Secondary structure of protamine in sperm nuclei: an infrared spectroscopy study

<p>Abstract</p> <p>Background</p> <p>Protamines are small basic proteins that condense the DNA in mature spermatozoa. Typical protamines are of simple composition and very arginine-rich, usually in the range of 60-80%. Arginine residues are distributed in a number of stretches separated by neutral amino acids. We have used Fourier transform infrared spectroscopy (FTIR) to gain access for the first time to the secondary structure of protamines in sperm nuclei. This technique is particularly well suited to the study of DNA-bound protamine in whole nuclei since it is not affected by turbidity.</p> <p>Results</p> <p>We show that DNA -bound salmon (salmine) and squid protamines contain <it>α</it>-helix, <it>β</it>-turns and a proportion of other structures not stabilized by intramolecular hydrogen bonding. No <it>β</it>-sheet was observed. In salmine, the <it>α</it>-helix amounted to ~20%, while in squid protamine it reached ~40%. In contrast, the structure not stabilized by intermolecular hydrogen bonding was more abundant in salmine (~40%) than in squid protamine (~20%). Both protamines contained ~40% <it>β</it>-turns. The different helical potential of salmine and squid protamine was confirmed by structure predictions and CD in the presence of trifluoroethanol.</p> <p>Conclusion</p> <p>DNA-bound protamine in sperm nuclei contains large amounts of defined secondary structure stabilized by intramolecular hydrogen bonding. Both salmine and squid protamine contain similar amounts of <it>β</it>-turns, but differ in the proportions of <it>α</it>-helix and non-hydrogen bonded conformations. In spite of the large differences in the proportions of secondary structure motifs between salmon and squid protamines, they appear to be equally efficient in promoting tight hexagonal packing of the DNA molecules in sperm nuclei.</p

Variations in Bacterial Community of Rearing Water and Gut of Common Dentex, Dentex dentex (Linnaeus 1758), Larvae Using Three Microalgae Management Approaches

Microorganisms present in the rearing water colonize the gut of first feeding larvae and represent the first barrier against opportunistic pathogens. The aim of the experiments presented herein was to standardize a protocol for the management of rearing water and microalgae suitable for the larval rearing of common dentex. In Experiment 1, bacteria–algae interactions were tested using a monospecific microalgal community, Tetraselmis chuii, suitable for nutritional experiments and with known antibacterial activity. In Experiment 2, the evolution of the bacterial community and larval performance (growth and survival) were monitored daily, in three conditions: (1) mature water: T. chuii was added 5 d before the rearing of common dentex larvae, (2) green water: T. chuii was added 1 d before, and (3) clear water: no T. chuii addition. The results show the influence of the presence of T. chuii on the evolution of the bacterial communities, both in terms of bacterial density and morphology, and indicate green water is the most suitable water treatment for management of larval rearing for common dentex.info:eu-repo/semantics/acceptedVersio

Administración de Riesgo y Teoria de Cartera : Importancia de una eficiente gestión operacional en el Banco de Finanzas,S.A. (BDF) Nicaragua para el año 2015

El presente trabajo investigativo tiene como objetivo demostrar la importancia que tiene una eficiente gestión de riesgo operativo en las entidades bancarias, con el propósito de hacerlo un procedimiento de continuidad dentro del banco e instituciones financieras y no meramente un concepto que se maneja a niveles de gobierno corporativo, sino que todos los miembros de la institución aporten y cumplan los controles operacionales establecidos. Su aplicación en las medidas y cuantificación de pérdidas por el tipo de riesgo operativo son un tema del que las instituciones no pueden obviar actualmente. Este trabajo se elaboró mediante la elaboración de consultas y entrevistas a personal del Banco de Finanzas, S.A durante el periodo 2015 con el fin de conocer las políticas, normas y procedimientos para la medición del riesgo operativo y de esta manera realizar una evaluación del mismo y poder determinar las estrategias de contingencia ante este tipo de riesgo. Mediante el caso práctico se muestran los resultados obtenidos a partir de una supervisión in situ cabe destacar que los datos presentados son meramente para fines de ejemplo y para el cumplimiento de la explicación metodológica. En conclusión para la institución financiera Banco de Finanzas, S.A, con certeza cumple con los procedimientos, políticas y seguimiento de mitigación de riesgo operativo. Se ha podido observar en el caso práctico que es posible la medición y cuantificación así como las estrategias del comité para su valoración y elaboración de políticas de Riesgo Operativo

Partial characterization of enzymatic activities produced by a wild strain of <i>A. niger</i>

Aspergillus niger, isolated from decay citrus peels in the province of Misiones, was able to produce pectinases by submerged fermentation. The enzymatic extract exhibited polygalacturonase, pectinesterase and lyase activities. Others enzymes capable of degrading cell wall polymers were also detected in the enzymatic extract such as cellulases and xylanases. Polygalacturonase was an endo-polygalacturonase. The enzyme exhibited a maximal activity at pH range between 4.5 to 5.0, was stable in the pH range from 2.5 to 5.5 and remained unchanged when was incubated at temperatures lower than 50 ºC. The fungi produced three PG isoenzymes. The enzymatic extract was able to clarify apple juice. The results observed make the pectinolytic enzymes produced by A. niger appropriate for future application in fruit juice processing industries.Centro de Investigación y Desarrollo en Fermentaciones Industriale

Partial characterization of enzymatic activities produced by a wild strain of <i>A. niger</i>

Aspergillus niger, isolated from decay citrus peels in the province of Misiones, was able to produce pectinases by submerged fermentation. The enzymatic extract exhibited polygalacturonase, pectinesterase and lyase activities. Others enzymes capable of degrading cell wall polymers were also detected in the enzymatic extract such as cellulases and xylanases. Polygalacturonase was an endo-polygalacturonase. The enzyme exhibited a maximal activity at pH range between 4.5 to 5.0, was stable in the pH range from 2.5 to 5.5 and remained unchanged when was incubated at temperatures lower than 50 ºC. The fungi produced three PG isoenzymes. The enzymatic extract was able to clarify apple juice. The results observed make the pectinolytic enzymes produced by A. niger appropriate for future application in fruit juice processing industries.Centro de Investigación y Desarrollo en Fermentaciones Industriale

Partial characterization of enzymatic activities produced by a wild strain of <i>A. niger</i>

Aspergillus niger, isolated from decay citrus peels in the province of Misiones, was able to produce pectinases by submerged fermentation. The enzymatic extract exhibited polygalacturonase, pectinesterase and lyase activities. Others enzymes capable of degrading cell wall polymers were also detected in the enzymatic extract such as cellulases and xylanases. Polygalacturonase was an endo-polygalacturonase. The enzyme exhibited a maximal activity at pH range between 4.5 to 5.0, was stable in the pH range from 2.5 to 5.5 and remained unchanged when was incubated at temperatures lower than 50 ºC. The fungi produced three PG isoenzymes. The enzymatic extract was able to clarify apple juice. The results observed make the pectinolytic enzymes produced by A. niger appropriate for future application in fruit juice processing industries.Centro de Investigación y Desarrollo en Fermentaciones Industriale

Gestión municipal y desarrollo sostenible del turismo en el distrito de Santa María –Huaura, 2014

La presente investigación tiene como objetivo determinar la relación entre la Gestión municipal y el desarrollo sostenible del turismo en el distrito de Santa María-Huaura, 2014. El estudio corresponde al enfoque de investigación cuantitativa, básico, de diseño no experimental descriptivo correlacional, transversal. Para la recolección de datos se tomó una muestra de 410 personas entre funcionarios de la municipalidad de santa maría y la población inmersa en el ámbito turístico. Para medir ambas variables y obtener información se aplicó dos instrumentos de medición, dicho instrumento fue validado y estandarizado lo cual nos permitió medir describir y explicar las variables: gestión municipal y desarrollo sostenible del turismo. En los resultados obtenidos se demuestra que existe una relación entre las variables Gestión municipal y desarrollo sostenible del turismo, para lo cual se utilizó la prueba de correlación de Rho Spearman para la asociación de variables con escala ordinal, por ser la significancia asintótica bilateral (Sig.=0.010), está por debajo del nivel de error máximo permisible (α=0.05), entonces hay evidencia suficiente para rechazar la hipótesis nula (Ho: La Gestión Municipal y el Desarrollo Sostenible de turismo son Independientes) y por tanto a un 95% de confianza podemos afirmar que, existe relación significativa entre La Gestión Municipal y el Desarrollo Sostenible de turismo

“Incentivos tributarios ambientales y la inversión ambiental, en empresas industriales, distrito de Los Olivos, 2017”

La presente investigación tiene como finalidad determinar si existe nivel de relación entre incentivos tributarios ambientales y la inversión ambiental en las empresas industriales de Los Olivos , 2017. El tema fue escogido por la necesidad que tiene hoy la importancia del cuidado del medio ambiente y como los empresarios pueden estar comprometidos con la inversión ambiental ante la aplicación de incentivos tributarios ambientales por parte de la política fiscal, ya que, el estado tiene como potestad salvaguardar los recursos naturales, disminuir los índices de contaminación y velar por la calidad de vida de sus habitantes. La investigación es de tipo cuantitativo, descriptivo correlacional, con un diseño no experimental transversal, se tomó como muestra a 45 gerentes generales y/o contadores los cuales pertenecen al rubro de empresas industriales ubicados dentro del Distrito de los Olivos. El instrumento aplicado fue la encuesta que está compuesta por 16 ítems con cinco alternativas cada una. Para obtener los resultados se aplicó la confiabilidad y validez del instrumento en el programa SPSS. En la presente investigación se arribó a la conclusión de que existe una relación positiva alta entre los incentivos tributarios ambientales y la inversión ambiental a partir de los resultados obtenidos con la prueba de Rho Spearman de manera que se comprobó la hipótesis y el objetivo general

Phosphorylation of the carboxy-terminal domain of histone H1: effects on secondary structure and DNA condensation

Linker histone H1 plays an important role in chromatin folding. Phosphorylation by cyclin-dependent kinases is the main post-translational modification of histone H1. We studied the effects of phosphorylation on the secondary structure of the DNA-bound H1 carboxy-terminal domain (CTD), which contains most of the phosphorylation sites of the molecule. The effects of phosphorylation on the secondary structure of the DNA-bound CTD were site-specific and depended on the number of phosphate groups. Full phosphorylation significantly increased the proportion of β-structure and decreased that of α-helix. Partial phosphorylation increased the amount of undefined structure and decreased that of α-helix without a significant increase in β-structure. Phosphorylation had a moderate effect on the affinity of the CTD for the DNA, which was proportional to the number of phosphate groups. Partial phosphorylation drastically reduced the aggregation of DNA fragments by the CTD, but full phosphorylation restored to a large extent the aggregation capacity of the unphosphorylated domain. These results support the involvement of H1 hyperphosphorylation in metaphase chromatin condensation and of H1 partial phosphorylation in interphase chromatin relaxation. More generally, our results suggest that the effects of phosphorylation are mediated by specific structural changes and are not simply a consequence of the net charge

Genome-wide recruitment profiling of transcription factor Crz1 in response to high pH stress

Background: Exposure of the budding Saccharomyces cerevisiae to an alkaline environment produces a robust transcriptional response involving hundreds of genes. Part of this response is triggered by an almost immediate burst of calcium that activates the Ser/Thr protein phosphatase calcineurin. Activated calcineurin dephosphorylates the transcription factor (TF) Crz1, which moves to the nucleus and binds to calcineurin/Crz1 responsive gene promoters. In this work we present a genome-wide study of the binding of Crz1 to gene promoters in response to high pH stress. Results: Environmental alkalinization promoted a time-dependent recruitment of Crz1 to 152 intergenic regions, the vast majority between 1 and 5 min upon stress onset. Positional evaluation of the genomic coordinates combined with existing transcriptional studies allowed identifying 140 genes likely responsive to Crz1 regulation. Gene Ontology analysis confirmed the relevant impact of calcineurin/Crz1 on a set of genes involved in glucose utilization, and uncovered novel targets, such as genes responsible for trehalose metabolism. We also identified over a dozen of genes encoding TFs that are likely under the control of Crz1, suggesting a possible mechanism for amplification of the signal at the transcription level. Further analysis of the binding sites allowed refining the consensus sequence for Crz1 binding to gene promoters and the effect of chromatin accessibility in the timing of Crz1 recruitment to promoters. Conclusions: The present work defines at the genomic-wide level the kinetics of binding of Crz1 to gene promoters in response to alkaline stress, confirms diverse previously known Crz1 targets and identifies many putative novel ones. Because of the relevance of calcineurin/Crz1 in signaling diverse stress conditions, our data will contribute to understand the transcriptional response in other circumstances that also involve calcium signaling, such as exposition to sexual pheromones or saline stress