Nivel de creatividad de los niños de 5 años de la I.E.I N° 407 de La Islilla – Paita - Piura, 2019.

La investigación tuvo como propósito determinar el nivel de creatividad de los niños y niñas de la Institución Educativa N° 407 de La Islilla – Paita – Piura. La investigación fue de diseño no experimental, tipo transversal, porque recolectó datos en un único momento. La muestra fue no probabilística y estuvo conformada por 18 niños, 16 hombres y 2 mujeres, matriculados en la sección de 5 años durante el año lectivo 2019. La recolección de datos se realizó a través del Test de Torrance y el análisis se centró en las 4 dimensiones de la creatividad: flexibilidad, fluidez, originalidad y elaboración. Los resultados de la investigación muestran que el 55.6% de los niños alcanzaron un nivel alto de creatividad y el 44.4% alcanzó el nivel medio. Concluyendo que el desarrollo de la creatividad en los niños y niñas se encuentra en proceso, siendo necesario continuar con las estrategias de mejora de aprendizaje orientadas a la creatividad

Assessing the inhibitory activity of culture supernatants against foodborne pathogens of two psychrotrophic bacteria isolated from river trout

There is a need for new natural products with antimicrobial activity to treat multidrug resistant bacteria that can cause human illness. Some of them are foodborne pathogens. Two different Gram-negative psychrotrophic strains were isolated from healthy trout river samples (Salmo trutta). Based on phenotypic characterization, proteomics, genotyping and phylogenetic analyses of 16 rRNA gene, strains TCPS12 and TCPS13 were identified as Shewanella baltica and Pseudomonas fragi, respectively. Both of them produced an exopolysaccharide that showed antimicrobial activity against four foodborne pathogens. P. fragi supernatant (AS13) showed higher antimicrobial activity than S. baltica supernatant (AS12) against all tested pathogens. The stability of the antimicrobial activity of AS13 was assessed against Enterococcus faecalis ATCC 29212 under different conditions. This solution was stable when exposed for 30 min to temperatures ranging from 40 to 100 °C. In addition, it retained its activity within a pH range of 2-8 during 2 h of incubation, showing higher activity at pH 6. Serine proteases and α-amylase inactivated significantly the antimicrobial activity of AS13, suggesting that the active molecule could most likely be a glycoprotein. These products are interesting for their possible application as biopreservatives in the food industry. Keywords: Antimicrobial activity; EPS production; Food preservation; Pseudomonas fragi; Shewanella baltica

Divergent evolution and purifying selection of the flaA gene sequences in Aeromonas

<p>Abstract</p> <p>Background</p> <p>The bacterial flagellum is the most important organelle of motility in bacteria and plays a key role in many bacterial lifestyles, including virulence. The flagellum also provides a paradigm of how hierarchical gene regulation, intricate protein-protein interactions and controlled protein secretion can result in the assembly of a complex multi-protein structure tightly orchestrated in time and space. As if to stress its importance, plants and animals produce receptors specifically dedicated to the recognition of flagella. Aside from motility, the flagellum also moonlights as an adhesion and has been adapted by humans as a tool for peptide display. Flagellar sequence variation constitutes a marker with widespread potential uses for studies of population genetics and phylogeny of bacterial species.</p> <p>Results</p> <p>We sequenced the complete flagellin gene <it>(flaA</it>) in 18 different species and subspecies of <it>Aeromonas</it>. Sequences ranged in size from 870 (<it>A. allosaccharophila</it>) to 921 nucleotides (<it>A. popoffii</it>). The multiple alignment displayed 924 sites, 66 of which presented alignment gaps. The phylogenetic tree revealed the existence of two groups of species exhibiting different FlaA flagellins (FlaA1 and FlaA2). Maximum likelihood models of codon substitution were used to analyze <it>flaA </it>sequences. Likelihood ratio tests suggested a low variation in selective pressure among lineages, with an ω ratio of less than 1 indicating the presence of purifying selection in almost all cases. Only one site under potential diversifying selection was identified (isoleucine in position 179). However, 17 amino acid positions were inferred as sites that are likely to be under positive selection using the branch-site model. Ancestral reconstruction revealed that these 17 amino acids were among the amino acid changes detected in the ancestral sequence.</p> <p>Conclusion</p> <p>The models applied to our set of sequences allowed us to determine the possible evolutionary pathway followed by the <it>flaA </it>gene in <it>Aeromonas</it>, suggesting that this gene have probably been evolving independently in the two groups of <it>Aeromonas </it>species since the divergence of a distant common ancestor after one or several episodes of positive selection.</p> <p>Reviewers</p> <p>This article was reviewed by Alexey Kondrashov, John Logsdon and Olivier Tenaillon (nominated by Laurence D Hurst).</p

Allelic diversity and population structure in Vibrio cholerae O139 Bengal based on nucleotide sequence analysis

Comparative analysis of gene fragments of six housekeeping loci, distributed around the two chromosomes of Vibrio cholerae, has been carried out for a collection of 29 V. cholerae O139 Bengal strains isolated from India during the first epidemic period (1992 to 1993). A toxigenic O1 ElTor strain from the seventh pandemic and an environmental non-O1/non-O139 strain were also included in this study. All loci studied were polymorphic, with a small number of polymorphic sites in the sequenced fragments. The genetic diversity determined for our O139 population is concordant with a previous multilocus enzyme electrophoresis study in which we analyzed the same V. cholerae O139 strains. In both studies we have found a higher genetic diversity than reported previously in other molecular studies. The results of the present work showed that O139 strains clustered in several lineages of the dendrogram generated from the matrix of allelic mismatches between the different genotypes, a finding which does not support the hypothesis previously reported that the O139 serogroup is a unique clone. The statistical analysis performed in the V. cholerae O139 isolates suggested a clonal population structure. Moreover, the application of the Sawyer's test and split decomposition to detect intragenic recombination in the sequenced gene fragments did not indicate the existence of recombination in our O139 population

Biochemical identification and numerical taxonomy of Aeromonas spp. isolated from environmental and clinical samples in Spain

Aims: To study the phenotypic characteristics of Aeromonas spp. from environmental and clinical samples in Spain and to cluster these strains by numerical taxonomy. Methods and Results: A collection of 202 Aeromonas strains isolated from bivalve molluscs, water and clinical samples was tested for 64 phenotypic properties; 91% of these isolates were identified at species level. Aeromonas caviae was predominant in bivalve molluscs and Aerom. bestiarum in freshwater samples. Cluster analyses revealed eight different phena: three containing more than one DNA-DNA hybridization group but including strains that belong to the same phenospecies complex (Aerom. hydrophila, Aerom. sobria and Aerom. caviae), Aerom. encheleia, Aerom. trota and three containing unidentified Aeromonas strains isolated from bivalve molluscs. Conclusions: Aeromonas spp. are widely distributed in environmental and clinical sources. A selection of 16 of the phenotypical tests chosen allowed the identification of most isolates (91%), although some strains remain unidentified, mainly isolates from bivalve molluscs, suggesting the presence of new Aeromonas species. Numerical taxonomy was not in total concordance with the identification of the studied strains. Significance and Impact of the Study: Numerical taxonomy of Aeromonas strains isolated from different sources revealed the presence of potentially pathogenic Aeromonas spp., especially in bivalve molluscs, and phena with unidentified strains that suggest new Aeromonas species

Population Genetics of the “Aeromonas hydrophila Species Complex”

Population genetics studies the genetic variability of individuals in a population based on the allele frequencies at several genes or loci and tries to explain this variability in terms of mutation, selection or genetic recombination. The statistical analysis of these frequencies allows models of evolution to be established, which will help us to understand and predict the past and present gene flow in the population (Maynard-Smith, 1991). For the most part population genetics has been designed for diploid organisms with sexual reproduction. In the words of Bruce Levin, “the genetic theory of adaptive evolution was developed by sexually reproducing eukaryotes, for sexually reproducing eukaryotes” (Levin & Bergstrom, 2000). As a consequence, before being applied to prokaryotes, population genetics needs to be adapted. In theory the haploid nature of bacteria should simplify their analysis, since dominance or over-dominance is not an issue and the genotype can usually be deduced directly from the phenotype. However, central to classical population genetics are infinite population size, random mating, and free recombination. Consequently, as expressed by Maynard-Smith, “the alleles present at one locus are independent of those at other loci. Changes in the frequency of an allele at one locus, therefore, are independent of what is happening elsewhere in the genome: each locus can be treated individually” (Maynard-Smith, 1995). It is true that the size of bacterial populations can be practically infinite but recombination occurs extremely rarely so that changes affecting one locus can lead to the modification of others. In the succinct words of Maynard-Smith, “the genome should be treated as an interrelated whole, and not as a set of independently changing genes”. The crux of the problem is knowing the exact level of recombination in bacterial populations, since “it is considerably more challenging to elaborate a theory for a population with little recombination than for one with no recombination, or a lot” (Maynard-Smith, 1995). In bacterial population genetics, sometimes we detect a degree of recombination that is too high for a pure phylogenetic approach, but too low for assessing a random interchange..

The reference strain Aeromonas hydrophicla CIP 57.50 should be reclassified as Aeromonas salmonicida CIP 57.50

The use of reference strains is a critical element for the quality control of different assays, from the development of molecular methods to the evaluation of antimicrobial activities. Most of the strains used in these assays are not type strains and some of them are cited erroneously because of subsequent reclassifications and descriptions of novel species. In this study, we propose that the reference strain Aeromonas hydrophila CIP 57.50 be reclassified as Aeromonas salmonicida CIP 57.50 based on phenotypic characterization and sequence analyses of the cpn60, dnaJ, gyrB and rpoD genes

Divergent evolution and purifying selection of the flaA gene sequences in Aeromonas

BACKGROUND: The bacterial flagellum is the most important organelle of motility in bacteria and plays a key role in many bacterial lifestyles, including virulence. The flagellum also provides a paradigm of how hierarchical gene regulation, intricate protein-protein interactions and controlled protein secretion can result in the assembly of a complex multi-protein structure tightly orchestrated in time and space. As if to stress its importance, plants and animals produce receptors specifically dedicated to the recognition of flagella. Aside from motility, the flagellum also moonlights as an adhesion and has been adapted by humans as a tool for peptide display. Flagellar sequence variation constitutes a marker with widespread potential uses for studies of population genetics and phylogeny of bacterial species. RESULTS: We sequenced the complete flagellin gene (flaA) in 18 different species and subspecies of Aeromonas. Sequences ranged in size from 870 (A. allosaccharophila) to 921 nucleotides (A. popoffii). The multiple alignment displayed 924 sites, 66 of which presented alignment gaps. The phylogenetic tree revealed the existence of two groups of species exhibiting different FlaA flagellins (FlaA1 and FlaA2). Maximum likelihood models of codon substitution were used to analyze flaA sequences. Likelihood ratio tests suggested a low variation in selective pressure among lineages, with an omega ratio of less than 1 indicating the presence of purifying selection in almost all cases. Only one site under potential diversifying selection was identified (isoleucine in position 179). However, 17 amino acid positions were inferred as sites that are likely to be under positive selection using the branch-site model. Ancestral reconstruction revealed that these 17 amino acids were among the amino acid changes detected in the ancestral sequence. CONCLUSION: The models applied to our set of sequences allowed us to determine the possible evolutionary pathway followed by the flaA gene in Aeromonas, suggesting that this gene have probably been evolving independently in the two groups of Aeromonas species since the divergence of a distant common ancestor after one or several episodes of positive selection. REVIEWERS: This article was reviewed by Alexey Kondrashov, John Logsdon and Olivier Tenaillon (nominated by Laurence D Hurst)

Prediction of whole-genome DNA G+C content within the genus Aeromonas based on housekeeping gene sequences

Different methods are available to determine the G+C content (e.g. thermal denaturation temperature or high performance liquid chromatography, HPLC), but obtained values may differ significantly between strains, as well as between laboratories. Recently, several authors have demonstrated that the genomic DNA G+C content of prokaryotes can be reliably estimated from one or several protein coding gene nucleotide sequences. Few G+C content values have been published for the Aeromonas species described and the data, when available, are often incomplete or provide only a range of values. Our aim in this current work was twofold. First, the genomic G+C content of the type or reference strains of all species and subspecies of the genus Aeromonas was determined with a traditional experimental method in the same laboratory. Second, we wanted to see if the sequence-based method to estimate the G+C content described by Fournier et al. [7] could be applied to determine the G+C content of the different species of Aeromonas from the sequences of the genes used in taxonomy or phylogeny for this genus

Direct evidence of recombination in the recA gene of Aeromonas bestiarum

tTwo hundred and twenty-one strains representative of all Aeromonas species were characterized usingthe recA gene sequence, assessing its potential as a molecular marker for the genus Aeromonas. The inter-species distance values obtained demonstrated that recA has a high discriminatory power. Phylogeneticanalysis, based on full-length gene nucleotide sequences, revealed a robust topology with clearly sepa-rated clusters for each species. The maximum likelihood tree showed the Aeromonas bestiarum strains ina well-defined cluster, containing a subset of four strains of different geographical origins in a deep inter-nal branch. Data analysis provided strong evidence of recombination at the end of the recA sequences inthese four strains. Intergenomic recombination corresponding to partial regions of the two adjacent genesrecA and recX (248 bp) was identified between A. bestiarum (major parent) and Aeromonas eucrenophila(minor parent). The low number of recombinant strains detected (1.8%) suggests that horizontal flowbetween recA sequences is relatively uncommon in this genus. Moreover, only a few nucleotide differ-ences were detected among these fragments, indicating that recombination has occurred recently. Finally,we also determined if the recombinant fragment could have influenced the structure and basic functionsof the RecA protein, comparing models reconstructed from the translated amino acid sequences of ourA. bestiarum strains with known Escherichia coli RecA structures