Extracción de pectinas a partir de los subproductos del beneficio del cacao

En este estudio se evaluó la posibilidad de obtener pectinas a partir de los subproductos del proceso del beneficio del cacao. Los experimentos se llevaron a cabo en el laboratorio de desarrollo de productos del departamento de ingeniería de procesos de la Universidad EAFIT.53 p.Contenido parcial: Cacao -- Pectina -- Materiales y equipos -- Procedimiento del desarrollo experimental -- Caracterización y comparación de las pectinas obtenidas con la pectina comercial -- Costos de materia prima

Detección de marcadores microsatélites asociados con la resistencia al añublo bacterial de la yuca (Manihot esculenta Crantz) en Colombia

Una de las principales estrategias para el manejo del Añublo Bacterial de la Yuca (CBB), causado por Xanthomonas axonopodis pv. manihotis es el uso de resistencia varietal, que implica desarrollar variedades de yuca con resistencia genética duradera. Para tal fin, es necesario conocer los genes que dominan la resistencia a la enfermedad, detectando inicialmente marcadores moleculares asociados con la respuesta fenotipica de la planta, siendo este el principal objetivo del presente estudio. Inicialmente, se evaluó la reacción a CBB de 4 familias de yuca BCI (retrocruce 1), se seleccionó la más segregante bajo presión natural de inóculo en Villavicencio (Meta, Colombia) y se confirmó la respuesta a CBB en condiciones de invernadero en CIAT (Palmira, Valle). La familia GM 315 presentó la mejor segregación, siendo la más adecuada para buscar asociación entre su reacción fenotípica y la presencia de un marcador molecular. Para esto, se evaluaron 486 cebadores microsatélites mediante análisis de grupos segregantes (BSA), encontrándose que 17 de ellos mostraron polimorfismo entre los grupos contrastantes y solo uno de ellos, el cebador SSRY 65, mostró diferencias significativas entre individuos resistentes y susceptibles. Al evaluar este cebador en toda la familia segregante se encontró asociación entre su presencia y los individuos evaluados fenotípicamente como resistentes en campo e invernadero, con una probabilidad mínima de P=0,OOl5 y P=0,OO7 respectivamente, en una prueba de Chicuadrado de independencia. Adicionalmente, a partir de los resultados obtenidos en el análisis estadístico, se calcularon los valores predictivos, especificidad y sensibilidad del marcador SSRY 65. Con base en los valores predictivos positivos generados, es posible sugerir la utilización de este marcador en pruebas diagnósticas para detectar la presencia de una banda específica en individuos resistentes de familias genéticamente relacionadas con la familia GM 315. = A major strategy for managing Cassava Bacterial blight (CBB), caused by Xanthomonas axonopodis pv. manihotis, is to use varietal resistance, that is, to develop cassava varieties with lasting genetic resistance. A search for the genes that dominate resistance to the disease was initially conducted by seeking the molecular markers associated with the plant s phenotypic response to CBB. The response in four BC1 (backcross 1) cassava families was accordingly evaluated under natural disease pressure at Villavicencio (Meta, Colombia). The most segregating family was then selected, and its response to CBB was verified under greenhouse conditions at CIAT (Palmira, Valle). Family GM 315 presented the best segregation, so, it was the most suitable for seeking association between its phenotypic reaction and the presence of a molecular marker. Of 486 microsatellite primers evaluated by bulked segregant analysis (BSA), 17 showed polymorphism among contrasting groups. Only one primer, SSRY 65, showed significant differences between resistant and susceptible individuals. On evaluating this primer for the entire segregating family, an association was found between its presence and individuals evaluated phenotypically as resistant in the field and greenhouse (minimum P = 0.0015 and P = 0.007, respectively, in a chi-square test of independence). With the results of the statistical analysis, the predictive values, specificity, and sensibility of marker SSRY 65 were calculated. The positive predictive values generated indicate that this marker can be used in diagnostic tests to detect the presence of a specific band in resistant individuals of families genetically related to the GM 315 family

Actin- and myosin-dependent vesicle loading of presynaptic docking sites prior to exocytosis.

Variance analysis of postsynaptic current amplitudes suggests the presence of distinct docking sites (also called release sites) where vesicles pause before exocytosis. Docked vesicles participate in the readily releasable pool (RRP), but the relation between docking site number and RRP size remains unclear. It is also unclear whether all vesicles of the RRP are equally release competent, and what cellular mechanisms underlie RRP renewal. We address here these questions at single glutamatergic synapses, counting released vesicles using deconvolution. We find a remarkably low variance of cumulative vesicle counts during action potential trains. This, combined with Monte Carlo simulations, indicates that vesicles transit through two successive states before exocytosis, so that the RRP is up to 2-fold higher than the docking site number. The transition to the second state has a very rapid rate constant, and is specifically inhibited by latrunculin B and blebbistatin, suggesting the involvement of actin and myosin

Mechanisms driving alteration of the Landau state in the vicinity of a second-order phase transition

The rearrangement of the Fermi surface of a homogeneous Fermi system upon approach to a second-order phase transition is studied at zero temperature. The analysis begins with an investigation of solutions of the equation $\epsilon(p)=\mu$, a condition that ordinarily has the Fermi momentum $p_F$ as a single root. The emergence of a bifurcation point in this equation is found to trigger a qualitative alteration of the Landau state, well before the collapse of the collective degree of freedom that is responsible for the second-order transition. The competition between mechanisms that drive rearrangement of the Landau quasiparticle distribution is explored, taking into account the feedback of the rearrangement on the spectrum of critical fluctuations. It is demonstrated that the transformation of the Landau state to a new ground state may be viewed as a first-order phase transition.Comment: 16 pages, 10 figure

Carta persuasiva al señor don Ignacio de Escandón

El comandante general de guerra Don Ignancio de Escandón con el respeto, que debe, dice: Que en todas las naciones políticas ha sido universal empeño conservar las memorias de sus sabios, no sólo por este un homenaje debido a su mérito, sino porque la patria se ilustra con sus literatos, y por que el número de estos acredita de cultas las regiones. Por otra parte nada más conveniente al aliento de la juventud en la carrera de las letras, que le recuerdo de los sabios patricios, cuyo ejemplo obra con más eficacia, porque se toca con mayor inmediatiación.CuencaAño 2, número 14 (julio 31 de 1891

Osteopoiquilosis y síndrome de Buschke-Ollendörf: a propósito de un caso

Presentamos una paciente de 22 años que tras estudios radiológicos rutinarios, muestra una displasia ósea condensante, completamente asintomática e inócua, que afectaba principalmente pelvis y extremidades distales, mientras que las costillas, cráneo y columna dorsolumbar estaban indemnes. Asimismo, aparecen nevus elásticos y fibromas en la piel. Esta entidad no puede confundirse con un carcinoma metastásico esclerosante, esclerosis tuberosa u otras displasias como la melorreostosis.A female patient, 22 years oíd, showing characteristic sclerotic bone images on radiographic examinations is reported. The main locations were on the distal limbs and pelvis. She has also elastic nevi as freckles in the skin. This entity was not stablished as inhered process. The differential diagnosis lies between sclerotic metastasis, neurofibromatosis (Von Recklinghausen), Bourneville disease and other displastyc lesions

Sugar, acid and furfural quantification in a sulphite pulp mill: Feedstock, product and hydrolysate analysis by HPLC/RID

Waste from pulp and paper mills consist of sugar-rich fractions comprising hemicellulose derivatives and cellulose by-products. A complete characterisation of the waste streams is necessary to study the possibilities of an existing mill. In this work, four chromatographic methods have been developed to obtain the most suitable chromatographic method conditions for measuring woody feedstocks, lignocellulosic hydrolysates and cellulose pulp in sulphite pulping processes. The analysis of major and minor monosaccharides, aliphatic carboxylic acids and furfurals has been optimised. An important drawback of the spent liquors generated after sulphite pulping is their acidic nature, high viscosity and adhesive properties that interfere in the column lifetime. This work recommends both a CHO-782Pb column for the sugar analysis and an SH-1011 resin-based cross-linked gel column to separate low-molecular-weight chain acids, alcohols and furfurals. Such columns resulted in a good separation with long lifetime, wide pH operating range and low fouling issues.The authors gratefully acknowledge the financial support of the European Union for this research by the BRIGIT “New tailor-made biopolymers produced from lignocellulosic sugars waste for highly demanding fire-resistant applications” research project under the seventh framework program www.brigit-project.eu