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Search Results: 1 - 10 of 462824 matches for " Gra?a Soveral "
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Biophysical Assessment of Human Aquaporin-7 as a Water and Glycerol Channel in 3T3-L1 Adipocytes
Ana Madeira, Marta Camps, Antonio Zorzano, Teresa F. Moura, Graa Soveral
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0083442
Abstract: The plasma membrane aquaporin-7 (AQP7) has been shown to be expressed in adipose tissue and its role in glycerol release/uptake in adipocytes has been postulated and correlated with obesity onset. However, some studies have contradicted this view. Based on this situation, we have re-assessed the precise localization of AQP7 in adipose tissue and analyzed its function as a water and/or glycerol channel in adipose cells. Fractionation of mice adipose tissue revealed that AQP7 is located in both adipose and stromal vascular fractions. Moreover, AQP7 was the only aquaglyceroporin expressed in adipose tissue and in 3T3-L1 adipocytes. By overexpressing the human AQP7 in 3T3-L1 adipocytes it was possible to ascertain its role as a water and glycerol channel in a gain-of-function scenario. AQP7 expression had no effect in equilibrium cell volume but AQP7 loss of function correlated with higher triglyceride content. Furthermore it is also reported for the first time a negative correlation between water permeability and the cell non-osmotic volume supporting the observation that AQP7 depleted cells are more prone to lipid accumulation. Additionally, the strong positive correlation between the rates of water and glycerol transport highlights the role of AQP7 as both a water and a glycerol channel and reflects its expression levels in cells. In all, our results clearly document a direct involvement of AQP7 in water and glycerol transport, as well as in triglyceride content in adipocytes.
Grapevine Aquaporins: Gating of a Tonoplast Intrinsic Protein (TIP2;1) by Cytosolic pH
Luís Leit?o, Catarina Prista, Teresa F. Moura, Maria C. Loureiro-Dias, Graa Soveral
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0033219
Abstract: Grapevine (Vitis vinifera L.) is one of the oldest and most important perennial crops being considered as a fruit ligneous tree model system in which the water status appears crucial for high fruit and wine quality, controlling productivity and alcohol level. V. vinifera genome contains 28 genes coding for aquaporins, which acting in a concerted and regulated manner appear relevant for plant withstanding extremely unfavorable drought conditions essential for the quality of berries and wine. Several Vv aquaporins have been reported to be expressed in roots, shoots, berries and leaves with clear cultivar differences in their expression level, making their in vivo biochemical characterization a difficult task. In this work V. vinifera cv. Touriga nacional VvTnPIP1;1, VvTnPIP2;2 and VvTnTIP2;1 were expressed in yeast and water transport activity was characterized in intact cells of the transformants. The three aquaporins were localized in the yeast plasma membrane but only VvTnTIP2;1 expression enhanced the water permeability with a concomitant decrease of the activation energy of water transport. Acidification of yeast cytosol resulted in loss of VvTnTIP2;1 activity. Sequence analysis revealed the presence of a His131 residue, unusual in TIPs. By site directed mutagenesis, replacement of this residue by aspartic acid or alanine resulted in loss of pHin dependence while replacement by lysine resulted in total loss of activity. In addition to characterization of VvTn aquaporins, these results shed light on the gating of a specific tonoplast aquaporin by cytosolic pH.
Targeting Aquaporin Function: Potent Inhibition of Aquaglyceroporin-3 by a Gold-Based Compound
Ana Paula Martins, Alessandro Marrone, Antonella Ciancetta, Ana Galán Cobo, Miriam Echevarría, Teresa F. Moura, Nazzareno Re, Angela Casini, Graa Soveral
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0037435
Abstract: Aquaporins (AQPs) are membrane channels that conduct water and small solutes such as glycerol and are involved in many physiological functions. Aquaporin-based modulator drugs are predicted to be of broad potential utility in the treatment of several diseases. Until today few AQP inhibitors have been described as suitable candidates for clinical development. Here we report on the potent inhibition of AQP3 channels by gold(III) complexes screened on human red blood cells (hRBC) and AQP3-transfected PC12 cells by a stopped-flow method. Among the various metal compounds tested, Auphen is the most active on AQP3 (IC50 = 0.8±0.08 μM in hRBC). Interestingly, the compound poorly affects the water permeability of AQP1. The mechanism of gold inhibition is related to the ability of Au(III) to interact with sulphydryls groups of proteins such as the thiolates of cysteine residues. Additional DFT and modeling studies on possible gold compound/AQP adducts provide a tentative description of the system at a molecular level. The mapping of the periplasmic surface of an homology model of human AQP3 evidenced the thiol group of Cys40 as a likely candidate for binding to gold(III) complexes. Moreover, the investigation of non-covalent binding of Au complexes by docking approaches revealed their preferential binding to AQP3 with respect to AQP1. The high selectivity and low concentration dependent inhibitory effect of Auphen (in the nanomolar range) together with its high water solubility makes the compound a suitable drug lead for future in vivo studies. These results may present novel metal-based scaffolds for AQP drug development.
Functional and Transcriptional Induction of Aquaporin-1 Gene by Hypoxia; Analysis of Promoter and Role of Hif-1α
Irene Abreu-Rodríguez, Rocío Sánchez Silva, Ana Paula Martins, Graa Soveral, Juan José Toledo-Aral, José López-Barneo, Miriam Echevarría
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0028385
Abstract: Aquaporin-1 (AQP1) is a water channel that is highly expressed in tissues with rapid O2 transport. It has been reported that this protein contributes to gas permeation (CO2, NO and O2) through the plasma membrane. We show that hypoxia increases Aqp1 mRNA and protein levels in tissues, namely mouse brain and lung, and in cultured cells, the 9L glioma cell line. Stopped-flow light-scattering experiments confirmed an increase in the water permeability of 9L cells exposed to hypoxia, supporting the view that hypoxic Aqp1 up-regulation has a functional role. To investigate the molecular mechanisms underlying this regulatory process, transcriptional regulation was studied by transient transfections of mouse endothelial cells with a 1297 bp 5′ proximal Aqp1 promoter-luciferase construct. Incubation in hypoxia produced a dose- and time-dependent induction of luciferase activity that was also obtained after treatments with hypoxia mimetics (DMOG and CoCl2) and by overexpressing stabilized mutated forms of HIF-1α. Single mutations or full deletions of the three putative HIF binding domains present in the Aqp1 promoter partially reduced its responsiveness to hypoxia, and transfection with Hif-1α siRNA decreased the in vitro hypoxia induction of Aqp1 mRNA and protein levels. Our results indicate that HIF-1α participates in the hypoxic induction of AQP1. However, we also demonstrate that the activation of Aqp1 promoter by hypoxia is complex and multifactorial and suggest that besides HIF-1α other transcription factors might contribute to this regulatory process. These data provide a conceptual framework to support future research on the involvement of AQP1 in a range of pathophysiological conditions, including edema, tumor growth, and respiratory diseases.
Sobre o financiamento da Educa??o: condicionantes globais e realidades nacionais
Graa,Vasco;
Revista Lusófona de Educa??o , 2009,
Abstract: this paper aims to analyze the evolution of education funding in portugal taking into consideration the global influences and constraints. it mentions the historic under funding of portuguese education and reflects on the criticism from some quarters that the cost of education approached average oecd levels during the late 1990s. traces a framework of international prospects for education and presents the current situation in the european union in this regard. also refers to the educational expectations of the oecd, namely for portugal, with emphasis on the consequences for educational funding. analyses the recent evolution of educational budgets specifically the decline in investment and the re-designation of funds to different categories, namely from payroll categories to others which correspond to european union objectives and goals.
Antioxidant and Anti-Inflammatory Activities of Essential Oils: A Short Review
Maria Graa Miguel
Molecules , 2010, DOI: 10.3390/molecules15129252
Abstract: Essential oils are complex mixtures isolated from aromatic plants which may possess antioxidant and anti-inflammatory activities of interest in thye food and cosmetic industries as well as in the human health field. In this work, a review was done on the most recent publications concerning their antioxidant and anti-inflammatory activities. At the same time a survey of the methods generally used for the evaluation of antioxidant activity and some of the mechanisms involved in the anti-inflammatory activities of essential oils are also reported.
Mídia, escola e leitura crítica do mundo
Caldas, Graa;
Educa??o & Sociedade , 2006, DOI: 10.1590/S0101-73302006000100006
Abstract: this paper focuses on the classroom use of newspaper and magazine texts and its connection with the learning process. it criticizes the excessive usage of fragments of journalistic discourse in school textbooks, to the detriment of other text forms. the quality of journalistic narration is questioned and the risks incumbent on an acritical reading of the media. it advocates the necessity of cooperation between educators and journalists to foster an effective understanding of the news production process, to improve language construction, and to generate awareness of the media's editorial lines and policies.
Língua, nome e identidade numa situa??o de plurilinguismo concorrencial: o caso de Timor-Leste
Feijó,Rui Graa;
Etnográfica , 2008,
Abstract: this essay discusses the interplay between language, name and identity in the plurilingual context of east-timor. namely, i will approach the relationships between given and family name as one of the distinctive characters of the timorese linguistic system. through names and naming practices in east--timor, and the way they are construed and articulated with other contemporary phenomena, i will discuss the different levels of cultural identity and the bases that support the configuration and sense of timorese national identity.
Aconselhamento psicológico a jovens do Ensino Superior: Uma abordagem psicodinamica e desenvolvimentista
Dias,Graa Figueiredo;
Análise Psicológica , 2006,
Abstract: the aim of this paper is to propose both a theoretical model of the psychological development, which we believe allows to understand the majority of the difficulties young people in higher education bring to counselling, and an intervention model in individual counselling arising from it. the theoretical model has come out from a dialectic reciprocal movement between clinical practice and reflection about that practice, in the light of several psychodynamic authors' developmental models. this reflection has allowed us to find commonalities and complementarities between those models, in spite of the use of different terminologies. the proposed theoretical model has been used as a template for empirical research, whose results allowed us to consolidate its suitability. from this model an intervention strategy, inscribed in brief psychodynamic therapies, is put forward. the intervention model will be illustrated with a clinical case, and its advantages and limitations discussed.
Trabalho, precariza??o e resistências: novos e velhos desafios?
Druck, Graa;
Caderno CRH , 2011, DOI: 10.1590/S0103-49792011000400004
Abstract: this paper discusses why the precarization of labor is an old and young phenomenon, different and equal, past and present, a phenomenon of a macro- and microssocial character. it presents some fetishes present in the analysis of labor in the context of globalization of capital, marked by the hegemony of finance capital, the restructuring of production and labor and a "new spirit of capitalism." there are five sections: introduction, discussion of methodological issues based on reflections of research projects in progress, theoretical considerations on the characterization of flexible capitalism and the centrality of social precarization of labor, a contextualization of labor in latin america and brazil in the light of ilo studies, indicators of precarization and resistances, and a debate on the new and old challenges brought about by the changes under the aegis of the social precarization of labor and a "spirit of capitalism" reformulated, which, while reaffirming the old spirit, constitutes a new spirit.
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