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The superoxide dismutases of Candida glabrata protect against oxidative damage and are required for lysine biosynthesis, DNA integrity and chronological life survival
No full text"El hongo patógeno oportunista Candida glabrata tiene una respuesta al estrés oxidante bien definida. C. glabrata es extremadamente resistente a estrés oxidante e inclusive sobrevive dentro de las células fagociticas. Para entender la respuesta a estrés oxidante en C. glabrata, caracterizamos las superóxido dismutasas (SODs): la Cu/Zn-SOD (Sod1) y la MnSOD (Sod2). Las SODs catalizan la dismutación de superóxido en peróxido de hidrógeno y oxígeno. Encontramos que principalmente Sod1 contribuye al total de la actividad de SOD en esta levadura y se localiza en el citoplasma. En cambio, Sod2 es una proteína mitocondrial. Ambas SODs juegan un papel central en la respuesta a estrés oxidante, Sod1 es más importante durante el crecimiento fermentativo y Sod2 durante la respiración y el crecimiento en fuentes de carbono no fermentables. Es interesante notar que la cepa de C. glabrata carente de ambos genes Sod1 y Sod2 muestra auxotrofia a lisina, tiene alta tasa de mutación espontanea y una vida cronológica reducida. En consecuencia nuestro estudio revela que las SODs juegan un papel importante en el metabolismo, biosíntesis de lisina, protección al ADN y la vida cronológica de C. glabrata.""The opportunistic fungal pathogen Candida glabrata has a well-defined oxidative stress response, and it is extremely resistant to oxidative stress. C. glabrata can survive and replicate inside phagocytic cells. In order to further our understanding of the oxidative stress response in C. glabrata, we characterized the superoxide dismutases (SODs) Cu/Zn-SOD (Sod1) and MnSOD (Sod2). SODs catalyze the dismutation of superoxide into hydrogen peroxide and oxygen. We show that Sod1 is the major contributor of the total SOD activity and is present in the cytoplasm, whereas Sod2 is a mitochondrial protein. Both SODs play a central role in the oxidative stress response. Sod1 plays a central role during fermentative growth and Sod2 is important during respiration and growth in non-fermentable carbon sources. Interestingly, C. glabrata cell lacking both SODs showed auxotrophy for lysine, a high rate of spontaneous mutation and a reduced chronological lifespan. Thus, our study reveals that SODs in C. glabrata play a central role in metabolism, lysine biosynthesis, DNA protection and chronological lifespan.
Evaluación de oxicloruros de bismuto como fotocatalizadores en la degradación de Rodamina B y Fenol
Get PDF"La fotocatálisis heterogénea emplea materiales semiconductores para la degradación de contaminantes presentes en agua y aire, mediante la excitación del semiconductor con energía UV principalmente. Actualmente se ha explorado el desarrollo de una gama de novedosos fotocatalizadores. Entre ellos, el Bismuto y sus compuestos relacionados han recibido amplia atención. Tales como BiVO4, Bi2WO6, Bi2S3 y BiOCl han mostrado una alta actividad fotocatalítica. Los oxicloruros de Bismuto (BiOCl) son de interés en el tratamiento de aguas y para la conversión de energía fotocatalítica debido a su estructura de capas que consiste en átomos de Bismuto enlazadas con Oxigeno [Bi2O2] que interaccionan con átomos de halógeno mediante fuerzas Van der Waals, dicha estructura promueve una alta eficiencia en la separación de los pares electrón-hueco fotogenerados. En el presente trabajo de tesis se desarrolló la evaluación fotocatalítica de tres muestras de oxicloruro de bismuto (BiOCl) obtenidos de una empresa cosmética, las cuales fueron nombradas por la empresa como Pearl Supreme, Pearl 2600 y Satin B debido a las características obtenidas durante su producción. La modificación de las muestras de BiOCl fue mediante el método de fotodeposición para la adicción de plata (Ag) y Óxido de Grafeno (OG) y el método de Sol-Gel para la modificación de Dióxido de Titanio (TiO2) con el fin de mejorar su actividad fotocatalítica bajo irradiación visible. Las muestras de BiOCl puros y modificados fueron caracterizados y evaluados fotocatalíticamente en la degradación de Rodamina B (Rh B) y Fenol en solución acuosa bajo irradiación visible y UV. Las modificaciones realizadas a las muestras de BiOCl realizaron cambios estructurales en los mismos, afectando la actividad fotocatalítica algunas de manera negativa (BiOCl-Ag), otras de manera positiva (BiOCl-OG y BiOCl-TiO2), lo cual da pie a seguir estudiando más a fondo dichos materiales.""Heterogeneous Photocatalysis employ semiconductors materials for the degradation of materials present in water and air, the process is through the excitation of semiconductor with UV energy mainly. Actually has been explored the development of a range of novel photocatalysts. Among them, bismuth and its related compounds have received wide attention. These compounds, such as BiVO4, Bi2WO6, Bi2MoO6 and Bi2S3 and BiOCl. Bismuth Oxychloride (BiOCl) are the interest on the water treatment and the photocatalytic energy conversion due to its layer structure consisting of Bismuth atoms linking with Oxygen atoms [Bi2O2] that interacting with Halogen atoms to Van der Waals forces, this structure promote a high efficiency in the separation of electron-holes photogenerates. In the present thesis has development the photocatalytic evaluation of three Bismuth Oxichloride (BiOCl) samples obtained of a cosmetic company, these samples was named by the company as Pearl Supreme, Pearl 2600 y Satin B due to the characteristic obtained during their production. The BiOCl samples modification was through photoseposition method for the addition of Silver (Ag) and Graphene Oxide (OG) and Sol-Gel method by the addition of Titanium Dioxide (TiO2) in order to improve their photocatalytic activity under visible light. The BiOCl samples pure and evaluated Photocatalytically in the Rhodamine B and Phenol degradation under Visible and UV light. The modifications realized to BiOCl samples carry out structural changes to them, affecting the photocatalytic activity so negatively (BiOCl-Ag), other positively (BiOCl-OG and BiOCl-TiO2), a which leads to continue study further such materials.
Análisis de transferencia de carga electrónica en el sistema Au15 –(SPh)m, m=1, …, 6.
Get PDF"En la década de los 90's se realizaron nuevos y diversos estudios en agregados metálicos de Au y Ag con un número pequeño de átomos con estructuras de capas llenas de n electrones (donde 2=2, 4, 6, 8, 18, 34, 54, 92…), estabilizados con moléculas orgánicas, los cuales presentan una alta estabilidad energética y estructural. También se observa mejoras o diferentes propiedades físico-químicas, en comparación a los arreglos atómicos previamente estudiados en secuencias geométricas estructurales, tales como: icosaedrica y la cubo-octaédrica con número de átomos N=4,13, 55, 147, 309, 561, …. Estos presentaban estabilidad teórica pero eran difíciles de sintetizar y carecían de estabilidad estructural a temperatura ambiente. Actualmente se sabe que esta clase de complejos organo-metálicos alcanza una estabilidad energética y estructural gracias a la adhesión de moléculas orgánicas principalmente tioles, debido al enlace covalente formado entre los átomos de Au y S, por lo cual, estos cúmulos forman un sistema con niveles electrónicos de capas cerrada (1S2, 1P6, 1D10, 2S2, 1F14, 2P2,… siguiendo el principio de exclusión de Pauli). Por otra parte, se observa una aparente carga total similar a un estado de valencia de un determinado elemento de la Tabla Periódica, lo que les confiere una alta estabilidad estructural y son capaces de formar super-redes o arreglos supra-cristalinos. Este hecho ha dado pie al nacimiento de un nuevo concepto conocido como el Modelo del Superátomo. El objetivo de este trabajo es el análisis y estudio teórico de la evolución en la estructura electrónica y atómica del cúmulo de Au15, que presenta el carácter de superátomo. Partiendo de este arreglo, el cual originalmente presenta una estructura tridimensional (3D) meta-estable, y se expone paulatinamente a m moléculas de tiofeno (SHPh), donde m = 1,..,6 y utilizando cálculos basados en la teoría del funcional de densidad (DFT) se analiza el efecto que tienen dichas moléculas sobre la estructura electrónica del cúmulo. Los resultados del análisis de Bader muestran que los átomos de S contribuyen en la distribución de la densidad de carga electrónica en el cúmulo de Au y ésta se ve distribuida en los átomos de C y H vecinos a S. Se observa que la estructura que se vuelve más estable conforme se van adhiriendo los tiofenos así como una reestructuración del agregado. Los resultados sugieren que el complejo [Au15(SPh)6]+1 como posible superátomo teniendo un número mágico de n=8(1S2, 1P6)""In the early 90's there were new studies on Au and Ag clusters formed by a magic sequence of valence electrons inc closed shells (n = 2, 4, 6, 8, 18, 34, 54, 92, ...), which were stabilized with organic molecules. These systems showed high electronic and energetic stability, as well as improvements in their physicochemical properties. These properties are very different from other atomic arrangements with different number of atoms previously studied, also in a wellknown magic geometrical sequences, such as the icosahedral and cuboctahedral. It is now known that this kind of organometallic complexes achieve energetic and structural stability due to the adhesion of organic molecules, mainly thiol molecules due to the covalent bond between the atoms of Au and S. Therefore, these clusters form a system with closed electronic shells (1S2, 1P6, 1D10, 2S2, 1F14, 2P6, …), based in Pauli exclusion principle. Besides, these clusters exhibit an apparent total load in a state of the valence similar to certain elements in the Periodic Table and thus these clusters are capable of forming super-solids or super-crystalline arrangements. This fact has led to the birth of a new concept known as the Superatom Model. The goal of this work is the theoretical study and analysis of the evolution of electronic properties and atomic structure of a cluster with superatom character, specifically the Au15. Results show that, once the cluster is gradually exposed to N molecules of thiophenol (SHPh), the cluster becomes more stable while adhering thiophenols until N=6. Charge Bader analysis also shows that the S atom contributes to the charge density distribution of the Au atoms where they are bonded. Also, S atoms affect the distribution of charge density of the neighboring carbon atoms of phenol ring. Final atomic restructuring is observed from the original aggregate as a result of rearrangement of the electronic charge density at the metal cluster. Our results suggest that we can propose a [Au15(SPh)6]+1 with superatom character with electronic magic number n=8 (1S2, 1P6).
One-parameter supersymmetric Hamiltonians in momentum space
Get PDF"Recent results on the one-parameter supersymmetric deformation in momentum space by Curtright and Zachos (2014 J. Phys. A: Math. and Theor. 47 145201) are presented in a more general framework following our own papers. We extend the analysis of Curtright and Zachos by including the supersymmetric partner one-parameter deformation.
Evaluation of a SUMO E2 conjugating enzyme involved in resistance to Clavibacter michiganensis subsp. michiganensis in Solanum peruvianum, through a tomato mottle virus VIGS assay
Get PDF"Clavibacter michiganensis subsp. michiganensis (Cmm) causes bacterial wilt and canker of tomato. Currently, no Solanum lycopersicum resistant varieties are commercially available, but some degree of Cmm resistance has been identified in Solanum peruvianurn. Previous research showed up regulation of a SUMO E2 conjugating enzyme (SCEI) transcript in S. peruvianum compared to S. lycopersicum following infection with Cmm. In order to test the role of SCEI in resistance to Cmm, a fragment of SCEI from S. peruvianum was cloned into a novel virus induced gene silencing (VIGS) vector based on the geminivirus, Tomato Mottle Virus (ToMoV). Using biolistic inoculation, the ToMoV-based VIGS vector was shown to be effective in S. peruvianum by silencing the magnesium chelatase gene, resulting in leaf bleaching. VIGS with the ToMoV_SCEI construct resulted in 61% silencing of SCEI in leaves of S. peruvianum as determined by quantitative RT-PCR. The SCEI -silenced plants showed unilateral wilting (15 dpi) and subsequent death (20 dpi) of the entire plant after Cmm inoculation, whereas the empty vector-treated plants only showed wilting in the Cmm-inoculated leaf. The SCEI-silenced plants showed higher Cmm colonization and an average of 4.5 times more damaged tissue compared to the empty vector control plants. SCEI appears to play an important role in the innate immunity of S. peruvianum against Cmm, perhaps through the regulation of transcription factors, leading to expression of proteins involved in salicylic acid dependent defense responses.
Análisis de la interacción entre las proteínas ABF1 y RAP1 de Candida glabrata con los elementos de regulación en CIS del telómero E derecho
Get PDFTesis (Maestría en Ciencias en Biología Molecular)"La regulación de la expresión génica está gobernada por la unión de los factores de transcripción a los elementos de regulación en cis del genoma eucariota. En el patógeno Candida glabrata, un ejemplo de este tipo de regulación se encuentra representado por la familia de genes EPA (adhesina epitelial, por su siglas en inglés), que codifican para proteínas de la pared celular, las cuales, median la adhesión de la levadura a las células epiteliales del hospedero. En la cepa BG2, EPA1 es el único gen de la familia EPA que se expresa in vitro, mientras los 22 parálogos EPA permanecen transcripcionalmente reprimidos o silenciados. EPA1 está codificado en la región subtelomérica del cromosoma E izquierdo (tE-R), adyacente a EPA2 y EPA3. Las regiones subteloméricas de C. glabrata presentan un silenciamiento regional, no obstante, el tE-R manifiesta una combinación de silenciamiento regional y local sobre los genes EPA localizados allí. Este efecto podría deberse a la formación de bucles teloméricos (T-loop) al extremo del cromosoma, posiblemente mediado por las proteínas de unión al ADN, Abf1 y Rap1, mediante el reclutamiento de las proteínas Sir, las cuales son necesarias para el silenciamiento subtelomérico en C. glabrata. Para estudiar la función de éstas proteínas en el silenciamiento subtelomérico de C. glabrata, las etiquetamos con los epítopos c-Myc y FLAG y encontramos que las etiquetas pueden interferir con la función nativa de las proteínas. Adicionalmente, determinamos que Abf1 y Rap1 participan en la regulación de la expresión de los genes EPA de los telómeros E-R e I-R, posiblemente a través de la formación de T-loops.""Regulation of gene expression in eukaryotes is governed by the binding of transcription factors to cis-acting elements in the genome. In the pathogenic yeast, Candida glabrata, an example of this regulation is the EPA (Epithelial Adhesin) gene family, which encodes cell surface proteins that mediate adhesion of the yeast to epithelial host cells. In the strain BG2, EPA1 is the only gene of this family that is expressed in vitro, whereas the remaining 22 EPA paralogues are transcriptionally repressed. EPA1 forms a cluster with EPA2 and EPA3 close to the right telomere of the Chromosome E (E-Rt). Contrary to the widespread silencing effect over the subtelomeric regions observed in other C. glabrata telomeres, the E-Rt exhibits a combination of regional and local silencing of the EPA genes. This effect could be due to repression at a distance, by telomere looping (T-loop), where the DNA-binding proteins Abf1 and Rap1 participate through the recruitment of the Sir proteins, which are completely necessary for the silencing at subtelomeric regions in C. glabrata. We tagged the Abf1 and Rap1 proteins with c- Myc and FLAG epitopes to study their function at Candida glabrata subtelomeric regions. We found that the tags can interfere with the normal silencing activity of the proteins and in the process, we determined that Abf1 and Rap1 participate in the regulation of the expression of EPA genes at the E-R and I-R telomeres, possibly through telomere loop formation.
The corn smut (‘Huitlacoche’) as a new latform for oral vaccines
Get PDF"The development of new alternative platforms for subunit vaccine production is a priority in the biomedical field. In this study, Ustilago maydis, the causal agent of common corn smut or 'huitlacoche' has been genetically engineered to assess expression and immunogenicity of the B subunit of the cholera toxin (CTB), a relevant immunomodulatory agent in vaccinology. An oligomeric CTB recombinant protein was expressed in corn smut galls at levels of up to 1.3 mg g(-1) dry weight (0.8% of the total soluble protein). Mice orally immunized with 'huitlacoche'-derived CTB showed significant humoral responses that were well-correlated with protection against challenge with the cholera toxin (CT). These findings demonstrate the feasibility of using edible corn smut as a safe, effective, and low-cost platform for production and delivery of a subunit oral vaccine. The implications of this platform in the area of molecular pharming are discussed.
Southward migration of magmatic activity in the Colima volcanic complex, Mexico: an ongoing process
Get PDF"The Colima Volcanic Complex trends in a nearly N-S direction in western Mexico, and one of its structures, Colima volcano, is the most historically active volcano in the country. Immediately to the N, there is another volcanic center called El Cántaro volcano, whose activity started around 1.7 Ma in its N portion and migrated to the S in various episodes. Volcanic activity migrated further south, from El Cántaro to the Colima Volcanic Complex where the southernmost manifestation, Hijos del Volcán domes, is located on the south slope of Fuego volcano. The above date appears to mark initiation of the rather continuous volcanic activity in the area. It has been noted that these volcanic manifestations lie on, or near the Rivera-Cocos inland plate boundary. Colima’s Fuego volcano is also the closest to the Middle America Trench, among the polygenetic volcanoes in Mexico. We submit that the anomalous location of volcanism in this area originates in an anomalous subduction process of the Rivera and Cocos plates and evoke a tectonic model, proposed elsewhere, to support the idea. Modeling gravimetric and aeromagnetic data we locate the magma chambers of the Fuego (active) and Nevado (extinct) volcanoes within a 65 mGals negative Bouguer anomaly elongated in a nearly N-S direction. The corresponding aeromagnetic map displays a magnetic high over the southern portion of the Fuego volcano edifice. We found two additional, associated structures whose anomalies have not been previously reported, which appear to follow the southward magmatic migration pattern. One of them is a collapse structure with a circular topographic expression, and the southernmost is a low-density intrusion ~1 km below sea level, associated with a moderate topographic bulge at the surface that we interpret as a magma body. Five lines cross the anomalies; gravimetric and magnetic fields are concurrently modeled along them to locate the magmatic bodies. In addition to the 2-D models we perform 3-D gravimetric and magnetic inversions. For each field a 3-D mesh is built under the area occupied by the Colima Volcanic Complex, the volume elements are then assigned density or magnetic susceptibility values and their surface contributions in various points are evaluated. The process is iterated until the difference between the measured and the calculated fields is less than a predetermined value. The results of each inversion adequately and independently define the location of the magmatic cham- bers
Nuevos registros de distribución del gorrión de Worthen Spizella wortheni en San Luis Potosí, México
Get PDF"El rango de distribución restringido y el pequeño tamaño poblacional del gorrión de Worthen han ocasionado que esta ave sea considerada una especie amenazada en México y a nivel internacional. Aquí reportamos nuevos registros de esta ave los cuales expanden su rango de distribución conocido en los últimos cuarenta años y abren la posibilidad del uso de hábitats adicionales que no habían sido documentados anteriormente. Por lo tanto es importante realizar esfuerzos para documentar posible actividad reproductiva en estos hábitats.
Community of thermoacidophilic and arsenic resistant microorganisms isolated from a deep profile of mine heaps
Get PDF"Soluble arsenic (As) in acidic feed solution may inhibit the copper (Cu) bioleaching process within mine heaps. To clarify the effect of soluble arsenic on the live biomass and bioxidative activity in heaps, toxicological assays were performed using a synthetic feed solution given by a mine company. The microorganisms had previously been isolated from two heap samples at up to 66 m depth, and cultured using specific media for chemolithotrophic acidophiles (pH 1-2) and moderate thermophiles (48 degrees C), for arsenic tolerance assay. The four media with the highest biomass were selected to assay As-resistance; one culture (Q63h) was chosen to assay biooxidative activity, using a heap sample that contained chalcopyrite and covellite. We found that 0.5 g/L of As does not affect living biomass or biooxidative activity on Cu sulfides, but it dissolves Cu, while As precipitates as arsenic acid (H3AsO4 center dot 1/2H(2)O). The arsenic tolerant community, as identified by 16S rDNA gene sequence analysis, was composed of three main metabolic groups: chemolithotrophs (Leptospirillum, Sulfobacillus); chemolithoheterotrophs and organoheterotrophs as Acidovorax temperans, Pseudomonas alcaligenes, P. mendocina and Sphingomonas spp. Leptospirillum spp. and S. thermosulfidooxidans were the dominant taxa in the Q63-66 cultures from the deepest sample of the oldest, highest-temperature heap. The results indicated arsenic resistance in the microbial community, therefore specific primers were used to amplify ars (arsenic resistance system), aio (arsenite oxidase), or arr (arsenate respiratory reduction) genes from total sample DNA. Presence of arsB genes in S. thermosulfidooxidans in the Q63-66 cultures permits H3AsO4-As(V) detoxification and strengthens the community's response to As.