8,366 research outputs found

    Comparative pan-genome analysis of Piscirickettsia salmonis reveals genomic divergences within genogroups

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    Indexación: Scopus.Piscirickettsia salmonis is the etiological agent of salmonid rickettsial septicemia, a disease that seriously affects the salmonid industry. Despite efforts to genomically characterize P. salmonis, functional information on the life cycle, pathogenesis mechanisms, diagnosis, treatment, and control of this fish pathogen remain lacking. To address this knowledge gap, the present study conducted an in silico pan-genome analysis of 19 P. salmonis strains from distinct geographic locations and genogroups. Results revealed an expected open pan-genome of 3,463 genes and a core-genome of 1,732 genes. Two marked genogroups were identified, as confirmed by phylogenetic and phylogenomic relationships to the LF-89 and EM-90 reference strains, as well as by assessments of genomic structures. Different structural configurations were found for the six identified copies of the ribosomal operon in the P. salmonis genome, indicating translocation throughout the genetic material. Chromosomal divergences in genomic localization and quantity of genetic cassettes were also found for the Dot/Icm type IVB secretion system. To determine divergences between core-genomes, additional pan-genome descriptions were compiled for the so-termed LF and EM genogroups. Open pan-genomes composed of 2,924 and 2,778 genes and core-genomes composed of 2,170 and 2,228 genes were respectively found for the LF and EM genogroups. The core-genomes were functionally annotated using the Gene Ontology, KEGG, and Virulence Factor databases, revealing the presence of several shared groups of genes related to basic function of intracellular survival and bacterial pathogenesis. Additionally, the specific pan-genomes for the LF and EM genogroups were defined, resulting in the identification of 148 and 273 exclusive proteins, respectively. Notably, specific virulence factors linked to adherence, colonization, invasion factors, and endotoxins were established. The obtained data suggest that these genes could be directly associated with inter-genogroup differences in pathogenesis and host-pathogen interactions, information that could be useful in designing novel strategies for diagnosing and controlling P. salmonis infection. © 2017 Nourdin-Galindo, Sánchez, Molina, Espinoza-Rojas, Oliver, Ruiz, Vargas-Chacoff, Cárcamo, Figueroa, Mancilla, Maracaja-Coutinho and Yañez.https://www.frontiersin.org/articles/10.3389/fcimb.2017.00459/ful

    Controlling a resonant transmission across the δ\delta'-potential: the inverse problem

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    Recently, the non-zero transmission of a quantum particle through the one-dimensional singular potential given in the form of the derivative of Dirac's delta function, λδ(x)\lambda \delta'(x) , with λR\lambda \in \R, being a potential strength constant, has been discussed by several authors. The transmission occurs at certain discrete values of λ\lambda forming a resonance set λnn=1{\lambda_n}_{n=1}^\infty. For λλnn=1\lambda \notin {\lambda_n}_{n=1}^\infty this potential has been shown to be a perfectly reflecting wall. However, this resonant transmission takes place only in the case when the regularization of the distribution δ(x)\delta'(x) is constructed in a specific way. Otherwise, the δ\delta'-potential is fully non-transparent. Moreover, when the transmission is non-zero, the structure of a resonant set depends on a regularizing sequence Δε(x)\Delta'_\varepsilon(x) that tends to δ(x)\delta'(x) in the sense of distributions as ε0\varepsilon \to 0. Therefore, from a practical point of view, it would be interesting to have an inverse solution, i.e. for a given λˉR\bar{\lambda} \in \R to construct such a regularizing sequence Δε(x)\Delta'_\varepsilon(x) that the δ\delta'-potential at this value is transparent. If such a procedure is possible, then this value λˉ\bar{\lambda} has to belong to a corresponding resonance set. The present paper is devoted to solving this problem and, as a result, the family of regularizing sequences is constructed by tuning adjustable parameters in the equations that provide a resonance transmission across the δ\delta'-potential.Comment: 21 pages, 4 figures. Corrections to the published version added; http://iopscience.iop.org/1751-8121/44/37/37530

    Análise de tendências dos principais fatores determinantes dos processos hidrológicos na Rede AgroHidro.

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    Este projeto propõe analisar a evolução histórica, identifi car tendências em séries temporais e caracterizar o estado presente de fatores correlacionados aos processos hidrológicos em grandes bacias hidrográfi cas nacionais, em bacias representativas de ecorregiões e nas bacias a serem monitoradas e/ou modeladas pelo projeto, distribuídas nos diferentes biomas brasileiros. Sendo assim, a análise de tendências é o tema central deste Projeto Componente e permitirá correlacionar fatores e entender, com foco no setor agrícola, como tem sido a evolução na oferta e demanda de água ao longo dos anos e como o uso da terra e variáveis sócio-econômicas infl uenciam na disponibilidade e na qualidade da água. A análise de tendências permite entender o passado, caracterizar o cenário atual e como chegamos a ele e, fi nalmente, projetar cenários futuros plausíveis, além de determinar com que velocidade as alterações ocorrem. Os resultados esperados deste projeto, somados às projeções de cenários de mudanças climáticas globais ou regionais, terão forte impacto na análise da vulnerabilidade dos sistemas hidrológicos brasileiros e nas propostas de mitigação e adaptação às novas situações, certamente embasadas em tecnologias que promovam o uso eficiente da água, em termos de quantidade e qualidade, buscando garantir, de maneira sustentável, as demandas da sociedade e do setor agrícola brasileiro

    Comparative Evolution of Sand Fly Salivary Protein Families and Implications for Biomarkers of Vector Exposure and Salivary Vaccine Candidates

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    Sand fly salivary proteins that produce a specific antibody response in humans and animal reservoirs have been shown to be promising biomarkers of sand fly exposure. Furthermore, immunity to sand fly salivary proteins were shown to protect rodents and non-human primates against Leishmania infection. We are missing critical information regarding the divergence amongst sand fly salivary proteins from different sand fly vectors, a knowledge that will support the search of broad or specific salivary biomarkers of vector exposure and those for vaccines components against leishmaniasis. Here, we compare the molecular evolution of the salivary protein families in New World and Old World sand flies from 14 different sand fly vectors. We found that the protein families unique to OW sand flies are more conserved than those unique to NW sand flies regarding both sequence polymorphisms and copy number variation. In addition, the protein families unique to OW sand flies do not display as many conserved cysteine residues as the one unique to the NW group (28.5% in OW vs. 62.5% in NW). Moreover, the expression of specific protein families is restricted to the salivary glands of unique sand fly taxon. For instance, the ParSP15 family is unique to the Larroussius subgenus whereas phospholipase A2 is only expressed in member of Larroussius and Adlerius subgenera. The SP2.5-like family is only expressed in members of the Phlebotomus and Paraphlebotomus subgenera. The sequences shared between OW and NW sand flies have diverged at similar rates (38.7 and 45.3% amino acid divergence, respectively), yet differences in gene copy number were evident across protein families and sand fly species. Overall, this comparative analysis sheds light on the different modes of sand fly salivary protein family divergence. Also, it informs which protein families are unique and conserved within taxon for the choice of taxon-specific biomarkers of vector exposure, as well as those families more conserved across taxa to be used as pan-specific vaccines for leishmaniasis

    Electron-positron pair production in the Aharonov-Bohm potential

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    In the framework of QED we evaluate the cross section for electron-positron pair production by a single photon in the presence of the external Aharonov-Bohm potential in first order of perturbation theory. We analyse energy, angular and polarization distributions at different energy regimes: near the threshold and at high photon energies.Comment: LaTeX file, 13 page

    Monitorização in continuum da Lagoa das Sete Cidades

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    Nas últimas décadas, a Lagoa das Sete Cidades (Ilha de São Miguel, Açores) tem sido afectada por um lento processo de eutrofização que, recentemente, conduziu a um agravamento da sua qualidade química e ecológica. Para avaliar o estado actual da Lagoa e monitorizar a sua evolução foi implementado um sistema de monitorização in continuum, baseado numa estação remota multiparamétrica e em análises periódicas do fitoplâncton. A monitorização in continuum permitiu caracterizar a evolução sazonal dos parâmetros físico-químicos, verificando-se uma rápida transição entre os períodos de mistura e estratificação da massa de água. O desenvolvimento da estratificação térmica foi determinante na evolução da comunidade fitoplanctónica

    Aqueous Biphasic Systems Comprising Natural Organic Acid-Derived Ionic Liquids

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    Despite the progress achieved by aqueous biphasic systems (ABSs) comprising ionic liquids (ILs) in extracting valuable proteins, the quest for bio‐based and protein‐friendly ILs continues. To address this need, this work uses natural organic acids as precursors in the synthesis of four ILs, namely tetrabutylammonium formate ([N4444][HCOO]), tetrabutylammonium acetate ([N4444][CH3COO]), tetrabutylphosphonium formate ([P4444][HCOO]), and tetrabutylphosphonium acetate ([P4444][CH3COO]). It is shown that ABSs can be prepared using all four organic acid‐derived ILs paired with the salts potassium phosphate dibasic (K2HPO4) and tripotassium citrate (C6H5K3O7). According to the ABSs phase diagrams, [P4444]‐based ILs outperform their ammonium congeners in their ability to undergo liquid–liquid demixing in the presence of salts due to their lower hydrogen‐bond acidity. However, deviations to the Hofmeister series were detected in the salts’ effect, which may be related to the high charge density of the studied IL anions. As a proof of concept for their extraction potential, these ABSs were evaluated in extracting human transferrin, allowing extraction efficiencies of 100% and recovery yields ranging between 86 and 100%. To further disclose the molecular‐level mechanisms behind the extraction of human transferrin, molecular docking studies were performed. Overall, the salting‐out exerted by the salt is the main mechanism responsible for the complete extraction of human transferrin toward the IL‐rich phase, whereas the recovery yield and protein‐friendly nature of these systems depend on specific “IL-transferrin” interactions.publishe
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