The Active Human Gut Microbiota Differs from the Total Microbiota

The human gut microbiota is considered one of the most fascinating reservoirs of microbial diversity hosting between 400 to 1000 bacterial species distributed among nine phyla with Firmicutes, Bacteroidetes and Actinobacteria representing around of the diversity. One of the most intriguing issues relates to understanding which microbial groups are active players in the maintenance of the microbiota homeostasis

Legionella pneumophila pangenome reveals strain-specific virulence factors

<p>Abstract</p> <p>Background</p> <p><it>Legionella pneumophila </it>subsp. <it>pneumophila </it>is a gram-negative <it>γ-Proteobacterium </it>and the causative agent of Legionnaires' disease, a form of epidemic pneumonia. It has a water-related life cycle. In industrialized cities <it>L. pneumophila </it>is commonly encountered in refrigeration towers and water pipes. Infection is always via infected aerosols to humans. Although many efforts have been made to eradicate <it>Legionella </it>from buildings, it still contaminates the water systems. The town of Alcoy (Valencian Region, Spain) has had recurrent outbreaks since 1999. The strain "Alcoy 2300/99" is a particularly persistent and recurrent strain that was isolated during one of the most significant outbreaks between the years 1999-2000.</p> <p>Results</p> <p>We have sequenced the genome of the particularly persistent <it>L. pneumophila </it>strain Alcoy 2300/99 and have compared it with four previously sequenced strains known as Philadelphia (USA), Lens (France), Paris (France) and Corby (England).</p> <p>Pangenome analysis facilitated the identification of strain-specific features, as well as some that are shared by two or more strains. We identified: (1) three islands related to anti-drug resistance systems; (2) a system for transport and secretion of heavy metals; (3) three systems related to DNA transfer; (4) two CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) systems, known to provide resistance against phage infections, one similar in the Lens and Alcoy strains, and another specific to the Paris strain; and (5) seven islands of phage-related proteins, five of which seem to be strain-specific and two shared.</p> <p>Conclusions</p> <p>The dispensable genome disclosed by the pangenomic analysis seems to be a reservoir of new traits that have mainly been acquired by horizontal gene transfer and could confer evolutionary advantages over strains lacking them.</p

Virulence factor rtx in Legionella pneumophila, evidence suggesting it is a modular multifunctional protein

<p>Abstract</p> <p>Background</p> <p>The repeats in toxin (Rtx) are an important pathogenicity factor involved in host cells invasion of <it>Legionella pneumophila </it>and other pathogenic bacteria. Its role in escaping the host immune system and cytotoxic activity is well known. Its repeated motives and modularity make Rtx a multifunctional factor in pathogenicity.</p> <p>Results</p> <p>The comparative analysis of <it>rtx </it>gene among 6 strains of <it>L. pneumophila </it>showed modularity in their structures. Among compared genomes, the N-terminal region of the protein presents highly dissimilar repeats with functionally similar domains. On the contrary, the C-terminal region is maintained with a fashionable modular configuration, which gives support to its proposed role in adhesion and pore formation. Despite the variability of <it>rtx </it>among the considered strains, the flanking genes are maintained in synteny and similarity.</p> <p>Conclusion</p> <p>In contrast to the extracellular bacteria <it>Vibrio cholerae</it>, in which the <it>rtx </it>gene is highly conserved and flanking genes have lost synteny and similarity, the gene region coding for the Rtx toxin in the intracellular pathogen <it>L. pneumophila </it>shows a rapid evolution. Changes in the <it>rtx </it>could play a role in pathogenicity. The interplay of the Rtx toxin with host membranes might lead to the evolution of new variants that are able to escape host cell defences.</p

Molecular evidence to suggest the origien of a colonization: Drosophila suboscura in América

The recent colonization of America by Drosophila subobscura represents a great opportunity for evolutionary biology studies. Knowledge of the populations from which the colonization started would provide an understanding of how genetic compo- sition changed during adaptation to the new environment. Thus, a 793 nucleotide frag- ment of the Odh (Octanol dehydrogenase) gene was sequenced in 66 chromosomal lines from Barcelona (western Mediterranean) and in 66 from Mt. Parnes (Greece, eastern Mediterranean). No sequence of Odh fragment in Barcelona or Mt. Parnes was identical to any of those previously detected in America. However, an Odh sequence from Bar- celona differed in only one nucleotide from another found in American populations. In both cases, the chromosomal lines presented the same inversion: O , and the Odh gene was located within this inversion. This evidence suggests a possible western Mediter- ranean origin for the colonization. Finally, the molecular and inversion data indicate that the colonization was not characterized by multiple reintroductions.The recent colonization of America by Drosophila subobscura represents a great opportunity for evolutionary biology studies. Knowledge of the populations from which the colonization started would provide an understanding of how genetic compo- sition changed during adaptation to the new environment. Thus, a 793 nucleotide frag- ment of the Odh (Octanol dehydrogenase) gene was sequenced in 66 chromosomal lines from Barcelona (western Mediterranean) and in 66 from Mt. Parnes (Greece, eastern Mediterranean). No sequence of Odh fragment in Barcelona or Mt. Parnes was identical to any of those previously detected in America. However, an Odh sequence from Bar- celona differed in only one nucleotide from another found in American populations. In both cases, the chromosomal lines presented the same inversion: O , and the Odh gene was located within this inversion. This evidence suggests a possible western Mediter- ranean origin for the colonization. Finally, the molecular and inversion data indicate that the colonization was not characterized by multiple reintroductions

Virulence factor rtx in , evidence suggesting it is a modular multifunctional protein-3

<p><b>Copyright information:</b></p><p>Taken from "Virulence factor rtx in , evidence suggesting it is a modular multifunctional protein"</p><p>http://www.biomedcentral.com/1471-2164/9/14</p><p>BMC Genomics 2008;9():14-14.</p><p>Published online 14 Jan 2008</p><p>PMCID:PMC2257941.</p><p></p>espondent colours (see legend)

Virulence factor rtx in , evidence suggesting it is a modular multifunctional protein-1

<p><b>Copyright information:</b></p><p>Taken from "Virulence factor rtx in , evidence suggesting it is a modular multifunctional protein"</p><p>http://www.biomedcentral.com/1471-2164/9/14</p><p>BMC Genomics 2008;9():14-14.</p><p>Published online 14 Jan 2008</p><p>PMCID:PMC2257941.</p><p></p>0% (500 replicates)

Virulence factor rtx in , evidence suggesting it is a modular multifunctional protein-2

<p><b>Copyright information:</b></p><p>Taken from "Virulence factor rtx in , evidence suggesting it is a modular multifunctional protein"</p><p>http://www.biomedcentral.com/1471-2164/9/14</p><p>BMC Genomics 2008;9():14-14.</p><p>Published online 14 Jan 2008</p><p>PMCID:PMC2257941.</p><p></p> described regions sharing a nucleotide similarity higher than 70%. Green boxes represent gene positions and strand. Rtx 5' and 3' regions are shaded in red. For an easy visualization, the Corby sequence was complemented and reversed. For a more detailed view see additional fil

Virulence factor rtx in , evidence suggesting it is a modular multifunctional protein-0

<p><b>Copyright information:</b></p><p>Taken from "Virulence factor rtx in , evidence suggesting it is a modular multifunctional protein"</p><p>http://www.biomedcentral.com/1471-2164/9/14</p><p>BMC Genomics 2008;9():14-14.</p><p>Published online 14 Jan 2008</p><p>PMCID:PMC2257941.</p><p></p>espondent colours (see legend)

Molecular evidence to suggest the origin of a colonization: Drosophila subobscura in America

Abstract The recent colonization of America by Drosophila subobscura represents a great opportunity for evolutionary biology studies. Knowledge of the populations from which the colonization started would provide an understanding of how genetic composition changed during adaptation to the new environment. Thus, a 793 nucleotide fragment of the Odh (Octanol dehydrogenase) gene was sequenced in 66 chromosomal lines from Barcelona (western Mediterranean) and in 66 from Mt. Parnes (Greece, eastern Mediterranean). No sequence of Odh fragment in Barcelona or Mt. Parnes was identical to any of those previously detected in America. However, an Odh sequence from Barcelona differed in only one nucleotide from another found in American populations. In both cases, the chromosomal lines presented the same inversion: O7, and the Odh gene was located within this inversion. This evidence suggests a possible western Mediterranean origin for the colonization. Finally, the molecular and inversion data indicate that the colonization was not characterized by multiple reintroductions