1,720,973 research outputs found
Study of new actors in the antioxidant metabolism of protozoan pathogens
No full textFil: Cabeza, Matías Sebastián. Universidad Nacional del Litoral. Facultad de Bioquímica y Ciencias Biológicas; Argentina.La tesis se centra en el estudio de diferentes sistemas antioxidantes presentes en parásitos humanos.
Entamoeba histolytica, un parásito intestinal, se expone a cantidades elevadas de especies reactivas del oxígeno (ERO) durante la invasión de tejidos. En primer lugar, esta tesis abarca estudios bioquímicos realizados para llegar a un mejor entendimiento de las propiedades cinéticas y estructurales de una rubredoxina reductasa (EhNROR), una proteína flavodiférrica (EhFDP1), una rubreritrina (EhRr) y dos ferredoxinas (EhFd1-2) presentes en E. histolytica. Dichas proteínas componen sistemas enzimáticos que podrían contribuir a la detoxificación in vivo de O2 y H2O2, y por lo tanto jugar un papel clave en la virulencia del parásito.
Se han hecho muchos esfuerzos para entender los mecanismos por los cuales los tripanosomátidos neutralizan las ERO pero se sabe poco sobre las proteínas responsables de la reparación de los daños causados por ellas. La metionina es un aminoácido susceptible de ser oxidado a metionina sulfóxido (MetSO). La reducción de MetSO a metionina es catalizada por las metionina sulfóxido reductasas (MSR), enzimas presentes en casi todos los organismos. MsrA y MsrB son las MSR más conocidas y reparan metionina-S-sulfóxido (Met-S-SO) y metionina-R-sulfóxido (Met-R-SO), respectivamente. Recientemente fue descripta una enzima de Escherichia coli (EcfRMsr), específica para Met-R-SO no peptídica. La segunda parte de esta tesis comprende la caracterización de los dos alelos de TcfRMsr presentes en el genoma diploide de Trypanosoma cruzi. Se llevó a cabo la clonación, expresión, purificación y caracterización enzimática de los dominios catalíticos N-terminales de ambos alelos.This thesis focuses on the study of different antioxidant systems present in human parasites.
Entamoeba histolytica, an intestinal parasite that is the causative agent of amoebiasis, is exposed to elevated amounts of reactive oxygen species (ROS) during tissue invasion. Firstly, this thesis deals with biochemical studies performed to reach a better understanding of the kinetic and structural properties of a rubredoxin reductase (EhNROR), a flavodiiron protein (EhFDP1), a rubrerythrin (EhRr) and two ferredoxins (EhFd1-2) from E. histolytica. In addition, the enzymatic systems herein characterized could contribute to the in vivo detoxification of O2 and H2O2, playing a key role for the parasite defense against ROS.
Many efforts have been made to understand the mechanisms by which trypanosomatids neutralize ROS but much less are known about the proteins responsible of repairing the damage created by them. Methionine, for example, is an amino acid susceptible to be oxidized to methionine sulfoxide (MetSO). Reduction of MetSO to methionine is catalyzed by methionine sulfoxide reductase (Msr), an enzyme present in almost all organisms. MsrA and MsrB are the best known Msrs that repair methionine-S-sulfoxide (Met-S-SO) and methionine-R sulfoxide (Met-R-SO) respectively. In addition, an Escherichia coli Msr enzyme (EcfRMsr), specific for non-peptidic Met-R-SO, was recently discovered. The second part of this thesis deals with the characterization of two allelic TcfRMsr present in the diploid genome of Trypanosoma cruzi. In this work, we carried out the cloning, expression, purification and enzymatic characterization of the catalytic TcfRMsr N-terminal domains of both alleles.Agencia Nacional de Promoción Científica y TecnológicaConsejo Nacional de Investigaciones Científicas y Técnica
Study of new actors in the antioxidant metabolism of protozoan pathogens
No full textFil: Cabeza, Matías Sebastián. Universidad Nacional del Litoral. Facultad de Bioquímica y Ciencias Biológicas; Argentina.La tesis se centra en el estudio de diferentes sistemas antioxidantes presentes en parásitos humanos.
Entamoeba histolytica, un parásito intestinal, se expone a cantidades elevadas de especies reactivas del oxígeno (ERO) durante la invasión de tejidos. En primer lugar, esta tesis abarca estudios bioquímicos realizados para llegar a un mejor entendimiento de las propiedades cinéticas y estructurales de una rubredoxina reductasa (EhNROR), una proteína flavodiférrica (EhFDP1), una rubreritrina (EhRr) y dos ferredoxinas (EhFd1-2) presentes en E. histolytica. Dichas proteínas componen sistemas enzimáticos que podrían contribuir a la detoxificación in vivo de O2 y H2O2, y por lo tanto jugar un papel clave en la virulencia del parásito.
Se han hecho muchos esfuerzos para entender los mecanismos por los cuales los tripanosomátidos neutralizan las ERO pero se sabe poco sobre las proteínas responsables de la reparación de los daños causados por ellas. La metionina es un aminoácido susceptible de ser oxidado a metionina sulfóxido (MetSO). La reducción de MetSO a metionina es catalizada por las metionina sulfóxido reductasas (MSR), enzimas presentes en casi todos los organismos. MsrA y MsrB son las MSR más conocidas y reparan metionina-S-sulfóxido (Met-S-SO) y metionina-R-sulfóxido (Met-R-SO), respectivamente. Recientemente fue descripta una enzima de Escherichia coli (EcfRMsr), específica para Met-R-SO no peptídica. La segunda parte de esta tesis comprende la caracterización de los dos alelos de TcfRMsr presentes en el genoma diploide de Trypanosoma cruzi. Se llevó a cabo la clonación, expresión, purificación y caracterización enzimática de los dominios catalíticos N-terminales de ambos alelos.This thesis focuses on the study of different antioxidant systems present in human parasites.
Entamoeba histolytica, an intestinal parasite that is the causative agent of amoebiasis, is exposed to elevated amounts of reactive oxygen species (ROS) during tissue invasion. Firstly, this thesis deals with biochemical studies performed to reach a better understanding of the kinetic and structural properties of a rubredoxin reductase (EhNROR), a flavodiiron protein (EhFDP1), a rubrerythrin (EhRr) and two ferredoxins (EhFd1-2) from E. histolytica. In addition, the enzymatic systems herein characterized could contribute to the in vivo detoxification of O2 and H2O2, playing a key role for the parasite defense against ROS.
Many efforts have been made to understand the mechanisms by which trypanosomatids neutralize ROS but much less are known about the proteins responsible of repairing the damage created by them. Methionine, for example, is an amino acid susceptible to be oxidized to methionine sulfoxide (MetSO). Reduction of MetSO to methionine is catalyzed by methionine sulfoxide reductase (Msr), an enzyme present in almost all organisms. MsrA and MsrB are the best known Msrs that repair methionine-S-sulfoxide (Met-S-SO) and methionine-R sulfoxide (Met-R-SO) respectively. In addition, an Escherichia coli Msr enzyme (EcfRMsr), specific for non-peptidic Met-R-SO, was recently discovered. The second part of this thesis deals with the characterization of two allelic TcfRMsr present in the diploid genome of Trypanosoma cruzi. In this work, we carried out the cloning, expression, purification and enzymatic characterization of the catalytic TcfRMsr N-terminal domains of both alleles.Agencia Nacional de Promoción Científica y TecnológicaConsejo Nacional de Investigaciones Científicas y Técnica
Development of a fiber-polymer composite based on Agaricomycetes fungi and agricultural residues from the north-central region of Santa Fe
Get PDFFil: Cabeza, Matías. Universidad Nacional del Litoral. FBCB; Argentina.La agricultura y las industrias de transformación agrícola generan cantidades considerables de desechos biomásicos. Algunos de estos residuos son la cascarilla de arroz de los molinos arroceros, restos de la industria del algodón o de la producción de biodiesel, por nombrar solo algunas industrias relevantes en la región. La utilización de estos materiales para la producción de bienes no solo tiene méritos ecológicos, sino que suma valor a las economías regionales, al industrializar lo que puede considerarse prácticamente un desperdicio. De esta forma los residuos y desechos son reutilizados como recursos, lo que acerca la cadena productiva local hacia el ideal de una economía circular. Por otro lado, a nivel mundial, los consumidores demandan materiales livianos, energéticamente eficientes, reciclables y más sostenibles ecológicamente. Tal es así en la industria del packaging, a la que se destina el 40% del poliestireno expandido (EPS) producido en el mundo. El objetivo general del presente proyecto consiste en desarrollar métodos de producción de biomateriales basados en la interacción de hongos con sustratos lignocelulósicos y en la generación de estructuras funcionales con propiedades físicas-químicas variables. Estos biocompuestos fibra-polímero basados en hongos son una innovación reciente y constituyen una alternativa ecológica a los plásticos basados en combustibles fósiles como el EPS. Para lograr esto se plantea como primera etapa el relevamiento y evaluación de distintos sustratos lignocelulósicos, mediante la vinculación con distintos actores del medio socio-productivo de la región centro-norte de Santa Fe. Las propiedades de los biocompositos dependen no solo del tipo de material lignocelulósico sino también del hongo que se utiliza como aglutinante, por lo que luego se evaluarán diversas especies de hongos. Se buscará poner a punto un nuevo método indirecto de medición de la biomasa, fundamental para la caracterización de la cinética de crecimiento en este tipo de compuestos. Además, se buscará mejorar la densidad del micelio hacia el interior de los biocompositos aumentando el nivel de oxígeno disponible para el crecimiento. Teniendo en cuenta resultados preliminares obtenidos con anterioridad por el grupo de investigación, se optimizará particularmente el crecimiento del micelio en la cascarilla de arroz que por sus características propias la hacen interesante para los objetivos de este proyecto. Por último, se desarrollarán biocompositos con formas específicas que cumplan con la funcionalidad prevista para piezas de packaging.Agriculture and agricultural processing industries generate considerable amounts of residual biomass. Some of these residues are rice husks from rice mills, rests of the cotton industry or biodiesel production, to name just a few relevant industries in the region. The use of biomass for the production of goods not only has ecological benefits but also improves regional economies, by industrializing what can be considered mostly waste. Thus, residues and waste are reused as resources, which brings the local production chain closer to the ideal for a circular economy. In addition to this, all over the world consumers are demanding lighter, more efficient, recyclable, and more sustainable materials. Such is the case of the packaging industry, to which 40% of the expanded polystyrene (EPS) produced in the world is destined. The main objective of this project is to develop methods for the production of biomaterials based on the interaction of fungi with lignocellulosic substrates and the generation of functional structures with variable physical-chemical properties. These fungal-based fiber-polymer biocomposites are a recent innovation and provide an environmentally friendly alternative to fossil fuel-based plastics such as EPS. To achieve this, we propose a study and evaluation of different lignocellulosic substrates, by inquiring different actors from the socio-productive environment of the north-central region of Santa Fe. The final properties of the biocomposites depend not only on the type of lignocellulosic material but also on the fungus that is used as a binder, thus various species of fungi will then be evaluated. We will sough to fine-tune a new indirect method for measuring biomass, which is essential for describing the growth kinetics in this type of composite. In addition, the density of the mycelium towards the interior of the biocomposites will be improved, increasing the level of oxygen available for growth. Taking into account preliminary results obtained by the research group, the mycelium growth using rice husk as substrate will be optimized due to its specific characteristics that make this substrate interesting for the objectives of this project. Finally, we will develop biocomposites with specific shapes that meet the expected functionality for packaging pieces
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
- …
