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Search Results: 1 - 10 of 113236 matches for " Joana Falc?o;Gitahy "
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Use of endophytic diazotrophic bacteria as a vector to express the cry3A gene from Bacillus thuringiensis
Salles, Joana Falco;Gitahy, Patrícia de Medeiros;Sk?t, Leif;Baldani, José Ivo;
Brazilian Journal of Microbiology , 2000, DOI: 10.1590/S1517-83822000000300001
Abstract: the goal of this study was to evaluate the potential of endophytic diazotrophic bacteria as a vector to express a cry gene from bacillus thuringiensis, envisaging the control of pests that attack sugarcane plants. the endophytic nitrogen-fixing bacteria gluconacetobacter diazotrophicus strain br11281 and herbaspirillum seropedicae strain br11335 were used as models. the cry3a gene was transferred by conjugation using a suicide plasmid and the recombinant strains were selected by their ability to fix nitrogen in semi-solid n-free medium. the presence of the cry gene was detected by southern-blot using an internal fragment of 1.0 kb as a probe. the production of d-endotoxin by the recombinant h. seropedicae strain was detected by dot blot while for g. diazotrophicus the western-blot technique was used. in both cases, a specific antibody raised against the b. thuringiensis toxin was applied. the d-endotoxin production showed by the g. diazotrophicus recombinant strain was dependent on the nitrogen fixing conditions since the cry3a gene was fused to a nif promoter. in the case of h. seropedicae the d-endotoxin expression was not affected by the promoter (rhi) used. these results suggest that endophytic diazotrophic bacteria can be used as vectors to express entomopathogenic genes envisaging control of sugarcane pests.
Use of endophytic diazotrophic bacteria as a vector to express the cry3A gene from Bacillus thuringiensis
Salles Joana Falco,Gitahy Patrícia de Medeiros,Sk?t Leif,Baldani José Ivo
Brazilian Journal of Microbiology , 2000,
Abstract: The goal of this study was to evaluate the potential of endophytic diazotrophic bacteria as a vector to express a cry gene from Bacillus thuringiensis, envisaging the control of pests that attack sugarcane plants. The endophytic nitrogen-fixing bacteria Gluconacetobacter diazotrophicus strain BR11281 and Herbaspirillum seropedicae strain BR11335 were used as models. The cry3A gene was transferred by conjugation using a suicide plasmid and the recombinant strains were selected by their ability to fix nitrogen in semi-solid N-free medium. The presence of the cry gene was detected by Southern-blot using an internal fragment of 1.0 kb as a probe. The production of delta-endotoxin by the recombinant H. seropedicae strain was detected by dot blot while for G. diazotrophicus the Western-blot technique was used. In both cases, a specific antibody raised against the B. thuringiensis toxin was applied. The delta-endotoxin production showed by the G. diazotrophicus recombinant strain was dependent on the nitrogen fixing conditions since the cry3A gene was fused to a nif promoter. In the case of H. seropedicae the delta-endotoxin expression was not affected by the promoter (rhi) used. These results suggest that endophytic diazotrophic bacteria can be used as vectors to express entomopathogenic genes envisaging control of sugarcane pests.
Topographical Analysis of the Subependymal Zone Neurogenic Niche
Ana Mendanha Falco, Joana Almeida Palha, Ana Catarina Ferreira, Fernanda Marques, Nuno Sousa, Jo?o Carlos Sousa
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0038647
Abstract: The emerging model for the adult subependymal zone (SEZ) cell population indicates that neuronal diversity is not generated from a uniform pool of stem cells but rather from diverse and spatially confined stem cell populations. Hence, when analysing SEZ proliferation, the topography along the anterior-posterior and dorsal-ventral axes must be taken into account. However, to date, no studies have assessed SEZ proliferation according to topographical specificities and, additionally, SEZ studies in animal models of neurological/psychiatric disorders often fail to clearly specify the SEZ coordinates. This may render difficult the comparison between studies and yield contradictory results. More so, by focusing in a single spatial dimension of the SEZ, relevant findings might pass unnoticed. In this study we characterized the neural stem cell/progenitor population and its proliferation rates throughout the rat SEZ anterior-posterior and dorsal-ventral axes. We found that SEZ proliferation decreases along the anterior-posterior axis and that proliferative rates vary considerably according to the position in the dorsal-ventral axis. These were associated with relevant gradients in the neuroblasts and in the neural stem cell populations throughout the dorsal-ventral axis. In addition, we observed spatially dependent differences in BrdU/Ki67 ratios that suggest a high variability in the proliferation rate and cell cycle length throughout the SEZ; in accordance, estimation of the cell cycle length of the neuroblasts revealed shorter cell cycles at the dorsolateral SEZ. These findings highlight the need to establish standardized procedures of SEZ analysis. Herein we propose an anatomical division of the SEZ that should be considered in future studies addressing proliferation in this neural stem cell niche.
The path from the choroid plexus to the subventricular zone: go with the flow!
Ana Mendanha Falco,Fernanda Marques,Ashley Novais,Nuno Sousa,Joana A. Palha,Jo?o Carlos Sousa
Frontiers in Cellular Neuroscience , 2012, DOI: 10.3389/fncel.2012.00034
Abstract: In adult mammals, under physiological conditions, neurogenesis, the process of generating new functional neurons from precursor cells, occurs mainly in two brain areas: the subgranular zone in the dentate gyrus of the hippocampus, and the subventricular zone (SVZ) lining the walls of the brain lateral ventricles. Taking into account the location of the SVZ and the cytoarchitecture of this periventricular neural progenitor cell niche, namely the fact that the slow dividing primary progenitor cells (type B cells) of the SVZ extend an apical primary cilium toward the brain ventricular space which is filled with cerebrospinal fluid (CSF), it becomes likely that the composition of the CSF can modulate both self-renewal, proliferation and differentiation of SVZ neural stem cells. The major site of CSF synthesis is the choroid plexus (CP); quite surprisingly, however, it is still largely unknown the contribution of molecules specifically secreted by the adult CP as modulators of the SVZ adult neurogenesis. This is even more relevant in light of recent evidence showing the ability of the CP to adapt its transcriptome and secretome to various physiologic and pathologic stimuli. By giving particular emphasizes to growth factors and axonal guidance molecules we will illustrate how CP-born molecules might play an important role in the SVZ niche cell population dynamics.
Comparative Analysis of Bacterial Communities in a Potato Field as Determined by Pyrosequencing
?zgül ?nceo?lu, Waleed Abu Al-Soud, Joana Falco Salles, Alexander V. Semenov, Jan Dirk van Elsas
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0023321
Abstract: Background Plants selectively attract particular soil microorganisms, in particular consumers of root-excreted compounds. It is unclear to what extent cultivar type and/or growth stage affect this process. Methodology/Principal Findings DNA-based pyrosequencing was used to characterize the structure of bacterial communities in a field cropped with potato. The rhizospheres of six cultivars denoted Aveka, Aventra, Karnico, Modena, Premiere and Desiree, at three growth stages (young, flowering and senescence) were examined, in addition to corresponding bulk soils. Around 350,000 sequences were obtained (5,700 to 38,000 per sample). Across all samples, rank abundance distributions best fitted the power law model, which indicates a community composed of a few highly dominant species next to numerous rare species. Grouping of the sequences showed that members of the Actinobacteria, Alphaproteobacteria, next to as-yet-unclassified bacteria, dominated. Other groups that were consistently found, albeit at lower abundance, were Beta-, Gamma- and Deltaproteobacteria and Acidobacteria. Principal components analyses revealed that rhizosphere samples were significantly different from corresponding bulk soil in each growth stage. Furthermore, cultivar effects were found in the young plant stage, whereas these became insignificant in the flowering and senescence stages. Besides, an effect of time of season was observed for both rhizosphere and bulk soils. The analyzed rhizosphere samples of the potato cultivars were grouped into two groups, in accordance with the allocation of carbon to starch in their tubers, i.e. Aveka, Aventra and Karnico (high) versus Premiere and Desiree (low) and thus replicates per group were established. Conclusions Across all potato cultivars, the young plant stages revealed cultivar-dependent bacterial community structures, which disappeared in the flowering and senescence stages. Furthermore, Pseudomonas, Beta-, Alpha- and Deltaproteobacteria flourished under different ecological conditions than the Acidobacteria.
Spatial and Temporal Variation of Archaeal, Bacterial and Fungal Communities in Agricultural Soils
Michele C. Pereira e Silva, Armando Cavalcante Franco Dias, Jan Dirk van Elsas, Joana Falco Salles
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0051554
Abstract: Background Soil microbial communities are in constant change at many different temporal and spatial scales. However, the importance of these changes to the turnover of the soil microbial communities has been rarely studied simultaneously in space and time. Methodology/Principal Findings In this study, we explored the temporal and spatial responses of soil bacterial, archaeal and fungal β-diversities to abiotic parameters. Taking into account data from a 3-year sampling period, we analyzed the abundances and community structures of Archaea, Bacteria and Fungi along with key soil chemical parameters. We questioned how these abiotic variables influence the turnover of bacterial, archaeal and fungal communities and how they impact the long-term patterns of changes of the aforementioned soil communities. Interestingly, we found that the bacterial and fungal β-diversities are quite stable over time, whereas archaeal diversity showed significantly higher fluctuations. These fluctuations were reflected in temporal turnover caused by soil management through addition of N-fertilizers. Conclusions Our study showed that management practices applied to agricultural soils might not significantly affect the bacterial and fungal communities, but cause slow and long-term changes in the abundance and structure of the archaeal community. Moreover, the results suggest that, to different extents, abiotic and biotic factors determine the community assembly of archaeal, bacterial and fungal communities.
Temporal Dynamics of Abundance and Composition of Nitrogen-Fixing Communities across Agricultural Soils
Michele C. Pereira e Silva, Brigitte Schloter-Hai, Michael Schloter, Jan Dirk van Elsas, Joana Falco Salles
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0074500
Abstract: Background Despite the fact that the fixation of nitrogen is one of the most significant nutrient processes in the terrestrial ecosystem, a thorough study of the spatial and temporal patterns in the abundance and distribution of N-fixing communities has been missing so far. Methodology/Principal Findings In order to understand the dynamics of diazotrophic communities and their resilience to external changes, we quantified the abundance and characterized the bacterial community structures based on the nifH gene, using real-time PCR, PCR-DGGE and 454-pyrosequencing, across four representative Dutch soils during one growing season. In general, higher nifH gene copy numbers were observed in soils with higher pH than in those with lower pH, but lower numbers were related to increased nitrate and ammonium levels. Results from nifH gene pyrosequencing confirmed the observed PCR-DGGE patterns, which indicated that the N fixers are highly dynamic across time, shifting around 60%. Forward selection on CCA analysis identified N availability as the main driver of these variations, as well as of the evenness of the communities, leading to very unequal communities. Moreover, deep sequencing of the nifH gene revealed that sandy soils (B and D) had the lowest percentage of shared OTUs across time, compared with clayey soils (G and K), indicating the presence of a community under constant change. Cosmopolitan nifH species (present throughout the season) were affiliated with Bradyrhizobium, Azospirillum and Methylocistis, whereas other species increased their abundances progressively over time, when appropriate conditions were met, as was notably the case for Paenibacilus and Burkholderia. Conclusions Our study provides the first in-depth pyrosequencing analysis of the N-fixing community at both spatial and temporal scales, providing insights into the cosmopolitan and specific portions of the nitrogen fixing bacterial communities in soil.
Correla o entre as express es de P-caderina e de receptores de estrógeno no cancer da mama
Paredes Joana Cancela de Amorim Falco,Milanezi Maria Fernanda Grillo,Reis-Filho Jorge Sérgio,Leit?o Dina Raquel Aguileira
Jornal Brasileiro de Patologia e Medicina Laboratorial , 2002,
Abstract: Introdu o: A manuten o da arquitetura dos tecidos adultos depende essencialmente da integridade estrutural e funcional das caderinas, uma superfamília de moléculas de ades o celular dependentes de cálcio, que medeiam normalmente a ades o intercelular homofílica e homotípica. A P-caderina é expressa pelas células mioepiteliais da glandula mamária normal, sendo aberrantemente expressa num pequeno subgrupo de carcinomas da mama. Vários estudos recentes têm demonstrado que a express o desta proteína está significativamente correlacionada com tumores de alto grau histológico e negativos para os receptores de estrógeno (RE). Objetivos: Investigar a express o da P-caderina e dos receptores de estrógeno (RE) em carcinomas da mama invasivos e correlacionar os resultados obtidos. Material e método: O padr o de express o da P-caderina e dos RE foi estudado imunoistoquimicamente em 149 carcinomas invasivos da mama; seguidamente, correlacionou-se estatisticamente a express o destas duas proteínas. Resultados: A P-caderina foi detectada nas células mioepiteliais do tecido mamário normal e em 46 de 146 (31,5%) casos de carcinoma invasivo da mama. A express o da P-caderina correlacionou-se inversamente com a express o dos RE, verificando-se que o subgrupo de tumores P-caderina positivos e RE negativos apresentava alto grau histológico e maior agressividade tumoral. Conclus o: Demonstrou-se que a P-caderina identifica um subgrupo de carcinomas da mama, que n o expressa RE e que parece representar um estado mais avan ado da progress o tumoral. Estes resultados levantam ainda a hipótese de que a express o desta proteína possa ser regulada por uma via alternativa, independente de estrógeno.
Correla??o entre as express?es de P-caderina e de receptores de estrógeno no cancer da mama
Paredes, Joana Cancela de Amorim Falco;Milanezi, Maria Fernanda Grillo;Reis-Filho, Jorge Sérgio;Leit?o, Dina Raquel Aguileira;Athanazio, Daniel Abensur;Schmitt, Fernando Carlos de Landér;
Jornal Brasileiro de Patologia e Medicina Laboratorial , 2002, DOI: 10.1590/S1676-24442002000400010
Abstract: background: the maintenance of adult tissue architecture largely depends on structural and functional integrity of cadherins, a superfamily of ca2+-dependent cell-cell adhesion molecules that usually mediate homophilic and homotypic intercellular adhesion. p-cadherin is expressed by myoepithelial cells of normal breast tissue, and is aberrantly expressed in a subset of breast carcinomas. in addition, recent studies have demonstrated that the expression of this protein in breast cancer is significantly correlated with high histological grade and negativity for estrogen receptors (er). objectives: to investigate the expression of p-cadherin and er in invasive breast carcinomas and correlate the obtained results. material and methods: the expression pattern of p-cadherin and er was immunohistochemically studied in 149 invasive carcinomas of the breast; subsequently, the statistic correlation between er and p-cadherin immunophenotypes was assessed. results: p-cadherin was detected in myoepithelial cells of normal breast tissue and in 46 out of 146 (31.5%) cases of invasive breast carcinomas. p-cadherin expression showed a high inverse correlation with er expression, and it was observed that the subset of p-cadherin positive and er negative tumours were related to higher histological grade and more agressive behaviour. conclusion: we demonstrated that p-cadherin identifies a subgroup of breast carcinomas, which lacks er expression, and that seems to represent an advanced step of cancer progression. our data suggests the hypothesis that an alternative estrogen independent pathway regulates p-cadherin expression.
Different Selective Effects on Rhizosphere Bacteria Exerted by Genetically Modified versus Conventional Potato Lines
Armando Cavalcante Franco Dias, Francisco Dini-Andreote, Silja Emilia Hannula, Fernando Dini Andreote, Michele de Cássia Pereira e Silva, Joana Falco Salles, Wietse de Boer, Johannes van Veen, Jan Dirk van Elsas
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0067948
Abstract: Background In this study, we assessed the actively metabolizing bacteria in the rhizosphere of potato using two potato cultivars, i.e. the genetically-modified (GM) cultivar Modena (having tubers with altered starch content) and the near-isogenic non-GM cultivar Karnico. To achieve our aims, we pulse-labelled plants at EC90 stage with 13C-CO2 and analysed their rhizosphere microbial communities 24 h, 5 and 12 days following the pulse. In the analyses, phospholipid fatty acid/stable isotope probing (PLFA-SIP) as well as RNA-SIP followed by reverse transcription and PCR-DGGE and clone library analysis, were used to determine the bacterial groups that actively respond to the root-released 13C labelled carbonaceous compounds. Methodology/Principal findings The PLFA-SIP data revealed major roles of bacteria in the uptake of root-released 13C carbon, which grossly increased with time. Gram-negative bacteria, including members of the genera Pseudomonas and Burkholderia, were strong accumulators of the 13C-labeled compounds at the two cultivars, whereas Gram-positive bacteria were lesser responders. PCR-DGGE analysis of cDNA produced from the two cultivar types showed that these had selected different bacterial, alpha- and betaproteobacterial communities at all time points. Moreover, an effect of time was observed, indicating dynamism in the structure of the active bacterial communities. PCR-DGGE as well as clone library analyses revealed that the main bacterial responders at cultivar Karnico were taxonomically affiliated with the genus Pseudomonas, next to Gluconacetobacter and Paracoccus. Cultivar Modena mainly attracted Burkholderia, next to Moraxella-like (Moraxellaceae family) and Sphingomonas types. Conclusions/Significance Based on the use of Pseudomonas and Burkholderia as proxies for differentially-selected bacterial genera, we conclude that the selective forces exerted by potato cultivar Modena on the active bacterial populations differed from those exerted by cultivar Karnico.
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