Nuevo conocimiento - NAT

URI permanente para esta colecciónhttp://hdl.handle.net/10906/78210

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Assessment of genetic diversity in Venezuelan rice cultivars using simple sequence repeats markers
(Pontificia Universidad Católica de Valparaíso, 2008-01-01) Ghneim Herrera, Thaura
In Venezuela, pedigree analyses indicate that the rice varieties currently under cultivation are closely related. Effective breeding programs, based on knowledge of the genetic diversity of cultivars, are needed to broaden the genetic bases of rice germplasm in the country. In this study, we used a set of 48 simple-sequence-repeat (SSR) markers to assess the genetic diversity of 11 Venezuelan rice cultivars, released by the National Rice Breeding Program between 1978 and 2007. A total of 203 alleles were detected, the number of alleles ( NA ) per marker ranged from 2 to 9, with an average of 4.23. The average genic diversity ( H ) over all SSR loci for the 18 genotypes was 0.524, ranging from 0.105 to 0.815. Positive correlations were found between H at each locus, NA , the allele size range and the maximum number of repeats. Venezuelan cultivars showed lower H (mean = 0.37) and NA (total = 124, mean = 2.58) than the whole sample. UPGMA-cluster-analysis based on genetic distance coefficients clearly separated all the genotypes , and showed that the Venezuelan rice varieties are closely related. Molecular identification of 7 Venezuelan cultivars could be done with 9 primers pairs which produced 10 genotype-specific-alleles. Although the genetic diversity was low, SSRs proved to be an efficient tool in assessing the genetic diversity of rice genotypes. Implications of the low genetic diversity detected and relatedness of Venezuelan cultivars are discussed.
Classical mechanics of dipolar asymmetric top molecules in collinear static electric and nonresonant linearly polarized laser fields: energy-momentum diagrams, bifurcations and accessible configuration space
(World Scientific Publishing, 2008-02-08) Arango Mambuscay, Carlos Alberto
We study classical energy-momentum ($E$-$m$) diagrams for rotational motion of dipolar asymmetric top molecules in strong external fields. Static electric fields, nonresonant linearly polarized laser fields, and collinear combinations of the two are investigated. We treat specifically the molecules iodobenzene (a nearly prolate asymmetric top), pyridazine (nearly oblate asymmetric top), and iodopentafluorobenzene (intermediate case). The location of relative equilibria in the $E$-$m$ plane and associated bifurcations are determined by straightforward calculation, with analytical results given where possible. In cases where analytical solutions cannot be obtained, we resort to numerical solutions, while keeping a geometrical picture of the nature of the solutions to the fore. The classification we obtain of the topology of classically allowed rotor configuration space regions in the $E$-$m$ diagram is of potential use in characterization of energy eigenstates of the corresponding quantum mechanical problem.
O -glycoside sequence of pentacyclic triterpene saponins from Phytolacca bogotensis using HPLC-ESI/multi-stage tandem mass spectrometry
(Wiley, 2009-07-23) Holzgrabe, Ulrike
The lack of pharmacopoeial methodologies for the quality control of plants used for therapeutic purposes is a huge problem that impacts directly upon public health. In the case of saponins, their great structural complexity, weak glycoside bonds and high polarity hinder their identification by conventional techniques. To apply high-performance liquid chromatography-electrospray tandem mass spectrometry (HPLC-ESI/MS(n)) to identify the O-glycoside sequence of saponins from the roots of Phytolacca bogotensis. Saponins were isolated by preparative HPLC and characterised by NMR spectroscopic experiments. Collision-induced dissociation (CID) of isolated saponins was performed producing typical degradation reactions that can be associated with several glycosidic bonds as empirical criteria. A method using solid-phase extraction (SPE) and HPLC/ESI-MS(n) for the characterisation of saponins and identification of novel molecules is described. Three saponins reported for the first time in P. bogotensis were isolated and characterised by NMR spectroscopy. Characteristic cross ring cleavage reactions have been used as empirical criteria for the characterisation of the glycosidic bonds most frequently reported for Phytolacca saponins. One new saponin was proposed on the basis of empirical criteria, and other five saponins were identified for the first time for P. bogotensis using HPLC-ESI/MS(n). Electrospray ionisation in combination with tandem mass spectrometry has been established as a powerful tool for the profiling of saponins from roots of P. bogotensis. CID proved to be a useful tool for the characterisation and identification of known and novel saponins from the plant family Phytolaccaceae and can be used for quality control purposes of crude plant extracts.
Interfaz gráfica para la operación remota de un prototipo de generación de energía hidroeléctrica
(Universidad Autónoma de Occidente, 2009-09-01) Cardozo Hernández, Carlos Fernando
En este artículo se presenta el diseño de la interfaz gráfica para la operación remota de un laboratorio prototipo automatizado orientado a la enseñanza en sistemas de generación hidroeléctricos (SGEH), ubicado en la EIEE (Escuela de Ingeniería Eléctrica y Electrónica) de la Universidad del Valle. Lo anterior implica abordar no solamente el desarrollo de software para lograr la interfaz, sino también la selección e instalación de los elementos de instrumentación y el control que permitan tales fines.
Caracterización fitoquímica de una fracción de biflavonoides de garcinia madruno: su inhibición de la oxidación de ldl humana y su mecanismo de estabilización de especies radicalarias
(Universidad de Antioquia, 2009-09-22) Osorio D., Edison
A una fracción biflavonoide (FB) caracterizada fitoquímicamente de Garcinia madruno (Clusiaceae), se le evalúa su potencial inhibitorio de la oxidación de LDL y su capacidad estabilizadora de especies radicalarias, correlacionando dichas actividades con su contenido en biflavonoides. Los biflavonoides morelloflavona, volkensiflavona y amentoflavona se identifican a partir de la FB. El extracto que contiene la FB (extracto AcOEt) se determina como el principal factor involucrado en la actividad estabilizadora de radicales libres de esta especie vegetal, obteniendo la actividad estabilizadora del radical DPPH• a una concentración de 4,50 µg/mL. La peroxidación inducida con CuSO4 de las lipoproteínas de baja densidad, se reduce significativamente en presencia de FB (CE50 = 11,85 µg/mL). El biflavonoide morelloflavona se determina como el principal responsable de la protección ejercida por la FB frente a la actividad estabilizadora de radicales libres y la peroxidación lipídica, aunque posiblemente existan procesos de sinergismo. Estas propiedades sugieren que la FB de G. madruno es un excelente candidato para ser utilizado como antioxidante.
Rapid differentiation of isobaric and positional isomers of structurally related glycosides from Phytolacca bogotensis.
(Wiley, 2009-09-25) Arango Mambuscay, Carlos Alberto
Through the action of glycosyltransferases, a plant can biosynthetically assemble small different aglycons or 'templates' to various polysaccharides to produce numerous glycoconjugates differing in the type of the attached aglycon, the anomeric configuration of C-1 of the glycosylating sugar, the type of sugar and the different position of attachments of the sugar unit present in the polysaccharide chain. The position of attachments and the anomeric configuration of the different sugar present in the polysaccharide create the opportunity to generate molecules with either the same or very close molecular weights, which have relative structural similarity--forming isobaric and positional isomers. Although isomeric differentiation was once considered outside of the domain of mass spectrometry, this task can now be resolved using tandem mass spectrometry. In a standardized purified glycoconjugate fraction (SPT01) from Phytolacca bogotensis, we report conventional electrospray ionization mass spectrometry and collision-induced dissociation (CID) MS/MS parameters which favored the formation of characteristic product ions. This allowed us to suggest the type of sugar linkages present in a specific glycoconjugate. Ten new glycoconjugate are described from this plant and another twelve known saponins were structurally characterized using the automatic MSn acquisition mode. The differentiation of two pairs of positional isomers and four isobaric glycosides and the production of a library of 30 glycosides present in P. bogotensis were accomplished.
Additive partitioning of spider diversity in a fragmented tropical dry forest (Valle del Cauca, Colombia)
(American Arachnological Society, 2010-01-01) Cabra García, Jimmy
Abstract Understanding the variation of diversity patterns requires analysis at multiple spatial scales. In this study we estimated the diversity components (alpha, beta and gamma) of the spider community at El Vínculo Natural Regional Park, using the additive partitioning of diversity (species richness, Shannon's diversity index and Simpson's index) for the first time on this taxon in Colombia. We collected the specimens following a nested sampling design that consisted of two spatial scales. At the local scale, we quantified additive diversity components in 238 sampling units, and at the regional scale in five vegetation types. Total observed regional diversity (γ) was partitioned into its additive components: within sampling units (α1), among sampling units (βl) and among vegetation types (β2). We used the same approach to compare common and infrequent spider species and to compare sampling methods. A total of 1565 adult spiders and 72 identifiable juveniles, including 193 morphospecies from 36 familie.
Riqueza y composición de arañas en diferentes coberturas vegetales del Parque Natural Regional el Vínculo (Valle del Cauca, Colombia)
(Inciva, 2010-01-01-) Valderrama Ardila, Carlos Humberto; Cabra-García, Jimmy; Ulloa-Chacón, Patricia
This study aimed to estimate the spider species richness at Parque Natural Regional El Vínculo (Valle del Cauca, Colombia). We sampled spiders during day and night sessions from August to December 2008 in five vegetation types: secondary forest, riparian forest, shrubs, grassland and highly disturbed area. We used aerial and ground hand collection, beating, sorting litter and pitfall traps. We used the non-parametric richness estimators ACE, ICE, Chao 1, Chao 2, first-order Jackknife and second-order Jackknife in order to calculate the average species richness. Additionally, we calculated the average sampling efficiency. A total of 1565 adult specimen, representing 36 families and 193 morphospecies in 238 sampling units were found. The average estimated richness ranged from 46 (shrubs) to 101 (secondary forest) morphospecies. The values of average sampling efficiency ranged from 70% (secondary forest) to 90% (shrubs). The average estimated richness for the natural park was 238 morphospecies and the average sampling efficiency was 81%. Our results increases the number of families registered in the park in 14 and suggest this location as the place with more families of spiders in the Valle del Cauca.
Environmental risk factors for the incidence of American cutaneous leishmaniasis in a sub-Andean zone of Colombia (Chaparral, Tolima).
(2010-02-01) Valderrama Ardila, Carlos; Alexander, Neal; Ferro, Cristina; Cadena, Horacio; Marín, Dairo; Holford, Theodore R.; Munstermann, Leonard E.; Ocampo, Clara B.
Environmental risk factors for cutaneous leishmaniasis were investigated for the largest outbreak recorded in Colombia. The outbreak began in 2003 in Chaparral, and in the following five years produced 2,313 cases in a population of 56,228. Candidate predictor variables were land use, elevation, and climatic variables such as mean temperature and precipitation. Spatial analysis showed that incidence of cutaneous leishmaniasis was higher in townships with mean temperatures in the middle of the county's range. Incidence was independently associated with higher coverage with forest or shrubs (2.6% greater for each additional percent coverage, 95% credible interval [CI] = 0.5-4.9%), and lower population density (22% lower for each additional 100 persons/km(2), 95% CI = 7-41%). The extent of forest or shrub coverage did not show major changes over time. These findings confirmed the roles of climate and land use in leishmaniasis transmission. However, environmental variables were not sufficient to explain the spatial variation in incidence.
Erratum: “Conditions for one-photon coherent phase control in isolated and open quantum systems”
(2010-02-07) Brumer, Paul
Coherent control of observables using the phase properties of weak light that induces one-photon transitions is considered. Measurable properties are shown to be categorizable as either class A, where control is not possible, or class B, where control is possible. Using formal arguments, we show that phase control in open systems can be environmentally assisted.
Regulation of spinal neuron axon outgrowth by calcium influx through mechanosensitive TrpC channels
(Federation of American Societies for Experimental Biology, 2010-04-01) Rengifo Gómez, Juliana
Intracellular calcium signals regulate the development and regeneration of spinal axons downstream of chemical and mechanical cues. Previously, we identified a novel calcium influx pathway through stretch-activated channels (SACs) that inhibits spinal neuron axon outgrowth. Here we show that TRPC1 functions as a SAC on growth cones, which constitutively suppresses neurite outgrowth. Reducing TRPC1 expression with anti-sense morpholinos prevents changes in the rate of axon outgrowth in response to stimuli that activate or inhibit calcium influx through mechanosensitive ion channels. Further, activating SACs increases calcium signals in nerve growth cones that are dependent on TRPC1 expression. The elastic properties of the substratum also modulate calcium signaling in growth cones and the extension of spinal axons in a TRPC1-dependent manner. Downstream of calcium signals, we find that the protease Calpain is activated by calcium influx through TRPC1 containing channels, which likely inhibits the growth promoting effects of the non-receptor tyrosine kinase Src. Together our results suggest that calcium influx through mechanosensitive channels containing TRPC1 subunits activates calpain, which in turn cleaves Src family kinases to restrict neurite outgrowth by developing spinal cord neurons.
Estimation of the indomethacin solubility in ethanol + water mixtures by the extended Hildebrand solubility approach - Open Access Library
(Universidad Nacional de Colombia, 2010-06-01) Mora Guerrero, Carolina Del Pilar
indomethacin (imc) is an analgesic drug whose physicochemical properties have not been thoroughly studied. in this work the extended hildebrand solubility approach (ehsa) was applied to evaluate the solubility of imc in ethanol + water mixtures at 298.15 k. an acceptable correlative capacity of ehsa was found using a regular polynomial model in order four (overall deviation lower than 4.1%), when the w interaction parameter is related to the solubility parameter of the mixtures. besides, the deviations obtained in the estimated solubility with respect to experimental solubility were lower compared with those obtained directly by means of an empiric regression of the experimental solubility as a function of the mixtures′ solubility parameters.
Thermodynamics of mixing of sodium naproxen and procaine hydrochloride in ethanol + water cosolvent mixtures
(Universidad Nacional de Colombia, 2010-07-01) Mora Guerrero, Carolina Del Pilar
Thermodynamic functions Gibbs energy, enthalpy, and entropy of mixing of sodium naproxen and procaine hydrochloride were evaluated. Mixing quantities were calculated based on fusion calorimetric values obtained from differential scanning calorimetry measurements and equilibrium solubility values reported in the literature for both drugs in ethanol + water mixtures. By means of enthalpy-entropy compensation analysis, non-linear ΔH°mix vs. ΔG°mix plots were obtained which indicates different mechanisms involved in the dissolution of these drugs according to mixtures composition. Nevertheless, the molecular and ionic events involved in the dissolution of this drug in this cosolvent system are unclear.
Communication: Conditions for one-photon coherent phase control in isolated and open quantum systems.
(AIP Publishing, 2010-10-15) Arango Mambuscay, Carlos Alberto
Coherent control of observables using the phase properties of weak light that induces one-photon transitions is considered. Measurable properties are shown to be categorizable as either class A, where control is not possible, or class B, where control is possible. Using formal arguments, we show that phase control in open systems can be environmentally assisted.
False sugar sequence phenomenon and structural analysis of alpha-hederin and hederacoside c through electrospray ionization and multi-stage tandem mass spectrometry
(Universidad de Antioquia, 2011-01-01) Montoya, Guillermo
Saponins are glycosides regularly found in plants, and they are frequently analyzed by means of electrospray ion sources and tandem mass spectrometry (ESI/MSn), not only to obtain an overall molecular weight through the high sensitivity of mass spectrometry but also to obtain their structural information. The use of modern analytic techniques (such as ESI/MSn) aids the discovery and quality control assessment of new molecules found in botanicals; however, some rearrangements have been described for oligosaccharides that produce an incorrect elucidation of the molecules. For the first time, evidence for an internal sugar loss on the protonated fragmentation of a-hederin has been reported. This phenomenon can be avoided by using alkali metal ion adducts, such as lithium and sodium cations, to confirm the real sugar sequence when a structural identification is performed. In this study, the structural characterization of alpha-hederin and hederacoside C is conducted by comparing positive and negative modes. Different fragmentation patterns occur, and such patterns are useful in the structural analysis of saponins when they are present on different matrixes.
Modelo de sistema de gestión ambiental para formar universidades ambientalmente sostenibles en Colombia
(Universidad Nacional de Colombia, 2011-05-01) Rivas Marin, Maria Isabel
Los campus sostenibles han llegado a ser uno de los principales objetivos de las agendas universitarias como resultado de los impactos generados por las actividades que allí se desarrollan y que afectan el medio ambiente. Por ello, existen sistemas de gestión ambiental, los cuales son el conjunto de prácticas, procedimientos, procesos y recursos necesarios para cumplir con una normativa ambiental en las empresas y están enfocados a la reducción de los impactos sobre el medio ambiente y a la efi ciencia en los procesos. En las Universidades, aún siendo consideradas empresas, estos sistemas no funcionan de manera eficiente, lo que hace necesario y urgente que un modelo de sistema de gestión ambiental sea adecuado y que, por medio de la enseñanza y la investigación, se ayude la sociedad a lograr la transición a estilos de vida sostenibles.
Atherosclerosis development in SLE patients is not determined by monocytes ability to bind/endocytose Ox-LDL.
(2011-06-14) Montoya Peláez, Guillermo León
Patients with systemic lupus erythematosus (SLE) have a high risk of developing cardiovascular disease; however, the mechanisms involved in the early onset of atherosclerosis in these patients are not clear. Scavenger receptors, CD36 and CD163 are expressed by mononuclear phagocytes and participate in the binding and uptake of oxidized low-density lipoproteins (Ox-LDL), contributing to foam-cells formation and atherosclerosis development. The aim of the present study was to evaluate CD36(+) and CD163(+) expression and Ox-LDL removal by monocytes from SLE and atherosclerotic patients, compared to similar age-range healthy controls. Healthy controls, SLE, and atherosclerotic patients were evaluated for carotid intima media thickness (CIMT), lipid profile, and native LDL (N-LDL) and Ox-LDL binding/endocytosis. SLE patients presented decreased high-density lipoproteins (HDL) and increased Triglyceride levels, and half of the SLE patients had increased CIMT, compared to their healthy controls (HC(SLE)). The number of CD14(+)CD163(+) cells was increased in atherosclerosis healthy controls (HC(Atheros)) compared to HC(SLE), but there were no differences between SLE or atherosclerotic patients and their respective healthy controls. Clearance assays revealed a similar capacity to bind/endocytose Ox-LDL by monocytes from SLE patients and HC(SLE), and an increased binding and endocytosis of Ox-LDL by monocytes from atherosclerotic patients, compared to HC(Atheros). The decreased CD36 and CD163 expression observed in atherosclerotic and SLE patients, respectively, suggest that these inflammatory conditions modulate these receptors differentially. The increased CIMT observed in SLE patients cannot be explained by Ox-LDL binding/endocytosis, which was comparable to their controls.
False sugar sequence phenomenon and structural analysis of α-hederin and hederacoside c through electrospray ionization and multi-stage tandem mass spectrometry
(Universidad de Antioquia, 2011-08-29) Montoya Pelaez, Guillermo Leon
Saponins are glycosides regularly found in plants, and they are frequently analyzed by means of electrospray ion sources and tandem mass spectrometry (ESI/MSn), not only to obtain an overall molecular weight through the high sensitivity of mass spectrometry, but also to obtain their structural information. The use of modern analytic techniques (such as ESI/MSn) aids the discovery and quality control assessment of new molecules found in botanicals; however, some rearrangements have been described for oligosaccharides that produce an incorrect elucidation of the molecules. For the first time, evidence for an internal sugar loss on the protonated fragmentation of -hederin has been reported. This phenomenon can be avoided by using alkali metal ion adducts, such as lithium and sodium cations, to confirm the real sugar sequence when a structural identification is performed. In this study, the structural characterization of -hederin and hederacoside C is conducted by comparing positive and negative modes. Different fragmentation patterns occur, and such patterns are useful in the structural analysis of saponins when they are present on different matrixes.
2-Bromo-N-(2-hy-droxy-5-methyl-phen-yl)-2-methyl-propanamide.
(International Union of Crystallography, 2011-09-01) Grande Tovar, Carlos
In the title mol-ecule, C(11)H(14)BrNO(2), there is twist between the mean plane of the amide group and the benzene ring [the C-N-C-C torsion angle is -172.1 (2)°]. The amide H atom forms an intra-molecular hydrogen bond with the Br atom. In the crystal, inter-molecular O-H⋯O and weak C-H⋯O hydrogen bonds link mol-ecules into a chain along [100].
Microsporogenesis and pollen formation in cassava
(Springer Netherlands, 2011-09-01) Tabares, Eddie
This article describes the complete microsporogenesis and pollen formation in cassava (Manihot esculenta Crantz) at the various developmental stages (pollen mother cell, meiosis, tetrads, early free spore, mid uninucleate, late uninucleate, binucleate and mature pollen grain). Light microscopy, transmission electron microscopy and confocal laser scanning microscopy were used for the study. Floral bud size and other inflorescence characteristics were correlated with specific stages of the microspore development. This association allows a rapid selection of floral buds with similar microspore developmental stages, useful when a large number of homogeneous cells are needed for analysis and for in vitro induction of androgenesis. This article also compares methods for digestion the exine wall in microspores.

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