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Caracterización de los efectos vasculares de extractos de amaranto
Get PDFTesis (Maestría en Ciencias en Biología Molecular)"El amaranto (Amaranthus spp.), es una planta originaria de América, utilizada como cultivo medicinal en diversas partes del mundo. La semilla de amaranto posee un valor nutricional superior en comparación con otros granos, debido a su contenido alto de proteínas, y un mejor balance de aminoácidos esenciales que cereales y legumbres. La digestión tríptica de la fracción glutelinas de la semilla de amaranto, origina, entre otros, péptidos inhibidores de la enzima convertidora de angiotensina (ECA). La ECA está implicada en procesos patológicos como la hipertensión y la ateroesclerosis, a través de la regulación de sustancias vasoactivas como angiotensina II y bradicidina. La bradicidina estimula la producción de óxido nítrico (NO), involucrado en la regulación de la vasodilatación. En el presente trabajo se caracterizaron los efectos vasculares dependientes de NO de los péptidos inhibidores de ECAderivados de digeridos trípticos de glutelinas (DTGs) de amaranto. Para tal efecto, se midió la actividad inhibitoria de los DTGs sobre ECA, obteniéndose una concentración inhibitoria del 50% (IC50) de 200 μg/mL. También se cuantificó la producción de NO en células endoteliales de aorta de rata (CEC), tratadas con diferentes concentraciones de estos péptidos. La producción de NO se incrementó hasta en un 40% (102.6 μM) con respecto a la producción basal (57.15 μM) de dicha molécula. Por otro lado, en segmentos de aorta de rata, los DGT`s tuvieron un efecto relajante dosis-dependiente. Estos datos sugieren que el incluir el amaranto en la dieta como alimento nutracéutico puede aportar beneficios en el tratamiento de enfermedades como la hipertensión, además de ayudar a proteger del riesgo de enfermedades cardiovasculares.""Amaranth (Amaranthus spp.), is native american plant, extensively used as a medicinal crop around the world. The amaranth seed has a higher nutritional value when compared with other grains, due to its high protein content, and a better balance of essential amino acids than cereals and legumes. The tryptic hydrolysis of glutelins fraction of amaranth seeds, originates, among others, angiotensin converting enzyme (ACE) inhibitory peptides. ACE is involved in pathological processes such as hypertension and atherosclerosis, through the regulation of vasoactive substances like as angiotensin II and bradykinin. Bradykinin stimulates the production of nitric oxide (NO), which is involved in the regulation of vasodilation. In the present study the NO-dependent vascular effects of ACE- inhibitory peptides derived from glutelin tryptic digest (DTGs) was characterized. For these, the ACE inhibitory activity of DTGs was measured, obtaining a 50% inhibitory concentration (IC50) of 200 μg/ml. The NO production in endothelial cells of rat aorta (CEC), treated with different concentrations of DTGs was quantified. The NO production was increased about 40% (102.6 μ M) compairing with the baseline (57.15 μM). On the other hand, in rat aorta segments, the DTG's had a dose-dependent relaxing effect. These data suggest that including amaranth as nutraceutical food in the diet could bring benefits in treating diseases such as hypertension, also helping in the prevention of cardiovascular diseases.
yKu70/yKu80 and Rif1 regulate silencing differentially at telomeres in Candida glabrata
No full text"Candida glabrata, a common opportunistic fungal pathogen, adheres efficiently to mammalian epithelial cells in culture. This interaction in vitro depends mainly on the adhesin Epa1, one of a large family of cell wall proteins. Most of the EPA genes are located in subtelomeric regions, where they are transcriptionally repressed by silencing. In order to better characterize the transcriptional regulation of the EPA family, we have assessed the importance of C. glabrata orthologues of known regulators of subtelomeric silencing in Saccharomyces cerevisiae. To this end, we used a series of strains containing insertions of the reporter URA3 gene within different intergenic regions throughout four telomeres of C. glabrata. Using these reporter strains, we have assessed the roles of SIR2, SIR3, SIR4, HDF1 (yKu70), HDF2 (yKu80), and RIF1 in mediating silencing at four C. glabrata telomeres. We found that, whereas the SIR proteins are absolutely required for silencing of the reporter genes and the native subtelomeric EPA genes, the Rif1 and the Ku proteins regulate silencing at only a subset of the analyzed telomeres. We also mapped a cis element adjacent to the EPA3 locus that can silence a reporter gene when placed at a distance of 31 kb from the telomere. Our data show that silencing of the C. glabrata telomeres varies from telomere to telomere. In addition, recruitment of silencing proteins to the subtelomeres is likely, for certain telomeres, to depend both on the telomeric repeats and on particular discrete silencing elements.
Optimization of human interferon gamma production in Escherichia coli by response surface methodology
Get PDF"The production of human interferon gamma (hIFN-γ) using a synthetic gene in Escherichia coli BL21-SI was optimized by response surface methodology (RSM) and a Box-Behnken design. The process variables studied were temperature, bio-mass concentration at induction time and the NaCl concentration as inducer. According to the Box-Behnken design, a second order response function was developed. The optimal expression conditions were a temperature of 32.6°C, induction biomass of 0.31 g/L and 0.3 M NaCl in minimal medium. The model prediction for the maximum hIFN-γ production was 77.3 mg/L, which corresponded satisfactorily with the experimental data. The hIFN-γ concentration attained under optimized conditions was 13-times higher than that obtained using the non-optimized conditions. We conclude that RSM is an effective method for the optimization of recombinant protein expression using synthetic genes in E. coli.
Riccati-parameter solutions of nonlinear second-order ODEs
Get PDF"It has been proven by Rosu and Cornejo-Pérez [1, 2] that for some nonlinear second-order ODEs it is a very simple task to find one particular solution once the nonlinear equation is factorized with the use of two first-order differential operators. Here, it is shown that an interesting class of parametric solutions are easy to obtain if the proposed factorization has a particular form, which happily turns out to be the case in many problems of physical interest. The method that we exemplify with a few explicitly solved cases consists in using the general solution of the Riccati equation, which contributes with one parameter to this class of parametric solutions. For these nonlinear cases, the Riccati parameter serves as a growth parameter from the trivial null solution up to the particular solution found through the factorization procedure.
Chaotic dynamics of a nonlinear electronic converter
Get PDF"The nonlinear electronic converter used by Rulkov and collaborators [Rulkov et al., 2001], which is the core of their chaotic oscillator, is modeled and simulated numerically by means of an appropriate direct relationship between the experimental values of the electronic components of the system and the mathematical model. This relationship allows us to analyze the chaotic behavior of the model in terms of a particular bifurcation parameter k. Varying the parameter k, quantitative results of the dynamics of the numerical system are presented, which are found to be in good agreement with the experimental measurements that we performed as well. Moreover, we show that this nonlinear converter belongs to a class of 3-D systems that can be mapped to the unfolded Chua's circuit. We also report a wavelet transform analysis of the experimental and numerical chaotic time series data of this chaotic system. The wavelet analysis provides us with information on such systems in terms of the concentration of energy which is the standard electromagnetic interpretation of the L2 norm of a given signal.
CdSe quantum dot-decorated double walled carbon nanotubes: the effect of chemical moieties
Get PDF"We report that fluorine atoms on the outer tubes of double walled carbon nanotubes (DWNTs) are more effective for nucleating and growing CdSe nanoparticles than oxygen-containing functional groups. The CdSe particles with an average size of 5–7 nm grow through infiltration into an interstitial space created by four to five thin bundled DWNTs. We envisage that DWNTs will replace single and multiwalled carbon nanotubes in a wide range of applications because chemical moieties could be introduced selectively on the outer tubes while the optical and physical properties of the inner tubes remain almost unchanged
Epigenética del sistema visual y del fenómeno de microparasitismo en Trichoderma atroviride: un análisis del gen ortólo a GCN5.
Get PDFTesis (Maestría en Ciencias en Biología Molecular)"La luz es un factor clave para la existencia de la vida en nuestro planeta, regula una amplia variedad de procesos fisiológicos y del desarrollo en los seres vivos a través de la alteración en la expresión de diversos genes que responden a la señal luminosa. En los organismos eucariotes un obstáculo para que se lleve a cabo la eficiente expresión de dichos genes es el alto grado de empaquetamiento en que se encuentra organizado el ADN nuclear formando una estructura denominada cromatina. Esta estructura está sujeta a modificaciones covalentes cuyo blanco son principalmente las histonas, las cuales juegan un papel muy importante en la regulación de la transcripción. Se sabe que la acetilación reversible de los tallos amino terminal de las histonas, principalmente H3 y H4 por proteínas Acetil Transferasas de Histonas (HAT) trae como consecuencia una débil interacción entre el nucleosoma y el ADN, permitiendo que éste se encuentre accesible a la maquinaria transcripcional, razón por la cual la acetilación está asociada a la activación transcripcional de diversos genes. Trichoderma atroviride es un hongo del suelo que parasita un amplio rango de hongos patógenos de plantas, motivo por el cual es comúnmente utilizado como agente de control biológico de hongos fitopatógenos. Este hongo responde a la luz azul formando un anillo de conidias en el perímetro de la colonia donde fue dado el estímulo luminoso. En el presente trabajo se analizó el patrón de expresión que presentaban los genes de respuesta a luz phr-1 y bld-2 de Trichoderma atroviride, en presencia de un inhibidor de desacetilasas de histonas. Nuestros resultados indican que dichos genes se encuentran regulados por procesos de acetilacióndesacetilación. Se obtuvo una mutante del gen homólogo a Gcn5 de Saccharomyces cerevisiae a la cual se llamo tago-2. Esta mutante presentó un fenotipo muy particular, ya que mostró una fuerte reducción en su crecimiento en comparación con la cepa silvestre, su conidiación fue escasa y después de un pulso de luz azul no presenta el anillo de conidiación característico de la cepa silvestre. Adicionalmente mostró una reducción significativa en su capacidad como micoparásita frente al fitopatógeno Sclerotium rolfsii. También, se obtuvo una cepa transformante que sobreexpresa el gen tago-2, esta cepa muestra un crecimiento similar al de la cepa silvestre, sin embargo es más eficiente en detener el crecimiento de Sclerotium rolfsii.""The light is a key factor for the existence of the life in our planet, due regulates a wide variety of physiological and development processes in the living organisms beings across the alteration in the expression of diverse genes that answer to the luminous sign. In eukaryotes an obstacle for carried out the efficient expression of the above mentioned genes is the high degree of packing in which the nuclear DNA is organized, forming a structure named chromatin. This structure is subject to post-translational modifications, whose targets are principally the histones, which play a very important role in the regulation of the transcription. It is known that the reversible acetylation of the amino-terminal tails of the core histones, principally H3 and H4, by Histone Acetyl Transferases (HAT), brings as consequence a weak interaction between the nucleosome and the DNA, allowing that this one being accessible to the transcripcional machinery, therefore the acetylation is associated with the transcripcional activation of diverse genes. Trichoderma atroviride is a common soil fungus widely used as a biocontrol agent due to its capacity to parasitize phytopathogenic fungi of major agricultural importance. In this fungus a pulse of blue/UVA light induces the synchronous production of conidia situated at the colony perimeter where the pulse was received. In this work we analyzed the expression pattern of the blue-lightregulated genes phr-1 and bld-2 of Trichoderma atroviride, in presence of an inhibitor of the histone deacetylases. Our results indicate that the above mentioned genes are regulated by processes of acetylation-deacetylation. We obtained a mutant of the equivalent gene to Gcn5 of Saccharomyces cerevisiae to which we named tago-2. This mutant presented a very particular phenotype, because it showed a strong reduction in its growth in comparison with the wild type strain, its conidiation was poor and after a pulse of blue light it doesn’t show the conidiation ring typically of the wild type strain. Additional tago-2 strain showed a significant reduction in its capacity as mycoparasite fungus when was confronted to the phytopathogenic Sclerotium rolfsii. Also we obtained a transforming that overexpresing the tago-2 gene, this strain shows a growth similar to that of the wild type, nevertheless it is more efficient in stopping the growth of Sclerotium rolfsii.
Biological hydrogen production: trends and perspectives
Get PDF"Biologically produced hydrogen (biohydrogen) is a valuable gas that is seen as a future energy carrier, since its utilization via combustion or fuel cells produces pure water. Heterotrophic fermentations for biohydrogen production are driven by a wide variety of microorganisms such as strict anaerobes, facultative anaerobes and aerobes kept under anoxic conditions. Substrates such as simple sugars, starch, cellulose, as well as diverse organic waste materials can be used for biohydrogen production. Various bioreactor types have been used and operated under batch and continuous conditions; substantial increases in hydrogen yields have been achieved through optimum design of the bioreactor and fermentation conditions. This review explores the research work carried out in fermentative hydrogen production using organic compounds as substrates. The review also presents the state of the art in novel molecular strategies to improve the hydrogen production.
Stabilization of a class of biomedical systems via stability preservation
No full text"We present a method for stabilization of a class of nonlinear systems. The notion of stability preservation is exploited to prove that a transformation allows to find a stabilizer. The nonlinear systems have uncontrollable linearized system. From this fact, we propose a method that departs from a controllable linearized system to a linear transformation. The linear transformation allows to take the uncontrolled system preserving the stability properties of the controlled one. Thus, the resulting controller is able to stabilize biomedical systems. Type I diabetes mellitus and HIV-I diseases are used to show the potential of method. Numerical simulations for this case illustrate the performance of closed loop approach.
Caracterización de ácidos fenólicos y flavonoides presentes en hojas de amaranto (Amaranthus hypochondriacus L.).
Get PDFTesis (Maestría en Ciencias en Biología Molecular)"Las hojas de amaranto (Amaranthus spp) son consideradas como plantas medicinales y son utilizadas para preparar alimentos. El objetivo de éste trabajo fue obtener el perfil cualitativo y cuantitativo de ácidos fenólicos y flavonoides en hojas de dos variedades de A. hypochondriacus con diferentes colores de hojas (rojas y verdes) crecidos en diferentes condiciones de cultivo (maceta chica y grande dentro de invernadero; cultivadas en campo, cultivadas en campo pero que presentaban daño por insecto. Los ácidos fenólicos son compuestos involucrados en la respuesta al estrés biótico y abiótico por las plantas mientras que los flavonoides son compuestos con mayor frecuencia relacionados con las propiedades nutracéuticas. La cuantificación de tres flavonoides y cinco ácidos fenólicos en hojas de amaranto se determinó empleando la metodología de extracción con solventes acelerada (ASE) y la cromatografía de líquidos acoplada a espectrómetro de masas (LC/MS/MS). En las hojas de amaranto, el principal flavonoide fue la rutina, en concentraciones de 3441 hasta 9236 μg/g. La concentración de nicotiflorin fue de 523 a 1,297 μg/g, y la de la iso-quercitrina fue de 371 a 930 μg/g. Los ácidos fenólicos fueron los compuestos detectados en menor proporción en las hojas de amaranto. El ácido ferúlico se detectó únicamente en hojas rojas (0.5 μg/g) crecidas en maceta pequeña en invernadero, mientras que el ácido cumárico solo se detectó en hojas verdes (0.7 μg/g) cultivadas en maceta grande en invernadero. Los resultados indican que la producción de ciertos productos naturales en hojas de amaranto puede ser influenciada por las condiciones de cultivo.""Leaves from amaranth (Amaranthus spp.) are used as medicines and in the preparation of food. The aim of this work was to obtain the qualitative and quantitative profile of flavonoid and phenolic acid compounds in leaves of two varieties of A. hypochondriacus with different leaf colors (red and green) that were grown in different conditions (small and big pots inside greenhouse, grown in fields, grown in fields with insect damage). Phenolic acids are compounds produced in response to biotic and abiotic stresses in plants, while flavonoids are related to the nutraceutical properties of amaranth leaves. The three flavonoids and five phenolic acids in amaranth leaves were determined using accelerated solvent extraction and Liquid Chromatography/Mass Spectrometry. In amaranth leaves the main flavonoid was rutin, with concentrations from 3,441-9,236 μg/g; the concentration of nicotiflorin ranged from 1,297–523 μg/g, and for iso-quercitrin 930–371 μg/g. Phenolic acids were minor compounds in amaranth leaves: ferulic acid was only present in red leaves grown in small pots in greenhouse (0.5 μg/g) and coumaric acid was only detected in green leaves (0.7 μg/g). Our findings indicate that the production of certain natural products in amaranth leaves could be influenced by growth conditions.