oalib
Search Results: 1 - 10 of 100 matches for " "
All listed articles are free for downloading (OA Articles)
Page 1 /100
Display every page Item
FRAGILARIA CAPUCINA DESM. VAR MESOGONGYLA FRENGUELLI, UNA DIATOMEA PRESENTE EN LA ZONA NORTE DE LA CORDILLERA DE LOS ANDES (CHILE), CON COMENTARIOS SOBRE LA VARIABILIDAD DEL NUMERO DE PROCESOS LABIADOS EN ALGUNOS GéNEROS ARAFIDALES
Rivera R,Patricio; Cruces L,Fabiola;
Gayana. Botánica , 2008, DOI: 10.4067/S0717-66432008000200002
Abstract: the diatom fragilaria capucina var. mesogongyla, originally described by frenguelli from calama, chile (22°28's, 68°56' w), was found in a sample collected in the lauca river, at high altitude in northern chile's (18°30's,69°16' w). for the first time, the taxon is studied by scanning electron microscopy (sem). unusual for the genus fragilaria, this variety exhibits one labiate process on each valve pole (two per valve). an amended diagnosis is given, and photographs illustrate the principal morphological features of this taxon.
FRAGILARIA CAPUCINA DESM. VAR MESOGONGYLA FRENGUELLI, UNA DIATOMEA PRESENTE EN LA ZONA NORTE DE LA CORDILLERA DE LOS ANDES (CHILE), CON COMENTARIOS SOBRE LA VARIABILIDAD DEL NUMERO DE PROCESOS LABIADOS EN ALGUNOS GéNEROS ARAFIDALES FRAGILARIA CAPUCINA DESM. VAR MESOGONGYLA FRENGUELLI, A DIATOM DISTRIBUTED IN NORTHERN ZONE OF LOS ANDES MOUNTAINS (CHILE), WITH COMMENTS ON THE VARIABILITY OF THE NUMBER OF LABIATE PROCESSES IN SOME ARAPHID GENERA  [cached]
Patricio Rivera R,Fabiola Cruces L
Gayana. Botanica , 2008,
Abstract: La diatomeaFragilaria capucina var. mesogongyla, descrita originalmente por Frenguelli desde Calama, Chile (22°28' S, 68°56'W), fue encontrada en una muestra recolectada en el río Lauca, a gran altitud en el norte de Chile (18°30'S, 69°16'W). Por primera vez este taxón se estudia mediante técnicas de microscopía electrónica (SEM). Siendo muy raro para el género Fragilaria, esta variedad presenta un proceso labiado en cada polo valvar (dos por valva). Se entrega una diagnosis corregida, y fotografías ilustran las principales características morfológicas del taxón. The diatom Fragilaria capucina var. mesogongyla, originally described by Frenguelli from Calama, Chile (22°28'S, 68°56' W), was found in a sample collected in the Lauca River, at high altitude in northern Chile's (18°30'S,69°16' W). For the first time, the taxon is studied by scanning electron microscopy (SEM). Unusual for the genus Fragilaria, this variety exhibits one labiate process on each valve pole (two per valve). An amended diagnosis is given, and photographs illustrate the principal morphological features of this taxon.
Laboratory Handling of Didymosphenia geminata (Lyngbye) Schmidt and the Effect of Control Efforts on Viability  [PDF]
Jorge Parodi, Pamela Olivares, Viviana Chavez, Matías Peredo-Parada
Advances in Bioscience and Biotechnology (ABB) , 2015, DOI: 10.4236/abb.2015.68053
Abstract: Didymosphenia geminata (Lyngbye) Schmidt is a type of diatom that exists in Chile as an introduced species, invading the country and its rivers. We collected samples of D. geminata from two sampling points in Chile, assessing their viability and response to control agents. Fresh D. geminata showed more than 90% of viable granular forms (containing granules in their cytoplasm); however, the dry form presents near 50% viability. By creating dry D. geminata through exposure to 38°C temperatures for 7 days, viability values of the granular form decreased to 20%. D. geminata kept at room temperature for more than 4 weeks reported values of granular forms at 50%, while samples that were refrigerated at 4°C maintained values of granular forms at 90% for 4 weeks. Previous studies suggest that high salt concentration affects the viability of D. geminata. When taking wet D. geminata samples and exposing them to a solution of 10% NaCl for 10 minutes, we observed no differences compared to the control samples, finding granular forms at 90%. When the D. geminata was exposed to a 5% soap solution, reductions of over 90% of the granular forms were observed. Our results suggest that the viability of D. geminata is associated with the granular content within their cytoplasm, and that it is possible to alter laboratory conditions for their study. These early studies are important in order to better manipulate the model in the laboratory, allowing us to obtain new evidence regarding the microalgae’s biology through in vitro studies.
Fragilaria and Staurosira (Bacillariophyceae) from sediment surfaces of 40 lakes in the Austrian Alps in relation to environmental variables, and their potential for palaeoclimatology  [cached]
Roland SCHMIDT,Christian KAMENIK,Horst LANGE-BERTALOT,Rolf KLEE
Journal of Limnology , 2004, DOI: 10.4081/jlimnol.2004.171
Abstract: The percentage distributions of Fragilaria and Staurosira taxa in surface sediment samples from 40 oligo- to ultra-oligotrophic, pH neutral to alkaline, mountain lakes of the central Austrian Alps (Niedere Tauern) were studied in relation to environmental variables using multivariate statistics. Selected taxa that were of uncertain taxonomy or that might be difficult to distinguish were illustrated in LM or SEM. The same statistics as they were applied to the total diatom data set were run on a Fragilariaceae subset with Fragilaria and Staurosira. These analyses emphasized on the high sensitivity of these genera to climate-driven environmental variables in mountain lakes. Canonical Correspondence Analyses (CCA) indicated that the pH, mean July water temperature (TJuly), length of ice cover, and dissolved organic carbon (DOC) made significant contributions to explain the variation in the diatom assemblages. In addition, water depth affected the distribution of benthic and planktonic taxa. Differences or similarities in ecological preferences of taxa provided suggestions for taxonomy. Correlations between the mean valve length and summer water temperatures increase the overall high potential of Fragilaria and Staurosira for palaeoclimatological reconstructions in mountain lakes.
PRIMER REGISTRO DE LA DIATOMEA EPIBIONTE PSEUDOHIMANTIDIUM PACIFICUM Y DE OTRAS ASOCIACIONES SIMBIóTICAS EN EL GOLFO DE CALIFORNIA
Ismael Gárate-Lizárraga,María del Socorro Mu?etón-Gómez
Acta botánica mexicana , 2009,
Abstract: En México existe poca información sobre las asociaciones simbióticas entre diatomeas y ciliados, así como con otras especies de microalgas y particularmente con crustáceos planctónicos marinos. Es por ello que en este trabajo se presenta el primer registro de la diatomea Pseudohimantidium Pacificum en epibiosis con el copépodo Farranula gibbula y otras asociaciones entre microalgas y ciliados marinos en la Bahía de La Paz. Las muestras biológicas se recolectaron mediante una red de plancton con una luz de malla de 20 um, en diversas áreas de la Bahía de La Paz. Se encontraron 62 copépodos machos de F. gibbula, de los cuales 27 presentaban sobre su caparazón un ramillete compuesto por la diatomea epibionte P. Pacificum. Los valores promedio de abundancia de P. Pacificum por estación de muestreo variaron entre 16 y 82 ejemplares/ copépodo. Otras diatomeas penales fueron observadas como epibiontes de copépodos del género Acartia. Asimismo se encontraron asociaciones simbióticas adicionales entre ciliados, microalgas y cianobacterias, destacando las siguientes: Chaetoceros coarctatum-Vorticella oceanica, Leptocylindrus mediterraneus-Solenicola setiguera. Se registra por primera vez la agrupación entre la diatomea Fragilariopsis doliolus y el silicoflagelado Dictyocha pentagona con un ciliado de tipo Vorticella.
Observations and comments on the diatom Stephanodiscus minutulus (Kützing) Cleve & M ller (Bacillariophyceae) found for the first time in Chile from bottom sediments collected in Lake Laja Observaciones y comentarios acerca de la diatomea Stephanodiscus minutulus (Kützing) Cleve & M ller (Bacillariophyceae) encontrada por primera vez en Chile en sedimentos recolectados en el Lago Laja  [cached]
Fabiola Cruces,Patricio Rivera,Roberto Urrutia
Gayana. Botanica , 2010,
Abstract: This study reports the presence of the diatom Stephanodiscus minutulus (Kützing) Cleve & M ller for the frst time in Chilean continental waters; it is a taxon reported in many aquatic systems in Europe and North America and there are only scanty records from South America (Argentina). The species was found in a sedimentary profle collected from Lake Laja (Andes Mountains), Central Chile. The principal morphological features of S. minutulus are described, and comments about its relationship with other closely related taxa are given. En este estudio se se ala la presencia de la diatomea Stephanodiscus minutulus (Kützing) Cleve & M ller por primera vez para aguas continentales de Chile; es un taxón muy común en diversos sistemas acuáticos de Europa y Norteamérica, y para Sudamérica sólo existen escasos registros en Argentina. La especie fue encontrada en un perfl sedimentario colectado en el Lago Laja (Cordillera de los Andes), Chile central. Se describen las principales características morfológicas de S. minutulus y se entregan comentarios sobre su relación con otras especies cercanas.
Fotoprotección antioxidante no-enzimática contra el potencial da o inducido por UVBR en una diatomea antártica (Thalassiosira sp.) Non-enzymatic antioxidant photoprotection against potential UVBR-induced damage in an Antarctic diatom (Thalassiosira sp.)
Marcelo Hernando,Gabriela Malanga,Susana Puntarulo,Gustavo Ferreyra
Latin american journal of aquatic research , 2011,
Abstract: In January 1999, unialgal cultures of the diatom Thalassiosira sp., solate from natural phyto-plankton assemblages from Potter Cove, Antarctica, were exposed to solar ultraviolet radiation (UVR, 280400 nm) in order to study the long-term acclimation of this species. Ultraviolet radiation B (UVBR, 280-315 nm) inhibited the growth rate during the first and second days of exposure. No UVBR inhibition was observed on the third day. The initial content of α-tocopherol (13 pmol (10(4) cell)-1) showed a marked decrease during the exponential growth phase (4 pmol (10(4) cell-1) by day 3). The initial content of β-carotene (3 pmol (10(4) cell)-1) did not show significant differences over time in cells exposed to UVBR. Two mycosporine-like amino acids (MAAs) were identified: porphyra-334 and shinorine. Cellular concentrations of MAAs increased significantly on days 2 and 3, and exposure of the algae to UVBR significantly enhanced this value. The relative importance of MAAs concentration was significant (P < 0.05) in relation to the α-tocopherol content. A positive correlation was shown between cellular MAAs concentration and growth rate. Our results suggest that photoprotection against UV-induced damage is characterized by short-term consumption of α-tocopherol and longer-term synthesis of MAAs. The UVBR damage/repair ratio during long-term exposure involves the combined action of several endogenous factors within the cell, with MAAs synthesis being the most effective factor related to photoprotection. Durante enero 1999, cultivos unialgales de una diatomea Thalassiosira sp., aislada de poblaciones fitoplanctónicas naturales de Caleta Carlos Potter, Antártida, fueron expuestos a radiación solar ultravioleta (UVR, 280-400 nm) con el objetivo de estudiar su aclimatación a largo plazo. La radiación ultravioleta B (UVBR, 280-315 nm) inhibió la tasa de crecimiento durante el primer y segundo día de exposición. No se observó inhibición por UVBR durante el tercer día. El contenido inicial de α-tocopherol (13 pmol (10(4) cel)-1) mostró una marcada disminución durante la fase de crecimiento exponencial (4 pmol (10(4) cel)-1 al día 3). El contenido inicial de β-caroteno (3 pmol (10(4) cel)-1) no mostró diferencias significativas entre días en células expuestas a UVBR. Se identificaron dos aminoácidos parecidos a micosporina (MAAs), porfira-334 y shinorina. Las concentraciones celulares de MAAs mostraron aumentos significativos en los días 2 y 3, que resultaron mayores cuando las algas fueron expuestas a UVBR. La importancia relativa de la concentración de MAAs fue signific
Effect of salinity on growth and chemical composition of the diatom Thalassiosira weissflogii at three culture phases Efecto de la salinidad en el crecimiento y composición química de la diatomea Thalassiosira weissflogii en tres fases de cultivo  [cached]
Norma García,José Antonio López-Elías,Anselmo Miranda,Marcel Martínez-Porchas
Latin american journal of aquatic research , 2012,
Abstract: The estuarine diatom Thalassiosira weissflogii (Fryxell & Hasle, 1977) has been widely used as live feed in aquaculture. The growth rate and biochemical composition of microalgae are highly influenced by environmental factors such as, light, salinity and nutrient availability. Salinity is difficult to control in some shrimp laboratories specialized in larvae production, because these laboratories depend upon the levels measured in estuaries or coastal lagoons, which are the water sources for larvae culture. The present study evaluated the effect of different salinities (25, 30, 35, 40, 45 and 50 psu), on the growth and chemical composition of T. weisflogii at three culture phases, under laboratory conditions. The highest growth rate and maximum cell density were found at 25 psu. Decrease in size and striking changes in morphology of the cells were observed at the higher salinities and drastic changes occurred at 50 psu. Protein and carbohydrate content were higher at low salinities (25 and 30 psu) during the stationary phase. The lipid production was higher at low salinities, but diminished as the phase changes occurred; in contrast, the lipid content was unaffected by the growth phase at higher salinities (≥ 35 psu). The higher growth rate and better biochemical composition were obtained at 25 and 30 psu. La diatomea estuarina Thalassiosira weissflogii (Fryxell & Hasle, 1977) ha sido utilizada como alimento vivo en acuacultura. La composición bioquímica del alimento vivo afecta la nutrición de los organismos durante su cultivo. La tasa de crecimiento y composición bioquímica de las microalgas están altamente influenciadas por factores ambientales como luz, salinidad y disponibilidad de nutrientes. En algunos laboratorios productores de larvas de camarón, es difícil controlar la salinidad, debido a que éstos dependen de los niveles presentes en estuarios o lagunas costeras, los cuales son la fuente de agua para el cultivo larvario. El presente estudio evaluó el efecto de diferentes salinidades (25, 30, 35, 40, 45 y 50 psu), sobre el crecimiento y la composición proximal de T. weissflogii en tres fases de cultivo, bajo condiciones de laboratorio. Las mayores tasas de crecimiento y la máxima densidad celular se obtuvieron a 25 psu. Se observó una reducción en tama o y cambios en la morfología de las células a altas salinidades y los cambios drásticos ocurrieron a 50 psu. El contenido de proteínas y de carbohidratos fue más elevado a salinidades bajas (25 y 30 psu), durante la fase estacionaria de crecimiento. La producción de lípidos fue elevada a bajas s
Granulomatosis linfomatoide: una entidad poco conocida
Cumplido Burón,J. D.; López-Barajas,I. Blancas; García García,J. A.; Cárdenas Quesada,N.; Iglesias Rozas,P.; Sánchez García,M. J.; Delgado Ure?a,T.; Ríos Pozo,B.; García-Puche,J. L.;
Oncología (Barcelona) , 2007, DOI: 10.4321/S0378-48352007000100004
Abstract: purpose: to describe a clinical case of lymphomatoid granulomatosis and to make a review of the existing bibliography for the better knowing of the disease. material and methods: a 27 year old man with a history of b-cell lymphoma at he age of 17 years that started with respiratory insufficiency after ten years of periodic checkups. conclusion: lymphomatoid granulomatosis is a rare entity, with a poor prognosis and a lack of an established treatment. although different treatments have been applied, further studies are necessary in order to improve its prognosis.
Epidermólisis bulosa: una dermatosis poco conocida
Castillo Romero,Esther; López Benítez,Humberto; Fernández Barrera,Roberto; Cordovés Jerez,Modesto;
Revista de Ciencias M??dicas de Pinar del R?-o , 2009,
Abstract: an infrequent case of acquired epidermolysis bullosa is showed. a 60 years old women was seen at the orl service of the "abel santamaria cuadrado" general hospital in pinar del rio, with the diagnosis of acquired epidermolysis bulosa" since 30 years ago. now she comes because of dispnea, disphagia. under the clinical exam a sinechia of the palladar velum to the pharyngeal posterior and to the laryngeal vestibule, smooth tongue and also fixed to the floor of the mouth were found. the tongue easily bleeds at instrumental touch, and tracheostomy was necessary.
Page 1 /100
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.