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Search Results: 1 - 10 of 209165 matches for " Nelda L Olivera "
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Bioprospection of marine microorganisms: biotechnological applications and methods
Dionisi,Hebe M; Lozada,Mariana; Olivera,Nelda L.;
Revista argentina de microbiolog?-a , 2012,
Abstract: environmental microorganisms constitute an almost inexhaustible reserve of genetic and functional diversity, accumulated during millions of years of adaptive evolution to various selective pressures. in particular, the extent of microbial biodiversity in marine habitats seems to grow larger as new techniques emerge to measure it. this has resulted in novel and more complex approaches for the screening of molecules and activities of biotechnological interest in these environments. in this review, we explore the different partially overlapping biotechnological fields that make use of microorganisms and we describe the different marine habitats that are particularly attractive for bioprospection. in addition, we review the methodological approaches currently used for microbial bioprospection, from the traditional cultivation techniques to state of the art metagenomic approaches, with emphasis in the marine environment.
Bioprospection of marine microorganisms: potential and challenges for Argentina Bioprospección de microorganismos marinos: potencialidades y desafíos para Argentina
Hebe M Dionisi,Mariana Lozada,Nelda L Olivera
Revista argentina de microbiolog?-a , 2012,
Abstract: The marine environments of Argentina have a remarkable extension, as well as high biological productivity and biodiversity of both macro- and microorganisms. Despite having a great potential for biotechnological applications, the microorganisms inhabiting these ecosystems remain mostly unexplored and unexploited. In this review, we study the research topics and the interactions among Argentinean laboratories, by analyzing current articles published on biotechnology-related marine microbiology by researchers of this country. In addition, we identify the challenges and opportunities for Argentina to take advantage of the genetic potential of its marine microorganisms. Finally, we suggest possible actions that could improve the development of this research field, as well as the utilization of this knowledge to solve societal needs. El medio ambiente marino de la Argentina tiene una notable extensión, como así también una alta productividad biológica y biodiversidad de macro y microorganismos. A pesar de presentar un gran potencial para aplicaciones biotecnológicas, los microorganismos que habitan estos ecosistemas permanecen mayormente inexplorados y sus propiedades aún no explotadas. En este trabajo de revisión, estudiamos los temas de investigación y las interacciones entre grupos de investigación argentinos, por medio del análisis de los artículos publicados hasta el momento en temáticas relacionadas con la aplicación biotecnológica de microorganismos marinos. Además, identificamos los desafíos y las oportunidades para que la Argentina tome ventaja del potencial genético de sus microorganismos marinos. Por último, sugerimos posibles acciones que podrían mejorar el desarrollo de este campo de estudio, como así también la utilización de este conocimiento para resolver las necesidades de la sociedad.
Isolation, identification and antimicrobial activity of lactic acid bacteria from the Bahía Blanca Estuary
Sica,María G; Olivera,Nelda L; Brugnoni,Lorena I; Marucci,Patricia L; López-Cazorla,Andrea C; Cubitto,María A;
Revista de biología marina y oceanografía , 2010, DOI: 10.4067/S0718-19572010000300003
Abstract: this study analyzed the biodiversity of lactic acid bacteria present in the bahía blanca estuary and their antimicrobial activity against pathogens associated with the cultivation of salmonid. a total of 21 lactic acid bacteria (lab) strains were isolated from superficial sediments and fish of the estuary. the fish species were selected from those that spend most of their life cycle in the estuary. according to 16s rdna analysis, isolates were affiliated with the genera lactobacillus, pediococcus, leuconostoc, enterococcus and weissella. the predominant lab isolates from the fish species belonged to weissella viridescens, which was isolated from three of the four species analyzed. none of the lab species isolated from fish was found in sediments. the agar diffusion method was used for detection of antagonistic activity against listeria monocytogenes, yersinia ruckeri, aeromonas salmonicida subsp. salmonicida and two strains of lactococcus garvieae. all the isolates exhibited some degree of antagonistic activity against l. monocytogenes, y. ruckeri and both strains of lc. garvieae. twelve strains were found to be inhibitory for a. salmonicida. this study is the first report on the diversity of lactic acid bacteria in a coastal marine environment and fish from argentina. the sediments and fish analyzed showed microbial strains with the ability to suppress pathogen growth under in vitro conditions, suggesting their potential as biological control agents for aquaculture and fish processing.
Factores de virulencia de cepas de Enterococcus aisladas de quesos ovinos
Marguet,Emilio Rogelio; Vallejo,Marisol; Olivera,Nelda Lila;
Acta bioqu?-mica cl?-nica latinoamericana , 2008,
Abstract: enterococci are used as starter and probiotic cultures in the food industry, and they occur as natural food contaminants. however, the genus enterococcus is of increased significance as a cause of nosocomial infections, exacerbated by the development of antibiotic resistance. in order to study the potential virulence of eight enterococcus faecium strains and two enterococcus faecalis strains isolated from ovine cheese, vancomicine resistance, hemolytic activity and gelatinase activity were investigated. in addition, polymerase chain reaction (pcr) tests were carried out in order to determine the presence of cytolicyn gene cylb, gelatinase gene gele, sex pheromone gene cpd and aggregation protein gene agg. none of the strains showed vancomicine resistance or hemolitic activity. gene cylb could not be identified by pcr amplification in any of the strains studied. the presence of gene gele was found in seven e. faecium strains and in one e. faecalis strain, however in no case was gelatinase activity detected. gene cpd was detected in e. faecium etw7 and e. faecalis etw23, while gene agg was found in e. faecium etw7 and e. faecalis etw27. these results suggest that the introduction of food products or probiotics based on the use of enterococal strains requires careful safety evaluations.
Factores de virulencia de cepas de Enterococcus aisladas de quesos ovinos Virulence factors of Enterococcus strains isolated from ovine cheese
Emilio Rogelio Marguet,Marisol Vallejo,Nelda Lila Olivera
Acta bioqu?-mica cl?-nica latinoamericana , 2008,
Abstract: Los enterococos son utilizados en la industria alimenticia como cultivos iniciadores o probióticos y constituyen contaminantes naturales de los alimentos. Sin embargo, el género Enterococcus ha cobrado relevancia como causal de infecciones nosocomiales, tendencia exacerbada por el desarrollo de resistencia antibiótica. Con el objetivo de estudiar la virulencia potencial de ocho cepas de Enterococcus faecium y de dos cepas de Enterococcus faecalis aislados de quesos ovinos se investigó la resistencia a vancomicina, la actividad hemolítica y la actividad de gelatinasa. En forma adicional se llevó a cabo la reacción en cadena de la polimerasa (PCR) para determinar la presencia de los genes cylB de la citolisina, gelE de la gelatinasa, cpd de la feromona sexual y agg de la proteína de agregación. Ninguna de las cepas mostró resistencia a la vancomicina o actividad hemolítica. El gen cylB no pudo ser identificado mediante amplificación por PCR en ninguna de las cepas estudiadas. La presencia del gen gelE fue detectada en siete cepas de E. faecium y en una cepa de E. faecalis, sin embargo en ningún caso se detectó actividad de la enzima. El gen cpd fue detectado en E. faecium ETw7 y E. faecalis ETw23, mientras que el gen agg fue hallado en las cepas de E. faecium ETw7 y E. faecalis ETw27. Estos resultados sugieren que la introducción de productos alimenticios o probióticos basados en el uso de cepas de enterococos requiere una cuidadosa evaluación sobre su seguridad. Enterococci are used as starter and probiotic cultures in the food industry, and they occur as natural food contaminants. However, the genus Enterococcus is of increased significance as a cause of nosocomial infections, exacerbated by the development of antibiotic resistance. In order to study the potential virulence of eight Enterococcus faecium strains and two Enterococcus faecalis strains isolated from ovine cheese, vancomicine resistance, hemolytic activity and gelatinase activity were investigated. In addition, polymerase chain reaction (PCR) tests were carried out in order to determine the presence of cytolicyn gene cylB, gelatinase gene gelE, sex pheromone gene cpd and aggregation protein gene agg. None of the strains showed vancomicine resistance or hemolitic activity. Gene cylB could not be identified by PCR amplification in any of the strains studied. The presence of gene gelE was found in seven E. faecium strains and in one E. faecalis strain, however in no case was gelatinase activity detected. Gene cpd was detected in E. faecium ETw7 and E. faecalis ETw23, while gene agg was found in
Variaciones temporales en cantidad de semillas en el suelo y en lluvia de semillas en un gradiente bosque-sabana en la gran sabana, Venezuela
Flores,Saúl; Dezzeo,Nelda;
Interciencia , 2005,
Abstract: seasonal variation in the total soil seed quantity and in seed rain were studied along a forest-savanna gradient consisting of primary forest (1: mature forest), forest slightly affected by fire (2: secondary forest), forest strongly affected by fire (3: matorral), and open savanna (4), at the gran sabana, venezuela. seed soil quantity was determined by collecting 10 samples of the organic surface layer or of the first 10cm of mineral soil with a 20×20cm steel frame in both dry and wet seasons. seed rain through the year was examined by collecting every two weeks the seeds that fell into 10 trays 90×40cm each. during the dry season the soil seed number was lower (p<0.05) in the savanna than in 1, 2 and 3. during the wet season it was higher (p<0.05) in the secondary forest than in the 1, 3 and 4. seed rain in the primary forest was low and variable, with no well defined production peaks. in the secondary forest the seed rain was slightly higher than in the mature forest, showed a clear peak in october and no production between november and january. in the matorral the seed rain was high and showed well defined production peaks in march and may; this can be associated with the presence of pioneer species in this community. in the savanna the seed rain was slightly higher than in the 1 and 2, with a production peak in february. spatial heterogeneity in the soil seed quantity and in seed rain was observed in all vegetation types, which may be associated with the distribution of species within each community, and with differences in the reproductive periods of these species. disturbances seem to accelerate the seed production and the germination processes in the soils of the gran sabana.
Seedlings dynamics in undisturbed and adjacent fire disturbed forest in the Gran Sabana, Southern Venezuela.
Dezzeo,Nelda; Flores,Saúl; Chacón,Noemí;
Interciencia , 2008,
Abstract: in the gran sabana, southern venezuela, the conversion of large forest areas to a mosaic of forest, bush vegetation and savanna ("savannization") is a critical environmental issue associated with forest fires. little is known about the behaviour of the seedling community in undisturbed and fire impacted forests in this region. recruitment, survival and growth of seedlings was followed over a 6 year period in permanent quadrats established in undisturbed and adjacent fire-disturbed (secondary) forest. at the beginning of the study, secondary forest showed lower (p<0.05) values of seedling abundance and tree seedling richness than undisturbed forest. abundance and species richness of tree seedling in both forests changed very little over the study period, which is associated to the partial balance between initial tree seedlings mortality rate (44-66%) and newly recruited tree seedlings survival rate (47-54%). at the end of the study ~80% of the recruited seedlings in undisturbed forest corresponded to tree species, whereas in secondary forest the proportions of tree (47%) and non-tree (53%) seedlings were rather similar. growth in height during the 6 year period was considerably higher in secondary forest than in undisturbed forest (p<0.05). it is concluded that in undisturbed forest the succession process is relatively at a standstill, whereas in secondary forest this process advances very slowly.
Metastatic melanoma and pregnancy
Nikolin Borislava L.,?veljo Olivera
Archive of Oncology , 2005, DOI: 10.2298/aoo0501031n
Abstract: Pregnancy after complete treatment of metastatic melanoma is an extremely rare event. We presented a case of a skin melanoma patient with lung and liver metastases who was treated by combined immunochemotherapy for the period of two years. A year and a half after the successful treatment, which resulted a complete remission of metastatic lesions she got pregnant and delivered a healthy baby girl.
Estructura y composición florística de bosques secos y sabanas en los Llanos Orientales del Orinoco, Venezuela
Dezzeo,Nelda; Flores,Saúl; Zambrano-Martínez,Sergio; Rodgers,Louise; Ochoa,Elisa;
Interciencia , 2008,
Abstract: in the llanos orientales of venezuela, agricultural activities, forestry and petroleum exploration and exploitation cause negative environmental impacts on the vegetation. in order to minimize such impacts and to justify the importance of preserving representative areas of fragile communities, detailed ecological and floristic information is required regarding the local vegetal communities. in an area located within the influence zone of the bituminous strip of the orinoco, the vegetation was mapped and characterized floristically and structurally. the area is covered by dense (54.8%) and sparse (18.4%) shrub savannas, palm swamp forests or "morichales" (1%), and riparian and deciduous and semideciduous forests (25.8%). the distribution of forests, morichales and savannas appears to be related with the topography and the gradient of soil humidity availability, since forests and morichales are present in the form of continuous and narrow strips along rivers, while the savannas predominate in the higher parts of the relief. forests and morichales showed high floristic and structural heterogeneity, which can be associated with soil characteristics and water availability. savannas showed structural and floristic differences between them, probably due to differences in soil depth and chemical characteristics. few species of each vegetation type presented a high importance value (ivi), which seems to be something common in other neotropical zones. forests and morichales should be given high priority for conservation because of the protection they provide to the soils and waters, the little surface that they occupy, and the high biodiversity these forests contain.
Puestos de altura de la Puna argentina: zooarqueología de Real Grande 1 y 6 y Alero Tomayoc
Daniel E. Olivera 1,Jennifer L. Grant
Revista del Museo de Antropologia , 2009,
Abstract: The societies from the Late Period in the Argentinean Puna introduced considerable technical improvements and an increase in agricultural production, in relationship with a process of change towards a greater sociopolitical complexity. For this period there are large settlements associated with crop elds in the low basins, but the settlement systems includes sites located at higher elevations, named “Puestos de altura” like Real Grande 1 y 6 (Catamarca) and Alero Tomayoc (Jujuy).The aim of this work is to study faunal remains from the above mentioned sites through a taxonomical/economical and osteometrical analysis in order to relate them with the total context of the settlements. The results seem to show that these sites played an important role for the herding of llamas and the hunting of wild camelids (vicu a and guanaco) in the regional economy. Even more, the high elevation sites would have performed a vital function making possible the circulation of information, goods and energy giving strength to the process of sociopolitical complexity of the late prehispanic societies of the Argentinean Puna.
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