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Search Results: 1 - 10 of 215 matches for " espeletia pycnophylla ssp. angelensis "
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EFECTO DEL GRADIENTE ALTITUDINAL SOBRE ASPECTOS AUTOECOLóGICOS DE ESPELETIA PYCNOPHYLLA ssp. ANGELENSIS CUATREC. (ASTERACEAE) EN EL PáRAMO EL INFIERNILLO (NARI?O-COLOMBIA)
Benavides-Martínez,Iván F.; Burbano-Martínez,Diana L.; Urbano-Apráez,Sandra M.; Solarte-Cruz,María E.;
Actualidades Biológicas , 2007,
Abstract: some autoecological features of espeletia pycnophylla ssp. angelensis cuatrec. such as its demographic structure, population density, spatial pattern of dispersion, production of reproductive structures, adult morphometry and survivorship, were studied in an altitudinal gradient on a dry paramo of nari?o (colombia). hypothesis proposed by other authors about a linear effect caused by the elevation on these variables were completely rejected. the elevation induces an ecoclinal effect on population density, and this density correlates negatively with both production of reproductive structures and adult sizes. these results elucidate an unequivocal effect of density-dependence phenomena on population fitness. the intermediate zone of the altitudinal gradient exhibits a high population density, but on the other hand show reduced corporal adult sizes, minimal production of reproductive structures and the probability of juveniles reaching advanced ages is low. evidently, this intermediate elevation can have favorable ecological conditions for the seedling establishment, wich increments population densities at long term. we propose that other author's generalizations about the influence of elevation on the autoecology of these plants are limited, because the particular life and disturbance stories of paramos and the spatial, ecological and genetic isolating are explicative factors impossible to take away from the context. the demographic structure of the population fitted the logarithmic model, revealing its early regeneration state from the last fire event on 2003 and the similarity of the survivorship curves among every elevation, probed a high demographic stability.
EFECTO DEL GRADIENTE ALTITUDINAL SOBRE ASPECTOS AUTOECOLóGICOS DE ESPELETIA PYCNOPHYLLA ssp. ANGELENSIS CUATREC. (ASTERACEAE) EN EL PáRAMO EL INFIERNILLO (NARI O-COLOMBIA) THE EFFECT OF THE ALTITUDINAL GRADIENT ON AUTOECOLOGICAL FEATURES OF ESPELETIA PYCNOPHYLLA ssp. ANGELENSIS CUATREC. (ASTERACEAE) IN THE PARAMO 'EL INFIERNILLO' (NARI O-COLOMBIA)
Iván F. Benavides-Martínez,Diana L. Burbano-Martínez,Sandra M. Urbano-Apráez,María E. Solarte-Cruz
Actualidades Biológicas , 2007,
Abstract: Se estudió el efecto de la elevación sobre algunos aspectos autoecológicos de la especie Espeletia pycnophylla ssp. angelensis Cuatrec. (Asteraceae), tales como su estructura demográfica, densidad poblacional, patrón de distribución espacial, producción de estructuras reproductivas, morfometría de adultos y supervivencia, en un páramo seco del departamento de Nari o (Colombia). Las hipótesis propuestas por otros autores acerca del efecto lineal que la elevación produce sobre estas variables, fueron completamente rechazadas. La elevación induce un efecto coenoclínico sobre la densidad poblacional y ésta a su vez, se correlaciona negativamente con la producción de estructuras reproductivas y el tama o de los adultos, evidenciándose un efecto inequívoco del fenómeno de la densodependencia sobre el potencial biótico de la población. En la zona intermedia del gradiente, la densidad poblacional es máxima, pero los tama os corporales son reducidos, la producción de estructuras reproductivas es mínima y la probabilidad de que un juvenil alcance edades avanzadas es baja. Evidentemente, esta elevación intermedia estaría presentando condiciones ecológicas favorables para el establecimiento y supervivencia de plántulas, lo que a largo plazo conlleva a un aumento de la densidad poblacional. Se propone que las generalizaciones de otros autores acerca de la influencia de la elevación sobre la autoecología de estas plantas son inverosímiles y limitadas, ya que la historia particular de vida y disturbio del páramo y los aislamientos espaciales, ecológicos y genéticos, son factores explicativos que no pueden aislarse del contexto. Paralelamente, la población se ajustó al modelo demográfico logarítmico, revelando su temprano estado de regeneración frente a la última quema ocurrida en el 2003, y la similitud de las curvas de supervivencia entre todas las elevaciones, probó una alta estabilidad demográfica. Some autoecological features of Espeletia pycnophylla ssp. angelensis Cuatrec. such as its demographic structure, population density, spatial pattern of dispersion, production of reproductive structures, adult morphometry and survivorship, were studied in an altitudinal gradient on a dry paramo of Nari o (Colombia). Hypothesis proposed by other authors about a linear effect caused by the elevation on these variables were completely rejected. The elevation induces an ecoclinal effect on population density, and this density correlates negatively with both production of reproductive structures and adult sizes. These results elucidate an unequivocal effect of density-dependen
Inferring possible population divergence in Espeletia pycnophylla (Asteraceae) through morphometric and paleogeographic approaches
Felipe Benavides,Jorge Burbano,Diana Burbano,Rodrigo Prieto
Revista de Biología Tropical , 2010,
Abstract: The phenotypic structure within and between plant populations is generally influenced by their distribution patterns in space and time; therefore, the study of their divergence is a central issue for the understanding of their microevolutive processes. We boarded the hypothesis that three populations of Espeletia pycnophylla show phenotypic divergence as one of the possible implications of their geographic isolation in the Southern Colombian Andes. We used the Elliptic Fourier Descriptors (leaf shape) and traditional leaf morphometry (leaf size) of 347 leaves to measure inter and intra-population variation and a comparison between a paleogeographic reconstruction with an actual estimate of the distribution areas of E. pycnophylla in order to identify their main changes during the last 14 000 years. The three populations showed significant differences in leaf morphometry and a positive correlation between the matrices of morphometric and geographic dissimilarities, indicating that the inter-population divergence increases between further populations, so that the morphometric structure reflects their spatial distribution. The geographical and paleogeographical estimates evidenced a conspicuous process of reduction and fragmentation of the distribution area of E. pycnophylla since the Late-Glacial until the Holocene. We suggest that these results support possible scenarios of vicariance events, which allow us to approach the divergence of these populations in terms of their historic biogeographic relations. However, genetic analyses are still needed to support these results. Rev. Biol. Trop. 58 (4): 1261-1270. Epub 2010 December 01. La estructuración fenotípica entre y dentro de poblaciones vegetales responde generalmente a sus patrones de distribución espacio-temporales, por lo tanto, el estudio de su divergencia es un tema central dentro de sus procesos microevolutivos. En esta investigación abordamos la hipótesis que tres poblaciones de Espeletia pycnophylla presentan divergencia fenotípica como uno de los posibles efectos de su aislamiento geográfico en los Paramos del suroeste de Colombia. Utilizamos los Descriptores Elípticos de Fourier (forma foliar) de 117 hojas y algunas medidas morfológicas tradicionales (tama o foliar) como indicadores de la variación intra e inter-poblacional, además de una comparación entre una reconstrucción paleogeográfica con una estimación del área de distribución actual de la especie para identificar sus principales cambios durante los últimos 14 000 a os. Todas las poblaciones mostraron diferencias significativas y ademá
Inferring possible population divergence in Espeletia pycnophylla (Asteraceae) through morphometric and paleogeographic approaches
Benavides,Felipe; Burbano,Jorge; Burbano,Diana; Prieto,Rodrigo; Torres,Carlos;
Revista de Biología Tropical , 2010,
Abstract: the phenotypic structure within and between plant populations is generally influenced by their distribution patterns in space and time; therefore, the study of their divergence is a central issue for the understanding of their microevolutive processes. we boarded the hypothesis that three populations of espeletia pycnophylla show phenotypic divergence as one of the possible implications of their geographic isolation in the southern colombian andes. we used the elliptic fourier descriptors (leaf shape) and traditional leaf morphometry (leaf size) of 347 leaves to measure inter and intra-population variation and a comparison between a paleogeographic reconstruction with an actual estimate of the distribution areas of e. pycnophylla in order to identify their main changes during the last 14 000 years. the three populations showed significant differences in leaf morphometry and a positive correlation between the matrices of morphometric and geographic dissimilarities, indicating that the inter-population divergence increases between further populations, so that the morphometric structure reflects their spatial distribution. the geographical and paleogeographical estimates evidenced a conspicuous process of reduction and fragmentation of the distribution area of e. pycnophylla since the late-glacial until the holocene. we suggest that these results support possible scenarios of vicariance events, which allow us to approach the divergence of these populations in terms of their historic biogeographic relations. however, genetic analyses are still needed to support these results. rev. biol. trop. 58 (4): 1261-1270. epub 2010 december 01.
Evaluación de la reproducción sexual de Espeletia grandiflora VAR. Multiflora en la Reserva Forestal Municipal de Cogua (Cundinamarca, Colombia)
Sánchez Zambrano Jairo,Bonilla María Argenis
Acta Biológica Colombiana , 2006,
Abstract: En este trabajo se estudiaron algunos aspectos de la estrategia reproductiva de Espeletia grandiflora var. Multiflora. Para esto se escogieron tres parches con plantas de la mencionada especie, ubicados en la reserva forestal municipal de Cogua (Cundinamarca, Colombia), lugar con antecedentes de explotación agrícola. La fase experimental de campo se realizó de julio a diciembre de 2003. Se pusieron a prueba cuatro hipótesis: 1) los antecedentes de disturbio del ecosistema nativo, causan baja producción de semillas; 2) el disturbio ocasionado induce un aumento en la producción de semillas viables por autogamia; 3) existe una relación directamente proporcional entre la altura de las plantas y su inversión en estructuras reproductivas; 4) la fenología es diferente en relación con la que se presenta en lugares con mayor grado de conservación. Los resultados se compararon con los encontrados por Fagua (2002) en otro estudio realizado en el Páramo de Chingaza, lugar con mayor grado de conservación. Para el presente sitio de estudio se reportó un porcentaje de viabilidad menor, un índice de autoincompatibilidad mayor, una producción de semillas por planta menor y etapas fenológicas más cortas que en el Páramo de Chingaza. Las diferencias en el estado de conservación, la composición genética de E. grandiflora, y el clima entre los dos sitios, pueden explicar los diferentes resultados.
Efectos citotoxicos in vitro de extractos y fracciones de Espeletia killipii Cuatr. frente a lineas celulares tumorales humanos
Téllez Alfonso, Alba N.;Castro, Clemencia de;Riveros de Murcia, Tulia;Torrenegra, Rubén;
Revista Brasileira de Farmacognosia , 2006, DOI: 10.1590/S0102-695X2006000100004
Abstract: it was found that the ethanol extracts and fractions of espeletia killipii (an endemic species of the páramo vegetation of the cundiboyacense plateau) exhibited cytotoxic activity against several human tumor cell lines. thus, the extracts and fractions exhibited significant cytotoxic activity against both the human tumor cell lines of breast cancer mcf-7, csc-1170, csc-1595, csc-3322, csc-3325 and the hep-2 cell lines of laryns. the ch2cl2 fraction and its sub-fractions were active against the breast lines at concentration of 50 μg/ml, with a viability percentage between 13 and 20%. the active principle, not identified yet, was obtained by successive bio-directed assays. it showed activity against the colombian cell lines csc-1170, csc-1595, csc-3322 and csc-3325 at a half cytotoxic concentration (cc50) less than 1 μg/ml, against mda mb-435 and nci-h23 at cc50= 1 μg/ml against mcf-7 at cc50= 2 μg/ml, and against pc-3 and u-251 at cc50 greater than 16 μg/ml.
Principio activo citotoxico de Espeletia killipii Cuatr. sobre células tumorales y su toxicidad frente a células normales humanas
Jaimes, Gustavo;Castro, Clemencia de;Ancizar Aristizaba, Fabio;Riveros de Murcia, Tulia;Torrenegra, Rubén;Téllez Alfonso, Alba N.;
Revista Brasileira de Farmacognosia , 2006, DOI: 10.1590/S0102-695X2006000200002
Abstract: the compound responsible for the citotoxic effect was identified as longipilin acetate, a sesquiterpenelactone isolated from espeletia killipi cuatr. citotoxicity was assessed by using normal cells obtained from peripheral blood, thyroid, testicle and mouth epithelium. bone marrow cells from patients with chronic myeloid leukemia, hodking lymphoma (from cancer national institute, bogotá colombia) and the cell line k562 were also assayed. citotoxicity was determined by the mtt cell viability test (3-(4,5-dimethyldiazol-2-yl)-2,5 diphenyl tetrazolium bromid]. the assays revealed that the substance is risk-free on normal cells but at 3 mg/ml has significant activity on tumor cells and k562 cell line. consequently, taken into account this significant action, new research approaches can be foreseen.
Inducción de apoptosis por el principio activo citotóxico de Espeletia killipii Cuatr. sobre líneas celulares humanas
Castro, Clemencia de;Riveros de Murcia, Tulia;Jaimes, Gustavo;Téllez Alfonso, Alba N.;
Revista Brasileira de Farmacognosia , 2007, DOI: 10.1590/S0102-695X2007000400004
Abstract: longipilin acetate is the compound exhibiting cytotoxicity, isolated from endemic plant specie from colombia, south america, espeletia killipii cuatr. longipilin acetate is a sesquiterpenelactone having the ability to induce apoptosis in several breast cancer cell-lines like mcf-7 y csc-1595 (obtained from national cancer institute, bogotá colombia), morphological examination, nuclear dna fragmentation, tunel and flow cytometry were used to evaluate apoptosis. therefore longipilin acetate is a compound showing potential as an antitumor agent.
Resistance to freezing in three Eucalyptus globulus Labill subspecies
Moraga S.,Priscila; Escobar,René; Valenzuela A.,Sofía;
Electronic Journal of Biotechnology , 2006,
Abstract: the resistance to low temperatures was assessed in seedlings of three subspecies of e. globulus (ssp globulus, ssp bicostata and ssp maidenii) of two different provenances. lethal temperature 50 (lt50) was obtained by measuring the electrolytic conductivity, nucleation and freezing temperatures were obtained by thermal analysis and the total soluble carbohydrates concentration was determined through the phenol-sulphuric method. results showed that the most resistant provenance corresponded to bolaro mountain of ssp maidenii with a lt50 lower than -9oc. the provenance moogora of ssp globulus, had a lt50 of -8.47oc, which situates it, as the second most resistant to low temperatures. according to the nucleation and freezing temperatures, the results indicate that all the provenances analyzed evaded the formation of ice, except for bolaro mountain of ssp maidenii which was tolerant to freezing. finally, an inverse correlation (r = -0.89) between the content of total soluble carbohydrates and the lt50 was found, indicating the cryoprotection effect of these in the resistance to low temperatures.
MORPHOLOGICAL CHARACTERIZATION OF MALAYSIAN WILD BANANA MUSA ACUMINATA
MUHAMMAD ASIF JAVED,MAK CHAI,ROFINA YASMIN OTHMAN
BIOTROPIA : the Southeast Asian Journal of Tropical Biology , 2002,
Abstract: Fourteen populations of Musa acuminata ranging from populations in the lowlands of northern (ssp. siamea) to central Malaysian region (ssp. malaccensis) and highland banana (ssp. truncata) were characterized based on chromosome number and 46 morphological characters. A large amount of variation was observed within the populations. However, only highland bananas appeared morphologically distinct. Lowland populations both from northern and central Malaysia were found to be overlapping and no distinguishing pattern was observed. The morphological characters found variable within these populations were related to developmental changes and mutations. The results ob tained in this study were not revolutionary. However, the survey of a large number of characters treated with multivariate techniques further sharpened the existing groupings of the Musa acuminata subspecies.
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