Página 26 dos resultados de 60878 itens digitais encontrados em 0.078 segundos

Aceitação/rejeição da evolução biológica: atitudes de alunos da educação básica; Acceptance / rejection of biological evolution: attitudes of students of basic education.

Oliveira, Graciela da Silva
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 23/01/2009 Português
Relevância na Pesquisa
45.75%
A teoria evolutiva fornece a compreensão das características fundamentais da vida e as relações dos organismos com seu ambiente. Embora seja atribuído à evolução biológica um papel unificador das Ciências Biológicas, os estudantes em geral a rejeitam ou apresentam dificuldades de compreensão de seus conceitos básicos. A controvérsia que envolve o tema extrapola as salas de aula de ciências e ganha uma dimensão mais conflitante nos Estados Unidos, onde grupos criacionistas buscam desqualificar a teoria evolutiva como conhecimento científico comprovado. Apesar de não existirem tradições fortes do criacionismo no Brasil, esse movimento tem ganhado cada vez mais espaço, principalmente no meio acadêmico. Tendo em vista as controvérsias que envolvem as construções afetivas e culturais no ensinoaprendizagem da teoria evolutiva, o multiculturalismo que caracteriza o Brasil e os resultados de levantamentos de opiniões que indicam que os brasileiros concordam com alguns itens do movimento criacionista, interessou-se pela realização desta investigação, que tem como objetivo verificar a aceitação/rejeição da teoria da evolução de alunos recém-egressos da oitava série (8ª série) do Ensino Fundamental de escolas públicas de Tangará da Serra MT e São Caetano do Sul SP; e caracterizar possíveis relações entre a atitude dos informantes sobre teoria evolutiva e a proximidade entre ciência e religião. A pesquisa consistiu de duas etapas: a primeira foi o levantamento bibliográfico das pesquisas brasileiras acerca da evolução biológica e a presença do movimento criacionista no contexto escolar. Essa etapa resultou em um balanço geral dos trabalhos publicados e indicou uma lacuna dentre as pesquisas nacionais acerca do tema. Na segunda etapa...

A divulgação científica na mídia impressa: as ciências biológicas em foco

Bertolli Filho, Claudio
Fonte: Universidade Estadual Paulista (UNESP), Faculdade de Ciências Publicador: Universidade Estadual Paulista (UNESP), Faculdade de Ciências
Tipo: Artigo de Revista Científica Formato: 351-368
Português
Relevância na Pesquisa
45.74%
Este artigo tem como objetivo discutir algumas características da divulgação científica que toma as ciências biológicas como tema central. Optou-se pela análise de livros que, no contexto brasileiro, alcançaram sucesso público e que são, freqüentemente, mencionados por alunos universitários, tanto em sala de aula quanto em seus escritos. O enfoque dado à pesquisa é de cunho antropológico, enfatizando-se que, na pós-modernidade, fluem paralelamente duas culturas, rotuladas por Giddens (2002) de a cultura da segurança e a cultura de risco.; The aim of this study is to discuss some characteristics of the diffusion of science taking the Biological Sciences as a central theme. Those books considered a commercial success in the Brazilian context and frequently mentioned by university students in classroom and in their papers, were selected for the analysis. The focus given to the research is an anthropological one, emphasizing that, in postmodernity, ideas flow in two parallel cultures labeled by Giddens (2002) as being the safety culture and the risk culture.

Abordagem dos conteúdos de biologia celular em cursos de Ciências Biológicas e sua relação com as avaliações nacionais; Addressing the contents of cell biology in Biological Courses and its relation to national assessments

Viktoria Kovesdy Ribeiro
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 31/01/2011 Português
Relevância na Pesquisa
45.74%
As políticas públicas ligadas à expansão do Ensino Superior brasileiro têm levado à implantação de sistemas de avaliação da qualidade do ensino, processo que vem evoluindo para uma concepção sistematizada de forma construtiva e que leva em conta a participação dos diferentes segmentos relacionados às instituições. Há, entretanto, componentes desse processo implantados de forma mais polêmica, destacando-se os instrumentos nacionais de avaliação aplicados a iniciantes e concluintes das graduações, ainda pouco estudada, exceto por análises superficiais dos meios de comunicação, mais interessados no ranqueamento das escolas do que na avaliação dessas práticas. Nesse contexto, os cursos de Biologia passaram a ter seus estudantes avaliados no ano de 2000 e até 2003, por meio do Exame Nacional de Cursos, seguindo-se, em 2005, avaliação amostral, nos termos propostos pela legislação federal que implantou o Sistema Nacional de Avaliação do Ensino Superior (SINAES). Como nesses exames foram preenchidos questionários socioeconômicos por parte dos estudantes, além de dados sobre as condições de oferta de tais cursos, há farto material para análise, ainda pouco explorado por pesquisadores nacionais e internacionais. O presente trabalho analisou os conteúdos de Biologia Celular dos exames nacionais realizados a partir do ano de 2000...

Concept maps as a useful instrument in the teaching practices : an applied research in the biological sciences

Silveira, Felipa Pacifco Ribeiro de Assis; Sousa, Célia Maria Soares Gomes de; Santovito, Rogério Fonseca
Fonte: Universidade de Brasília Publicador: Universidade de Brasília
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
45.74%
ABSTRACT; This paper presents the results of an applied research experience conducted with a group of undergraduate students in Biological Sciences at the Teaching Practice discipline. The research aimed to surpass pedagogical deficiencies, making use of the concept maps technique, through which it was possible to externalize and share meanings that arise from the reading of supporting texts. The concept maps were discussed, in this paper, through the literal translation of meanings. The results evidenced improvement in the ability of discussing ideas, in group working and in the rebuilding of knowledge.

The biological lifetime of nitric oxide: Implications for the perivascular dynamics of NO and O2

Thomas, Douglas D.; Liu, Xiaoping; Kantrow, Stephen P.; Lancaster, Jack R.
Fonte: The National Academy of Sciences Publicador: The National Academy of Sciences
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
45.74%
Endothelial nitric oxide (nitrogen monoxide) is synthesized at the intravascular/extravascular interface. We previously have reported the intravascular half-life of NO, as a result of consumption by erythrocytes, as approximately 2 ms. We report here studies designed to estimate the lifetime of NO in the parenchymal (extravascular) tissue and describe the implications of these results for the distribution of NO and oxygen concentration gradients away from the blood vessel. The rate of consumption of NO by parenchymal cells (hepatocytes) linearly depends on both NO and O2 concentration. We estimate that the extravascular half-life of NO will range from 0.09 to > 2 s, depending on O2 concentration and thus distance from the vessel. Computer modeling reveals that this phenomenon, coupled with reversible NO inhibition of cellular mitochondrial oxygen consumption, substantially extends the zone of adequate tissue cellular oxygenation away from the blood vessel, with an especially dramatic effect during conditions of increased tissue work (oxygen consumption). This represents a second action of NO, in addition to vasodilation, in enhancing tissue cellular respiration and provides a possible physiological function for the known reversible inhibition of mitochondrial respiration by low concentrations of NO.

Direct evidence for the participation of gap junction-mediated intercellular communication in the transmission of damage signals from α-particle irradiated to nonirradiated cells

Azzam, Edouard I.; de Toledo, Sonia M.; Little, John B.
Fonte: The National Academy of Sciences Publicador: The National Academy of Sciences
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
45.74%
It has generally been considered that important biological effects of ionizing radiation arise as a direct consequence of DNA damage occurring in irradiated cells. We have examined this hypothesis by exposing cells to very low fluences of α-particles, similar to those emitted by radon gas, such that as few as 1% of the cells in a population are traversed by a particle and thus receive any radiation exposure. By using the endpoints of changes in gene expression and induction of DNA damage, we show that nonirradiated “bystander” cells participate in the overall response of confluent density-inhibited populations of cultured fibroblast and epithelial cells. By in situ immunofluorescence techniques and the use of cells genetically compromised in their ability to perform gap junction intercellular communication, we present direct evidence for the involvement of connexin43-mediated intercellular communication in the transmission of damage signals to nonirradiated cells. Induction of the stress-inducible p21Waf1 protein in aggregates of neighboring cells far exceeding the fraction of cells whose nucleus has been traversed occurred in gap junction-competent cells only. These changes in p21Waf1 expression correlated with both the induction of DNA damage (as measured by micronucleus formation) as well as increased Ser-15 phosphorylation of p53.

Dark field imaging of biological macromolecules with the scanning transmission electron microscope

Ohtsuki, Mitsuo; Isaacson, Michael S.; Crewe, A. V.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /03/1979 Português
Relevância na Pesquisa
45.75%
A scanning transmission electron microscope (STEM) equipped with a field emission gun has been employed for the examination of biological macromolecules at high resolution. The quality of micrographs obtained with the STEM is dependent upon the quality of the substrate used to support biological objects because the image contrast in dark field is proportional to the mass density of the specimen. In order to reduce deleterious effects of the substrates on the image quality, we have developed a method of fabricating substrates consisting of very thin, very clean carbon films supported on very clean fenestrated plastic films. These films are approximately 15 Å thick. Well-known biological macromolecules such as glutamine synthetase and tobacco mosaic virus (both stained) and low-density lipoprotein and ferritin (both unstained were placed on these substrates and examined with the STEM by using various modes of contrast. The micrographs obtained by using the dark field mode of contrast employing an annular detector were free from phase contrast, as expected. Using this contrast mode, we have been able to directly observe (in-focus) 2.5- to 4.4-Å lattice spacings in the ferritin core. The effect of electron radiation damage on the helical structure of tobacco mosaic virus was also examined. Micrographs as well as corresponding optical diffraction patterns obtained with moderately low doses showed very clear helical structure from both sides of the virus. In addition...

Biological Activity of Human Chorionic Gonadotropin Released from Testis Binding-Sites

Dufau, M. L.; Catt, K. J.; Tsuruhara, T.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /09/1972 Português
Relevância na Pesquisa
45.75%
The effect of testicular binding of human chorionic gonadotropin upon the biological activities of the hormone was examined by comparison of the binding and activation properties of 125I-labeled gonadotropin before and after binding to rat testis in vitro. Biologically active 125I-gonadotropin taken up by rat testis was dissocated from testis binding-sites at low pH and evaluated for its ability to bind again to testis, adenylate cyclase activation, and stimulation of steroidogenesis during subsequent incubation with fresh testis. Binding to tissue receptor-sites for 4 hr did not impair the biological properties of gonadotropin, though hormone remaining in the incubation medium had reduced affinity for tissue binding-sites during subsequent incubation with rat testes. In comparison to the original preparation, 125I-labeled gonadotropin previously eluted from specific binding-sites of rat testis showed significantly increased binding activity and stimulation of cyclic AMP and testosterone release during further incubation with rat testes in vitro. The enhancement of biological activity of the eluted hormone is attributable to affinity purification of the original hormone preparation by selective uptake at receptorsites. These results demonstrate that gonadotropin is not inactivated or degraded during combination with gonadotropin receptors of rat testis.

The Contribution of Subunits of Thyroid Stimulating Hormone to the Binding and Biological Activity of Thyrotropin

Wolff, J.; Winand, Roger J.; Kohn, Leonard D.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /09/1974 Português
Relevância na Pesquisa
45.75%
The binding of bovine TSH (thyroid stimulating hormone), LH (luteinizing hormone), and their subunits to the TSH receptor of beef thyroid membranes was compared to stimulation by these agents of adenylate cyclase [ATP pyrophosphate-lyase(cyelizing), EC 4.6.1.1] in the same membranes, glucose oxidation in dog thyroid slices, and the secretory process in mouse thyroids in vitro (colloid droplet formation) and in vivo (hormone release). The β-subunits of TSH and LH can bind to the TSH receptor and can activate thyroid function in vitro. In contrast, the α-subunit of TSH binds negligibly to the TSH receptor and has very low potency for stimulation of thyroid function (except for colloid droplet formation). Neither binding nor the biological activity of the β-subunits can be accounted for by TSH contamination, whereas this cannot be ruled out for α-TSH. LH binds to the TSH receptor even better than the β-subunit of TSH but the increased binding does not result in a corresponding activation of thyroid function. Neither α- nor β-TSH alone can induce more than 4-8% of the response to intact TSH in any of the investigated parameters. It is proposed that the β-subunit has within its structure the primary determinants which are necessary to stimulate biological activity...

Is Altered Expression of Hepatic Insulin-Related Genes in Growth Hormone Receptor Knockout Mice Due to GH Resistance or a Difference in Biological Life Spans?

Panici, Jacob A.; Wang, Feiya; Bonkowski, Michael S.; Spong, Adam; Bartke, Andrzej; Pawlikowska, Ludmila; Kwok, Pui-Yan; Masternak, Michal M.
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
45.75%
Growth hormone receptor knockout (GHRKO) mice live about 40%–55% longer than their normal (N) littermates. Previous studies of 21-month-old GHRKO and N mice showed major alterations of the hepatic expression of genes involved in insulin signaling. Differences detected at this age may have been caused by the knockout of the growth hormone receptor (GHR) or by differences in biological age between GHRKO and N mice. To address this question, we compared GHRKO and N mice at ages corresponding to the same percentage of median life span to see if the differences of gene expression persisted. Comparison of GHRKO and N mice at ∼50% of biological life span showed significant differences in hepatic expression of all 14 analyzed genes. We conclude that these changes are due to disruption of GHR gene and the consequent suppression of growth hormone signaling rather than to differences in “biological age” between mutant and normal animals sampled at the same chronological age.

Open vessel microwave extraction of metals in biological and botanical materials.

LOMBARDI, M. C.; COSTA, L.; NOBREGA, J.; NOGUEIRA, A. R. de A.
Fonte: In: ANNUAL CONFERENCE OF THE FEDERATION OF ANALYTICAL CHEMISTRY AND SPECTROSCOPY SOCIETIES - FACSS, 26.; INTERNATIONAL CONFERENCE ON ANALYTICAL SCIENCES AND SPECTROSCOPY - ICASS, 1999, Vancouver. Proceedings...Vancouver: FACSS, 1999. p.223. Publicador: In: ANNUAL CONFERENCE OF THE FEDERATION OF ANALYTICAL CHEMISTRY AND SPECTROSCOPY SOCIETIES - FACSS, 26.; INTERNATIONAL CONFERENCE ON ANALYTICAL SCIENCES AND SPECTROSCOPY - ICASS, 1999, Vancouver. Proceedings...Vancouver: FACSS, 1999. p.223.
Tipo: Resumo em anais de congresso (ALICE)
Português
Relevância na Pesquisa
45.75%
The complete sample decomposition is not always necessary when measurements are carried out using optical techniques. Depending on both technique employed and sample matrix characteristics, an extraction procedure can be completely suitable for quantitative determinations. To implement this approach is essential to perform a critical evaluation of the behavior of each element, of the extractor solution, and of the temperature and time of extraction. The temperature can be controlled adopting microwave-assisted procedures that guarantee fast heating and repeatability. In this work an open-vessel microwave system (Star 6, CEM) was employed to investigate the efficiency of the extraction procedures. The extraction of Al, Ca, Cu, Fe, Mg, Mn,:and Zn was evaluated in biological (bovine liver, SRM 1577b, NIST) and botanical (apple leaves, SRM 1515, NIST; trace elements in spinach leaves, SR!vf 1570a, NIST; and commercial teas) materials. The extraction procedures were investigated using 1 or 10% v/v hydrochloric or nitric acid solutions. An alkaline solution containing a mixture of water- soluble tertiary amines (CFA-C, Spectrasol) was also tested. All procedures were carried out at temperatures in the range 80-105 oC during time intervals shorter than 10 min. The analytes were determined by flame and graphite furnace atomic absorption spectrophotometry (Intralab...

Identifying the subproteome of kinetically stable proteins via diagonal 2D SDS/PAGE

Xia, Ke; Manning, Marta; Hesham, Helai; Lin, Qishan; Bystroff, Christopher; Colón, Wilfredo
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
45.8%
Most proteins are in equilibrium with partially and globally unfolded conformations. In contrast, kinetically stable proteins (KSPs) are trapped by an energy barrier in a specific state, unable to transiently sample other conformations. Among many potential roles, it appears that kinetic stability (KS) is a feature used by nature to allow proteins to maintain activity under harsh conditions and to preserve the structure of proteins that are prone to misfolding. The biological and pathological significance of KS remains poorly understood because of the lack of simple experimental methods to identify this property and its infrequent occurrence in proteins. Based on our previous correlation between KS and a protein's resistance to the denaturing detergent SDS, we show here the application of a diagonal 2D (D2D) SDS/PAGE assay to identify KSPs in complex mixtures. We applied this method to the lysate of Escherichia coli and upon proteomics analysis have identified 50 nonredundant proteins that were SDS-resistant (i.e., kinetically stable). Structural and functional analyses of a subset (44) of these proteins with known 3D structure revealed some potential structural and functional biases toward and against KS. This simple D2D SDS/PAGE assay will allow the widespread investigation of KS...

Mean mass-specific metabolic rates are strikingly similar across life's major domains: Evidence for life's metabolic optimum

Makarieva, Anastassia M.; Gorshkov, Victor G.; Li, Bai-Lian; Chown, Steven L.; Reich, Peter B.; Gavrilov, Valery M.
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
45.8%
A fundamental but unanswered biological question asks how much energy, on average, Earth's different life forms spend per unit mass per unit time to remain alive. Here, using the largest database to date, for 3,006 species that includes most of the range of biological diversity on the planet—from bacteria to elephants, and algae to sapling trees—we show that metabolism displays a striking degree of homeostasis across all of life. We demonstrate that, despite the enormous biochemical, physiological, and ecological differences between the surveyed species that vary over 1020-fold in body mass, mean metabolic rates of major taxonomic groups displayed at physiological rest converge on a narrow range from 0.3 to 9 W kg−1. This 30-fold variation among life's disparate forms represents a remarkably small range compared with the 4,000- to 65,000-fold difference between the mean metabolic rates of the smallest and largest organisms that would be observed if life as a whole conformed to universal quarter-power or third-power allometric scaling laws. The observed broad convergence on a narrow range of basal metabolic rates suggests that organismal designs that fit in this physiological window have been favored by natural selection across all of life's major kingdoms...

Helical Lévy walks: Adjusting searching statistics to resource availability in microzooplankton

Bartumeus, Frederic; Peters, Francesc; Pueyo, Salvador; Marrasé, Cèlia; Catalan, Jordi
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
45.8%
The searching trajectories of different animals can be described with a broad class of flight length (lj) distributions with P(lj) = lj–μ. Theoretical studies have shown that changes in these distributions (i.e., different μ values) are key to optimizing the long-term encounter statistics under certain searcher–resource scenarios. In particular, they predict the advantage of Lévy searching (μ ≈ 2) over Brownian motion (μ ≥ 3) for low-prey-density scenarios. Here, we present experimental evidence of predicted optimal changes in the flight-time distribution of a predator's walk in response to gradual density changes of its moving prey. Flight times of the dinoflagellate Oxyrrhis marina switched from an exponential to an inverse square power-law distribution when the prey (Rhodomonas sp.) decreased in abundance. Concomitantly, amplitude and frequency of the short-term helical path increased. The specific biological mechanisms involved in these searching behavioral changes are discussed. We suggest that, in a three-dimensional environment, a stronger helical component combined with a Lévy walk searching strategy enhances predator's encounter rates. Our results support the idea of universality of the statistical laws in optimal searching processes despite variations in the biological details of the organisms.

Ordered cyclic motifs contribute to dynamic stability in biological and engineered networks

Ma'ayan, Avi; Cecchi, Guillermo A.; Wagner, John; Rao, A. Ravi; Iyengar, Ravi; Stolovitzky, Gustavo
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
45.8%
Representation and analysis of complex biological and engineered systems as directed networks is useful for understanding their global structure/function organization. Enrichment of network motifs, which are over-represented subgraphs in real networks, can be used for topological analysis. Because counting network motifs is computationally expensive, only characterization of 3- to 5-node motifs has been previously reported. In this study we used a supercomputer to analyze cyclic motifs made of 3–20 nodes for 6 biological and 3 technological networks. Using tools from statistical physics, we developed a theoretical framework for characterizing the ensemble of cyclic motifs in real networks. We have identified a generic property of real complex networks, antiferromagnetic organization, which is characterized by minimal directional coherence of edges along cyclic subgraphs, such that consecutive links tend to have opposing direction. As a consequence, we find that the lack of directional coherence in cyclic motifs leads to depletion in feedback loops, where the number of nodes affected by feedback loops appears to be at a local minimum compared with surrogate shuffled networks. This topology provides more dynamic stability in large networks.

A biochemical rationale for the discrete behavior of nitroxyl and nitric oxide in the cardiovascular system

Miranda, Katrina M.; Paolocci, Nazareno; Katori, Tatsuo; Thomas, Douglas D.; Ford, Eleonora; Bartberger, Michael D.; Espey, Michael G.; Kass, David A.; Feelisch, Martin; Fukuto, Jon M.; Wink, David A.
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
45.8%
The redox siblings nitroxyl (HNO) and nitric oxide (NO) have often been assumed to undergo casual redox reactions in biological systems. However, several recent studies have demonstrated distinct pharmacological effects for donors of these two species. Here, infusion of the HNO donor Angeli's salt into normal dogs resulted in elevated plasma levels of calcitonin gene-related peptide, whereas neither the NO donor diethylamine/NONOate nor the nitrovasodilator nitroglycerin had an appreciable effect on basal levels. Conversely, plasma cGMP was increased by infusion of diethylamine/NONOate or nitroglycerin but was unaffected by Angeli's salt. These results suggest the existence of two mutually exclusive response pathways that involve stimulated release of discrete signaling agents from HNO and NO. In light of both the observed dichotomy of HNO and NO and the recent determination that, in contrast to the O2/\documentclass[10pt]{article} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \pagestyle{empty} \setlength{\oddsidemargin}{-69pt} \begin{document} \begin{equation*}{\mathrm{O}}_{2}^{-}\end{equation*}\end{document} couple, HNO is a weak reductant...

Ultrasensitivity and noise propagation in a synthetic transcriptional cascade

Hooshangi, Sara; Thiberge, Stephan; Weiss, Ron
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
45.8%
The precise nature of information flow through a biological network, which is governed by factors such as response sensitivities and noise propagation, greatly affects the operation of biological systems. Quantitative analysis of these properties is often difficult in naturally occurring systems but can be greatly facilitated by studying simple synthetic networks. Here, we report the construction of synthetic transcriptional cascades comprising one, two, and three repression stages. These model systems enable us to analyze sensitivity and noise propagation as a function of network complexity. We demonstrate experimentally steady-state switching behavior that becomes sharper with longer cascades. The regulatory mechanisms that confer this ultrasensitive response both attenuate and amplify phenotypical variations depending on the system's input conditions. Although noise attenuation allows the cascade to act as a low-pass filter by rejecting short-lived perturbations in input conditions, noise amplification results in loss of synchrony among a cell population. The experimental results demonstrating the above network properties correlate well with simulations of a simple mathematical model of the system.

Capture Hi-C reveals novel candidate genes and complex long-range interactions with related autoimmune risk loci

Martin, Paul; McGovern, Amanda; Orozco, Gisela; Duffus, Kate; Yarwood, Annie; Schoenfelder, Stefan; Cooper, Nicholas J.; Barton, Anne; Wallace, Chris; Fraser, Peter; Worthington, Jane; Eyre, Steve
Fonte: Nature Publishing Group Publicador: Nature Publishing Group
Tipo: Article; published version
Português
Relevância na Pesquisa
45.8%
This is the final version of the article. It first appeared from Nature Publishing Group via http://dx.doi.org/10.1038/ncomms10069; Genome-wide association studies have been tremendously successful in identifying genetic variants associated with complex diseases. The majority of association signals are intergenic and evidence is accumulating that a high proportion of signals lie in enhancer regions. We use Capture Hi-C to investigate, for the first time, the interactions between associated variants for four autoimmune diseases and their functional targets in B- and T-cell lines. Here we report numerous looping interactions and provide evidence that only a minority of interactions are common to both B- and T-cell lines, suggesting interactions may be highly cell-type specific; some disease-associated SNPs do not interact with the nearest gene but with more compelling candidate genes (for example, FOXO1, AZI2) often situated several megabases away; and finally, regions associated with different autoimmune diseases interact with each other and the same promoter suggesting common autoimmune gene targets (for example, PTPRC, DEXI and ZFP36L1).; We thank Frank Dudbridge for providing the R scripts to analyse the interaction data. We would like to acknowledge the Faculty of Life Sciences Genomics Facility...

Analysis of the Stability of a Type III Secretion System Containing Pathogenicity Island (PII-3) in the Human Pathogen Vibrio Cholerae

Peters, Molly
Fonte: University of Delaware Publicador: University of Delaware
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
45.8%
Fidelma Boyd; Vibrio cholerae is an enteric pathogen that is the causative agent of the secretory diarrhea, cholera, that affects millions of people each year. While the V. cholerae O1 serogroup pathovar strains are well studied due to their propensity to cause epidemic and pandemic cholera, a second pathovar has been identified that causes inflammatory diarrhea. Strains of this pathovar encode a Type III Secretion system (T3SS) that is present on a Pathogenicity Island (PAI), a mobile genetic element integrated into the chromosome of some non-O1 serogroup strains. Our hypothesis is that this PAI was horizontally acquired and was an essential acquisition in the emergence of this pathovar. The aims of this study were to investigate the genetic structure of T3SS island regions, examine the excision behavior of the region in strain NRT36S and reconstruct the evolutionary history of the region. To accomplish this, we first performed a bioinformatics analysis among a group of strains that contain a T3SS. We constructed a genetic deletion of cognate T3SS island integrase, intV2, and determined the excision phenotype of the island using a two stage nested PCR assay. We showed that intV2 is necessary for the excision of the region. Lastly...

El uso de técnicas de biología molecular en los artículos publicados en la Revista Médica de Chile

Herskovic M,Viviana; Jacard C,Marcela; Reyes B,Humberto
Fonte: Sociedad Médica de Santiago Publicador: Sociedad Médica de Santiago
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/04/2000 Português
Relevância na Pesquisa
45.8%
Background: Molecular biology is a new branch of biological sciences, with novel laboratory techniques that are being progressively applied into biomedical and clinical research and, furthermore, into medical practice. Aims: To evaluate the use of molecular biology techniques in Chilean biomedical and clinical research and its evolution in the recent decade. Methods: All papers published as research articles, clinical experiences or case reports, in Revista Médica de Chile, during two time periods: 1987-1989 and 1997-1999, were reviewed to find out whether molecular biology techniques had been used or not. This journal publishes roughly 40% of papers generated in Chile, in biomedical or clinical topics, while another 15% appears in foreign journals. Results: Among 341 papers published in 1987-1989, 57 (16.7%) had used one or more molecular biology techniques; in contrast, among 318 papers published in 1997-1999, 91 (28.8%) had used them (p<0.001). Most papers using molecular biology techniques were research articles. Immunology, genetics, endocrinology, hematology, hepatology and rheumatology were the specialties providing a greater number and proportion of papers using molecular biology techniques. Chilean universities were the main institutions sponsoring these articles and FONDECYT (the Chilean Government Research Granting Office) was the main source of funding. The University of Chile (State-owned) provided most centers where these publications had been generated...