\u3cem\u3eRhizobium phaseoli\u3c/em\u3e Symbiotic Mutants with Transposon Tn5 Insertions

Rhizobium phaseoli CFN42 DNA was mutated by random insertion of Tn5 from suicide plasmid pJB4JI to obtain independently arising strains that were defective in symbiosis with Phaseolus vulgaris but grew normally outside the plant. When these mutants were incubated with the plant, one did not initiate visible nodule tissue (Nod-), seven led to slow nodule development (Ndv), and two led to superficially normal early nodule development but lacked symbiotic nitrogenase activity (Sna-). The Nod- mutant lacked the large transmissible indigenous plasmid pCFN42d that has homology to Klebsiella pneumoniae nitrogenase (nif) genes. The other mutants had normal plasmid content. In the two Sna- mutants and one Ndv mutant, Tn5 had inserted into plasmid pCFN42d outside the region of nif homology. The insertions of the other Ndv mutants were apparently in the chromosome. They were not in plasmids detected on agarose gels, and, in contrast to insertions on indigenous plasmids, they were transmitted in crosses to wild-type strain CFN42 at the same frequency as auxotrophic markers and with the same enhancement of transmission by conjugation plasmid R68.45. In these Ndv mutants the Tn5 insertions were the same as or very closely linked to mutations causing the Ndv phenotype. However, in two mutants with Tn5 insertions on plasmid pCFN42d, an additional mutation on the same plasmid, rather than Tn5, was responsible for the Sna- or Ndv phenotype. When plasmid pJB4JI was transferred to two other R. phaseoli strains, analysis of symbiotic mutants was complicated by Tn5-containing deleted forms of pJB4JI that were stably maintained

The Rhizobium etli σ(70) (SigA) factor recognizes a lax consensus promoter

A collection of Rhizobium etli promoters was isolated from a genomic DNA library constructed in the promoter-trap vector pBBMCS53, by their ability to drive the expression of a gusA reporter gene. Thirty-seven clones were selected, and their transcriptional start-sites were determined. The upstream sequence of these 37 start-sites, and the sequences of seven previously identified promoters were compared. On the basis of sequence conservation and mutational analysis, a consensus sequence CTTGACN(16–23)TATNNT was obtained. In this consensus sequence, nine on of twelve bases are identical to the canonical Escherichia coli σ(70) promoter, however the R.etli promoters only contain 6.4 conserved bases on average. We show that the R.etli sigma factor SigA recognizes all R.etli promoters studied in this work, and that E.coli RpoD is incapable of recognizing them. The comparison of the predicted structure of SigA with the known structure of RpoD indicated that regions 2.4 and 4.2, responsible for promoter recognition, are different only by a single amino acid, whereas the region 1 of SigA contains 72 extra residues, suggesting that the differences contained in this region could be related to the lax promoter recognition of SigA

The replication origin of a repABC plasmid

<p>Abstract</p> <p>Background</p> <p><it>repABC </it>operons are present on large, low copy-number plasmids and on some secondary chromosomes in at least 19 α-proteobacterial genera, and are responsible for the replication and segregation properties of these replicons. These operons consist, with some variations, of three genes: <it>repA</it>, <it>repB</it>, and <it>repC</it>. RepA and RepB are involved in plasmid partitioning and in the negative regulation of their own transcription, and RepC is the limiting factor for replication. An antisense RNA encoded between the <it>repB-repC </it>genes modulates <it>repC </it>expression.</p> <p>Results</p> <p>To identify the minimal region of the <it>Rhizobium etli </it>p42d plasmid that is capable of autonomous replication, we amplified different regions of the <it>repABC </it>operon using PCR and cloned the regions into a suicide vector. The resulting vectors were then introduced into <it>R. etli </it>strains that did or did not contain p42d. The minimal replicon consisted of a <it>repC </it>open reading frame under the control of a constitutive promoter with a Shine-Dalgarno sequence that we designed. A sequence analysis of <it>repC </it>revealed the presence of a large A+T-rich region but no iterons or DnaA boxes. Silent mutations that modified the A+T content of this region eliminated the replication capability of the plasmid. The minimal replicon could not be introduced into <it>R. etli </it>strain containing p42d, but similar constructs that carried <it>repC </it>from <it>Sinorhizobium meliloti </it>pSymA or the linear chromosome of <it>Agrobacterium tumefaciens </it>replicated in the presence or absence of p42d, indicating that RepC is an incompatibility factor. A hybrid gene construct expressing a RepC protein with the first 362 amino acid residues from p42d RepC and the last 39 amino acid residues of RepC from SymA was able to replicate in the presence of p42d.</p> <p>Conclusions</p> <p>RepC is the only element encoded in the <it>repABC </it>operon of the <it>R. etli </it>p42d plasmid that is necessary and sufficient for plasmid replication and is probably the initiator protein. The <it>oriV </it>of this plasmid resides within the <it>repC </it>gene and is located close to or inside of a large A+T region. RepC can act as an incompatibility factor, and the last 39 amino acid residues of the carboxy-terminal region of this protein are involved in promoting this phenotype.</p

Horizontal gene transfer and diverse functional constrains within a common replication-partitioning system in Alphaproteobacteria: the repABC operon

<p>Abstract</p> <p>Background</p> <p>The <it>repABC </it>plasmid family, which is extensively present within <it>Alphaproteobacteria</it>, and some secondary chromosomes of the <it>Rhizobiales </it>have the particular feature that all the elements involved in replication and partitioning reside within one transcriptional unit, the <it>repABC </it>operon. Given the functional interactions among the elements of the <it>repABC </it>operon, and the fact that they all reside in the same operon, a common evolutionary history would be expected if the entire operon had been horizontally transferred. Here, we tested whether there is a common evolutionary history within the <it>repABC </it>operon. We further examined different incompatibility groups in terms of their differentiation and degree of adaptation to their host.</p> <p>Results</p> <p>We did not find a single evolutionary history within the <it>repABC </it>operon. Each protein had a particular phylogeny, horizontal gene transfer events of the individual genes within the operon were detected, and different functional constraints were found within and between the Rep proteins. When different <it>repABC </it>operons coexisted in the same genome, they were well differentiated from one another. Finally, we found different levels of adaptation to the host genome within and between <it>repABC </it>operons coexisting in the same species.</p> <p>Conclusion</p> <p>Horizontal gene transfer with conservation of the <it>repABC </it>operon structure provides a highly dynamic operon in which each member of this operon has its own evolutionary dynamics. In addition, it seems that different incompatibility groups present in the same species have different degrees of adaptation to their host genomes, in proportion to the amount of time the incompatibility group has coexisted with the host genome.</p

Estimation of Resilience in University Students

The objective of the work is to estimate the resilience level of university students for future resilience interventions. The paper presents a conceptual analysis of the term resilience, based on the criteria of contemporary authors framed in two generations. The methods and techniques used in the work are exposed, where two tools for measuring resilience are highlighted. The importance of the study of resilience in the university environment is discussed and the statistical and graphical results related to the application of the aforementioned instruments are shown in terms of measuring the resilience level in the university students of seven faculties of the Technical University of Manabí

Autonomy, Good Humor and Support Networks, Potential of Community Resilience Intervention in People Victims of the Earthquake in the Calderón Parish

Resilience is a concept widely used in recent years, especially when it comes to evaluating the level of recovery of communities that are hit by natural phenomena. It can be stated that conceptually resilience constitutes the ability to react effectively and quickly to the effects of disasters, being a complex phenomenon to evaluate and define. And although the level of resilience does not necessarily imply greater control of vulnerability, it can be affirmed that the reduction of vulnerable conditions can strengthen and consolidate the resilient capacity of individuals and communities, in the face of the effects of natural disasters

Rapid evolutionary change of common bean (Phaseolus vulgaris L) plastome, and the genomic diversification of legume chloroplasts

<p>Abstract</p> <p>Background</p> <p>Fabaceae (legumes) is one of the largest families of flowering plants, and some members are important crops. In contrast to what we know about their great diversity or economic importance, our knowledge at the genomic level of chloroplast genomes (cpDNAs or plastomes) for these crops is limited.</p> <p>Results</p> <p>We sequenced the complete genome of the common bean (<it>Phaseolus vulgari</it>s cv. Negro Jamapa) chloroplast. The plastome of <it>P. vulgaris </it>is a 150,285 bp circular molecule. It has gene content similar to that of other legume plastomes, but contains two pseudogenes, <it>rpl</it>33 and <it>rps</it>16. A distinct inversion occurred at the junction points of <it>trn</it>H-GUG/<it>rpl</it>14 and <it>rps</it>19/<it>rps</it>8, as in adzuki bean <abbrgrp><abbr bid="B1">1</abbr></abbrgrp>. These two pseudogenes and the inversion were confirmed in 10 varieties representing the two domestication centers of the bean. Genomic comparative analysis indicated that inversions generally occur in legume plastomes and the magnitude and localization of insertions/deletions (indels) also vary. The analysis of repeat sequences demonstrated that patterns and sequences of tandem repeats had an important impact on sequence diversification between legume plastomes and tandem repeats did not belong to dispersed repeats. Interestingly, <it>P. vulgaris </it>plastome had higher evolutionary rates of change on both genomic and gene levels than <it>G. max</it>, which could be the consequence of pressure from both mutation and natural selection.</p> <p>Conclusion</p> <p>Legume chloroplast genomes are widely diversified in gene content, gene order, indel structure, abundance and localization of repetitive sequences, intracellular sequence exchange and evolutionary rates. The <it>P. vulgaris </it>plastome is a rapidly evolving genome.</p

Whole-Genome Sequences of Five Acinetobacter baumannii Strains From a Child With Leukemia M2

Acinetobacter baumannii is an opportunistic pathogen and is one of the primary etiological agents of healthcare-associated infections (HAIs). A. baumannii infections are difficult to treat due to the intrinsic and acquired antibiotic resistance of strains of this bacterium, which frequently limits therapeutic options. In this study, five A. baumannii strains (810CP, 433H, 434H, 483H, and A-2), all of which were isolated from a child with leukemia M2, were characterized through antibiotic susceptibility profiling, the detection of genes encoding carbapenem hydrolyzing oxacillinases, pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), adherence and invasion assays toward the A549 cell line, and the whole-genome sequence (WGS). The five strains showed Multidrug resistant (MDR) profiles and amplification of the blaOXA-23 gene, belonging to ST758 and grouped into two PFGE clusters. WGS of 810CP revealed the presence of a circular chromosome and two small plasmids, pAba810CPa and pAba810CPb. Both plasmids carried genes encoding the Sp1TA system, although resistance genes were not identified. A gene-by-gene comparison analysis was performed among the A. baumannii strains isolated in this study and others A. baumannii ST758 strains (HIMFG and INCan), showing that 86% of genes were present in all analyzed strains. Interestingly, the 433H, 434H, and 483H strains varied by 8–10 single-nucleotide variants (SNVs), while the A2 and 810CP strains varied by 46 SNVs. Subsequently, an analysis using BacWGSTdb showed that all of our strains had the same resistance genes and were ST758. However, some variations were observed in relation to virulence genes, mainly in the 810CP strain. The genes involved in the synthesis of hepta-acylated lipooligosaccharides, the pgaABCD locus encoding poly-β-1-6-N-acetylglucosamine, the ompA gene, Csu pili, bap, the two-component system bfms/bfmR, a member of the phospholipase D family, and two iron-uptake systems were identified in our A. baumannii strains genome. The five A. baumannii strains isolated from the child were genetically different and showed important characteristics that promote survival in a hospital environment. The elucidation of their genomic sequences provides important information for understanding their epidemiology, antibiotic resistance, and putative virulence factors

Diseño de un sistema de monitorización de la calidad de aire, basado en una red sensorial y técnicas de IOT para la ciudad de Esmeraldas / Projeto de um sistema de monitoramento da qualidade do ar baseado em uma rede de sensores e técnicas IOT para a cidade de Esmeraldas

El presenta artículo define la estructura funcional de una red de monitoreo de calidad de aire. Es importante destacar que la implementación se la realiza con contralores que permiten una programación escalable, y cuya conexión a sensores no implica el coste adicional de buses de comunicación o software propietarios. La arquitectura planteada permite la interconectividad de la red, y la distribución en varios nodos. Se analiza también la causalidad de las emisiones contaminantes que afectan a una determinada comunidad, la misma que abarca a la ciudad de Esmeraldas. La estrategia de implementación esta denotada y enmarcada por la ley y la legislación ambiental, y deberá ser contrastada con los datos de emisiones de las fuentes industriales. También será de amplia ayuda para cuantificar las emisiones vehiculares

Genomic and proteomic analyses of Mycobacterium bovis BCG Mexico 1931 reveal a diverse immunogenic repertoire against tuberculosis infection

<p>Abstract</p> <p>Background</p> <p>Studies of <it>Mycobacterium bovis </it>BCG strains used in different countries and vaccination programs show clear variations in the genomes and immune protective properties of BCG strains. The aim of this study was to characterise the genomic and immune proteomic profile of the BCG 1931 strain used in Mexico.</p> <p>Results</p> <p>BCG Mexico 1931 has a circular chromosome of 4,350,386 bp with a G+C content and numbers of genes and pseudogenes similar to those of BCG Tokyo and BCG Pasteur. BCG Mexico 1931 lacks Region of Difference 1 (RD1), RD2 and N-RD18 and one copy of IS6110, indicating that BCG Mexico 1931 belongs to DU2 group IV within the BCG vaccine genealogy. In addition, this strain contains three new RDs, which are 53 (RDMex01), 655 (RDMex02) and 2,847 bp (REDMex03) long, and 55 single-nucleotide polymorphisms representing non-synonymous mutations compared to BCG Pasteur and BCG Tokyo. In a comparative proteomic analysis, the BCG Mexico 1931, Danish, Phipps and Tokyo strains showed 812, 794, 791 and 701 protein spots, respectively. The same analysis showed that BCG Mexico 1931 shares 62% of its protein spots with the BCG Danish strain, 61% with the BCG Phipps strain and only 48% with the BCG Tokyo strain. Thirty-nine reactive spots were detected in BCG Mexico 1931 using sera from subjects with active tuberculosis infections and positive tuberculin skin tests.</p> <p>Conclusions</p> <p>BCG Mexico 1931 has a smaller genome than the BCG Pasteur and BCG Tokyo strains. Two specific deletions in BCG Mexico 1931 are described (RDMex02 and RDMex03). The loss of RDMex02 (<it>fadD23</it>) is associated with enhanced macrophage binding and RDMex03 contains genes that may be involved in regulatory pathways. We also describe new antigenic proteins for the first time.</p