Characterization of RNA Helicase CshA and Its Role in Protecting mRNAs and Small RNAs of Staphylococcus aureus Strain Newman

The toxin MazFsa in Staphylococcus aureus is a sequence-specific endoribonuclease that cleaves the majority of the mRNAs in vivo but spares many essential mRNAs (e.g., secY mRNA) and, surprisingly, an mRNA encoding a regulatory protein (i.e., sarA mRNA). We hypothesize that some mRNAs may be protected by RNA-binding protein(s) from degradation by MazFsa. Using heparin-Sepharose-enriched fractions that hybridized to sarA mRNA on Northwestern blots, we identified among multiple proteins the DEAD box RNA helicase CshA (NWMN_1985 or SA1885) by mass spectroscopy. Purified CshA exhibits typical RNA helicase activities, as exemplified by RNA-dependent ATPase activity and unwinding of the DNA-RNA duplex. A severe growth defect was observed in the cshA mutant compared with the parent when grown at 25°C but not at 37°C. Activation of MazFsa in the cshA mutant resulted in lower CFU per milliliter accompanied by a precipitous drop in viability (∼40%) compared to those of the parent and complemented strains. NanoString analysis reveals diminished expression of a small number of mRNAs and 22 small RNAs (sRNAs) in the cshA mutant versus the parent upon MazFsa induction, thus implying protection of these RNAs by CshA. In the case of the sRNA teg049 within the sarA locus, we showed that the protective effect was likely due to transcript stability as revealed by reduced half-life in the cshA mutant versus the parent. Accordingly, CshA likely stabilizes selective mRNAs and sRNAs in vivo and as a result enhances S. aureus survival upon MazFsa induction during stress

Star clusters with dual red clumps

A few star clusters in the Magellanic Clouds exhibit composite structures in the red-clump region of their colour-magnitude diagrams. The most striking case is NGC419 in the SMC, where the red clump is composed of a main blob as well as a distinct secondary feature. This structure is demonstrated to be real and corresponds to the simultaneous presence of stars which passed through electron degeneracy after central-hydrogen exhaustion and those that did not. This rare occurrence in a single cluster allows us to set stringent constraints on its age and on the efficiency of convective-core overshooting during main-sequence evolution. We present a more detailed analysis of NGC419, together with a first look at other populous LMC clusters which are apparently in the same phase: NGC1751, NGC1783, NGC1806, NGC1846, NGC1852 and NGC1917. We also compare these Magellanic Cloud cases with their Galactic counterparts, NGC752 and NGC7789. We emphasise the extraordinary potential of these clusters as absolute calibration marks on the age scale of stellar populations.Comment: contributed talk at IAUS 266 'Star clusters: basic galactic building blocks', eds R. de Grijs and J. Lepine. A high resolution version of Fig. 1 is available in http://stev.oapd.inaf.it/~lgirardi/NGC419_hr.pd

A Influência de fatores socioeconômicos na determinação do perfil de risco de alunos universitários

O estudo das finanças comportamentais vem ocupando espaço na área de finanças e, ao mesmo tempo, ensejando e estimulando trabalhos acadêmicos com vistas à explorar e desenvolver esta área de estudo. O objetivo principal deste trabalho consiste na análise da influência dos fatores socioeconômicos dos estudantes de Graduação de Administração na Mesorregião do Centro-Sul do Paraná na determinação do perfil de risco. O estudo caracteriza-se como exploratório, ex post facto, dimensão temporal transversal e escopo quantitativo. Os dados foram coletados dados por meio de questionário estruturado aplicado à uma amostra de 309 estudantes, em um universo de 648. O estudo testou a influência de três aspectos socioeconômicos: gênero, idade e renda – que consistiram as hipóteses da pesquisa. Concluiu-se que o gênero e a idade são aspectos determinantes do perfil de risco, evidenciando-se que os homens são mais propensos ao risco que as mulheres e que, à medida que aumenta a idade do indivíduo, diminui a propensão ao risco.  A renda não se mostrou significativa

Discovery of two distinct red clumps in NGC419: a rare snapshot of a cluster at the onset of degeneracy

Colour-magnitude diagrams (CMD) of the SMC star cluster NGC419, derived from HST/ACS data, reveal a well-delineated secondary clump located below the classical compact red clump typical of intermediate-age populations. We demonstrate that this feature belongs to the cluster itself, rather than to the underlying SMC field. Then, we use synthetic CMDs to show that it corresponds very well to the secondary clump predicted to appear as a result of He-ignition in stars just massive enough to avoid electron-degeneracy settling in their H-exhausted cores. The main red clump instead is made of the slightly less massive stars which passed through electron-degeneracy and ignited He at the tip of the RGB. In other words, NGC419 is the rare snapshot of a cluster while undergoing the fast transition from classical to degenerate H-exhausted cores. At this particular moment of a cluster's life, the colour distance between the main sequence turn-off and the red clump(s) depends sensitively on the amount of convective core overshooting, Lambda_c. By coupling measurements of this colour separation with fits to the red clump morphology, we are able to estimate simultaneously the cluster mean age (1.35(-0.04,+0.11) Gyr) and overshooting efficiency (Lambda_c=0.47(-0.04,+0.14)). Therefore, clusters like NGC419 may constitute important marks in the age scale of intermediate-age populations. After eye inspection of other CMDs derived from HST/ACS data, we suggest that the same secondary clump may also be present in the LMC clusters NGC1751, 1783, 1806, 1846, 1852, and 1917.Comment: To appear in MNRAS Letters (www.blackwell-synergy.com). Better printed in colou

Efeito do Cermet na manutenção do esmalte sem apoio de dentina em restaurações de amálgama

This research evaluated the effect of CERMET in maintenance of dental enamel without dentin suport in amalgam restorations.Este estudo avaliou o efeito do CERMET na manutenção do esmalte socavado em restaurações de amálgama

A LIDERANÇA E A GESTÃO ESTRATÉGICA DE PESSOAS NAS INSTITUIÇÕES FINANCEIRAS

A temática da liderança tem sido objeto de inúmeros estudos e pesquisas, notadamente quando o crescimento e a expansão das organizações passam a requerer, cada vez mais, estratégias diferenciadas para a conquista e adesão das pessoas aos objetivos corporativos. Essa configuração elege a liderança como diferencial competitivo em um cenário que visa alcançar metas e resultados. A gestão de pessoas, apoiada pelas lideranças, desempenha uma função estratégica nas organizações, alinhando as pessoas à estratégia da organização. Está pesquisa tem como propósito analisar os estilos de liderança, a orientação para resultados e as praticas de gestão estratégica de pessoas utilizadas pelas Instituições Financeiras públicas e privadas. O estudo possui corte temporal transversal e é de natureza exploratória, com revisão em periódicos científicos. A pesquisa foi baseada em questionários estruturados que procuram medir as Políticas de Recursos Humanos (14 questões) e as Características de Liderança (13 questões). Os dados foram coletados no mês de Março de 2013, em 13 agencias bancárias com uma amostra de 124 bancários escolhidos aleatoriamente. Com uso da Análise Fatorial, as 27 questões iniciais foram resumidas em três fatores (dimensões): 1) Políticas de Recursos Humanos; 2) Liderança: Motivação e Eficiência em Resultados, e; 3) Liderança: Foco em Resultados. Nos três fatores identificados, as frequências concentraram-se substancialmente no último quartil, demonstrando avaliação elevada dos aspectos relacionados às Políticas de Recursos Humanos e características de Liderança.

Hardness evaluation of two composites restorative due to the variation of the distance from the curing light source, of further polymerization and of the surface finish

O objetivo deste trabalho foi avaliar a dureza de dois compósitos fotoativados. Os resultados mostraram que a dureza dos materiais variou com o tipo de material, a distância da fonte de luz, a polimerização adicional (60s) e o acabamento superficial.Surface hardness studies have been performed on two visible light-activated composit resins. It was found that the surface hardness of these materiais varied with: the material, the distance of the light source, the 60 second additional exposure end the surface finish

The star formation history of the SMC star cluster NGC419

The rich SMC star cluster NGC419 has recently been found to present both a broad main sequence turn-off and a dual red clump of giants, in the sharp colour-magnitude diagrams (CMD) derived from the High Resolution Channel of the Advanced Camera for Surveys on board the Hubble Space Telescope. In this work, we apply to the NGC419 data the classical method of star formation history (SFH) recovery via CMD reconstruction, deriving for the first time this function for a star cluster with multiple turn-offs. The values for the cluster metallicity, reddening, distance and binary fraction, were varied within the limits allowed by present observations. The global best-fitting solution is an excellent fit to the data, reproducing all the CMD features with striking accuracy. The corresponding star formation rate is provided together with estimates of its random and systematic errors. Star formation is found to last for at least 700 Myr, and to have a marked peak at the middle of this interval, for an age of 1.5 Gyr. Our findings argue in favour of multiple star formation episodes (or continued star formation) being at the origin of the multiple main sequence turn-offs in Magellanic Cloud clusters with ages around 1 Gyr. It remains to be tested whether alternative hypotheses, such as a main sequence spread caused by rotation, could produce similarly good fits to the data.Comment: 10 pages, MNRAS in pres

The star formation history of the Large Magellanic Cloud star cluster NGC1751

The HST/ACS colour-magnitude diagrams (CMD) of the populous LMC star cluster NGC1751 present both a broad main sequence turn-off and a dual clump of red giants. We show that the latter feature is real and associate it to the first appearance of electron-degeneracy in the H-exhausted cores of the cluster stars. We then apply to the NGC1751 data the classical method of star formation history (SFH) recovery via CMD reconstruction, for different radii corresponding to the cluster centre, the cluster outskirts, and the underlying LMC field. The mean SFH derived from the LMC field is taken into account during the stage of SFH-recovery in the cluster regions, in a novel approach which is shown to significantly improve the quality of the SFH results. For the cluster centre, we find a best-fitting solution corresponding to prolonged star formation for a for a timespan of 460 Myr, instead of the two peaks separated by 200 Myr favoured by a previous work based on isochrone fitting. Remarkably, our global best-fitting solution provides an excellent fit to the data - with chi^2 and residuals close to the theoretical minimum - reproducing all the CMD features including the dual red clump. The results for a larger ring region around the centre indicate even longer star formation, but in this case the results are of lower quality, probably because of the differential extinction detected in the area. Therefore, the presence of age gradients in NGC1751 could not be probed. Together with our previous findings for the SMC cluster NGC419, the present results for the NGC1751 centre argue in favour of multiple star formation episodes (or continued star formation) being at the origin of the multiple main sequence turn-offs in Magellanic Cloud clusters with ages around 1.5 Gyr.Comment: To appear soon in MNRAS. 12 pages, better printed in colou

The VMC Survey -- XXXIV. Morphology of Stellar Populations in the Magellanic Clouds

The Magellanic Clouds are nearby dwarf irregular galaxies whose morphologies show different properties when traced by different stellar populations, making them an important laboratory for studying galaxy morphologies. We study the morphology of the Magellanic Clouds using data from the VISTA survey of the Magellanic Clouds system (VMC). We used about $10$ and $2.5$ million sources across an area of $\sim105$ deg$^2$ and $\sim42$ deg$^2$ towards the Large and Small Magellanic Cloud (LMC and SMC), respectively. We estimated median ages of stellar populations occupying different regions of the near-infrared ($J-K_\mathrm{s}, K_\mathrm{s}$) colour-magnitude diagram. Morphological maps were produced and detailed features in the central regions were characterised for the first time with bins corresponding to a spatial resolution of $0.13$ kpc (LMC) and $0.16$ kpc (SMC). In the LMC, we find that main sequence stars show coherent structures that grow with age and trace the multiple spiral arms of the galaxy, star forming regions become dimmer as we progress in age, while supergiant stars are centrally concentrated. Intermediate-age stars, despite tracing a regular and symmetrical morphology, show central clumps and hints of spiral arms. In the SMC, young main sequence stars depict a broken bar. Intermediate-age populations show signatures of elongation towards the Magellanic Bridge that can be attributed to the LMC-SMC interaction $\sim200$ Myr ago. They also show irregular central features suggesting that the inner SMC has also been influenced by tidal interactions.Comment: Accepted for publication in MNRAS, 20 pages, 12 figures and 2 table