Comparación de la potencia aeróbica máxima e indicadores de saltabilidad según sexo en estudiantes de octavo básico y segundo medio del Colegio San Francisco Javier de Huechuraba

Tesis (Profesor de Educación Física, Licenciado en Educación)Actualmente, Chile presenta elevados índices de obesidad y enfermedades asociadas al sedentarismo, siendo la actividad física una de las principales maneras de prevenir y contrarrestar sus consecuencias negativas. Esta problemática también se observa al interior de los establecimientos educacionales, donde una correcta planificación de las actividades físicas permite maximizar sus efectos positivos sobre la salud física y mental de los estudiantes. Para ello, es relevante realizar un diagnóstico y recabar información respecto a la situación actual en términos de aptitud física en los estudiantes de un determinado colegio, y cómo el sexo influye sobre dicho parámetro. En la presente tesis se realizó un estudio comparativo para determinar las diferencias que existen entre distintos sexos en cursos de octavo y segundo medio, al momento de realizar un esfuerzo físico de tipo aeróbico y anaeróbico. Para ello, se utilizó el test Course Navette y la batería de saltos creada por el profesor Carmelo Bosco, respectivamente, comparando las diferencias observadas entre hombres y mujeres de los mencionados cursos en el colegio San Francisco Javier de Huechuraba. En base a la aplicación de los diferentes tests, se observó que el promedio de varones fue superior al de las damas, es decir, el sexo masculino obtuvo mejores resultados en las distintas pruebas de resistencia aeróbica y de saltos, lo que podría estar relacionado a las diferencias fisiológicas existentes entre ambos sexos. Los resultados anteriores evidencian la necesidad de generar nuevas pautas y proyectos donde se plantean ejercicios de forma más personalizada y acorde al nivel de maduración del sexo, evaluando de distinta manera a hombres y mujeres. Las conclusiones generadas a partir de esta tesis permitieron además ampliar un camino de investigación, recalcando la necesidad y utilidad de abarcar distintos temas relacionados a cómo se están desarrollando los estudiantes y qué caminos de acción y evaluación se debe tomar como profesores para entregar las mejores herramientas, formando jóvenes activamente motrices y capaces de realizar tanto actividad física en la vida cotidiana como desempeñarse en algún deporte de elite.Currently, Chile country has a very high prevalence of obesity and sedentarism-associated diseases, being the physical activity one of the principal of preventing and counteracting its negative consequences. This problem is also observed in educational establishment, where a correct planing of the physical activity programs allows to a maximization of its beneficial effects on the mental and physical health of students. For this, it is very important to diagnose and gather information the current situation in terms of physical condition of students from a defined school, and how gender influences such parameter. The thesis of this work was comparative study to determine the existing gender differences in eight and tenth graders of each gender inresponse to aerobic and anaerobic excercises. For this purpose, we used the Curse Navette test and the jump battery test developed by the professor Carmelo Bosco, respectively, comparing the differences observed between men and women from the grades mentionaed above in the school San Francisco of Huechuraba. Based on the application of different tests, observed that the average of physical condition was higher in men compared to women in both aerobic and jump resistence tests, and this could be related with the physiological differences that exists between both genders. These results ilustrate the importance of generating new excercise programs, tending to a personalized routine in agreement with sex maturation, and evaluating men and women distinctly. The conclusions generated from this thesis allowed us the exploration of to the problem from a wider point of view, evidenciating the importance and utility of discussing how students are learning which teaching strategies teaching and evaluations should be follow by teachers, to provide the best learning tools to form active and healthy young people, able to practice both routinary or domestic exercise programs and a high-performance sport

Properties of genes encoding transfer RNAs as integration sites for genomic islands and prophages in <i>Klebsiella pneumoniae</i>

ABSTRACTThe evolution of traits including antibiotic resistance, virulence, and increased fitness in Klebsiella pneumoniae and related species has been linked to the acquisition of mobile genetic elements through horizontal transfer. Among them, genomic islands (GIs) preferentially integrating at genes encoding tRNAs and the tmRNA (t(m)DNAs) would be significant in promoting chromosomal diversity. Here, we studied the whole set of t(m)DNAs present in 66 Klebsiella chromosomes, investigating their usage as integration sites and the properties of the integrated GIs. A total of 5,624 t(m)DNAs were classified based on their sequence conservation, genomic context, and prevalence. 161 different GIs and prophages were found at these sites, hosting 3,540 gene families including various related to virulence and drug resistance. Phylogenetic analyses supported the acquisition of several of these elements through horizontal gene transfer, likely mediated by a highly diverse set of encoded integrases targeting specific t(m)DNAs and sublocations inside them. Only a subset of the t(m)DNAs had integrated GIs and even identical tDNA copies showed dissimilar usage frequencies, suggesting that the genomic context would influence the integration site selection. This usage bias, likely towards avoiding disruption of polycistronic transcriptional units, would be conserved across Gammaproteobacteria. The systematic comparison of the t(m)DNAs across different strains allowed us to discover an unprecedented number of K. pneumoniae GIs and prophages and to raise important questions and clues regarding the fundamental properties of t(m)DNAs as targets for the integration of mobile genetic elements and drivers of bacterial genome evolution and pathogen emergence.</jats:p

In-Depth Genomic and Phenotypic Characterization of the Antarctic Psychrotolerant Strain Pseudomonas sp. MPC6 Reveals Unique Metabolic Features, Plasticity, and Biotechnological Potential

We obtained the complete genome sequence of the psychrotolerant extremophile Pseudomonas sp. MPC6, a natural Polyhydroxyalkanoates (PHAs) producing bacterium able to rapidly grow at low temperatures. Genomic and phenotypic analyses allowed us to situate this isolate inside the Pseudomonas fluorescens phylogroup of pseudomonads as well as to reveal its metabolic versatility and plasticity. The isolate possesses the gene machinery for metabolizing a variety of toxic aromatic compounds such as toluene, phenol, chloroaromatics, and TNT. In addition, it can use both C6- and C5-carbon sugars like xylose and arabinose as carbon substrates, an uncommon feature for bacteria of this genus. Furthermore, Pseudomonas sp. MPC6 exhibits a high-copy number of genes encoding for enzymes involved in oxidative and cold-stress response that allows it to cope with high concentrations of heavy metals (As, Cd, Cu) and low temperatures, a finding that was further validated experimentally. We then assessed the growth performance of MPC6 on glycerol using a temperature range from 0 to 45°C, the latter temperature corresponding to the limit at which this Antarctic isolate was no longer able to propagate. On the other hand, the MPC6 genome comprised considerably less virulence and drug resistance factors as compared to pathogenic Pseudomonas strains, thus supporting its safety. Unexpectedly, we found five PHA synthases within the genome of MPC6, one of which clustered separately from the other four. This PHA synthase shared only 40% sequence identity at the amino acid level against the only PHA polymerase described for Pseudomonas (63-1 strain) able to produce copolymers of short- and medium-chain length PHAs. Batch cultures for PHA synthesis in Pseudomonas sp. MPC6 using sugars, decanoate, ethylene glycol, and organic acids as carbon substrates result in biopolymers with different monomer compositions. This indicates that the PHA synthases play a critical role in defining not only the final chemical structure of the biosynthesized PHA, but also the employed biosynthetic pathways. Based on the results obtained, we conclude that Pseudomonas sp. MPC6 can be exploited as a bioremediator and biopolymer factory, as well as a model strain to unveil molecular mechanisms behind adaptation to cold and extreme environments

Bacterial Amyloids

Amyloids are supramolecular protein assemblies based on fibrillar arrangements of β- sheets that were first found as linked to neurodegenerative and systemic human diseases. However, there is now overwhelming evidence on alternative roles of amyloids as functional assemblies and as epigenetic determinants of beneficial traits, both in Fungi and Metazoa. Bacteria also use amyloids as functional devices, mainly as extracellular scaffolds in biofilms, but there is increasing evidence for functional roles of amyloids in the bacterial cytosol, and these have enabled to engineer minimal models of a ‘generic’ amyloid disease. Amyloids are thus key players in the physiology of bacteria and versatile building blocks in Synthetic Biology.Peer reviewe

Whole-genome sequence of the microcin E492-producing strain Klebsiella pneumoniae RYC492

© 2013 Marcoleta et al. Here, we report the draft genome sequence of the Gram-negative strain Klebsiella pneumoniae RYC492, which produces the amyloid-forming and antibacterial peptide microcin E492. The sequenced genome consists of a 5,095,761-bp assembled open chromosome where the gene cluster for microcin production is located in a putative 31-kb genomic island flanked by sequence repeats and containing a putative integrase-coding gene

Klebsiella pneumoniae asparagine tDNAs are integration hotspots for different genomic islands encoding microcin E492 production determinants and other putative virulence factors present in hypervirulent strains

Due to the developing of multi-resistant and invasive hypervirulent strains, Klebsiella pneumoniae has become one of the most urgent bacterial pathogen threats in the last years. Genomic comparison of a growing number of sequenced isolates has allowed the identification of putative virulence factors, proposed to be acquirable mainly through horizontal gene transfer. In particular, those related with synthesizing the antibacterial peptide microcin E492 (MccE492) and salmochelin siderophores were found to be highly prevalent among hypervirulent strains. The determinants for the production of both molecules were first reported as part of a 13-kbp segment of K. pneumoniae RYC492 chromosome, and were cloned and characterized in E. coli. However, the genomic context of this segment in K. pneumoniae remained uncharacterized.In this work we provided experimental and bioinformatics evidence indicating that the MccE492 cluster is part of a highly conserved 23-kbp genomic island (GI) named GIE492, that was integrated in a specific asparagine-tRNA gene (asn-tDNA) and was found in a high proportion of isolates from liver abscesses sampled around the world. This element resulted to be unstable and its excision frequency increased after treating bacteria with mytomicin C and upon the overexpression of the island-encoded integrase. Besides the MccE492 genetic cluster, it invariably included an integrase-coding gene, at least 7 protein-coding genes of unknown function, and a putative transfer origin that possibly allows this GI to be mobilized through conjugation. In addition, we analyzed the asn-tDNA loci of all the available K. pneumoniae assembled chromosomes to evaluate them as GI-integration sites. Remarkably, 73% of the strains harbored at least one GI integrated in one of the four asn-tDNA present in this species, confirming them as integration hotspots. Each of these tDNAs was occupied with different frequencies, although they were 100% identical. Also, we identified a total of 47 asn-tDNA-associated GIs that were classified into 12 groups of homology differing in the encoded functionalities but sharing with GIE492 a conserved recombination module and potentially its mobility features. Most of these GIs encoded factors with proven or potential role in pathogenesis, constituting a major reservoir of virulence factors in this species

"Glucose and ethanol-dependent transcriptional regulation of the astaxanthin biosynthesis pathway in <it>Xanthophyllomyces dendrorhous</it>"

Abstract Background The yeast Xanthophyllomyces dendrorhous is one of the most promising and economically attractive natural sources of astaxanthin. The biosynthesis of this valuable carotenoid is a complex process for which the regulatory mechanisms remain mostly unknown. Several studies have shown a strong correlation between the carbon source present in the medium and the amount of pigments synthesized. Carotenoid production is especially low when high glucose concentrations are used in the medium, while a significant increase is observed with non-fermentable carbon sources. However, the molecular basis of this phenomenon has not been established. Results In this work, we showed that glucose caused transcriptional repression of the three genes involved in the synthesis of astaxanthin from geranylgeranyl pyrophosphate in X. dendrorhous, which correlates with a complete inhibition of pigment synthesis. Strikingly, this regulatory response was completely altered in mutant strains that are incapable of synthesizing astaxanthin. However, we found that addition of ethanol caused the induction of crtYB and crtS gene expression and promoted de novo synthesis of carotenoids. The induction of carotenogenesis was noticeable as early as 24 h after ethanol addition. Conclusion For the first time, we demonstrated that carbon source-dependent regulation of astaxanthin biosynthesis in X. dendrorhous involves changes at the transcriptional level. Such regulatory mechanism provides an explanation for the strong and early inhibitory effect of glucose on the biosynthesis of this carotenoid.</p

Identification of factors affecting aggregation of Microcin E492, a bacterial functional amyloid

FONDECYT 114043

Cloning of the cytochrome p450 reductase <it>(crtR) </it>gene and its involvement in the astaxanthin biosynthesis of <it>Xanthophyllomyces dendrorhous</it>

Abstract Background The yeast Xanthophyllomyces dendrorhous synthesizes astaxanthin, a carotenoid with high commercial interest. The proposed biosynthetic route in this organism is isopentenyl-pyrophosphate (IPP) → geranyleranyl pyrophosphate (GGPP) → phytoene → lycopene → β-carotene → astaxanthin. Recently, it has been published that the conversion of β-carotene into astaxanthin requires only one enzyme, astaxanthin synthase or CrtS, encoded by crtS gene. This enzyme belongs to the cytochrome P450 protein family. Results In this work, a crtR gene was isolated from X. dendrorhous yeast, which encodes a cytochrome P450 reductase (CPR) that provides CrtS with the necessary electrons for substrate oxygenation. We determined the structural organization of the crtR gene and its location in the yeast electrophoretic karyotype. Two transformants, CBSTr and T13, were obtained by deleting the crtR gene and inserting a hygromycin B resistance cassette. The carotenoid composition of the transformants was altered in relation to the wild type strain. CBSTr forms yellow colonies because it is unable to produce astaxanthin, hence accumulating β-carotene. T13 forms pale colonies because its astaxanthin content is reduced and its β-carotene content is increased. Conclusion In addition to the crtS gene, X. dendrorhous requires a novel gene, crtR, for the conversion of β-carotene to astaxanthin.</p

The Ferric uptake regulator (Fur) and iron availability control the production and maturation of the antibacterial peptide microcin E492

© 2018 Marcoleta et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Microcin E492 is a pore-forming bacteriocin with toxic activity against Enterobacteriaceae, which undergoes amyloid aggregation as a mechanism to regulate its toxicity. To be active, it requires the posttranslational attachment to the C-terminus of a glycosylated enterochelin derivative (salmochelin), a process carried out by the proteins MceC, MceI and MceJ encoded in the MccE492 gene cluster. Both microcin E492 and salmochelin have a proposed role in the virulence of the bacterial pathogen Klebsiella pneumoniae. Besides, enterochelin is produced as a response to low iron availability and its synthesis is controlled by the global iron regulator Fur. Since the production of active microcin E492 depends on enterochelin biosynthesi