Caracterización de los sistemas de captación de zinc y de hierro en Streptococcus suis : potencial antigénico y protector

Consultable des del TDXTítol obtingut de la portada digitalitzadaStreptococcus suis es un importante patógeno que causa grandes pérdidas económicas en la industria porcina a nivel mundial, siendo también un importante agente zoonótico. Aunque son varias las aproximaciones que se han desarrollado mediante vacunas vivas o recombinantes para prevenir las enfermedades provocadas por S. suis, los esfuerzos para controlar su infección se ven dificultados por la falta de herramientas efectivas contra este patógeno. Diferentes tipos de transportadores implicados en la captación de cationes divalentes y asociados a la pared celular, entre ellos los transportadores ABC, se relacionan con la virulencia bacteriana y presentan propiedades inmunogénicas contra las especies bacterianas de las que derivan. Atendiendo a todas estas características, se han desarrollado estrategias para producir vacunas contra las bacterias patógenas basadas en la sobreexpresión en la superficie celular bacteriana de transportadores de cationes divalentes inducidos mediante agentes quelantes o a través de la construcción de cepas deficientes en los represores de la transcripción de estos transportadores. En este contexto, el objetivo del presente trabajo ha sido estudiar los mecanismos de captación de cationes divalentes de S. suis, así como su papel en la virulencia y su posible uso para el desarrollo de herramientas eficaces contra este patógeno. Para abordar el objetivo propuesto, se identificaron in silico diversos transportadores de S. suis implicados en la captación de zinc y hierro y también sus posibles reguladores (AdcR y Fur, respectivamente). Además, se clonó el gen adcR de S. suis, que codifica un posible regulador de los transportadores implicados en la captación de Zn2+ y/o Mn2+ en Streptococcus spp., se purificó la proteína AdcR y mediante ensayos con DNasaI (footprinting) y de movilidad electroforética se demostró, por primera vez, que dicha proteína reconoce y se une específicamente a la secuencia TTAACNRGTTAA. Asimismo, también se ha demostrado que in vitro se requiere Zn2+ o Mn2+ para establecer dicha unión y que la proteína AdcR controla la expresión de los genes que codifican las proteínas SsuiDRAFT 0103 y SsuiDRAFT 1237, componentes de transportadores ABC implicados en la captación de zinc y/o manganeso. Por otra parte, se clonó el gen fur de S. suis, que codifica el posible regulador de los transportadores implicados en la captación de Fe2+, y se sobreexpresó su producto en Escherichia coli. Ensayos de movilidad electroforética con extracto crudo de esta cepa de E. coli mostraron que la proteína Fur de S. suis controla la expresión de los genes feoAB, implicados en la captación de hierro. Seguidamente, se obtuvieron mutantes mediante la deleción de los genes adcR y fur en una cepa virulenta de S. suis con el objetivo de caracterizar ambos regulones. Varios transportadores implicados en la captación de cationes aparecieron desreprimidos en las cepas mutantes cuando la expresión génica fue comparada con la de la cepa salvaje a través de ensayos de RT-PCR a tiempo real. En concordancia con ello, los ensayos de movilidad electroforética mostraron que estos reguladores se unen específicamente al promotor de dichos genes. Asimismo, la ausencia de los genes adcR y/o fur en un estreptococo patógeno mostró, por primera vez, una importante atenuación de su virulencia en el modelo animal de ratón. Finalmente, se abordaron estudios de inmunogenicidad y protección. Para ello, se purificaron tres proteínas periplásmicas de S. suis implicadas en la captación de cationes divalentes (SsuiDRAFT 0103, SsuiDRAFT 0174 y SsuiDRAFT 1237), resultando ser todas ellas inmunogénicas, aunque sólo SsuiDRAFT 0103 confiere una protección significativa contra S. suis en el modelo animal de ratón. Además, las proteínas Ssu0309 y Ssu1103 asociadas a la pared celular, que están sobreexpresadas en el mutante adcR, fueron identificadas mediante espectrometría de masas como factores de virulencia pertenecientes a la familia de proteínas Pht (Pneumococcal histidine triad). Asimismo, se estudiaron las propiedades protectoras de las cepas mutantes demostrándose que aunque enteras no confieren protección contra S. suis en el modelo animal de ratón, las proteínas asociadas a la pared celular del doble mutante adcR fur sí que inducen una protección significativa ante una infección con la cepa virulenta de S. suis 89/1591 en dicho modelo.Streptococcus suis is an important pathogen that causes significant economical losses in the swine industry worldwide and it is also an important zoonotic agent. Although several approaches to develop either live or recombinant vaccines to prevent S. suis-mediated disease have been tested, efforts to control the infection are hampered by the lack of effective weapons against this pathogen. Different cell-wall-associated transporters involved in divalent-cation uptake, including ABC transporters, have been shown to be involved in bacterial virulence and have immunogenic properties against the bacterial species from which they are derived. Accordingly, several strategies have been developed to produce vaccines against this pathogenic bacterium. One of them involves overexpression on the bacterial cell surface of divalent-cation-uptake transporters induced by chelator agents or by the construction of deficient strains in the cation-uptake repressors. In this context, the aim of this work has been to study the S. suis-cation-uptake mechanisms and their role in virulence as well as their putative use as a tool to achieve broad protection against this pathogen. To achieve this purpose, several transporters involved in zinc and iron uptake and their putative regulators (AdcR and Fur, respectively) have been identified in silico. Furthermore, the S. suis adcR gene, which encodes a predicted regulator of Zn2+ and/or Mn2+ uptake in streptococci, was cloned and its protein product was purified. Footprinting and electrophoretic mobility shift assays with purified S. suis AdcR protein showed, for the first time, that the AdcR-DNA binding sequence corresponds to the TTAACNRGTTAA motif. In addition, the requirement for either Zn2+ or Mn2+ to establish in vitro binding of AdcR to its target sequence and the ability of AdcR to control the genes codifying the ABC-transporter components SsuiDRAFT 0103 and SsuiDRAFT 1237, involved in zinc and/or manganese uptake, were demonstrated. Besides, the S. suis fur gene, which encodes a predicted regulator of Fe2+ uptake, was cloned and its protein product was overexpressed in Escherichia coli. Electrophoretic mobility shift assays with crude extract of this E. coli strain showed that S. suis Fur protein controls the feoAB genes, involved in ferric uptake. In addition, both adcR and fur genes were deleted in a virulent S. suis strain in order to charecterize these regulons. Several cation-uptake transporters appeared desrepressed in the knockout strains when gene expression was compared with wild-type strain through real-time RT-PCR analyses. Accordingly, EMSA results showed that these regulators specifically bind to the promoter of these genes. Moreover, the absence of adcR and/or fur genes in pathogenic streptococci showed, for the first time, an important attenuation of its virulence in mice. Finally, immunogenic and protective analysis were carried out with the products of three genes encoding putative divalent-cation-binding lipoproteins of S. suis (SsuiDRAFT 0103, SsuiDRAFT 0174, and SsuiDRAFT 1237), being all of them immunogenic although only one (SsuiDRAFT 0103) induces a significant protective response against a virulent S. suis strain in mice. Moreover, the overexpressed cell wall-associated proteins Ssu0309 and Ssu1103 of the adcR mutant, were identified by mass spectrometry as putative virulence factors belonging to the Pht (Pneumococcal histidine triad) family. Likewise, protective abilities of mutant strains were analyzed showing that although mutant cells are not effective to confer protection in mice, the combination of adcR- and fur-regulated cell wall-associated proteins confers a significant protection against S. suis 89/1591 challenge to mice vaccinated with them

El templo, la capilla y el camarín de Nuestra Señora de Atocha de Madrid

Análisis y puesta al día del proceso constructivo del templo y capilla de Nuestra Señora de Atocha de Madrid a partir de una atenta re lectura bibliográfica, documental y planimétrica, con el fin de intentar la reconstrucción de sus espacios y la decoración de los mismos, haciéndola coincidir con el momento en que visitó el edificio Antonio Ponz, reubicando todo aquello que contempló.Analysis and updating of constructive process of church and chapel of Nuestra Señora de Atocha in Madrid through a bibliographic, documentary and planimetric observant reading with the aim of trying the reconstruction of their rooms and decoration, coinciding with the moment that Antonio Ponz visited the building and replacing everything he contemplated

Towards Formal Interaction-Based Models of Grid Computing Infrastructures

Grid computing (GC) systems are large-scale virtual machines, built upon a massive pool of resources (processing time, storage, software) that often span multiple distributed domains. Concurrent users interact with the grid by adding new tasks; the grid is expected to assign resources to tasks in a fair, trustworthy way. These distinctive features of GC systems make their specification and verification a challenging issue. Although prior works have proposed formal approaches to the specification of GC systems, a precise account of the interaction model which underlies resource sharing has not been yet proposed. In this paper, we describe ongoing work aimed at filling in this gap. Our approach relies on (higher-order) process calculi: these core languages for concurrency offer a compositional framework in which GC systems can be precisely described and potentially reasoned about.Comment: In Proceedings DCM 2013, arXiv:1403.768

Identificat un nou mecanisme pel qual un patogen genera resistència als antibiòtics

Els pacients hospitalitzats, especialment els malalts crítics, són susceptibles a l'acció del microorganisme Acinetobacter baumannii, que pot provocar infeccions greus com septicèmia, pneumònia o meningitis i que té una gran capacitat de desenvolupar resistències a pràcticament tots els antibiòtics en ús clínic. Investigadors de la UAB conjuntament amb l'Hospital d'A Coruña i amb la col∙laboració d'una universitat australiana han descobert un nou mecanisme pel qual aquest patogen és capaç d'adquirir resistència als antibiòtics.Los pacientes hospitalizados, especialmente los enfermos críticos, son susceptibles a la acción del microorganismo Acinetobacter baumannii, que puede provocar infecciones graves como septicemia, neumonía o meningitis y que tiene una gran capacidad de desarrollar resistencias a prácticamente todos los antibióticos en uso clínico. Investigadores de la UAB conjuntamente con el Hospital de A Coruña y con la colaboración de una universidad australiana han descubierto un nuevo mecanismo por el cual este patógeno es capaz de adquirir resistencia a los antibióticos

Motion Coordination Problems with Collision Avoidance for Multi-Agent Systems

This chapter studies the collision avoidance problem in the motion coordination control strategies for multi-agent systems. The proposed control strategies are decentralised, since agents have no global knowledge of the goal to achieve, knowing only the position and velocity of some agents. These control strategies allow a set of mobile agents achieve formations, formation tracking and containment. For the collision avoidance, we add a repulsive vector field of the unstable focus type to the motion coordination control strategies. We use formation graphs to represent interactions between agents. The results are presented for the front points of differential-drive mobile robots. The theoretical results are verified by numerical simulation

The relevance of seed size in modulating leaf physiology and early plant performance in two tree species

he size of seeds and the microsite of seed dispersal may affect the early establishment of seedlings through different physiological processes. Here, we examined the effects of seed size and light availability on seedling growth and survival, and whether such effects were mediated by water use efficiency. Acorns of Quercus petraea and the more drought-tolerant Quercus pyrenaica were sowed within and around a tree canopy gap in a sub-Mediterranean forest stand. We monitored seedling emergence and measured predawn leaf water potential (Ψpd), leaf nitrogen per unit area (Na), leaf mass per area, leaf carbon isotope composition (δ13C) and plant growth at the end of the first summer. Survival was measured on the next year. Path analysis revealed a consistent pattern in both species of higher δ13C as Ψpd decreased and higher δ13C as seedlings emerged later in the season, indicating an increase in 13C as the growing season is shorter and drier. There was a direct positive effect of seed size on δ13C in Q. petraea that was absent in Q. pyrenaica. Leaf δ13C had no effect on growth but the probability of surviving until the second year was higher for those seedlings of Q. pyrenaica that had lower δ13C on the first year. In conclusion, leaf δ13C is affected by seed size, seedling emergence time and the availability of light and water, however, leaf δ13C is irrelevant for first year growth, which is directly dependent on the amount of seed reserves

A bound on the number of twice-punctured tori in a knot exterior

This paper continues a program due to Motegi regarding universal bounds for the number of non-isotopic essential $n$-punctured tori in the complement of a hyperbolic knot in $S^3$. For $n=1$, Valdez-S\'anchez showed that there are at most five non-isotopic Seifert tori in the exterior of a hyperbolic knot. In this paper, we address the case $n=2$. We show that there are at most six non-isotopic, nested, essential 2-holed tori in the complement of every hyperbolic knot.Comment: 15 pages, 6 figure

Laminin-binding protein of Streptococcus suis serotype 2 influences zinc acquisition and cytokine responses

Streptococcus suis serotype 2 is an important bacterial pathogen of swine, responsible for substantial economic losses to the swine industry worldwide. The knowledge on the pathogenesis of the infection caused by S. suis is still poorly known. It has been previously described that S. suis possesses at least one lipoprotein with double laminin and zinc (Zn)-binding properties, which was described in the literature as either laminin-binding protein (Lmb, as in the current study), lipoprotein 103, CDS 0330 or AdcAII. In the present study, the role of the Lmb in the pathogenesis of the infection caused by S. suis serotype 2 was dissected. Using isogenic mutants, results showed that Lmb does not play an important role in the laminin-binding activity of S. suis, even when clearly exposed at the bacterial surface. In addition, the presence of this lipoprotein does not infuence bacterial adhesion to and invasion of porcine respiratory epithelial and brain endothelial cells and it does not increase the susceptibility of S. suis to phagocytosis. On the other hand, the Lmb was shown to play an important role as cytokine activator when tested in vitro with dendritic cells. Finally, this lipoprotein plays a critical role in Zn acquisition from the host environment allowing bacteria to grow in vivo. The signifcant lower virulence of the Lmb defective mutant may be related to a combination of a lower bacterial survival due to the incapacity to acquire Zn from their surrounding milieu and a reduced cytokine activation

Pharmaceutical Pollution in Aquatic Environments: A Concise Review of Environmental Impacts and Bioremediation Systems

MO received a Ph.D. grant from the Junta de Castilla y Leon (Spain). Open Access Funding was provided by the University of Helsinki.The presence of emerging contaminants in the environment, such as pharmaceuticals, is a growing global concern. The excessive use of medication globally, together with the recalcitrance of pharmaceuticals in traditional wastewater treatment systems, has caused these compounds to present a severe environmental problem. In recent years, the increase in their availability, access and use of drugs has caused concentrations in water bodies to rise substantially. Considered as emerging contaminants, pharmaceuticals represent a challenge in the field of environmental remediation; therefore, alternative add-on systems for traditional wastewater treatment plants are continuously being developed to mitigate their impact and reduce their effects on the environment and human health. In this review, we describe the current status and impact of pharmaceutical compounds as emerging contaminants, focusing on their presence in water bodies, and analyzing the development of bioremediation systems, especially mycoremediation, for the removal of these pharmaceutical compounds with a special focus on fungal technologies.Junta de Castilla y LeonUniversity of Helsink

Agent-mediated shared conceptualizations in tagging services

Some of the most remarkable innovative technologies from the Web 2.0 are the collaborative tagging systems. They allow the use of folksonomies as a useful structure for a number of tasks in the social web, such as navigation and knowledge organization. One of the main deficiencies comes from the tagging behaviour of different users which causes semantic heterogeneity in tagging. As a consequence a user cannot benefit from the adequate tagging of others. In order to solve the problem, an agent-based reconciliation knowledge system, based on Formal Concept Analysis, is applied to facilitate the semantic interoperability between personomies. This article describes experiments that focus on conceptual structures produced by the system when it is applied to a collaborative tagging service, Delicious. Results will show the prevalence of shared tags in the sharing of common resources in the reconciliation process.Ministerio de Ciencia e Innovación TIN2009-09492Ministerio de Ciencia e Innovación TIN2010-20967-C04-0