Aquaporins and Glia

Glial cells coordinate the differentiation, metabolism, and excitability of neurons; they modulate synaptic transmission and integrate signals emanating from neurons and other glial cells. Several evidences underlying the relation between these pathways and the regulatory mechanisms of ion concentration, supporting the role of Aquaporins (AQPs) in these processes

Thermo-hydraulic analysis of the windowless target system

The target system, whose function is to supply an external neutron source to a subcritical core in order to sustain the neutron chain reaction, is the most critical part of an ADS being subject to severe thermo-mechanical loading and material damage due to accelerator protons and fission neutrons. In order to reduce the material damage and to increase the life of the target system a windowless option was chosen in the framework of the European PDS-XADS project as reference configuration for the experimental ADS cooled by lead–bismuth eutectic alloy. This document deals with the results of the thermo-hydraulic analysis performed with STAR-CD and RELAP5 codes to assess the behaviour of the windowless target system during off-normal operating conditions. It also reports a description of modifications properly implemented in the codes for studying this kind of plant. The windowless target system shows a satisfactory thermo-hydraulic behaviour for the analysed accidents, except for the loss of both pumps without proton beam shut-off and for the beam trips lasting more than 1 s.2135–2145Pubblicat

S-100 protein, but not calmodulin, binds to the glial fibrillary acidic protein and inhibits its polymerization in a Ca(2+)-dependent manner.

S-100 protein, a Ca(2+)-binding protein of the EF-hand type, interacts with the glial fibrillary acidic protein (GFAP) in a Ca(2+)-dependent manner. The binding of S-100 protein to GFAP was investigated by fluorescence spectroscopy using acrylodan-S-100 protein and cross-linking experiments using the bifunctional cross-linker, disuccinimidyl suberate. The binding affinity was observed to be in the nanomolar range with a stoichiometry of 2 mol of GFAP/mol of S-100 protein (dimer). S-100 protein was found to inhibit the polymerization of GFAP in a dose- and Ca(2+)-dependent manner, with a half-maximal effect at an S-100 protein/GFAP molar ratio of 0.2 and maximal effect at a molar ratio of 0.5. Identical results were obtained irrespective of whether the unfractionated bovine brain S-100 protein mixture (S-100a plus S-100b), S-100ao, S-100a, or S-100b was used. S-100 protein was observed to be maximally effective as an inhibitor of GFAP polymerization at approximately 3 microM free Ca2+. Calmodulin neither bound to GFAP nor inhibited its polymerization. Altogether, the present results suggest that S-100 protein might be involved in the regulation of the state of assembly of glial filaments by binding to and sequestering unpolymerized GFAP

Two novel brain proteins, CaBP33 and CaBP37, are calcium-dependent phospholipid- and membrane-binding proteins

AbstractTwo acidic Ca2+ -binding proteins (CaBP33 and CaBP37) purified from bovine brain have been characterized in terms of immunological properties, heat-sensitivity, electrophoretic mobility, and Ca2+-dependent binding to negatively charged phospholipids and to brain membranes. They were induced to bind to membranes by homogenization of brain tissue in the presence of CaCl2. The membrane-bound CaBP33/CaBP37 mixture resisted extraction with detergents and was solubilized with high concentrations of EGTA/KC1. However, apparent Ca2+-independent binding of the two proteins to membranes seemed to occur as well. This latter fraction of membrane-bound CaBP33 and CaBP37 could be solubilized with Triton X-100, indicating that brain membranes normally contain the two proteins as intrinsic components

S100B Increases Proliferation in PC12 Neuronal Cells and Reduces Their Responsiveness to Nerve Growth Factor via Akt Activation

S100B is a Ca2+-modulated protein of the EF-hand type expressed in high abundance in a restricted set of cell types including certain neuronal populations. S100B has been suggested to participate in cell cycle progression, and S100B levels are high in tumor cells, compared with normal parental cells. We expressed S100B in the neuronal cell line PC12, which normally does not express the protein, by the Tet-Off technique, and found the following: (i) proliferation was higher in S100B+ PC12 cells than in S100B- PC12 cells; (ii) nerve growth factor (NGF), which decreased the proliferation of S100B- PC12 cells, was less effective in the case of S100B+ PC12 cells; (iii) expression of S100B made PC12 cells resistant to the differentiating effect of NGF; and (iv) interruption of S100B expression did not result in an immediate restoration of PC12 cell sensitivity to the differentiating effect of NGF. Expression of S100B in PC12 cells resulted in activation of Akt; increased levels of p21WAF1, an inhibitor of cyclin-dependent kinase (cdk) 2 and a positive regulator of cdk4; increased p21WAF1-cyclin D1 complex formation; and increased phosphorylation of the retinoblastoma suppressor protein, Rb. These S100B-induced effects, as well as the reduced ability of S100B+ PC12 cells to respond to NGF, were dependent on Akt activation because they were remarkably reduced or abrogated in the presence of LY294002, an inhibitor of the Akt upstream kinase phosphatidylinositol 3-kinase. Thus, S100B might promote cell proliferation and interfere with NGF-induced PC12 cell differentiation by stimulating a p21WAF1/cyclin D1/cdk4/Rb/E2F pathway in an Akt-mediated manner

Oligodendroglioma cells lack glutamine synthetase and are auxotrophic for glutamine, but do not depend on glutamine anaplerosis for growth

In cells derived from several types of cancer, a transcriptional program drives high consumption of glutamine (Gln), which is used for anaplerosis, leading to a metabolic addiction for the amino acid. Low or absent expression of Glutamine Synthetase (GS), the only enzyme that catalyzes de novo Gln synthesis, has been considered a marker of Gln-addicted cancers. In this study, two human cell lines derived from brain tumors with oligodendroglioma features, HOG and Hs683, have been shown to be GS-negative. Viability of both lines depends from extracellular Gln with EC of 0.175 ± 0.056 mM (Hs683) and 0.086 ± 0.043 mM (HOG), thus suggesting that small amounts of extracellular Gln are sufficient for OD cell growth. Gln starvation does not significantly affect the cell content of anaplerotic substrates, which, consistently, are not able to rescue cell growth, but causes hindrance of the Wnt/β-catenin pathway and protein synthesis attenuation, which is mitigated by transient GS expression. Gln transport inhibitors cause partial depletion of intracellular Gln and cell growth inhibition, but do not lower cell viability. Therefore, GS-negative human oligodendroglioma cells are Gln-auxotrophic but do not use the amino acid for anaplerosis and, hence, are not Gln addicted, exhibiting only limited Gln requirements for survival and growth

Characterization of mammalian heart annexins with special reference to CaBP33 (annexin V)

AbstractPorcine heart was observed to express annexins V (CaBP33) and VI in large amounts, and annexins III and IV in much smaller amounts. Annexin V (CaBP33) in porcine heart was examined in detail by immunochemistry. Homogenization and further processing of heart in the presence of EGTA resulted in the recovery of annexin V (CaBP33) in the cytosolic fraction and in an EGTA-resistant, Triton X-100-soluble fraction from cardiac membranes. Including Ca2+ in the homogenization medium resulted in a significant decrease in the annexin V (CaBP33) content of the cytosolic fraction with concomitant increase in the content of this protein in myofibrils, mitochrondria, the sarcoplasmic reticulum and the sarcolemma. The amount of annexin V (CaBP33) in each of these subfractions depended on the free Ca2+ concentration in the homogenizing medium. At the lowest free Ca2+ concentration tested, 0.8 μM, only the sarcolemma appeared to contain bound annexin V (CaBP33). Membrane-bound annexins V (CaBP33) and VI partitioned in two fractions, one EGTA-resistant and Triton X-100-extractable, and one Triton X-100-resistant and EGTA-extractable. Altogether, these data suggest that annexins V and VI are involved in the regulation of membrane-related processes

A (RE)ESCRITA COMO ARTIFÍCIO PARA A AQUISIÇÃO DA AUTONOMIA, DA CRITICIDADE E DA COMPETÊNCIA DO ALUNO EM ATIVIDADES DE PRODUÇÃO TEXTUAL

O presente trabalho que segue é o resultado do período de observação e intervenção docente. Apresenta-se a análise das observações e da prática docente que foi aplicada realizada na Escola de Educação Básica Professor Iracy Tonello, em Xanxerê (SC), durante as 6ª, 7ª e 8ª fases da graduação, nos anos de 2015 e 2016. O estágio de observação e regência proporcionou ao acadêmico uma verdadeira visão do papel do docente em relação à sala de aula, proporcionando um confronto entre teoria e prática. Durante o processo de observação, elencou-se uma problemática que norteou o referencial teórico e o planejamento das aulas, sendo como tema: Como despertar no aluno o gosto pela leitura, possibilitando uma reescrita de qualidade. Para desenvolver o plano de ensino foi utilizada como metodologia a sequência didática, sendo possível desenvolver com os alunos a leitura, seguido da interpretação dos textos, visando a uma internalização do conteúdo seguido de uma melhor acomodação dos temas trabalhados. Conclui-se que o estágio de observação e regência deixaram marcas significativas na vida da acadêmica, possibilitando um confronto real entre a teoria e a prática, as quais vem acrescentar uma melhor preparação para a vida docente

OS MEIOS TECNOLÓGICOS NA EDUCAÇÃO

O presente trabalho apresenta considerações e vivências acerca da escola de Educação Básica, tendo como foco “a tecnologia atrelada ao Ensino de Língua Portuguesa e Literatura”. Atualmente a tecnologia exerce grande influência na vida dos educandos, dessa forma, o professor tem grandes desafios em sua prática docente, buscando diversificar seus métodos para conseguir resultados mais eficazes no seu fazer pedagógico. Com isso, este trabalho traz um apanhado geral dos motivos pelos quais a escola entra em divergência com os educandos ao tentar ministrar aulas somente de modo tradicional conservador, construindo métodos e formas de trabalhar em sala de aula atrelado à tecnologia, buscando da sequência didática para a elaboração dos planos aplicados. Também, considerações de vivências e práticas na Escola de Educação Básica Anacleto Damiani, instituição na qual se desenvolveu este projeto. A partir da experiência na elaboração deste estudo, foi possível estabelecer relações entre teoria e prática no cotidiano escolar e aprimorar práticas diárias que se traduzem num melhor desempenho da ação docente. Foi, ainda, uma experiência enriquecedora e estimulante para o autor, na medida em que lhe permitiu um contato direto com a realidade escolar, ministrando conteúdos internalizados no decorrer do Curso de Letras que foram postos em prática ao ministrar aulas nos Ensinos Médio e Fundamental. Por fim, a realização deste estudo foi uma grande oportunidade de verificar o quão importante é o contato direto com o ambiente profissional visando ao enriquecimento acadêmico-profissinal