Resumen La disminución del valor comercial del frijol por almacenamiento, se debe a la disminución de la calidad culinaria y al oscurecimiento de la testa. El objetivo de este trabajo fue estudiar ...los cambios en el color de la testa y en la calidad culinaria promovidos por el almacenamiento prolongado en dos períodos de tiempo, en contraste con el cambio bajo envejecimiento acelerado en cinco variedades de frijol. El color del grano se cuantificó por espectrofotometría de reflectancia y la calidad culinaria por el tiempo y los sólidos en el caldo de cocción. El envejecimiento acelerado propició “dureza a la cocción”, pero no testa dura, por el contrario el almacenamiento prolongado a temperatura ambiente, si bien no promovió dureza a la cocción, una de las cinco variedades mostró testa dura. El oscurecimiento de la testa mostró una correlación positiva entre todas las condiciones de almacenamiento. La correlación para L* entre el envejecimiento acelerado y el almacenado por cuatro años fue de r= 0.84**, en tanto que la relación del primero, con dos años de almacenamiento fue de r= 0.65*. Estos resultados indican que el envejecimiento acelerado del frijol, es un método adecuado para seleccionar materiales con menor propensión al envejecimiento porque permite anticipar el cambio de color que podría ocurrir durante el almacenamiento prolongado.
La caracterización del germoplasma nativo es fundamental para el conocimiento de la diversidad genética y su aprovechamiento en el fitomejoramiento de la calidad del grano para satisfacer la demanda ...de los consumidores y mejorar su nutrición sin modificar sus hábitos alimenticios. Por lo anterior, el objetivo de este trabajo fue estimar la variabilidad genética de 111 genotipos nativos de frijol (Phaseolus vulgaris L.) de diferentes estados de México con marcadores RAPD y por sus atributos de calidad física, culinaria y contenido de proteína. Se determinó la similitud genética entre variedades por el método de promedios aritméticos de grupos apareados no ponderados (UPGMA). Con los datos sobre calidad, se realizó un análisis de componentes principales y de agrupamiento jerárquico. Cuando se utilizaron todas las variedades para generar los dendrogramas, los grupos no fueron claros, aunque parecieron estar determinados por localización geográfica; cuando se analizaron por separado los genotipos de colores amarillo mostaza y negro, en ambos casos se generaron grupos bien definidos y similares entre los obtenidos con las características tecnológicas y con los RAPD. Los genotipos nativos sobresalientes por combinar las características de calidad culinaria y alto contenido de proteína (>24.8%) fueron Ph.vulg.2346 (beige), Ph.vulg.403 (azufrado), Ph.vulg.2435 (bayo) y Ph.vulg.2519 (amarillo mostaza), las cuales podrían ser útiles en los programas de mejoramiento.
La productividad académica constituye uno de los rubros que se toma en cuenta al evaluar el desempeño del personal académico en las instituciones de educación superior (Gaceta UNAM, 1994). Para el ...caso de los académicos con perfil de investigador, los productos evaluados son las publicaciones emanadas de sus líneas de investigación
The use of lignocellulosic softwood residues as feedstock for the production of bioethanol and other value-added chemical products has been limited by its high recalcitrance. Alkaline or ...organosolvent pretreatments have been used to remove recalcitrance in softwoods. Although these methods partially remove lignin and hemicellulose, they also result in low glucose recovery. In the first case, there is low cellulose hydrolizability, and in the second, there is a loss of cellulose. This study evaluated both methods combined into one step: alkaline hydrolysis of the biomass in the presence of an organosolvent. Different conditions of temperature and residence times were assayed. The efficiency of these conditions was quantified as the percentage of lignin and hemicellulose removed from the biomass without loss of cellulose. The substrate produced with the most efficient conditions removed 91% of the lignin and 89.1% of the hemicellulose with no loss of cellulose. Enzymatic hydrolysis of this biomass was 90% to 95%, with a substrate concentration of 3% and with five filter paper units per gram of cellulose (FPU/g cellulose). These results indicated that this one-step alkaline-organsolvent process, applied as a pretreatment to softwood, allows highly efficient lignin and hemicellulose removal. 100% of cellulose was recovered, and there was between 90 and 95% glucose yield after enzymatic digestion.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Cooking time is an important trait in the breeding of common beans (Phaseolus vulgaris L.), especially in Mexico where 96% of beans consumed are prepared in the household. Because of the ...characteristics of the cooking time trait, a method of indirect selection would increase selection efficiency. The objective of this study was to identify random amplified polymorphic DNA (RAPD) markers associated with the trait and estimate genetic parameters of cooking time. For that purpose, 104 recombinant inbred lines (RILs), derived from contrasting cooking time bean cultivars were evaluated for three consecutive generations (F5 to F8). In each generation, cooking time was determined and plants in the F7 generation were genotyped. One marker was associated with cooking time. The polymorphic UNAM‐16 of 310 base pairs (bp) explained 23% of the variation in cooking time of the lines studied. Narrow sense heritability (h2) was estimated for cooking time, as was the number of genes involved in the trait. A high value of h2 (0.74) was estimated for cooking time. Also, it was estimated that two genes control the cooking time trait.
In recent years, the selective role of ribosomes in the translational process of eukaryotes has been suggested. Evidence indicates that ribosomal heterogeneity at the level of protein stoichiometry ...and phosphorylation status differs among organisms, suggesting ribosomal specialization according to the state of development and the surrounding environment. During germination, protein synthesis is an active process that begins with the translation of the mRNAs stored in quiescent seeds and continues with the newly synthesized mRNAs. In this study, we identified differences in the abundance of ribosomal proteins (RPs) in maize embryos at different developmental stages. The relative quantification of RPs during germination revealed changes in six small subunit proteins, S3 (uS3), S5 (uS7), S7 (eS7), two isoforms of S17 (eS17), and S18 (uS13), and nine large subunit proteins, L1 (uL1), L5 (uL18), two isoforms of P0 (uL10), L11 (uL5), L14 (eL14), L15 (eL15), L19 (eL19), and L27 (eL27). Further analysis of ribosomal protein phosphorylation during germination revealed that the phosphorylation of PRP0 (uL10) and P1 increased and that of PRS3 (uS3) decreased in germinated versus quiescent embryos. The addition of insulin during germination increased the phosphorylation of the P1 protein, suggesting that its phosphorylation is controlled by the TOR pathway. Our results indicate that a heterogeneous ribosomal population provides to maize ribosomes during germination a different ability to translate mRNAs, suggesting another level of regulation by the ribosomes.
Considerable amounts of information is available on the complex carbohydrates that are mobilized and utilized by the seed to support early seedling development. These events occur after radicle has ...protruded from the seed. However, scarce information is available on the role of the endogenous soluble carbohydrates from the embryo in the first hours of germination. The present work analysed how the soluble carbohydrate reserves in isolated maize embryos are mobilized during 6–24 h of water imbibition, an interval that exclusively embraces the first two phases of the germination process. It was found that sucrose constitutes a very significant reserve in the scutellum and that it is efficiently consumed during the time in which the adjacent embryo axis is engaged in an active metabolism. Sucrose transporter was immunolocalized in the scutellum and in vascular elements. In parallel, a cell-wall invertase activity, which hydrolyses sucrose, developed in the embryo axis, which favoured higher glucose uptake. Sucrose and hexose transporters were active in the embryo tissues, together with the plasma membrane H+-ATPase, which was localized in all embryo regions involved in both nutrient transport and active cell elongation to support radicle extension. It is proposed that, during the initial maize germination phases, a net flow of sucrose takes place from the scutellum towards the embryo axis and regions that undergo elongation. During radicle extension, sucrose and hexose transporters, as well as H+-ATPase, become the fundamental proteins that orchestrate the transport of nutrients required for successful germination.
La caracterización del germoplasma nativo es fundamental para el conocimiento de la diversidad genética y su aprovechamiento en el fitomejoramiento de la calidad del grano para satisfacer la ...demanda de los consumidores y mejorar su nutrición sin modificar sus hábitos alimenticios. Por lo anterior, el objetivo de este trabajo fue estimar la variabilidad genética de 111 genotipos nativos de frijol (Phaseolus vulgaris L.) de diferentes estados de México con marcadores RAPD y por sus atributos de calidad física, culinaria y contenido de proteína. Se determinó la similitud genética entre variedades por el método de promedios aritméticos de grupos apareados no ponderados (UPGMA). Con los datos sobre calidad, se realizó un análisis de componentes principales y de agrupamiento jerárquico. Cuando se utilizaron todas las variedades para generar los dendrogramas, los grupos no fueron claros, aunque parecieron estar determinados por localización geográfica; cuando se analizaron por separado los genotipos de colores amarillo mostaza y negro, en ambos casos se generaron grupos bien definidos y similares entre los obtenidos con las características tecnológicas y con los RAPD. Los genotipos nativos sobresalientes por combinar las características de calidad culinaria y alto contenido de proteína (>24.8%) fueron Ph.vulg.2346 (beige), Ph.vulg.403 (azufrado), Ph.vulg.2435 (bayo) y Ph.vulg.2519 (amarillo mostaza), las cuales podrían ser útiles en los programas de mejoramiento.
Reactive oxygen species (ROS) are involved in redox regulation by their capacity to reversibly oxidize cysteine residues. This regulation is used by cells to modulate and integrate different ...responses to extracellular stimuli. In the barley (
Hordeum vulgare L.) aleurone layer, gibberellic acid (GA
3) is perceived at the plasma membrane and induces the synthesis and secretion of α-amylase. All aleurone membrane systems participate in the elaboration of this response. During these events, ROS are generated as a by-product from intense lipid metabolism. Therefore, we hypothesized that redox regulation may be operating in the GA
3-induced response. To test this hypothesis, we measured if GA
3 treatment induced changes in the redox state of aleurone membrane-associated proteins. Membrane proteins with sulfhydryl and disulfide groups were isolated from reduced and in situ NEM-alkylated microsomal fractions, respectively. Each fraction was enriched by thiol-affinity chromatography and separated by two-dimensional electrophoresis. The in vivo redox state of each membrane protein present in GA
3-treated and -untreated tissue was determined. Results showed that GA
3 induced the reduced state in 17 constitutive proteins and the oxidized state in another 5. These data indicate that redox changes occur in membrane proteins after GA
3 signaling in the aleurone layer.
PDF
