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Search Results: 1 - 10 of 412338 matches for " Marcelo M. Zerillo "
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Characterization of new IS elements and studies of their dispersion in two subspecies of Leifsonia xyli
Marcelo M Zerillo, Marie-Anne Van Sluys, Luis Camargo, Claudia B Monteiro-Vitorello
BMC Microbiology , 2008, DOI: 10.1186/1471-2180-8-127
Abstract: Sample sequencing of Lxc genome and comparative analysis with Lxx complete DNA sequence revealed a variable number of IS transposable elements acting upon genomic diversity. A detailed characterization of Lxc IS elements and a comparative review with IS elements of Lxx are presented. Each genome showed a unique set of elements although related to same IS families when considering features such as similarity among transposases, inverted and direct repeats, and element size. Most of the Lxc and Lxx IS families assigned were reported to maintain transposition at low levels using translation regulatory mechanisms, consistent with our in silico analysis. Some of the IS elements were found associated with rearrangements and specific regions of each genome. Differences were also found in the effect of IS elements upon insertion, although none of the elements were preferentially associated with gene disruption. A survey of transposases among genomes of Actinobacteria showed no correlation between phylogenetic relatedness and distribution of IS families. By using Southern hybridization, we suggested that diversification of Lxc isolates is also mediated by insertion sequences in probably recent events.Collectively our data indicate that transposable elements are involved in genome diversification of Lxc and Lxx. The IS elements were probably acquired after the divergence of the two subspecies and are associated with genome organization and gene contents. In addition to enhancing understanding of IS element dynamics in general, these data will contribute to our ongoing comparative analyses aimed at understanding the biological differences of the Lxc and Lxx.The Gram-positive, coryneform, fastidious, xylem-inhabiting bacteria Leifsonia xyli comprises two subspecies: L. xyli subsp. xyli (Lxx) and L. xyli subsp. cynodontis (Lxc). In its unique natural host, Lxx causes ratoon-stunting disease, a malady that affects sugarcane commercial fields worldwide, promoting losses of up to 3
Comparative Genomics Reveals Insight into Virulence Strategies of Plant Pathogenic Oomycetes
Bishwo N. Adhikari, John P. Hamilton, Marcelo M. Zerillo, Ned Tisserat, C. André Lévesque, C. Robin Buell
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0075072
Abstract: The kingdom Stramenopile includes diatoms, brown algae, and oomycetes. Plant pathogenic oomycetes, including Phytophthora, Pythium and downy mildew species, cause devastating diseases on a wide range of host species and have a significant impact on agriculture. Here, we report comparative analyses on the genomes of thirteen straminipilous species, including eleven plant pathogenic oomycetes, to explore common features linked to their pathogenic lifestyle. We report the sequencing, assembly, and annotation of six Pythium genomes and comparison with other stramenopiles including photosynthetic diatoms, and other plant pathogenic oomycetes such as Phytophthora species, Hyaloperonospora arabidopsidis, and Pythium ultimum var. ultimum. Novel features of the oomycete genomes include an expansion of genes encoding secreted effectors and plant cell wall degrading enzymes in Phytophthora species and an over-representation of genes involved in proteolytic degradation and signal transduction in Pythium species. A complete lack of classical RxLR effectors was observed in the seven surveyed Pythium genomes along with an overall reduction of pathogenesis-related gene families in H. arabidopsidis. Comparative analyses revealed fewer genes encoding enzymes involved in carbohydrate metabolism in Pythium species and H. arabidopsidis as compared to Phytophthora species, suggesting variation in virulence mechanisms within plant pathogenic oomycete species. Shared features between the oomycetes and diatoms revealed common mechanisms of intracellular signaling and transportation. Our analyses demonstrate the value of comparative genome analyses for exploring the evolution of pathogenesis and survival mechanisms in the oomycetes. The comparative analyses of seven Pythium species with the closely related oomycetes, Phytophthora species and H. arabidopsidis, and distantly related diatoms provide insight into genes that underlie virulence.
Carbohydrate-Active Enzymes in Pythium and Their Role in Plant Cell Wall and Storage Polysaccharide Degradation
Marcelo M. Zerillo, Bishwo N. Adhikari, John P. Hamilton, C. Robin Buell, C. André Lévesque, Ned Tisserat
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0072572
Abstract: Carbohydrate-active enzymes (CAZymes) are involved in the metabolism of glycoconjugates, oligosaccharides, and polysaccharides and, in the case of plant pathogens, in the degradation of the host cell wall and storage compounds. We performed an in silico analysis of CAZymes predicted from the genomes of seven Pythium species (Py. aphanidermatum, Py. arrhenomanes, Py. irregulare, Py. iwayamai, Py. ultimum var. ultimum, Py. ultimum var. sporangiiferum and Py. vexans) using the “CAZymes Analysis Toolkit” and “Database for Automated Carbohydrate-active Enzyme Annotation” and compared them to previously published oomycete genomes. Growth of Pythium spp. was assessed in a minimal medium containing selected carbon sources that are usually present in plants. The in silico analyses, coupled with our in vitro growth assays, suggest that most of the predicted CAZymes are involved in the metabolism of the oomycete cell wall with starch and sucrose serving as the main carbohydrate sources for growth of these plant pathogens. The genomes of Pythium spp. also encode pectinases and cellulases that facilitate degradation of the plant cell wall and are important in hyphal penetration; however, the species examined in this study lack the requisite genes for the complete saccharification of these carbohydrates for use as a carbon source. Genes encoding for xylan, xyloglucan, (galacto)(gluco)mannan and cutin degradation were absent or infrequent in Pythium spp.. Comparative analyses of predicted CAZymes in oomycetes indicated distinct evolutionary histories. Furthermore, CAZyme gene families among Pythium spp. were not uniformly distributed in the genomes, suggesting independent gene loss events, reflective of the polyphyletic relationships among some of the species.
Genome sequence of the necrotrophic plant pathogen Pythium ultimum reveals original pathogenicity mechanisms and effector repertoire
C André Lévesque, Henk Brouwer, Liliana Cano, John P Hamilton, Carson Holt, Edgar Huitema, Sylvain Raffaele, Gregg P Robideau, Marco Thines, Joe Win, Marcelo M Zerillo, Gordon W Beakes, Jeffrey L Boore, Dana Busam, Bernard Dumas, Steve Ferriera, Susan I Fuerstenberg, Claire MM Gachon, Elodie Gaulin, Francine Govers, Laura Grenville-Briggs, Neil Horner, Jessica Hostetler, Rays HY Jiang, Justin Johnson, Theerapong Krajaejun, Haining Lin, Harold JG Meijer, Barry Moore, Paul Morris
Genome Biology , 2010, DOI: 10.1186/gb-2010-11-7-r73
Abstract: The P. ultimum genome (42.8 Mb) encodes 15,290 genes and has extensive sequence similarity and synteny with related Phytophthora species, including the potato blight pathogen Phytophthora infestans. Whole transcriptome sequencing revealed expression of 86% of genes, with detectable differential expression of suites of genes under abiotic stress and in the presence of a host. The predicted proteome includes a large repertoire of proteins involved in plant pathogen interactions, although, surprisingly, the P. ultimum genome does not encode any classical RXLR effectors and relatively few Crinkler genes in comparison to related phytopathogenic oomycetes. A lower number of enzymes involved in carbohydrate metabolism were present compared to Phytophthora species, with the notable absence of cutinases, suggesting a significant difference in virulence mechanisms between P. ultimum and more host-specific oomycete species. Although we observed a high degree of orthology with Phytophthora genomes, there were novel features of the P. ultimum proteome, including an expansion of genes involved in proteolysis and genes unique to Pythium. We identified a small gene family of cadherins, proteins involved in cell adhesion, the first report of these in a genome outside the metazoans.Access to the P. ultimum genome has revealed not only core pathogenic mechanisms within the oomycetes but also lineage-specific genes associated with the alternative virulence and lifestyles found within the pythiaceous lineages compared to the Peronosporaceae.Pythium is a member of the Oomycota (also referred to as oomycetes), which are part of the heterokont/chromist clade [1,2] within the 'Straminipila-Alveolata-Rhizaria' superkingdom [3]. Recent phylogenies based on multiple protein coding genes indicate that the oomycetes, together with the uniflagellate hyphochytrids and the flagellates Pirsonia and Developayella, form the sister clade to the diverse photosynthetic orders in the phylum Ochrophyta [2,
Poly(Vinyl Alcohol)/Collagen/Hydroxyapatite Nanoparticles Hybrid System Containing Yttrium-90 as a Potential Agent to Treat Osteosarcoma  [PDF]
Marcelo F. Cipreste, Edesia M. B. Sousa
Journal of Biomaterials and Nanobiotechnology (JBNB) , 2014, DOI: 10.4236/jbnb.2014.51004

Osteosarcoma is the most common primary malignant bone tumors, affecting mostly children, adolescents and young adults. This is an aggressive tumor that results in a high mortality rate and poor prognosis. Due to the low sensitivity of osteosarcoma to ionizing radiation, such treatment is not used very often and it can be recommended only to postsurgical therapy. As an alternative therapy, functionalized nanomaterials allow their accumulation in tumor tissues due to their unique properties, making them good agents to act as stable carriers for radionuclides. In this work, mesoporous hydroxyapatite nanoparticles were synthesized and the functionalization process with poly(vinyl alcohol) and collagen was investigated. The samples were characterized by X-ray diffraction (XRD), N2 adsorption, elemental analysis (CHN), Fourier Transform Infrared Spectroscopy (FTIR), Nitrogen Adsorption, Transmission Electron Microscopy (TEM), and Thermal Analysis. Also, the yttrium incorporation potential and its release kinetics in the hydroxyapatite matrix were evaluated to study the capacity of this system to treat osteosarcomas. The results indicate that this material has a promisor potential to treat this kind of tumor.

Genetic and Environmental Influences on Perceptual-Motor Abilities  [PDF]
Cassio M. Meira Jr., Marcelo Massa
Psychology (PSYCH) , 2017, DOI: 10.4236/psych.2017.811110
Abstract: Ability poses limitations on a person’s potential for success in a given task. Perceptual-motor abilities are thought to be traits regarded as having been either genetically determined or developed through motor experience. This study examined genetic and environmental influences on perceptual-motor abilities in twins (13 sets of monozygotic and 18 sets of dizygotic, mean age = 17.2 ± 3.5 years) by measuring the performance on tasks whose main underlying perceptual-motor abilities are rate control, simple reaction time, hand-eye coordination, finger dexterity, and manual force control. The results suggest that little support was given to Turkheimer’s Laws of Behavior Genetics, as high proportions of variance on the performance were attributable to 1) additive genetic factors for rate control only, 2) shared family environment for finger dexterity and hand-eye coordination, and 3) nonshared environment for rate control and simple reaction time.
A educa??o científica sob a perspectiva da pedagogia histórico-crítica e do movimento C.T.S. no ensino de ciências
Teixeira, Paulo Marcelo M.;
Ciência & Educa??o (Bauru) , 2003, DOI: 10.1590/S1516-73132003000200003
Abstract: the article tries to discuss how historico-critical pedagogy and the sts movement in science education can contribute to the change of scientific education that we have at the present time. we visualize points of convergence between these two theoretical currents, with interesting implications in respect to the formation of teachers. finally, we will claim that these two theories can place science education in a differentiated perspective, which can contribute to the formation of citizenship and the transformation of society through popular interests.
Gálvez M,Marcelo;
Revista chilena de radiología , 2006, DOI: 10.4067/S0717-93082006000300003
Abstract: the biomedical publications are very important for the update of the knowledge and for the daily clinical practice. the scientific activity parameters, quality and impact of the chilean and latin american journals were reviewed. few systems of indexing like medline, science citation index, scielo and lilacs were described. the evolution of language publication and some strategies for the internalization of latin american biomedical journals were reviewed
Marcelo Gálvez M
Revista Chilena de Radiología , 2007,
Abstract: Con el fin de conocer la opinión de nuestros lectores, se realizó una encuesta en marzo del 2007. La cual muestra que la mayor de parte de los encuestados recibe la revista y sabe que su contenido se encuentra on-line. Los entrevistados leen la revista y les interesa seguir recibiéndola. En relación a la calidad, los encuestados piensan que la revista es un aporte al quehacer profesional. La mayor parte de los lectores nunca ha publicado, lo que contrasta con el interés en publicar In order to knowing the opinion of our readers was carried out a survey in on march 2007. The biggest part of the readers receives the magazine and knows that its content is found On-Line. The readers receive the magazine and they are interested in continuing receiving it. Relating to the quality they think that the magazine contribute to professional task. Most of the readers never has published, what contrasts with the interest in publishing
Marcelo Gálvez M
Revista Chilena de Radiología , 2006,
Abstract: Las publicaciones biomédicas son muy importantes en la actualización de los conocimientos y en la práctica clínica diaria. Se revisan los parámetros de actividad científica, calidad e impacto de las revistas chilenas y latinoamericanas. Se describen algunos sistemas de indexación como MEDLINE, SCIENCE CITATION INDEX, SCIELO y LILACS. Se revisa también la evolución que han tenido los idiomas de publicación y algunas estrategias para la internalización de las revistas biomédicas The biomedical publications are very important for the update of the knowledge and for the daily clinical practice. The scientific activity parameters, quality and impact of the Chilean and Latin American journals were reviewed. Few systems of indexing like MEDLINE, SCIENCE CITATION INDEX, SCIELO and LILACS were described. The evolution of language publication and some strategies for the internalization of Latin American biomedical journals were reviewed
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