A model study of oceanic mechanisms affecting Equatorial Pacific sea surface temperature during the 1997-98 El Niño

In this study, the processes affecting sea surface temperature variability over the 1992–98 period, encompassing the very strong 1997–98 El Niño event, are analyzed. A tropical Pacific Ocean general circulation model, forced by a combination of weekly ERS1–2 and TAO wind stresses, and climatological heat and freshwater fluxes, is first validated against observations. The model reproduces the main features of the tropical Pacific mean state, despite a weaker than observed thermal stratification, a 0.1 m s−1 too strong (weak) South Equatorial Current (North Equatorial Countercurrent), and a slight underestimate of the Equatorial Undercurrent. Good agreement is found between the model dynamic height and TOPEX/Poseidon sea level variability, with correlation/rms differences of 0.80/4.7 cm on average in the 10°N–10°S band. The model sea surface temperature variability is a bit weak, but reproduces the main features of interannual variability during the 1992–98 period. The model compares well with the TAO current variability at the equator, with correlation/rms differences of 0.81/0.23 m s−1 for surface currents. The model therefore reproduces well the observed interannual variability, with wind stress as the only interannually varying forcing. This good agreement with observations provides confidence in the comprehensive three-dimensional circulation and thermal structure of the model. A close examination of mixed layer heat balance is thus undertaken, contrasting the mean seasonal cycle of the 1993–96 period and the 1997–98 El Niño. In the eastern Pacific, cooling by exchanges with the subsurface (vertical advection, mixing, and entrainment), the atmospheric forcing, and the eddies (mainly the tropical instability waves) are the three main contributors to the heat budget. In the central–western Pacific, the zonal advection by low-frequency currents becomes the main contributor. Westerly wind bursts (in December 1996 and March and June 1997) were found to play a decisive role in the onset of the 1997–98 El Niño. They contributed to the early warming in the eastern Pacific because the downwelling Kelvin waves that they excited diminished subsurface cooling there. But it is mainly through eastward advection of the warm pool that they generated temperature anomalies in the central Pacific. The end of El Niño can be linked to the large-scale easterly anomalies that developed in the western Pacific and spread eastward, from the end of 1997 onward. In the far-western Pacific, because of the shallower than normal thermocline, these easterlies cooled the SST by vertical processes. In the central Pacific, easterlies pushed the warm pool back to the west. In the east, they led to a shallower thermocline, which ultimately allowed subsurface cooling to resume and to quickly cool the surface layer.

Mechanisms of internalization and recycling of the chemokine receptor, CCR5

CCR5 is a G protein-coupled receptor that binds several natural chemokines but it is also a coreceptor for the entry of M tropic strains of HIV-1 into cells. Levels of CCR5 on the cell surface are important for the rate of HIV-1 infection and are determined by a number of factors including the rates of CCR5 internalization and recycling. Here we investigated the involvement of the actin cytoskeleton in the control of ligand-induced internalization and recycling of CCR5. Cytochalasin D, an actin depolymerizing agent, inhibited chemokine-induced internalization of CCR5 and recycling of the receptor in stably transfected CHO cells and in the monocytic cell line, THP-1. CCR5 internalization and recycling were inhibited by Toxin B and C-3 exoenzyme treatment in CHO and THP-1 cells, confirming activation of members of the RhoGTPase family by CCR5. The specific Rho kinase inhibitor Y27632, however, had no effect on CCR5 internalization or recycling. Ligand-induced activation of CCR5 leads to Rho kinase-dependent formation of focal adhesion complexes. These data indicate that CCR5 internalization and recycling are regulated by actin polymerization and activation of small G proteins in a Rho-dependent manner.

Effect of fluid mechanical stresses and plasma constituents on aggregation of LDL

LDL aggregates when exposed to even moderate fluid mechanical stresses in the laboratory, yet its half-life in the circulation is 2-3 days, implying that little aggregation occurs. LDL may be protected from aggregation in vivo by components of plasma, or by a qualitative difference in flows. Previous studies have shown that HDL and albumin inhibit the aggregation induced by vortexing. Using a more reproducible method of inducing aggregation and assessing aggregation both spectrophotometrically and by sedimentation techniques, we showed that at physiological concentrations, albumin is the more effective inhibitor, and that aggregation is substantially but not completely inhibited in plasma. Heat denatured and fatty-acid-stripped albumin were more effective inhibitors than normal albumin, supporting the idea that hydrophobic interactions are involved. Aggregation of LDL in a model reproducing several aspects of flow in the circulation was 200-fold slower, but was still inhibited by HDL and albumin, suggesting similar mechanisms are involved. Within the sensitivity of our technique, LDL aggregation did not occur in plasma exposed to these flows.jlr Thus, as a result of the characteristics of blood flow and the inhibitory effects of plasma components, particularly albumin, LDL aggregation is unlikely to occur within the circulation.

Upper-mantle seismic structure beneath SE and Central Brazil from P- and S-wave regional traveltime tomography

We present models for the upper-mantle velocity structure beneath SE and Central Brazil using independent tomographic inversions of P- and S-wave relative arrival-time residuals (including core phases) from teleseismic earthquakes. The events were recorded by a total of 92 stations deployed through different projects, institutions and time periods during the years 1992-2004. Our results show correlations with the main tectonic structures and reveal new anomalies not yet observed in previous works. All interpretations are based on robust anomalies, which appear in the different inversions for P-and S-waves. The resolution is variable through our study volume and has been analyzed through different theoretical test inversions. High-velocity anomalies are observed in the western portion of the Sao Francisco Craton, supporting the hypothesis that this Craton was part of a major Neoproterozoic plate (San Franciscan Plate). Low-velocity anomalies beneath the Tocantins Province (mainly fold belts between the Amazon and Sao Francisco Cratons) are interpreted as due to lithospheric thinning, which is consistent with the good correlation between intraplate seismicity and low-velocity anomalies in this region. Our results show that the basement of the Parana Basin is formed by several blocks, separated by suture zones, according to model of Milani & Ramos. The slab of the Nazca Plate can be observed as a high-velocity anomaly beneath the Parana Basin, between the depths of 700 and 1200 km. Further, we confirm the low-velocity anomaly in the NE area of the Parana Basin which has been interpreted by VanDecar et al. as a fossil conduct of the Tristan da Cunha Plume related to the Parana flood basalt eruptions during the opening of the South Atlantic.

Basement depths in the Parecis Basin (Amazon) with receiver functions from small local earthquakes in the Porto dos Gauchos seismic zone

Receiver functions from small local earthquakes were used to determine sediment thicknesses in Porto dos Gauchos seismic zone (PGSZ), Parecis basin, Amazonian craton, Brazil. The high velocity contrast between basement and sediments (P-wave velocities of 6.1 and 3.0 km/s, respectively) favors the generation of clear P-to-S converted phases (Ps) seen in the radial component, and also S-to-P conversions (Sp) seen in the vertical component. A reference 10 velocity model determined with shallow refraction experiment in PGSZ helped to convert Ps P time differences to basement depths at 15 stations deployed for aftershocks studies. The results of receiver function integrated with the shallow refraction reveal that the basement depths in the PGSZ increases from the basin border in the north up to about 600 m depth in the south. The basement topography, however, does not vary smoothly and a basement high with a steep topography was detected near the epicentral area. A 400 m elevation difference within 1.7 km distance suggests a possible border fault of a buried graben. This feature seems to be oriented roughly WSW-ENE and could indicate basement structures related to the seismicity of the Porto dos Gauchos Seismic Zone. (C) 2011 Elsevier Ltd. All rights reserved.

Organizações sociais em Pernambuco: o desenho institucional do controle externo sobre os contratos de gestão

O objetivo desta pesquisa foi analisar o desenho institucional do controle externo sobre os contratos de gestão no âmbito do Tribunal de Contas do estado de Pernambuco quanto a sua aderência aos conteúdos da lei estadual que disciplina as Organizações Sociais e quanto a sua observância por parte dos atores envolvidos: Administração Pública, técnicos do tribunal de contas e membros do seu corpo julgador. Foram assumidas as seguintes premissas: que os novos arranjos de prestação de serviços públicos, por meio de parcerias com as Organizações Sociais, demandam por parte dos Tribunais de Contas desenhos institucionais de fiscalização específicos, que a pesar de variáveis devem primar por sua capacidade de revelar informações; que o processo de formatação destes desenhos institucionais deve ser dinâmico, permitindo-se que as contigências experimentadas na sua implementação possam contribuir no seu aperfeiçoamento; e que esses desenhos institucionais geram impacto no comportamento dos atores envolvidos. O estudo foi realizado por meio de pesquisa documental. A metodologia qualitativa de análise de conteúdo foi escolhida para análise dos dados. Os resultados da pesquisa permitiram concluir que o desenho institucional de controle dos contratos de gestão no âmbito do TCE-PE caracteriza-se por sua fragilidade como mecanismo de revelação de informação e, consequentemente, não contribui para a redução da assimetria de informação que se estabelece com a implementação dos contratos de gestão. Adicionalmente, compromete e limita o desempenho do Tribunal de Contas no controle destes ajustes. Verificou-se, também, uma a baixa observância do desenho institucional identificado, em que pese sua fragilidade, por parte dos atores envolvidos no controle dos contratos de gestão, implicando em uma baixa institucionalização deste desenho. Os resultados devem proporcionar uma rediscussão acerca dos mecanismos de controle dos contratos de gestão por parte do TCE-PE, que poderá resultar em um novo desenho institucional com vistas a conferir maior transparência às parcerias com as Organizações Sociais.

Chronic restraint or variable stresses differently affect the behavior, corticosterone secretion and body weight in rats

Organisms are constantly subjected to stressful stimuli that affect numerous physiological processes and activate the hypothalamo-pituitary-adrenal (HPA) axis, increasing the release of glucocorticoids. Exposure to chronic stress is known to alter basic mechanisms of the stress response. The purpose of the present study was to compare the effect of two different stress paradigms (chronic restraint or variable stress) on behavioral and corticosterone release to a subsequent exposure to stressors. Considering that the HPA axis might respond differently when it is challenged with a novel or a familiar stressor we investigated the changes in the corticosterone levels following the exposure to two stressors: restraint (familiar stress) or forced novelty (novel stress). The changes in the behavioral response were evaluated by measuring the locomotor response to a novel environment. In addition, we examined changes in body, adrenals, and thymus weights in response to the chronic paradigms. Our results showed that exposure to chronic variable stress increased basal plasma corticosterone levels and that both, chronic restraint and variable stresses, promote higher corticosterone levels in response to a novel environment, but not to a challenge restraint stress, as compared to the control (non-stressed) group. Exposure to chronic restraint leads to increased novelty-induced locomotor activity. Furthermore, only the exposure to variable stress reduced body weights. In conclusion, the present results provide additional evidence on how chronic stress affects the organism physiology and point to the importance of the chronic paradigm and challenge stress on the behavioral and hormonal adaptations induced by chronic stress. (c) 2006 Elsevier B.V. All rights reserved.

Chlorophyll fluorescence as a marker for herbicide mechanisms of action

Photosynthesis is the single most important source of 02 and organic chemical energy necessary to support all non-autotrophic life forms. Plants compartmentalize this elaborate biochemical process within chloroplasts in order to safely harness the power of solar energy and convert it into usable chemical units. Stresses (biotic or abiotic) that challenge the integrity of the plant cell are likely to affect photosynthesis and alter chlorophyll fluorescence. A simple three-step assay was developed to test selected herbicides representative of the known herbicide mechanisms of action and a number of natural phytotoxins to determine their effect on photosynthesis as measured by chlorophyll fluorescence. The most active compounds were those interacting directly with photosynthesis (inhibitors of photosystem I and II), those inhibiting carotenoid synthesis, and those with mechanisms of action generating reactive oxygen species and lipid peroxidation (uncouplers and inhibitors of protoporphyrinogen oxidase). Other active compounds targeted lipids (very-long-chain fatty acid synthase and removal of cuticular waxes). Therefore, induced chlorophyll fluorescence is a good biomarker to help identify certain herbicide modes of action and their dependence on light for bioactivity. Published by Elsevier B.V.

Selection of endogenous genes for gene expression studies in Eucalyptus under biotic (Puccinia psidii) and abiotic (acibenzolar-S-methyl) stresses using RT-qPCR

Background: Rust caused by Puccinia psidii Winter has been limiting for the establishment of new Eucalyptus plantations, as well as for resprouting of susceptible genetic materials. Identifying host genes involved in defense responses is important to elucidate resistance mechanisms. Reverse transcription-quantitative PCR is the most common method of mRNA quantitation for gene expression analysis. This method generally employs a reference gene as an internal control to normalize results. A good endogenous control transcript shows minimal variation due to experimental conditions. Findings. We analyzed the expression of 13 genes to identify transcripts with minimal variation in leaves of 60-day-old clonal seedlings of two Eucalyptus clones (rust-resistant and susceptible) subjected to biotic (P. psidii) and abiotic (acibenzolar-S-methyl, ASM) stresses. Conclusions. For tissue samples of clones that did not receive any stimulus, a combination of the eEF2 and EglDH genes was the best control for normalization. When pathogen-inoculated and uninoculated plant samples were compared, eEF2 and UBQ together were more appropriate as normalizers. In ASM-treated and untreated leaves of both clones, transcripts of the CYP and elF4B genes combined were the ones with minimal variation. Finally, when comparing expression in both clones for ASM-treated leaves, P. psidii-inoculated leaves, ASM-treated plus P. psidii-inoculated leaves, and their respective controls, the genes with the most stable expression were EgIDH and UBQ. The chitinase gene, which is highly expressed in studies on plant resistance to phytopathogens, was used to confirm variation in gene expression due to the treatments. © 2010 Laia et al; licensee BioMed Central Ltd.

Design sistêmico e ecoinovação em APLs: o método F.L.O.R.A como estratégia sustentável aplicada para o polo de confecções de Pernambuco

Pós-graduação em Design - FAAC

Análise morfotectônica do Planalto Ocidental Paulista, ao sul do Rio Tietê: indicadores de deformações neotectônicas na fisiografia da paisagem

Pós-graduação em Geologia Regional - IGCE

Selenium and sulfur: mitigation in plant stresses

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Selenium and sulfur: mitigation in plant stresses

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Focal adhesion kinase governs cardiac concentric hypertrophic growth by activating the AKT and mTOR pathways

The heart responds to sustained overload by hypertrophic growth in which the myocytes distinctly thicken or elongate on increases in systolic or diastolic stress. Though potentially adaptive, hypertrophy itself may predispose to cardiac dysfunction in pathological settings. The mechanisms underlying the diverse morphology and outcomes of hypertrophy are uncertain. Here we used a focal adhesion kinase (FAK) cardiac-specific transgenic mice model (FAK-Tg) to explore the function of this non-receptor tyrosine kinase on the regulation of myocyte growth. FAK-Tg mice displayed a phenocopy of concentric cardiac hypertrophy, reflecting the relative thickening of the individual myocytes. Moreover, FAK-Tg mice showed structural, functional and molecular features of a compensated hypertrophic growth, and preserved responses to chronic pressure overload. Mechanistically, FAK overexpression resulted in enhanced myocardial FAK activity, which was proven by treatment with a selective FAK inhibitor to be required for the cardiac hypertrophy in this model. Our results indicate that upregulation of FAK does not affect the activity of Src/ERK1/2 pathway, but stimulated signaling by a cascade that encompasses PI3K, AKT, mTOR, S6K and rpS6. Moreover, inhibition of the mTOR complex by rapamycin extinguished the cardiac hypertrophy of the transgenic FAK mice. These findings uncover a unique role for FAK in regulating the signaling mechanisms that governs the selective myocyte growth in width, likely controlling the activity of PI3K/AKT/mTOR pathway, and suggest that FAK activation could be important for the adaptive response to increases in cardiac afterload. This article is part of a Special Issue entitled "Local Signaling in Myocytes". (C) 2011 Elsevier Ltd. All rights reserved.

LGI2 truncation causes a remitting focal epilepsy in dogs

One quadrillion synapses are laid in the first two years of postnatal construction of the human brain, which are then pruned until age 10 to 500 trillion synapses composing the final network. Genetic epilepsies are the most common neurological diseases with onset during pruning, affecting 0.5% of 2-10-year-old children, and these epilepsies are often characterized by spontaneous remission. We previously described a remitting epilepsy in the Lagotto romagnolo canine breed. Here, we identify the gene defect and affected neurochemical pathway. We reconstructed a large Lagotto pedigree of around 34 affected animals. Using genome-wide association in 11 discordant sib-pairs from this pedigree, we mapped the disease locus to a 1.7 Mb region of homozygosity in chromosome 3 where we identified a protein-truncating mutation in the Lgi2 gene, a homologue of the human epilepsy gene LGI1. We show that LGI2, like LGI1, is neuronally secreted and acts on metalloproteinase-lacking members of the ADAM family of neuronal receptors, which function in synapse remodeling, and that LGI2 truncation, like LGI1 truncations, prevents secretion and ADAM interaction. The resulting epilepsy onsets at around seven weeks (equivalent to human two years), and remits by four months (human eight years), versus onset after age eight in the majority of human patients with LGI1 mutations. Finally, we show that Lgi2 is expressed highly in the immediate post-natal period until halfway through pruning, unlike Lgi1, which is expressed in the latter part of pruning and beyond. LGI2 acts at least in part through the same ADAM receptors as LGI1, but earlier, ensuring electrical stability (absence of epilepsy) during pruning years, preceding this same function performed by LGI1 in later years. LGI2 should be considered a candidate gene for common remitting childhood epilepsies, and LGI2-to-LGI1 transition for mechanisms of childhood epilepsy remission.