377 research outputs found
Resposta funcional de Telenomus remus (Hymenoptera: Scelionidae) com diferentes densidades de ovos de Spodoptera frugiperda (Lepidoptera: Noctuidae).
Estudou-se o efeito de diferentes densidades de ovos da lagarta Spodoptera frugiperda Smith sobre o parasitismo do parasitóide de ovos Telenomus remus Nixon. As densidades de 40,50,60,70 e 80 ovos, com até 24 horas de idade, foram submetidos ao parasitismo por fêmeas de T. remus, durante 24 horas. A relação linear crescente de adultos de T. remus emergidos e da razão sexual com o aumento da densidade de ovos da lagarta demonstrou resposta funcional (tipo I) e indica aspecto funcional na dinâmica parasitóide - presa em relação a densidade de presas e o número de presas atacadas. A percentagem de eclosão dos ovos parasitados (viabilidade) demonstrou resposta funcional sigmóide com maior percentagem de eclosão de T. remus na densidade de 60 ovos indicando ser a melhor densidade para utilização em cartelas ofertadas nas criações massais
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Syk-dependent Phosphorylation of CLEC-2: A Novel Mechanism of Hem-Immunoreceptor Tyrosine-Based Activation Motif Signaling
The C-type lectin-like receptor CLEC-2 signals via phosphorylation of a single cytoplasmic YXXL sequence known as a hem-immunoreceptor tyrosine-based activation motif (hemITAM). In this study, we show that phosphorylation of CLEC-2 by the snake toxin rhodocytin is abolished in the absence of the tyrosine kinase Syk but is not altered in the absence of the major platelet Src family kinases, Fyn, Lyn, and Src, or the tyrosine phosphatase CD148, which regulates the basal activity of Src family kinases. Further, phosphorylation of CLEC-2 by rhodocytin is not altered in the presence of the Src family kinase inhibitor PP2, even though PLCγ2 phosphorylation and platelet activation are abolished. A similar dependence of phosphorylation of CLEC-2 on Syk is also seen in response to stimulation by an IgG mAb to CLEC-2, although interestingly CLEC-2 phosphorylation is also reduced in the absence of Lyn. These results provide the first definitive evidence that Syk mediates phosphorylation of the CLEC-2 hemITAM receptor with Src family kinases playing a critical role further downstream through the regulation of Syk and other effector proteins, providing a new paradigm in signaling by YXXL-containing receptors
Atypical Non-H2S-Producing Monophasic Salmonella Typhimurium ST3478 Strains from Chicken Meat at Processing Stage Are Adapted to Diverse Stresses
Poultry products are still an important cause of Salmonella infections worldwide, with an increasingly reported expansion of less-frequent serotypes or atypical strains that are frequently multidrug-resistant. Nevertheless, the ability of Salmonella to survive antimicrobials promoted in the context of antibiotic reducing/replacing and farming rethinking (e.g., organic acids and copper in feed/biocides) has been scarcely explored. We investigated Salmonella occurrence (conventional and molecular assays) among chicken meat at the processing stage (n = 53 batches/29 farms) and characterized their tolerance to diverse stress factors (antibiotics, copper, acid pH, and peracetic acid). Whole-genome sequencing was used to assess adaptive features and to perform comparative analysis. We found a low Salmonella occurrence (4%) and identified S. Enteritidis/ST11 plus atypical non-H2S-producing S. 1,4,[5],12:i:-/ST3478. The ST3478 presented the ability to grow under diverse stresses (antibiotics, copper, and acid-pH). Comparative genomics among ST3478 isolates showed similar antibiotic/metal resistance gene repertoires and identical nonsense phsA thiosulfate reductase mutations (related to H2S-negative phenotype), besides their close phylogenetic relationship by cgMLST and SNPs. This study alerts for the ongoing national and international spread of an emerging monophasic Salmonella Typhimurium clonal lineage with an enlarged ability to survive to antimicrobials/biocides commonly used in poultry production, being unnoticed by conventional Salmonella detection approaches due to an atypical non-H2S-producing phenotype
Enhancement of the Magnetocaloric Effect in Geometrically Frustrated Cluster Spin Glass Systems
In this work, we theoretically demonstrate that a strong enhancement of the
Magnetocaloric Effect is achieved in geometrically frustrated cluster
spin-glass systems just above the freezing temperature. We consider a network
of clusters interacting randomly which have triangular structure composed of
Ising spins interacting antiferromagnetically. The intercluster disorder
problem is treated using a cluster spin glass mean-field theory, which allows
exact solution of the disordered problem. The intracluster part can be solved
using exact enumeration. The coupling between the inter and intracluster
problem incorporates the interplay between effects coming from geometric
frustration and disorder. As a result, it is shown that there is the onset of
cluster spin glass phase even with very weak disorder. Remarkably, it is
exactly within a range of very weak disorder and small magnetic field that is
observed the strongest isothermal release of entropy.Comment: 10 pages, 7 figures. Provisionally accepted in Journal of Physics:
Condensed Matte
The effects of varying colour-luminosity relations on supernova science
The success of Type Ia supernova (SN Ia) distance standardisation for
cosmology relies on a single global linear relationship between their peak
luminosity and colour, the parameter. However, there are several pieces
of evidence and physical reasons to believe that this relation is not universal
and may change within different subgroups, or even among individual objects. In
this work, we allow to vary among subpopulations with different
observed properties in the cosmological fits. Although the inferred
cosmological parameters are consistent with previous studies that assume a
single colour-luminosity relation, we find that the SN data favour nonuniversal
distributions of when split according to SN colour and/or host-galaxy
mass. For galaxy mass, we obtain a -step relation in which low
values occur in more massive galaxies, a trend that can be explained by
differing dust reddening laws for two types of environments. For colour, we
find that bluer/redder SNe Ia are consistent with a lower/larger . This
trend is explained with being a combination of a low intrinsic
colour-luminosity relation dominant in bluer SNe and a higher extrinsic
reddening relation dominant at redder colours. The host galaxy mass-step
correction always provides better distance calibration, regardless of the
multiple approaches, and we suggest that it may come from a difference
in intrinsic colour-luminosity properties of SNe Ia in two types of
environments. Additionally, we find that blue SNe in low-mass environments are
better standard candles than the others.Comment: 11 pages, 7 figures, 2 tables. Accepted in MNRA
Manejo das forrageiras dos gêneros Brachiaria e Panicum consorciadas com o milho em sistemas de Integração Lavoura-Pecuária.
bitstream/CNPMS-2010/22387/1/Circ-130.pd
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