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Use of endophytic diazotrophic bacteria as a vector to express the cry3A gene from Bacillus thuringiensis
Salles, Joana Falc?o;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 Falc?o,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.
Higgs-Like Mechanism by Confinement of Quarks in a Chemical Non-Equilibrium Model  [PDF]
Leif Matsson
World Journal of Mechanics (WJM) , 2016, DOI: 10.4236/wjm.2016.611031
Abstract: A chemical non-equilibrium equation for binding of massless quarks to antiquarks, combined with the spatial correlations occurring in the condensation process, yields a density dependent form of the double-well potential in the electroweak theory. The Higgs boson acquires mass, valence quarks emerge and antiparticles become suppressed when the system relaxes and symmetry breaks down. The hitherto unknown dimensionless coupling parameter to the superconductor-like potential becomes a re-gulator of the quark-antiquark asymmetry. Only a small amount of quarks become “visible”—the valence quarks, which are 13% of the total sum of all quarks and antiquarks—suggesting that the quarks-antiquark pair components of the becoming quark-antiquark sea play the role of dark matter. When quark-masses are in-weighted, this number approaches the observed ratio between ordinary matter and the sum of ordinary and dark matter. The model also provides a chemical non-equilibrium explanation for the information loss in black holes, such as of baryon number.
On Dark Matter Identification  [PDF]
Leif Matsson
World Journal of Mechanics (WJM) , 2017, DOI: 10.4236/wjm.2017.74012
Abstract: A chemical non-equilibrium form of the superconductor like potential in the EW theory has been derived. It is obtained from the rate-equation for binding of fermions (quarks) to antifermions (antiquarks) and the spatial correlations for such pairs. In this model, the dimensionless coupling becomes a function of the fermion and antifermion field amplitudes, providing a measure of the matter-antimatter asymmetry from which the ratio between ordinary mass and dark mass is obtained. The dark mass becomes related to the Higgs boson mass and is estimated to about 192 GeV, which could be consistent with a signal observed from the Milky Way.
A Guide to Population Modelling for Simulation  [PDF]
Leif Gustafsson, Mikael Sternad
Open Journal of Modelling and Simulation (OJMSi) , 2016, DOI: 10.4236/ojmsi.2016.42007
Abstract: This paper outlines the fundamentals of a consistent theory of numerical modelling of a population system under study. The focus is on the systematic work to construct an executable simulation model. There are six fundamental choices of model category and model constituents to make. These choices have a profound impact on how the model is structured, what can be studied, possible introduction of bias, lucidity and comprehensibility, size, expandability, performance of the model, required information about the system studied and its range of validity. The first choice concerns a discrete versus a continuous description of the population system under study—a choice that leads to different model categories. The second choice is the model representation (based on agents, entities, compartments or situations) used to describe the properties and behaviours of the objects in the studied population. Third, incomplete information about structure, transitions, signals, initial conditions or parameter values in the system under study must be addressed by alternative structures and statistical means. Fourth, the purpose of the study must be explicitly formulated in terms of the quantities used in the model. Fifth, irrespective of the choice of representation, there are three possible types of time handling: Event Scheduling, Time Slicing or Micro Time Slicing. Sixth, start and termination criteria for the simulation must be stated. The termination can be at a fixed end time or determined by a logical condition. Population models can thereby be classified within a unified framework, and population models of one type can be translated into another type in a consistent way. Understanding the pros and cons for different choices of model category, representation, time handling etc. will help the modeller to select the most appropriate type of model for a given purpose and population system under study. By understanding the rules for consistent population modelling, an appropriate model can be created in a systematic way and a number of pitfalls can be avoided.
Impact of Mutations on K-Ras-p120GAP Interaction  [PDF]
Chunxia Gao, Leif A. Eriksson
Computational Molecular Bioscience (CMB) , 2013, DOI: 10.4236/cmb.2013.32002
Abstract:


The K-Ras protein plays a key role in the signal transduction cascade. Certain mutations in K-Ras lead to a permanent “on” state which results in tumorigenesis due to failed interaction with the GTPase activating protein (GAP). In this study, we examined the mutations E31N, D33N and D38N of K-Ras coupled and decoupled to wildtype GAP-334 and mutation K935N of GAP-334 coupled and decoupled to wildtype K-Ras, to illustrate the potential mechanism by which these mutants affect the interaction between the two proteins. We identify Tyr32 in the Ras Switch I region as a critical residue that acts as a gate to the GTP binding site and which needs to be “open” during Ras coupling with GAP to allow for insertion of GAP residue Arg789. This residue plays a vital role in stabilizing the transition state during GTP hydrolysis. The different mutations studied herein caused a reduced binding affinity, and the fluctuation of the Tyr32 side chain might hinder the insertion of Arg789. This may in turn be the cause of decreased GTP hydrolysis, and permanent on state of K-Ras, observed for these mutants.


Economic Burden of Disability Adjusted Life Years (DALYs) of Injuries  [PDF]
Koustuv Dalal, Leif Svanstr?m
Health (Health) , 2015, DOI: 10.4236/health.2015.74058
Abstract: Economic burdens of injuries at the country level are unknown. In the current study we tried to explore the economic burden of DALYs loss due to injuries at the country level, then distributed according to the World Bank’s income groups. Methods: Data from the World Bank and the World Health Organization websites were used. Disability adjusted life year (DALY) and gross domestic product (GDP) per capita were used to estimate the economic loss for RTIs. Estimates of economic burdens were presented in tables and figures. Results: The total economic loss of the world during 2004 by means of DALYs due to injuries was 613. 144 billion USD, corresponding value of 848.205 billion USD in 2014. DALYs burden of injuries were concentrated (almost 75%) among low and lower middle income countries. Economic burdens of injuries were concentrated (over 80%) among higher middle and high income countries. Iraq had lost almost one-fifth of its GDP due to injuries. The USA had the highest amount of economic loss for injuries (169.136 billion USD) among all countries. Conclusion: Injuries are highly expensive and they account for heavy losses to GDP. Injury prevention should be prioritized in order to save such losses to life and economies.
History on the biological nitrogen fixation research in graminaceous plants: special emphasis on the Brazilian experience
Baldani, José I.;Baldani, Vera L.D.;
Anais da Academia Brasileira de Ciências , 2005, DOI: 10.1590/S0001-37652005000300014
Abstract: this review covers the history on biological nitrogen fixation (bnf) in graminaceous plants grown in brazil, and describes research progress made over the last 40 years, most of whichwas coordinated by johanna d?bereiner. one notable accomplishment during this period was the discovery of several nitrogen-fixing bacteria such as the rhizospheric (beijerinckia fluminensis and azotobacter paspali), associative (azospirillum lipoferum, a. brasilense, a. amazonense) and the endophytic (herbaspirillum seropedicae, h. rubrisubalbicans, gluconacetobacter diazotrophicus, burkholderia brasilensis and b. tropica). the role of these diazotrophs in association with grasses, mainly with cereal plants, has been studied and a lot of progress has been achieved in the ecological, physiological, biochemical, and genetic aspects. the mechanisms of colonization and infection of the plant tissues are better understood, and the bnf contribution to the soil/plant system has been determined. inoculation studies with diazotrophs showed that endophytic bacteria have a much higher bnf contribution potential than associative diazotrophs. in addition, it was found that the plant genotype influences the plant/bacteria association. recent data suggest that more studies should be conducted on the endophytic association to strengthen the bnf potential. the ongoing genome sequencing programs: riogene (gluconacetobacter diazotrophicus) and genopar (herbaspirillum seropedicae) reflect the commitment to the bnf study in brazil and should allow the country to continue in the forefront of research related to the bnf process in graminaceous plants.
History on the biological nitrogen fixation research in graminaceous plants: special emphasis on the Brazilian experience
Baldani José I.,Baldani Vera L.D.
Anais da Academia Brasileira de Ciências , 2005,
Abstract: This review covers the history on Biological Nitrogen Fixation (BNF) in Graminaceous plants grown in Brazil, and describes research progress made over the last 40 years, most of whichwas coordinated by Johanna D bereiner. One notable accomplishment during this period was the discovery of several nitrogen-fixing bacteria such as the rhizospheric (Beijerinckia fluminensis and Azotobacter paspali), associative (Azospirillum lipoferum, A. brasilense, A. amazonense) and the endophytic (Herbaspirillum seropedicae, H. rubrisubalbicans, Gluconacetobacter diazotrophicus, Burkholderia brasilensis and B. tropica). The role of these diazotrophs in association with grasses, mainly with cereal plants, has been studied and a lot of progress has been achieved in the ecological, physiological, biochemical, and genetic aspects. The mechanisms of colonization and infection of the plant tissues are better understood, and the BNF contribution to the soil/plant system has been determined. Inoculation studies with diazotrophs showed that endophytic bacteria have a much higher BNF contribution potential than associative diazotrophs. In addition, it was found that the plant genotype influences the plant/bacteria association. Recent data suggest that more studies should be conducted on the endophytic association to strengthen the BNF potential. The ongoing genome sequencing programs: RIOGENE (Gluconacetobacter diazotrophicus) and GENOPAR (Herbaspirillum seropedicae) reflect the commitment to the BNF study in Brazil and should allow the country to continue in the forefront of research related to the BNF process in Graminaceous plants.
O controle das consultas odontológicas dos bebês por meio da carteira de vacina: avalia??o de um programa-piloto desenvolvido na Estratégia Saúde da Família em Ponta Grossa (PR, Brasil)
Stocco,Geraldo; Baldani,Marcia Helena;
Ciência & Saúde Coletiva , 2011, DOI: 10.1590/S1413-81232011000400031
Abstract: this study evaluated a concept-program developed in the area of a family health unity, which monitored, for two years, the returns of infant children to regular attendance by the dentist, through their vaccines cards. a cross-sectional study was conducted, involving a convenience sample of 123 children aged 12 to 36 months, residents in the area. data were collected during a campaign of immunization, in 2007, through a questionnaire answered by parents, vaccines cards checking, and clinical examination of children. the results showed that 81% of the examined children were registered in the fhu for dental care; from them, 95% had entered before reaching one year of life, having vaccines cards registration. it was also found that 50% of the children had visited the dentist more than once per year of life and 58% of them returned for dental appointments in the year before the survey. the prevalence of dental caries was lower in this group of children (17%), than in the group without frequent returns, or the one not registered in the fhu (26%). it was concluded that the vaccines card can be a useful tool for tracking the frequency of babies to dentist.
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