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Search Results: 1 - 10 of 10309 matches for " Carmen Buchrieser "
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Comparative and Functional Genomics of Legionella Identified Eukaryotic Like Proteins as Key Players in Host–Pathogen Interactions
Carmen Buchrieser
Frontiers in Microbiology , 2011, DOI: 10.3389/fmicb.2011.00208
Abstract: Although best known for its ability to cause severe pneumonia in people whose immune defenses are weakened, Legionella pneumophila and Legionella longbeachae are two species of a large genus of bacteria that are ubiquitous in nature, where they parasitize protozoa. Adaptation to the host environment and exploitation of host cell functions are critical for the success of these intracellular pathogens. The establishment and publication of the complete genome sequences of L. pneumophila and L. longbeachae isolates paved the way for major breakthroughs in understanding the biology of these organisms. In this review we present the knowledge gained from the analyses and comparison of the complete genome sequences of different L. pneumophila and L. longbeachae strains. Emphasis is given on putative virulence and Legionella life cycle related functions, such as the identification of an extended array of eukaryotic like proteins, many of which have been shown to modulate host cell functions to the pathogen’s advantage. Surprisingly, many of the eukaryotic domain proteins identified in L. pneumophila as well as many substrates of the Dot/Icm type IV secretion system essential for intracellular replication are different between these two species, although they cause the same disease. Finally, evolutionary aspects regarding the eukaryotic like proteins in Legionella are discussed.
Legionella: From Protozoa to Humans
Carmen Buchrieser
Frontiers in Microbiology , 2011, DOI: 10.3389/fmicb.2011.00182
Comparative Genomics Uncovers Large Tandem Chromosomal Duplications in Mycobacterium bovis BCG Pasteur
Roland Brosch,Stephen V. Gordon,Carmen Buchrieser,Alexander S. Pym,Thierry Garnier,Stewart T. Cole
Comparative and Functional Genomics , 2000, DOI: 10.1002/1097-0061(20000630)17:2<111::aid-yea17>3.0.co;2-g
Abstract: On direct comparison of minimal sets of ordered clones from bacterial artificial chromosome (BAC) libraries representing the complete genomes of Mycobacterium tuberculosis H37Rv and the vaccine strain, Mycobacterium bovis BCG Pasteur, two major rearrangements were identified in the genome of M. bovis BCG Pasteur. These were shown to correspond to two tandem duplications, DU1 and DU2, of 29 668 bp and 36 161 bp, respectively. While DU1 resulted from a single duplication event, DU2 apparently arose from duplication of a 100 kb genomic segment that subsequently incurred an internal deletion of 64 kb. Several lines of evidence suggest that DU2 may continue to expand, since two copies were detected in a subpopulation of BCG Pasteur cells. BCG strains harbouring DU1 and DU2 are diploid for at least 58 genes and contain two copies of oriC, the chromosomal origin of replication. These findings indicate that these genomic regions of the BCG genome are still dynamic. Although the role of DU1 and DU2 in the attenuation and/or altered immunogenicity of BCG is yet unknown, knowledge of their existence will facilitate quality control of BCG vaccine lots and may help in monitoring the efficacy of the world's most widely used vaccine.
In Vivo Transcriptional Profiling of Listeria monocytogenes and Mutagenesis Identify New Virulence Factors Involved in Infection
Ana Camejo,Carmen Buchrieser,Elisabeth Couvé,Filipe Carvalho,Olga Reis,Pierre Ferreira,Sandra Sousa,Pascale Cossart,Didier Cabanes
PLOS Pathogens , 2009, DOI: 10.1371/journal.ppat.1000449
Abstract: Listeria monocytogenes is a human intracellular pathogen able to colonize host tissues after ingestion of contaminated food, causing severe invasive infections. In order to gain a better understanding of the nature of host–pathogen interactions, we studied the L. monocytogenes genome expression during mouse infection. In the spleen of infected mice, ≈20% of the Listeria genome is differentially expressed, essentially through gene activation, as compared to exponential growth in rich broth medium. Data presented here show that, during infection, Listeria is in an active multiplication phase, as revealed by the high expression of genes involved in replication, cell division and multiplication. In vivo bacterial growth requires increased expression of genes involved in adaptation of the bacterial metabolism and stress responses, in particular to oxidative stress. Listeria interaction with its host induces cell wall metabolism and surface expression of virulence factors. During infection, L. monocytogenes also activates subversion mechanisms of host defenses, including resistance to cationic peptides, peptidoglycan modifications and release of muramyl peptides. We show that the in vivo differential expression of the Listeria genome is coordinated by a complex regulatory network, with a central role for the PrfA-SigB interplay. In particular, L. monocytogenes up regulates in vivo the two major virulence regulators, PrfA and VirR, and their downstream effectors. Mutagenesis of in vivo induced genes allowed the identification of novel L. monocytogenes virulence factors, including an LPXTG surface protein, suggesting a role for S-layer glycoproteins and for cadmium efflux system in Listeria virulence.
Extensive recombination events and horizontal gene transfer shaped the Legionella pneumophila genomes
Laura Gomez-Valero, Christophe Rusniok, Sophie Jarraud, Benoit Vacherie, Zoé Rouy, Valerie Barbe, Claudine Medigue, Jerome Etienne, Carmen Buchrieser
BMC Genomics , 2011, DOI: 10.1186/1471-2164-12-536
Abstract: We show that L. pneumophila Sg1 has a highly conserved and syntenic core genome that comprises the many eukaryotic like proteins and a conserved repertoire of over 200 Dot/Icm type IV secreted substrates. However, recombination events and horizontal gene transfer are frequent. In particular the analyses of the distribution of nucleotide polymorphisms suggests that large chromosomal fragments of over 200 kbs are exchanged between L. pneumophila strains and contribute to the genome dynamics in the natural population. The many secretion systems present might be implicated in exchange of these fragments by conjugal transfer. Plasmids also play a role in genome diversification and are exchanged among strains and circulate between different Legionella species.Horizontal gene transfer among bacteria and from eukaryotes to L. pneumophila as well as recombination between strains allows different clones to evolve into predominant disease clones and others to replace them subsequently within relatively short periods of time.Legionella pneumophila is the etiologic agent of Legionnaires' disease, an atypical pneumonia, which is often fatal if not treated promptly. However, it is principally an environmental bacterium that inhabits fresh water reservoirs worldwide where it parasitizes within free-living protozoa but also survives in biofilms [1-3]. Since L. pneumophila does not spread from person-to-person, humans have been inconsequential for the evolution of this pathogen. Instead, the virulence strategies of L. pneumophila have been shaped by selective pressures in aquatic ecosystems. Indeed, the co-evolution of L. pneumophila with fresh-water amoebae is reflected in its genome sequence. The analysis of two L. pneumophila genomes identified the presence of an unexpected high number and variety of eukaryotic-like proteins and proteins containing motifs mainly found in eukaryotes [4]. These proteins were predicted to interfere in different steps of the infectious cycle by mimick
NeMeSys: a biological resource for narrowing the gap between sequence and function in the human pathogen Neisseria meningitidis
Christophe Rusniok, David Vallenet, Stéphanie Floquet, Helen Ewles, Coralie Mouzé-Soulama, Daniel Brown, Aurélie Lajus, Carmen Buchrieser, Claudine Médigue, Philippe Glaser, Vladimir Pelicic
Genome Biology , 2009, DOI: 10.1186/gb-2009-10-10-r110
Abstract: By determining and manually annotating the complete genome sequence of a serogroup C clinical isolate of N. meningitidis (strain 8013) and assembling a library of defined mutants in up to 60% of its non-essential genes, we have created NeMeSys, a biological resource for Neisseria meningitidis systematic functional analysis. To further enhance the versatility of this toolbox, we have manually (re)annotated eight publicly available Neisseria genome sequences and stored all these data in a publicly accessible online database. The potential of NeMeSys for narrowing the gap between sequence and function is illustrated in several ways, notably by performing a functional genomics analysis of the biogenesis of type IV pili, one of the most widespread virulence factors in bacteria, and by identifying through comparative genomics a complete biochemical pathway (for sulfur metabolism) that may potentially be important for nasopharyngeal colonization.By improving our capacity to understand gene function in an important human pathogen, NeMeSys is expected to contribute to the ongoing efforts aimed at understanding a prokaryotic cell comprehensively and eventually to the design of new therapies.By revealing complete repertoires of genes, genome sequences provide the key to a better and eventually global understanding of the biology of living organisms. It is widely accepted that this will have important consequences on human health and economics by leading to the rational design of novel therapies against pathogens infecting humans, livestock or crops [1]. For example, identifying genes essential for cell viability or pathogenesis would uncover targets for new antibiotics or drugs that selectively interfer with virulence mechanisms of pathogenic species, respectively. The major obstacle to this is the fact that hundreds of predicted coding sequences (CDSs) in every genome remain uncharacterized. Unraveling gene function on such a large scale requires suitable biological resources
Acesso de pessoas deficientes auditivas a servi?os de saúde em cidade do Sul do Brasil
Freire, Daniela Buchrieser;Gigante, Luciana Petrucci;Béria, Jorge Umberto;Palazzo, Lílian dos Santos;Figueiredo, Andréia Cristina Leal;Raymann, Beatriz Carmen Warth;
Cadernos de Saúde Pública , 2009, DOI: 10.1590/S0102-311X2009000400020
Abstract: this cross-sectional study aimed to compare access to health services and preventive measures by persons with hearing disability and those with normal hearing in canoas, rio grande do sul state, brazil. the sample included 1,842 individuals 15 years or older (52.9% of whom were females). the most frequent income bracket was twice the minimum wage or more, or approximately u$360/month (42.7%). individuals with hearing disability were more likely to have visited a physician in the previous two months (pr = 1.3, 95%ci: 1.10-1.51) and to have been hospitalized in the previous 12 months (pr = 2.1, 95%ci: 1.42-3.14). regarding mental health, individuals with hearing disability showed 1.5 times greater probability of health care due to mental disorders and 4.2 times greater probability of psychiatric hospitalization as compared to those with normal hearing. consistent with other studies, women with hearing disability performed less breast self-examination and had fewer pap smears. the data indicate the need to invest in specific campaigns for this group of individuals with special needs.
Analysis of the Legionella longbeachae Genome and Transcriptome Uncovers Unique Strategies to Cause Legionnaires' Disease
Christel Cazalet equal contributor,Laura Gomez-Valero equal contributor,Christophe Rusniok,Mariella Lomma,Delphine Dervins-Ravault,Hayley J. Newton,Fiona M. Sansom,Sophie Jarraud,Nora Zidane,Laurence Ma,Christiane Bouchier,Jer?me Etienne,Elizabeth L. Hartland,Carmen Buchrieser
PLOS Genetics , 2010, DOI: 10.1371/journal.pgen.1000851
Abstract: Legionella pneumophila and L. longbeachae are two species of a large genus of bacteria that are ubiquitous in nature. L. pneumophila is mainly found in natural and artificial water circuits while L. longbeachae is mainly present in soil. Under the appropriate conditions both species are human pathogens, capable of causing a severe form of pneumonia termed Legionnaires' disease. Here we report the sequencing and analysis of four L. longbeachae genomes, one complete genome sequence of L. longbeachae strain NSW150 serogroup (Sg) 1, and three draft genome sequences another belonging to Sg1 and two to Sg2. The genome organization and gene content of the four L. longbeachae genomes are highly conserved, indicating strong pressure for niche adaptation. Analysis and comparison of L. longbeachae strain NSW150 with L. pneumophila revealed common but also unexpected features specific to this pathogen. The interaction with host cells shows distinct features from L. pneumophila, as L. longbeachae possesses a unique repertoire of putative Dot/Icm type IV secretion system substrates, eukaryotic-like and eukaryotic domain proteins, and encodes additional secretion systems. However, analysis of the ability of a dotA mutant of L. longbeachae NSW150 to replicate in the Acanthamoeba castellanii and in a mouse lung infection model showed that the Dot/Icm type IV secretion system is also essential for the virulence of L. longbeachae. In contrast to L. pneumophila, L. longbeachae does not encode flagella, thereby providing a possible explanation for differences in mouse susceptibility to infection between the two pathogens. Furthermore, transcriptome analysis revealed that L. longbeachae has a less pronounced biphasic life cycle as compared to L. pneumophila, and genome analysis and electron microscopy suggested that L. longbeachae is encapsulated. These species-specific differences may account for the different environmental niches and disease epidemiology of these two Legionella species.
Comparative genomics and transcriptomics of lineages I, II, and III strains of Listeria monocytogenes
Torsten Hain, Rohit Ghai, Andre Billion, Carsten Tobias Kuenne, Christiane Steinweg, Benjamin Izar, Walid Mohamed, Mobarak Mraheil, Eugen Domann, Silke Schaffrath, Uwe K?rst, Alexander Goesmann, Sebastian Oehm, Alfred Pühler, Rainer Merkl, Sonja Vorwerk, Philippe Glaser, Patricia Garrido, Christophe Rusniok, Carmen Buchrieser, Werner Goebel, Trinad Chakraborty
BMC Genomics , 2012, DOI: 10.1186/1471-2164-13-144
Abstract: The genome analysis of the weakly pathogenic L99 serotype 4a provides extensive evidence of virulence gene decay, including loss of several important surface proteins. The 4b CLIP80459 genome, unlike the previously sequenced 4b F2365 genome harbours an intact inlB invasion gene. These lineage I strains are characterized by the lack of prophage genes, as they share only a single prophage locus with other L. monocytogenes genomes 1/2a EGD-e and 4a L99. Comparative transcriptome analysis during intracellular growth uncovered adaptive expression level differences in lineages I, II and III of Listeria, notable amongst which was a strong intracellular induction of flagellar genes in strain 4a L99 compared to the other lineages. Furthermore, extensive differences between strains are manifest at levels of metabolic flux control and phosphorylated sugar uptake. Intriguingly, prophage gene expression was found to be a hallmark of intracellular gene expression. Deletion mutants in the single shared prophage locus of lineage II strain EGD-e 1/2a, the lma operon, revealed severe attenuation of virulence in a murine infection model.Comparative genomics and transcriptome analysis of L. monocytogenes strains from three lineages implicate prophage genes in intracellular adaptation and indicate that gene loss and decay may have led to the emergence of attenuated lineages.
Application of Statistical Methods to Assess Carbon Monoxide Pollution Variations within an Urban Area  [PDF]
Carmen Capilla
International Journal of Geosciences (IJG) , 2012, DOI: 10.4236/ijg.2012.325090
Abstract: In recent years there have been considerable new legislation and efforts by vehicle manufactures aimed at reducing pollutant emission to improve air quality in urban areas. Carbon monoxide is a major pollutant in urban areas, and in this study we analyze monthly carbon monoxide (CO) data from Valencia City, a representative Mediterranean city in terms of its structure and climatology. Temporal and spatial trends in pollution were recorded from a monitoring net- work that consisted of five monitoring sites. A multiple linear model, incorporating meteorological parameters, annual cycles, and random error due to serial correlation, was used to estimate the temporal changes in pollution. An analysis performed on the meteorologically adjusted data reveals a significant decreasing trend in CO concentrations and an annual seasonal cycle. The model parameters are estimated by applying the least-squares method. The standard error of the parameters is determined while taking into account the serial correlation in the residuals. The decreasing trend im- plies to a certain extent an improvement in the air quality of the study area. The seasonal cycle shows variations that are mainly associated with traffic and meteorological patterns. Analysis of the stochastic spatial component shows that most of the intersite covariances can be analyzed using an exponential variogram model.
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