve this aim, we conducted in vitro TTR acid-mediated aggregation and isothermal titration calorimetry experiments and determined the TTR:GC-1 and TTR:GC-24 crystal structures. Our data indicate that both GC-1 and GC-24 bind to TTR in a non-cooperative manner and are good inhibitors of TTR aggregation, with dissociation constants for both hormone binding sites (HBS) in the low micromolar range. Analysis of the crystal structures of TTRwt:GC-1(24) complexes and their comparison with the TTRwt X-ray structure bound to its natural ligand thyroxine (T4) suggests, at the molecular level, the basis for the cooperative process displayed by T4 and the non-cooperative process provoked by both GC-1 and GC-24 during binding to TTR. (C) 2010 Elsevier Inc. All rights reserved.

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Human transthyretin (TTR) is a homotetrameric protein involved in several amyloidoses. Zn(2+) enhances TTR aggregation in vitro, and is a component of ex vivo TTR amyloid fibrils. We report the first crystal structure of human TTR in complex with Zn(2+) at pH 4.6-7.5. All four structures reveal three tetra-coordinated Zn(2+)-binding sites (ZBS 1-3) per monomer, plus a fourth site (ZBS 4) involving amino acid residues from a symmetry-related tetramer that is not visible in solution by NMR.Zn(2+) binding perturbs loop E-alpha-helix-loop F, the region involved in holo-retinol-binding protein (holo-RBP) recognition, mainly at acidic pH; TTR affinity for holo-RBP decreases similar to 5-fold in the presence of Zn(2+). Interestingly, this same region is disrupted in the crystal structure of the amyloidogenic intermediate of TTR formed at acidic pH in the absence of Zn(2+). HNCO and HNCA experiments performed in solution at pH 7.5 revealed that upon Zn(2+) binding, although the alpha-helix persists, there are perturbations in the resonances of the residues that flank this region, suggesting an increase in structural flexibility. While stability of the monomer of TTR decreases in the presence of Zn(2+), which is consistent with the tertiary structural perturbation provoked by Zn(2+) binding, tetramer stability is only marginally affected by Zn(2+). These data highlight structural and functional roles of Zn(2+) in TTR-related amyloidoses, as well as in holo-RBP recognition and vitamin A homeostasis.

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To shed more light on the molecular requirements for recognition of thyroid response elements (TRES) by thyroid receptors (TRs), we compared the specific aspects of DNA TRE recognition by different TR constructs. Using fluorescence anisotropy, we performed a detailed and hierarchical study of TR-TRE binding. This wits done by comparing the binding affinities of three different TR constructs for four different TRE DNA elements, including palindromic sequences and direct repeats (F2, PAL, DR-1, and DR-4) as well as their interactions with nonspecific DNA sequences. The effect of MgCl(2) on suppressing of nonselective DNA binding to TR was also investigated. Furthermore, we determined the dissociation constants of the hTR beta DBD (DNA binding domain) and hTR beta DBD-LBD (DNA binding and ligand binding domains) for specific TRES. We found that a minimum DNA recognition peptide derived from DBD (H1TR) is sufficient for recognition and interaction with TREs, whereas scrambled DNA sequences were unrecognized. Additionally, we determined that the TR DBD binds to F2, PAL, and DR-4 with high affinity and similar K(d) values. The TR DBD-LBD recognizes all the tested TRES but binds preferentially to F2, with even higher affinity. Finally, our results demonstrate the important role played by LBDs in modulating TR-DNA binding.

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The ligand binding domain (LBD) of nuclear hormone receptors adopts a very compact, mostly alpha-helical structure that binds specific ligands with very high affinity. We use circular dichroism spectroscopy and high-temperature molecular dynamics Simulations to investigate unfolding of the LBDs of thyroid hormone receptors (TRs). A molecular description of the denaturation mechanisms is obtained by molecular dynamics Simulations of the TR alpha and TR beta LBDs in the absence and in the presence of the natural ligand Triac. The Simulations Show that the thermal unfolding of the LBD starts with the loss of native contacts and secondary Structure elements, while the Structure remains essentially compact, resembling a molten globule state. This differs From most protein denaturation simulations reported to date and suggests that the folding mechanism may start with the hydrophobic collapse of the TR LBDs. Our results reveal that the stabilities of the LBDs of the TR alpha and TR beta Subtypes are affected to different degrees by the binding of the isoform selective ligand Triac and that ligand binding confers protection against thermal denaturation and unfolding in a subtype specific manner. Our Simulations indicate two mechanisms by which the ligand stabilizes the LBD: (1) by enhancing the interactions between H8 and H 11, and the interaction of the region between H I and the Omega-loop with the core of the LBD, and (2) by shielding the hydrophobic H6 from hydration.

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Transthyretin (TTR) is a tetrameric beta-sheet-rich transporter protein directly involved in human amyloid diseases. It was recently found that the isoflavone genistein (GEN) potently inhibits TTR amyloid fibril formation (Green et al., 2005) and is therefore a promising candidate for TTR amyloidosis treatment. Here we used structural and biophysical approaches to characterize genistein binding to the wild type (TTRwt) and to its most frequent amyloidogenic variant, the V30M mutant. In a dose-dependent manner, genistein elicited considerable increases in both mutant and TTRwt stability as demonstrated by high hydrostatic pressure (HHP) and acid-mediated dissociation/denaturation assays. TTR:GEN crystal complexes and isothermal titration calorimetry (ITC) experiments showed that the binding mechanisms of genistein to the TTRwt and to V30M are different and are dependent on apoTTR structure conformations. Furthermore, we could also identify potential allosteric movements caused by genistein binding to the wild type TTR that explains, at least in part, the frequently observed negatively cooperative process between the two sites of TTRwt when binding ligands. These findings show that TTR mutants may present different ligand recognition and therefore are of value in ligand design for inhibiting TTR amyloidosis. (C) 2010 Elsevier Inc. All rights reserved.