The importance of side branches of glycosylphosphatidylinositol anchors : a molecular dynamics perspective

Many proteins are anchored to the cell surface of eukaryotes using a unique family of glycolipids called glycosylphosphatidylinositol (GPI) anchors. These glycolipids also exist without a covalently bound protein, in particular on the cell surfaces of protozoan parasites where they are densely populated. GPIs and GPI-anchored proteins participate in multiple cellular processes such as signal transduction, cell adhesion, protein trafficking and pathogenesis of Malaria, Toxoplasmosis, Trypanosomiasis and prion diseases, among others. All GPIs share a common conserved glycan core modified in a cell-dependent manner with additional side glycans or phosphoethanolamine residues. Here, we use atomistic molecular dynamic simulations and perform a systematic study to evaluate the structural properties of GPIs with different side chains inserted in lipid bilayers. Our results show a flop-down orientation of GPIs with respect to the membrane surface and the presentation of the side chain residues to the solvent. This finding agrees well with experiments showing the role of the side residues as active epitopes for recognition of GPIs by macrophages and induction of GPI-glycan-specific immune responses. Protein-GPI interactions were investigated by attaching parasitic GPIs to Green Fluorescent Protein. GPIs are observed to recline on the membrane surface and pull down the attached protein close to the membrane facilitating mutual contacts between protein, GPI and the lipid bilayer. This model is efficient in evaluating the interaction of GPIs and GPI-anchored proteins with membranes and can be extended to study other parasitic GPIs and proteins and develop GPI-based immunoprophylaxis to treat infectious diseases

Evolution of grape polyphenol oxidase activity and phenolic content during maturation and vinification

The activity of polyphenol oxidase (PPO) and content of phenolic compounds were followed during the maturation in two varieties of wine grapes grown in south-eastern Spain and during vinification at different sulphur dioxide concentrations.Both cresolase and catecholase activities (measured at pH 7.0 and 4.5, respectively) increased throughout the studied period and the content of phenolic compounds decreased rapidly when expressed as concentration (mg gallic acid/g total fresh weight), while when expressed as total amount per berry (mg/berry) it remained constant. During wine production, the enzyme activity was highest immediately after crushing of the fresh grapes and was not detected at the end of the fermentation process. The phenolic content also decreased during vinification to a constant level depending on the S02 level used

Bacterial communities involved in the nitrogen cycle in constructed wetlands

La elevada producción de agua residual y su falta de tratamiento ha llevado a la búsqueda de sistemas de depuración eficiente, económica, fácil de operar y que permitan considerar el agua residual como un recurso. Los humedales construidos son sistemas de tratamiento promisorios para este fin, pero la investigación de los microorganismos involucrados en la transformación de los nutrientes en éstos es aún incipiente. En este estudio se reportan los resultados de la evaluación de poblaciones de bacterias nitrificantes, heterotróficas y fijadoras de nitrógeno presentes en el medio de soporte, en este caso grava y columna de agua en tres humedales construidos (HC) sometidos a distintas cargas hidráulicas y con diferentes especies vegetales: Phragmites australis, Heliconia psittacorum y uno sin vegetación como control. El humedal con P. australis presentó mayores densidades de bacterias nitrificantes y fijadoras de Nitrógeno (5.35 y 7.18 unidades log gr-1, respectivamente); el humedal con H. psittacorum presentó las menores densidades para todos los grupos de bacterias y el humedal control mostró la mayor densidad de bacterias heterótrofas (7.22 unidades log gr-1). El número de bacterias de las poblaciones encontradas, sugiere la importante actividad metabólica y dinámica de estos microorganismos en los sistemas de humedales construidos en el trópico

ESTUDIO DEL AZAFRÁN (CROCUS SATlVUS L.) EN LA PROVINCIA DE ALBACETE. II. COLOR

In this paper the colouring power of diverse saffron population of the province Albacete is studied, as well as its variation with time.En este trabajo se estudia el poder colorante de diversas poblaciones de azafrán de la provincia de Albacete, así como su variación con el tiempo

Nematodos asociados con el cultivo del plátano (Musa AAB o ABB) en el Valle del Cauca.

Se realizó un reconocimiento cualitativo y cuantitativo de los principales nemátodos fitoparásitos asociados con el cultivo de plátano. El estudio se llevó a cabo en fincas de agricultores minifundistas localizadas en los municipios vallecaucanos de El Bolo, Rozo y Cerrito. Se analizaron 87 muestras tanto de suelo como de raíces, discriminados así: 31 en El Bolo, 25 en Rozo y 31 en Cerrito, para un área total de 88.7 ha, aproximadamente. Se encontró que los géneros más importantes por su incidencia, población y distribución observada fueron: Meloidogyne, Helicotylenchus, Pratylenchus, Rotylenchulus y Radopholus. El género Meloidogyne se encontró ampliamente distribuído en las 3 zonas. Otros nemátodos que se encontraron asociados con este cultivo fueron: Trophurus sp, Paratylenchus sp. Hoplotylus sp. Criconemoides sp. Trichodorus sp. Ditylenchus sp. Tylenchorhynchus sp. Psilenchus sp. y Xiphinema sp. Las plantaciones donde se registraron altas poblaciones de nemátodos en general, presentaron síntomas de amarillamiento y clorosis del área foliar, racimos pequeños y raquíticos, tallos delgados en su parte inferior, necrosis y muerte de raíces, ausencia de raicillas y embalconamiento de la plantaPlátano-Musa sapientu

ESTUDIO DEL AZAFRÁN (CROCUS SATIVUS L.) EN LA PROVINCIA DE ALBACETE. I. PRODUCCIÓN

In this paper the relative efficiency during the first years of cultivation of several saffron selections is valued, tanking into account the factors such as bulb size, dried stigmes weight per flower, flowering index and extension of the floral mantle.Se valora el rendimiento relativo de las distintas selecciones de azafrán, durante su primer año de cultivo en distintas zonas de la provincia de Albacete. Se tienen en cuenta los factores como el tamaño del bulbo, peso de estigmas desecados por flor, índice de floración y extensión del manto floral

Binomial sampling of Paraleyrodes Quaintance pos. bondari (Hemiptera: Aleyrodidae) in Persea americana Mill.

Fresno (Tolima), in Colombia, is a notable avocado producer, with 36% of the national production. In this paper, two sampling methods are presented to assess natural populations of Paraleyrodes Quaintance pos. bondari attacking avocado trees of Hass and Lorena cultivars under field conditions. The presence/absence of whitefly nymph colonies on 30 leaves located at the high, medium and low strata per host plant from both cultivars was evaluated. Visual estimations were performed to count the number of whitefly nymphs on 1.25 cm2 of five leaves/bud in low and medium strata per tree to evaluate the spatial distribution of whitefly population in accordance to Poisson distribution, Negative Binomial distribution and b parameter of Law of Taylor. Significant differences in percentages of infestation (P≤0.03) from leaves that belonged to the low avocado tree strata were found between the Lorena (31.88±1.2%) and Hass (15.64±1.8%) cultivars. Natural populations of P. pos. bondari were located on the abaxial leaf side, showing an aggregate distribution in avocado tree from orchards located at different altitudes. Our findings recommend entomological surveillance for Paraleyrodes sp. pos. bondari in Fresno (Tolima), sampling four branches from the medium and low avocado tree strata through inspection of five buds/branches/tree throughout each branch with the presence/absence method to count whitefly nymph colonies on the abaxial side of pre-basal leaves. In total, the sampling involved five leaves/branch (20 leaves/strata or 40 leaves/tree) on 13 avocado trees per hectare

Study and analysis of injection molding of thermoplastic polymeric materials

[EN] This article aims at analyzing the injection molding of thermoplastic polymeric materials by examining their current situation from the perspective of industrial production, the evolution of technology and modeling of the injection process.[ES] El presente artículo tiene como objetivo el análisis del moldeo por inyección de materiales poliméricos termoplásticos, estudiando su situación actual desde la perspectiva de la producción industrial, la evolución de la técnica y la modelización del proceso de inyección.Authors thank “Ministerio de Ciencia y Tecnología”, Ref: DPI2007-66849-C02-02 and Generalitat Valenciana FPA/2010/027 for financial support.Juárez Varón, D.; Balart, R.; Peydro, MA.; Ferrándiz Bou, S. (2012). Estudio y análisis del moldeo por inyección de materiales poliméricos termoplásticos. 3c Tecnologia. (3):40-53. http://hdl.handle.net/10251/33135S4053