The two-component system BvrR/BvrS essential for Brucella abortus virulence regulates the expression of outer membrane proteins with counterparts in members of the Rhizobiaceae

The Brucella BvrR/BvrS two-component regulatory system is homologous to the ChvI/ChvG systems of Sinorhizobium meliloti and Agrobacterium tumefaciens necessary for endosymbiosis and pathogenicity in plants. BvrR/BvrS controls cell invasion and intracellular survival. Probing the surface of bvrR and bvrS transposon mutants with monoclonal antibodies showed all described major outer membrane proteins (Omps) but Omp25, a protein known to be involved in Brucella virulence. Absence of Omp25 expression was confirmed by two-dimensional electrophoresis of envelope fractions and by gene reporter studies. The electrophoretic analysis also revealed reduction or absence in the mutants of a second set of protein spots that by matrix-assisted laser desorption ionization MS and peptide mass mapping were identified as a non-previously described Omp (Omp3b). Because bvrR and bvrS mutants are also altered in cell-surface hydrophobicity, permeability, and sensitivity to surf ace-targeted bactericidal peptides, it is proposed that BvrR/BvrS controls cell envelope changes necessary to transit between extracellular and intracellular environments. A genomic search revealed that Omp25 (Omp3a) and Omp3b belong to a family of Omps of plant and animal cell-associated alpha-Proteobacteria, which includes Rhizobium leguminosarum RopB and A. tumefaciens AopB. Previous work has shown that RopB is not expressed in bacteroids, that AopB is involved in tumorigenesis, and that dysfunction of A. tumetaciens ChvI/ChvG alters surface properties. It is thus proposed that the BvrR/BvrS and Omp3 homologues of the cell-associated a-Proteobacteria play a role in bacterial surface control and host cell interactions

Actividades preventivas en la mujer. Actualización PAPPS 2020

Se revisa la evidencia científica en las actividades preventivas de la atención de la mujer en relación con el seguimiento del embarazo, las actividades preventivas en la planificación y seguimiento de los métodos anticonceptivos, actividades preventivas en la menopausia, y la prevención de las fracturas osteoporóticas

Brucellosis Vaccines: Assessment of Brucella melitensis Lipopolysaccharide Rough Mutants Defective in Core and O-Polysaccharide Synthesis and Export

Background: The brucellae are facultative intracellular bacteria that cause brucellosis, one of the major neglected zoonoses. In endemic areas, vaccination is the only effective way to control this disease. Brucella melitensis Rev 1 is a vaccine effective against the brucellosis of sheep and goat caused by B. melitensis, the commonest source of human infection. However, Rev 1 carries a smooth lipopolysaccharide with an O-polysaccharide that elicits antibodies interfering in serodiagnosis, a major problem in eradication campaigns. Because of this, rough Brucella mutants lacking the O-polysaccharide have been proposed as vaccines. Methodology/Principal Findings: To examine the possibilities of rough vaccines, we screened B. melitensis for lipopolysaccharide genes and obtained mutants representing all main rough phenotypes with regard to core oligosaccharide and O-polysaccharide synthesis and export. Using the mouse model, mutants were classified into four attenuation patterns according to their multiplication and persistence in spleens at different doses. In macrophages, mutants belonging to three of these attenuation patterns reached the Brucella characteristic intracellular niche and multiplied intracellularly, suggesting that they could be suitable vaccine candidates. Virulence patterns, intracellular behavior and lipopolysaccharide defects roughly correlated with the degree of protection afforded by the mutants upon intraperitoneal vaccination of mice. However, when vaccination was applied by the subcutaneous route, only two mutants matched the protection obtained with Rev 1 albeit at doses one thousand fold higher than this reference vaccine. These mutants, which were blocked in O-polysaccharide export and accumulated internal O-polysaccharides, stimulated weak anti-smooth lipopolysaccharide antibodies. Conclusions/Significance: The results demonstrate that no rough mutant is equal to Rev 1 in laboratory models and question the notion that rough vaccines are suitable for the control of brucellosis in endemic areas.This work was funded by the European Commission (Research Contract QLK2-CT-2002-00918) and the Ministerio de Ciencia y Tecnología of Spain (Proyecto AGL2004-01162/GAN)

Estudios de marcado y recaptura de especies marinas

Los resultados obtenidos del marcado y posterior recaptura de los ejemplares son una herramienta muy valiosa para contribuir a mejorar el conocimiento de la biología y ecología de una especie, examinando ciertos aspectos como son: el crecimiento, los movimientos o migraciones, la mortalidad o supervivencia, la abundancia y distribución de la especie, el hábitat y diferenciación de poblaciones o stocks. Actualmente la técnica de marcado se aplica a muchas especies, tanto terrestres como marinas, pertenecientes a diversos grupos zoológicos: peces, crustáceos, reptiles, moluscos y mamíferos. Este libro repasa algunos ejemplos de marcado de especies marinas de interés comercial. No todas las especies pueden ser marcadas, porque es necesario cumplir una serie de requisitos para poder llevar a cabo con éxito un experimento de marcado. En uno de los apartados de esta guía, se describen los distintos aspectos a tener en cuenta para obtener buenos resultados. Se describen los principales proyectos de marcado actualmente en ejecución o en marcha llevados a cabo por el Instituto Español de Oceanografía (IEO). En primer lugar, se describe brevemente la especie, su distribución, crecimiento, reproducción, alimentación, etc. A continuación, se presenta la información del marcado, es decir, campañas realizadas, número de ejemplares marcados y algunos de los resultados obtenidos hasta la fecha a partir de las recapturas disponibles. En algunas especies, los programas de marcado se llevan realizando desde hace más de 20 años, como es el caso del atún rojo, por lo que la información disponible es bastante amplia. En otros casos por el contrario como la merluza, los proyectos son relativamente recientes, no obstante los resultados son bastante interesantes y prometedores.Nowadays many different marine animals are being tagged. This book summarizes recent tagging programs carried out by the Spanish Institute of Oceanography (IEO). Although the objectives of these various studies mainly depend on the species and each project in particular, the general aim is to better understand the biology and ecology of these animals the structure and dynamics of their populations and their capacity to respond to human activities. This book provides an overview of different aspects of this technique such as a brief history of tagging, the types of tags currently used, including both conventional and electronic tags, where and how to put them on the marine animals, some recommendations regarding how to perform a tagging survey and where to go or what to do if anyone recovers a tagged fish or marine animal. The book then summarizes the main species tagged by the IEO, making a short description of their biology followed by some of the results obtained from tagging studies undertaken until now. Other applications are to know the spatial distribution (spawning or feeding areas), estimate growth parameters, mortality and survival rates, longevity, the size of the population or identifying stocks. Nowadays the advances in electronics have also open new fields such us the possibility of tracking an animal and knowing its habitat preferences and behaviour. Besides some of these tags have the capacity of recording this information during long periods and sending the data from long distances even without the need to recover the animal. Tagging activities constitute a very useful tool to improve the knowledge of many species and contribute to their management and conservation. For that reason this methodology is included in many IEO projects in which other activities like the monitoring of the fishery (landings, fishing effort, fleet characteristics, fishing areas, biological sampling, etc.) are carried out. Some projects are related with coastal pelagic fisheries including anchovy, sardine and mackerel or oceanic pelagic fisheries like tuna and billfish species and pelagic sharks. Others are focused on benthic and demersal species such as hake, black spot seabream, anglerfish, flatfish, etc. Nevertheless not all species can be tagged, as they have to survive being caught and handled before being release. For this reason, tagging techniques may not easily be applied to some species.Versión del edito

The two-component system BvrR/BvrS essential for Brucella abortus virulence regulates the expression of outer membrane proteins with counterparts in members of the Rhizobiaceae

The Brucella BvrR/BvrS two-component regulatory system is homologous to the ChvI/ChvG systems of Sinorhizobium meliloti and Agrobacterium tumefaciens necessary for endosymbiosis and pathogenicity in plants. BvrR/BvrS controls cell invasion and intracellular survival. Probing the surface of bvrR and bvrS transposon mutants with monoclonal antibodies showed all described major outer membrane proteins (Omps) but Omp25, a protein known to be involved in Brucella virulence. Absence of Omp25 expression was confirmed by two-dimensional electrophoresis of envelope fractions and by gene reporter studies. The electrophoretic analysis also revealed reduction or absence in the mutants of a second set of protein spots that by matrix-assisted laser desorption ionization MS and peptide mass mapping were identified as a non-previously described Omp (Omp3b). Because bvrR and bvrS mutants are also altered in cell-surface hydrophobicity, permeability, and sensitivity to surface-targeted bactericidal peptides, it is proposed that BvrR/BvrS controls cell envelope changes necessary to transit between extracellular and intracellular environments. A genomic search revealed that Omp25 (Omp3a) and Omp3b belong to a family of Omps of plant and animal cell-associated α-Proteobacteria, which includes Rhizobium leguminosarum RopB and A. tumefaciens AopB. Previous work has shown that RopB is not expressed in bacteroids, that AopB is involved in tumorigenesis, and that dysfunction of A. tumefaciens ChvI/ChvG alters surface properties. It is thus proposed that the BvrR/BvrS and Omp3 homologues of the cell-associated α-Proteobacteria play a role in bacterial surface control and host cell interactions

The Lipopolysaccharide of Brucella abortus BvrS/BvrR Mutants Contains Lipid A Modifications and Has Higher Affinity for Bactericidal Cationic Peptides

The two-component BvrS/BvrR system is essential for Brucella abortus virulence. It was shown previously that its dysfunction abrogates expression of some major outer membrane proteins and increases bactericidal peptide sensitivity. Here, we report that BvrS/BvrR mutants have increased surface hydrophobicity and susceptibility to killing by nonimmune serum. The bvrS and bvrR mutant lipopolysaccharides (LPSs) bound more polymyxin B, chimeras constructed with bvrS mutant cells and parental LPS showed augmented polymyxin B resistance, and, conversely, parental cells and bvrS mutant LPS chimeras were more sensitive and displayed polymyxin B-characteristic outer membrane lesions, implicating LPS as being responsible for the phenotype of the BvrS/BvrR mutants. No qualitative or quantitative changes were detected in other envelope and outer membrane components examined: periplasmic β(1-2) glucans, native hapten polysaccharide, and phospholipids. The LPS of the mutants was similar to parental LPS in O-polysaccharide polymerization and fine structure but showed both increased underacylated lipid A species and higher acyl-chain fluidity that correlated with polymyxin B binding. These lipid A changes did not alter LPS cytokine induction, showing that in contrast to other gram-negative pathogens, recognition by innate immune receptors is not decreased by these changes in LPS structure. Transcription of Brucella genes required for incorporating long acyl chains into lipid A (acpXL and lpxXL) or implicated in lipid A acylation control (bacA) was not affected. We propose that in Brucella the outer membrane homeostasis depends on the functioning of BvrS/BvrR. Accordingly, disruption of BvrS/BvrR damages the outer membrane, thus contributing to the severe attenuation manifested by bvrS and bvrR mutants

The lipopolysaccharide of Brucella abortus BvrS/BvrR mutants contains lipid A modifications and has higher affinity for bactericidal cationic peptides

The two-component BvrS/BvrR system is essential for Brucella abortus virulence. It was shown previously that its dysfunction abrogates expression of some major outer membrane proteins and increases bactericidal peptide sensitivity. Here, we report that BvrS/BvrR mutants have increased surface hydrophobicity and susceptibility to killing by nonimmune serum. The bvrS and bvrR mutant lipopolysaccharides (LPSs) bound more polymyxin B, chimeras constructed with bvrS mutant cells and parental LPS showed augmented polymyxin B resistance, and, conversely, parental cells and bvrS mutant LPS chimeras were more sensitive and displayed polymyxin B-characteristic outer membrane lesions, implicating LPS as being responsible for the phenotype of the BvrS/BvrR mutants. No qualitative or quantitative changes were detected in other envelope and outer membrane components examined: periplasmic beta(1-2) glucans, native hapten polysaccharide, and phospholipids. The LPS of the mutants was similar to parental LPS in O-polysaccharide polymerization and fine structure but showed both increased underacylated lipid A species and higher acyl-chain fluidity that correlated with polymyxin B binding. These lipid A changes did not alter LPS cytokine induction, showing that in contrast to other gram-negative pathogens, recognition by innate immune receptors is not decreased by these changes in LPS structure. Transcription of Brucella genes required for incorporating long acyl chains into lipid A (acpXL and lpxXL) or implicated in lipid A acylation control (bacA) was not affected. We propose that in Brucella the outer membrane homeostasis depends on the functioning of BvrS/BvrR. Accordingly, disruption of BvrS/BvrR damages the outer membrane, thus contributing to the severe attenuation manifested by bvrS and bvrR mutants

Brucella abortus transits through the autophagic pathway and replicates in the endoplasmic reticulum of nonprofessional phagocytes

Brucella abortus is an intracellular pathogen that replicates within a membrane-bounded compartment. In this study, we have examined the intracellular pathway of the virulent B. abortus strain 2308 (S2308) and the attenuated strain 19 (S19) in HeLa cells. At 10 min after inoculation, both bacterial strains are transiently detected in phagosomes characterized by the presence of early endosomal markers such as the early endosomal antigen 1. At approximately 1 h postinoculation, bacteria are located within a compartment positive for the lysosome-associated membrane proteins (LAMPs) and the endoplasmic reticulum (ER) marker sec61beta but negative for the mannose 6-phosphate receptors and cathepsin D. Interestingly, this compartment is also positive for the autophagosomal marker monodansylcadaverin, suggesting that S2308 and S19 are located in autophagic vacuoles. At 24 h after inoculation, attenuated S19 is degraded in lysosomes, while virulent S2308 multiplies within a LAMP- and cathepsin D-negative but sec61beta- and protein disulfide isomerase-positive compartment. Furthermore, treatment of infected cells with the pore-forming toxin aerolysin from Aeromonas hydrophila causes vacuolation of the bacterial replication compartment. These results are compatible with the hypothesis that pathogenic B. abortus exploits the autophagic machinery of HeLa cells to establish an intracellular niche favorable for its replication within the ER