1,651 research outputs found
Sobrevivência e obtenção de mutantes induzidos por agentes mutagênicos em Metarhizium anisopliae
Uma linhagem selvagem do fungo entomopatogênico Metarhizium anisopliae foi submetida à ação de três agentes mutagênicos: radiação gama, luz ultravioleta e ácido nitroso. Curvas de sobrevivência foram obtidas para cada mutagênicos utilizado e mutantes foram selecionados a partir de doses dos mutagênicos que proporcionassem de 1 a 5% de sobrevivência. Mutantes morfológicos para a coloração de conídios e mutantes auxotróficos foram isolados. Mutantes para coloração de conidios foram agrupados em duas classes, uma com conídios amarelos e outra com conídios vinho pálido. Os mutantes auxotróficos obtidos foram deficientes para aminoácidos e vitaminas e mais de 58% deles eram auxotróficos para prolina/argmina. Radiação gama foi o mutagênico mais eficiente com uma porcentagem de obtenção de mulantes auxotróficos de aproximadamente 0,2%, seguido pela luz ultravioleta (0.12%) e pelo ácido nitroso (0.06%).Os mulantes morfológicos e auxotróficos obtidos até o momento em Metarhizium anisopliae foram revistos.A wild strain of Metarhizium anisopliae, an entomopathogenic fungus, was submitted to three mutagenic agents: gamma radiation, ultraviolet light and nitrous acid. Survival curves were obtained and mutants were selected using different mutagenic doses which gave 1 to 5% survival. Morphological and auxotrophic mutants were isolated. Morphological mutants were grouped in a class with yellow conidia and other with pale vinaceous conidia as opposed to the green wild type conidia. Auxotrophic mutants had requirements for vitamin and aminoacid biosynthesis. More than 58% of the total auxotrophk mutants required proline/aipnine. Gamma radiation showed to be the most efficient mutagenic agent giving 0.2% of auxotrophk mutants followed by ultraviolet light (0.12%) and nitrous acid (0.06%).The conidial colour and auxotrophk mutants isolated until now from M. anisopliae were reviewed
Magnetoelastic modelling in soft nanocrystalline alloys
Magnetoelastic effects in ultra soft nanocrystalline alloys are investigated theoretically and experimentally. From Hc measurements, extraction of magnetoelastic contribution is carried out using a formalism obtained revisiting random anisotropy model (RAM) in the light of domain walls (DW) displacements, our approach based on theoretical investigations on the way of a reversal of a correlated volume (CV) located in the vicinity of a DW. Modelling of magnetoelastic effects shows that even in perfectly relaxed samples, a magnetoelastic contribution exists due to elastic frustration experienced by a CV during its magnetization reversal. Magnitude of this energy is large enough to drive coercivity of samples featuring grain diameter D around 10 nm, which are of major interest for applications
Numerical comparison of two approaches for the study of phase transitions in small systems
We compare two recently proposed methods for the characterization of phase
transitions in small systems. The validity and usefulness of these approaches
are studied for the case of the q=4 and q=5 Potts model, i.e. systems where a
thermodynamic limit and exact results exist. Guided by this analysis we discuss
then the helix-coil transition in polyalanine, an example of structural
transitions in biological molecules.Comment: 16 pages and 7 figure
Structural analysis of APOB variants, p.(Arg3527Gln), p.(Arg1164Thr) and p.(Gln4494del), causing Familial Hypercholesterolaemia provides novel insights into variant pathogenicity
Free PMC Article: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4672294/Familial hypercholesterolaemia (FH) is an inherited autosomal dominant disorder resulting from defects in the low-density lipoprotein receptor (LDLR), in the apolipoprotein B (APOB) or in the proprotein convertase subtilisin/kexin type 9 (PCSK9) genes. In the majority of the cases FH is caused by mutations occurring within LDLR, while only few mutations in APOB and PCSK9 have been proved to cause disease. p.(Arg3527Gln) was the first mutation in APOB being identified and characterized. Recently two novel pathogenic APOB variants have been described: p.(Arg1164Thr) and p.(Gln4494del) showing impaired LDLR binding capacity, and diminished LDL uptake. The objective of this work was to analyse the structure of p.(Arg1164Thr) and p.(Gln4494del) variants to gain insight into their pathogenicity. Secondary structure of the human ApoB100 has been investigated by infrared spectroscopy (IR) and LDL particle size both by dynamic light scattering (DLS) and electron microscopy. The results show differences in secondary structure and/or in particle size of p.(Arg1164Thr) and p.(Gln4494del) variants compared with wild type. We conclude that these changes underlie the defective binding and uptake of p.(Arg1164Thr) and p.(Gln4494del) variants. Our study reveals that structural studies on pathogenic variants of APOB may provide very useful information to understand their role in FH disease
Indução de mutação visando a redução de altura de planta e resistência às doenças no cultivar de trigo (Triticum aestivum L.) IAC-17
The objective of the present research was to obtain mutants with reduced plant height and resistance to diseases in wheat (Triticum aestivum L.), variety IAC-17, through gamma-irradiation. Seeds were irradiated with gamma-rays (35 krad) and the selection was started in the M2 generation. Three selected lines were compared to the control IAC-17 during three years, in seven trials carried out in several localities under or without irrigation. One mutant line showed significant reduction in plant height, less lodging and increased resistance to powdery mildew (Erysiphe graminis f. sp. tritici) This mutant also showed the same yield, yield components, tolerance to aluminium, cycle and reaction to Helminthosporium sativum, Puccinia graminis f. sp. tritici, P. recondita as the original variety. The results indicated the usefulness of the mutation breeding method to correct defects of simple inherited characters in oustanding commercial varieties.A redução na altura da planta e obtenção de resistência às doenças foi experimentada através da indução de mutação por raios-gama na variedade de trigo (Triticum aestivum L.) IAC-17. Sementes foram irradiadas com 35 krad e a partir da geração M2 iniciou-se a seleção. Três das linhagens selecionadas foram comparadas com o cultivar original IAC-17, durante três anos, em sete ensaios avançados realizados em vários locais, em condição de sequeiro e irrigação. Os resultados demonstraram a obtenção de um mutante que apresentou redução na altura da planta, tendência de sofrer menos acamamento e maior resistência a oídio (Erysiphe graminis f. sp. tritici). As demais características agronômicas avaliadas, tais como produção de grãos e seus componentes, reação ao Helminthosporium sativum, causador da mancha das folhas, reação a Puccinia graminis f. sp. tritici (ferrugem do colmo) e P. recôndita (ferrugem da folha), tolerância a alumínio e ciclo permaneceram inalteradas em relação a IAC-17. Os resultados indicaram a utilidade da indução de mutações por raios gama para a correção de defeitos de caracteres de herança simples em variedades elites
Universality and scaling study of the critical behavior of the two-dimensional Blume-Capel model in short-time dynamics
In this paper we study the short-time behavior of the Blume-Capel model at
the tricritical point as well as along the second order critical line. Dynamic
and static exponents are estimated by exploring scaling relations for the
magnetization and its moments at early stage of the dynamic evolution. Our
estimates for the dynamic exponents, at the tricritical point, are and .Comment: 12 pages, 9 figure
Phylogenetic lineages in the Botryosphaeriaceae
Botryosphaeria is a species-rich genus with a cosmopolitan
distribution, commonly associated with dieback and cankers of woody plants. As
many as 18 anamorph genera have been associated with Botryosphaeria,
most of which have been reduced to synonymy under Diplodia (conidia
mostly ovoid, pigmented, thick-walled), or Fusicoccum (conidia mostly
fusoid, hyaline, thin-walled). However, there are numerous conidial anamorphs
having morphological characteristics intermediate between Diplodia
and Fusicoccum, and there are several records of species outside the
Botryosphaeriaceae that have anamorphs apparently typical of
Botryosphaeria s.str. Recent studies have also linked
Botryosphaeria to species with pigmented, septate ascospores, and
Dothiorella anamorphs, or Fusicoccum anamorphs with
Dichomera synanamorphs. The aim of this study was to employ DNA
sequence data of the 28S rDNA to resolve apparent lineages within the
Botryosphaeriaceae. From these data, 12 clades are recognised. Two of
these lineages clustered outside the Botryosphaeriaceae, namely
Diplodia-like anamorphs occurring on maize, which are best
accommodated in Stenocarpella (Diaporthales), as well as an
unresolved clade including species of
Camarosporium/Microdiplodia. We recognise 10 lineages within
the Botryosphaeriaceae, including an unresolved clade
(Diplodia/Lasiodiplodia/Tiarosporella),
Botryosphaeria s.str. (Fusicoccum anamorphs),
Macrophomina, Neoscytalidium gen. nov.,
Dothidotthia (Dothiorella anamorphs), Neofusicoccum
gen. nov. (Botryosphaeria-like teleomorphs, Dichomera-like
synanamorphs), Pseudofusicoccum gen. nov., Saccharata
(Fusicoccum- and Diplodia-like synanamorphs),
“Botryosphaeria” quercuum
(Diplodia-like anamorph), and Guignardia
(Phyllosticta anamorphs). Separate teleomorph and anamorph names are
not provided for newly introduced genera, even where both morphs are known.
The taxonomy of some clades and isolates (e.g. B. mamane) remains
unresolved due to the absence of ex-type cultures
Departure from the vogel behaviour in the glass transition region-thermally stimulated recovery, creep and dynamic mechanical analysis studies
In this work the study of the dynamics of the segmental motions close to Tg of a poly(methyl methacrylate), PMMA, network was analysed
by distinct mechanical spectroscopy techniques. Three techniques were employed: dynamic mechanical analysis (DMA), creep and
thermally stimulated recovery (TSR). The time–temperature superposition principle was applied to the DMA and creep results, and master
curves were successfully constructed. A change from a Vogel to an Arrhenius behaviour was observed in these results. Above Tg it was found
a distinct temperature dependence for the retardation times calculated from creep and the relaxation times calculated from DMA. This
unexpected behaviour was attributed to the merging of the a and the b relaxations that occurs in PMMA systems. The apparent activation
energies ðEaÞ were also calculated from DMA, creep and TSR experiments. Above Tg the Ea values obtained agreed very well for all the
techniques. In addition, the fragility exhibited by this material was investigated by the mechanical spectroscopy techniques referred above
and by differential scanning calorimetry (DSC). The obtained values of the fragility index m indicated that the PMMA network is a
kinetically fragile system. The thermodynamic manifestation of the fragility was also analysed
COMPARAÇÃO ENTRE FITOTERÁPICOS DE USO TÓPICO NA CICATRIZAÇÃO DE PELE EM EQÜINOS
Foram utilizados seis eqüinos adultos sem raça definida (SRD), com o objetivo de
estudar os aspectos macroscópicos e histopatológicos da cicatrização de pele por segunda intenção,
em feridas provocadas cirurgicamente e tratadas topicamente por fitoterápicos: barbatimão
(Stryphnodendron barbatiman), calêndula (Calendula officinalis) e confrey (Symphytum officinale),
tendo a solução salina como controle das demais. Foram feitas quatro lesões de cada lado da
região lombar, do lado direito destinadas à macroscopia e do lado esquerdo à análise histopatológica.
As lesões foram tratadas diariamente, observando-se a evolução de cada ferida quanto à retração
centrípeta e aspecto macroscópico, até a cicatrização completa. Finalizado o experimento, a análise
estatística não revelou variações significativas no estudo comparativo dos fitoterápicos. As
observações macroscópicas, histopatológica e a retração centrípeta do halo da lesão nos 15 primeiros
dias permitiram concluir que o barbatimão revelou efeito benéfico no processo de cicatrização, seguido
pela calêndula, sendo os resultados do grupo controle superiores ao confrey.
Comparison between phytotherapics on equine wound healing
Abstract
It has been carried out a study on the macroscopic and histopathologic aspects of
equine skin healing by second intention in wounds cirurgically performed and topically treated with
phytotherapics: barbatiman (Stryphnodendrom barbattiman), calendula (Calendula officinalis) and
confrey (Symphytum officinale) and physiological solution as control. Four lesions were performed in
each side of the lumbar area: the ones in the right side for macroscopic observations and the ones
on the left side for histopathologic analysis. The lesions were daily treated with the above mentioned
phytotherapics. Each wounds was observed in regard to its centripetal contraction and macroscopic
aspects until the complete healing. In this model, the statistic analysis did not reveal significant variations
in regard to the comparative effect of the phytoterapics. Macroscopic observations, histopathologic
analysis and wound area centripetal retraction in the first fifteen days displayed a beneficial effect of
barbatiman in the healing process, better than the other treatment groups, followed by calendula.
The results displayed by the control group showed to be superior when compared with confrey
Atomic Dark Matter
We propose that dark matter is dominantly comprised of atomic bound states.
We build a simple model and map the parameter space that results in the early
universe formation of hydrogen-like dark atoms. We find that atomic dark matter
has interesting implications for cosmology as well as direct detection:
Protohalo formation can be suppressed below for weak scale dark matter due to Ion-Radiation interactions in the
dark sector. Moreover, weak-scale dark atoms can accommodate hyperfine
splittings of order 100 \kev, consistent with the inelastic dark matter
interpretation of the DAMA data while naturally evading direct detection
bounds.Comment: 17 pages, 3 figure
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