884 resultados para Protection by p-cycles


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In Alzheimer disease (AD) the amyloid beta-peptide (A beta) accumulates in plaques in the brain. A beta can be neurotoxic by a mechanism involving induction of reactive oxygen species (ROS) and elevation of intracellular free calcium levels ([Ca2+]i). In light of evidence for an inflammatory response in the brain in AD and reports of increased levels of tumor necrosis factor (TNF) in AD brain we tested the hypothesis that TNFs affect neuronal vulnerability to A beta. A beta-(25-35) and A beta-(1-40) induced neuronal degeneration in a concentration- and time-dependent manner. Pretreatment of cultures for 24 hr with TNF-beta or TNF-alpha resulted in significant attenuation of A beta-induced neuronal degeneration. Accumulation of peroxides induced in neurons by A beta was significantly attenuated in TNF-pretreated cultures, and TNFs protected neurons against iron toxicity, suggesting that TNFs induce antioxidant pathways. The [Ca2+]i response to glutamate (quantified by fura-2 imaging) was markedly potentiated in neurons exposed to A beta, and this action of A beta was suppressed in cultures pretreated with TNFs. Electrophoretic mobility-shift assays demonstrated an induction of a kappa beta-binding activity in hippocampal cells exposed to TNFs. Exposure of cultures to I kappa B (MAD3) antisense oligonucleotides, a manipulation designed to induce NF-kappa B, mimicked the protection by TNFs. These data suggest that TNFs protect hippocampal neurons against A beta toxicity by suppressing accumulation of ROS and Ca2+ and that kappa B-dependent transcription is sufficient to mediate these effects. A modulatory role for TNF in the neurodegenerative process in AD is proposed.

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Os mecanismos moleculares envolvidos na resistência de plantas contra patógenos são um tema bastante discutido no meio acadêmico, sendo o objetivo maior dos estudos a diminuição das perdas de produtividade provocadas por doenças em plantações do mundo todo. Muitos modelos de interação patógeno-hospedeiro foram propostos e desenvolvidos priorizando plantas e culturas de rápido desenvolvimento com ciclo de vida curto. Espécies de ciclo longo, porém, devem lidar durante anos - ao menos até a idade reprodutiva - contra o ataque de bactérias, fungos e vírus, sem contar, nesse meio tempo, com recombinações genéticas e mutações que tornariam possível o escape contra as moléstias causadas por microrganismos. Assim, como alternativa aos modelos usuais, o presente trabalho estudou um diferente par de antagonistas: Eucalyptus grandis e Puccinia psidii. Apesar da contribuição de programas de melhoramento genético, o patossistema E. grandis X P. psidii ainda é pouco descrito no nível molecular, havendo poucos estudos sobre os processos e as moléculas que agem de forma a conferir resistência às plantas. Assim, buscando o melhor entendimento da relação entre E. grandis X P. psidii, o presente trabalho estudou a mudança dos perfis de proteínas e metabólitos secundários ocorrida nos tecidos foliares de plantas resistentes e susceptíveis durante a infecção pelo patógeno, com o auxílio da técnica de cromatografia líquida acoplada à espectrometria de massas. Os resultados obtidos indicam que as plantas resistentes percebem a presença do patógeno logo nas primeiras horas pós-infecção, produzindo proteínas ligadas à imunidade (HSP90, ILITYHIA, LRR Kinase, NB-ARC disease resistance protein). Essa percepção desencadeia a produção de proteínas de parede celular e de resposta oxidativa, além de modificar o metabolismo primário e secundário. As plantas susceptíveis, por outro lado, têm o metabolismo subvertido, produzindo proteínas responsáveis pelo afrouxamento da parede celular, beneficiando a absorção de nutrientes, crescimento e propagação de P. psidii. No trabalho também são propostos metabólitos biomarcadores de resistência, moléculas biomarcadoras de resposta imune e sinais da infecção por patógeno em E. grandis.

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En 1933, por iniciativa municipal y con el apoyo del Gobierno, con la intención de captar un turismo extranjero y nacional de élite generando una nueva ‘industria’, se convoca el concurso de anteproyectos para la construcción de una ciudad satélite (a modo de ciudad jardín) para destinarla a ciudad de vacaciones en la Playa de San Juan (cvPSJ), Alicante, al que se presentan tres propuestas. Aquí se estudia el anteproyecto ganador (de P. Muguruza), que resulta pionero por las técnicas urbanísticas empleadas (información y zonificación), por la aplicación de la fotografía para la inserción de arquitecturas y equipamientos y por la sensibilidad desplegada en la protección del patrimonio cultural (medioambiental e histórico). Los referentes para este macro complejo turístico (de casi 10 km2), coetáneo a la Ciutat del Repós i Vacances (CRV) de Castelldefels, no proceden tanto de Europa como de EUA. Se realiza un análisis pormenorizado de la ordenación urbanística en atención a cómo el territorio existente la condiciona y se entrelaza con estrategias de promoción turística, donde se combinan la tríada: hotel, deporte y naturaleza (alojamiento, ocio y salud). Pero toda la ciudad está enfocada a un turismo burgués, para el que se prevé una arquitectura comercial que pronto envejecería en su repertorio. Veinticinco años después, en 1958, cuando las condiciones económicas y sociales fueron favorables al desarrollo de la zona, el mundo sería ya otro y el proyecto quedó obsoleto.

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Plant crop yields are negatively conditioned by a large set of biotic and abiotic factors. An alternative to mitigate these adverse effects is the use of fungal biological control agents and endophytes. The egg-parasitic fungus Pochonia chlamydosporia has been traditionally studied because of its potential as a biological control agent of plant-parasitic nematodes. This fungus can also act as an endophyte in monocot and dicot plants, and has been shown to promote plant growth in different agronomic crops. An Affymetrix 22K Barley GeneChip was used in this work to analyze the barley root transcriptomic response to P. chlamydosporia root colonization. Functional gene ontology (GO) and gene set enrichment analyses showed that genes involved in stress response were enriched in the barley transcriptome under endophytism. An 87.5 % of the probesets identified within the abiotic stress response group encoded heat shock proteins. Additionally, we found in our transcriptomic analysis an up-regulation of genes implicated in the biosynthesis of plant hormones, such as auxin, ethylene and jasmonic acid. Along with these, we detected induction of brassinosteroid insensitive 1-associated receptor kinase 1 (BR1) and other genes related to effector-triggered immunity (ETI) and pattern-triggered immunity (PTI). Our study supports at the molecular level the growth-promoting effect observed in plants endophytically colonized by P. chlamydosporia, which opens the door to further studies addressing the capacity of this fungus to mitigate the negative effects of biotic and abiotic factors on plant crops.

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Pochonia chlamydosporia (Pc), a nematophagous fungus and root endophyte, uses appressoria and extracellular enzymes, principally proteases, to infect the eggs of plant parasitic nematodes (PPN). Unlike other fungi, Pc is resistant to chitosan, a deacetylated form of chitin, used in agriculture as a biopesticide to control plant pathogens. In the present work, we show that chitosan increases Meloidogyne javanica egg parasitism by P. chlamydosporia. Using antibodies specific to the Pc enzymes VCP1 (a subtilisin), and SCP1 (a serine carboxypeptidase), we demonstrate chitosan elicitation of the fungal proteases during the parasitic process. Chitosan increases VCP1 immuno-labelling in the cell wall of Pc conidia, hyphal tips of germinating spores, and in appressoria on infected M. javanica eggs. These results support the role of proteases in egg parasitism by the fungus and their activation by chitosan. Phylogenetic analysis of the Pc genome reveals a large diversity of subtilisins (S8) and serine carboxypeptidases (S10). The VCP1 group in the S8 tree shows evidence of gene duplication indicating recent adaptations to nutrient sources. Our results demonstrate that chitosan enhances Pc infectivity of nematode eggs through increased proteolytic activities and appressoria formation and might be used to improve the efficacy of M. javanica biocontrol.

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Plasmodium falciparum infection during pregnancy leads to abortions, stillbirth, low birth weight, and maternal mortality. Infected erythrocytes (IEs) accumulate in the placenta by adhering to chondroitin sulfate A (CSA) via var2CSA protein exposed on the P. falciparum IE membrane. Plasmodium berghei IE infection in pregnant BALB/c mice is a model for severe placental malaria (PM). Here, we describe a transgenic P. berghei parasite expressing the full-length var2CSA extracellular region (domains DBL1X to DBL6ε) fused to a P. berghei exported protein (EMAP1) and characterize a var2CSA-based mouse model of PM. BALB/c mice were infected at midgestation with different doses of P. berghei-var2CSA (P. berghei-VAR) or P. berghei wild-type IEs. Infection with 10(4) P. berghei-VAR IEs induced a higher incidence of stillbirth and lower fetal weight than P. berghei At doses of 10(5) and 10(6) IEs, P. berghei-VAR-infected mice showed increased maternal mortality during pregnancy and fetal loss, respectively. Parasite loads in infected placentas were similar between parasite lines despite differences in maternal outcomes. Fetal weight loss normalized for parasitemia was higher in P. berghei-VAR-infected mice than in P. berghei-infected mice. In vitro assays showed that higher numbers of P. berghei-VAR IEs than P. berghei IEs adhered to placental tissue. Immunization of mice with P. berghei-VAR elicited IgG antibodies reactive to DBL1-6 recombinant protein, indicating that the topology of immunogenic epitopes is maintained between DBL1-6-EMAP1 on P. berghei-VAR and recombinant DBL1-6 (recDBL1-6). Our data suggested that impairments in pregnancy caused by P. berghei-VAR infection were attributable to var2CSA expression. This model provides a tool for preclinical evaluation of protection against PM induced by approaches that target var2CSA.

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In this short review, we provide some new insights into the material synthesis and characterization of modern multi-component superconducting oxides. Two different approaches such as the high-pressure, high-temperature method and ceramic combinatorial chemistry will be reported with application to several typical examples. First, we highlight the key role of the extreme conditions in the growth of Fe-based superconductors, where a careful control of the composition-structure relation is vital for understanding the microscopic physics. The availability of high-quality LnFeAsO (Ln = lanthanide) single crystals with substitution of O by F, Sm by Th, Fe by Co, and As by P allowed us to measure intrinsic and anisotropic superconducting properties such as Hc2, Jc. Furthermore, we demonstrate that combinatorial ceramic chemistry is an efficient way to search for new superconducting compounds. A single-sample synthesis concept based on multi-element ceramic mixtures can produce a variety of local products. Such a system needs local probe analyses and separation techniques to identify compounds of interest. We present the results obtained from random mixtures of Ca, Sr, Ba, La, Zr, Pb, Tl, Y, Bi, and Cu oxides reacted at different conditions. By adding Zr but removing Tl, Y, and Bi, the bulk state superconductivity got enhanced up to about 122 K.

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The research cruise SO79 with RV SONNE (April 18 to June 09 1992) aimed to assess the impact of a potential mining activity on the sensitive deep-sea ecosystem of the Peru Basin. Up to now only results of reconnaissance surveys of the extended manganese nodule field discovered in 1978 in the Peru Basin are available. The hydroacoustic, sedimentological, and geochemical studies on data and sample material of SO79 came to the following results: a small-scaled variation in thickness respectively type of surface sediments shown by the sediment echosounder respectively the side-scan-sonar is assumably due to variations in deposition or erosion. The composition of sediments is controlled by climatic cycles of different length which were caused by the variable influence of glaciation of the northern hemisphere. We think that during the quaternary a deep-water circulation reduced in intensity and O2-content may have produced a suboxic diagenetic environment which led to a remobilization and redeposition of Mn forming manganese nodules in the oxic surface sediments. Near the distinct redox boundary at about 10 cm depth the growth conditions for nodules are extremely favourable. Due to the great variability of sediments the impact of deep-sea mining will be highly variable and the disturbance of the seafloor will change the ecosystem considerably.

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"Reactor technology."

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Includes bibliographies.

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Mode of access: Internet.

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CONTENTS. (cont.) --The Christianity of the fourth Gospel, by the Rev. C. B. Hedrick.--Correctness, by the Rev. M. B. Stewart.--An optimistic realist, Ernst Zahn, by B. Q. Morgan.--The hermit story, as used by Voltaire and Mark Twain, by F. A. G. Cowper.--Thumbnail classics. Jack Harker at Yalevard, by P. Curtiss.--The man who heard everything, by W. Trumbull.--"Whiskey, bullets, and..."--The novelist takes to real estate, by R. Wright.