Induction of neutralizing antibodies in mice immunized with an amino-terminal polypeptide of Streptococcus mutans P1 protein produced by a recombinant Bacillus subtilis strain

The oral pathogen Streptococcus mutans expresses a surface protein, P1, which interacts with the salivary pellicle on the tooth surface or with fluid-phase saliva, resulting in bacterial adhesion or aggregation, respectively. P1 is a target of protective immunity. Its N-terminal region has been associated with adhesion and aggregation functions and contains epitopes recognized by efficacious antibodies. In this study, we used Bacillus subtilis, a gram-positive expression host, to produce a recombinant N-terminal polypeptide of P1 (P1(39-512)) derived from the S. mutans strain UA159. Purified P1(39-512) reacted with an anti-full-length P1 antiserum as well as one raised against intact S. mutans cells, indicating preserved antigenicity. Immunization of mice with soluble and heat-denatured P1(39-512) induced antibodies that reacted specifically with native P1 on the surface of S. mutans cells. The anti-P1(39-512) antiserum was as effective at blocking saliva-mediated aggregation of S. mutans cells and better at blocking bacterial adhesion to saliva-coated plastic surfaces compared with the anti-full-length P1 antiserum. In addition, adsorption of the anti-P1 antiserum with P1(39-512) eliminated its ability to block the adhesion of S. mutans cells to abiotic surfaces. The present results indicate that P1(39-512), expressed and purified from a recombinant B. subtilis strain, maintains important immunological features of the native protein and represents an additional tool for the development of anticaries vaccines.

Phylogenetic analysis of a near-full-length sequence of an erythrovirus genotype 3 strain isolated in Brazil

Human parvovirus B19 is the only member of the genus Erythrovirus that causes human disease. Recent findings of several strains with considerable sequence divergence from B19 have suggested a new classification for parvovirus genotypes as 1 (B19), 2 (A-6 and LaLi) and 3 (V9). In their overall DNA sequence, the three genotypes differ by similar to 10%. Here, we report the isolation of a genotype-3-related strain named BR543 during a prospective study conducted in Sao Paulo, Brazil. Analysis of the nearly full-length genome sequence of BR543 indicates that this B19 variant sequence clusters with Gh2768, a strain from Ghana belonging to subtype 3b, and showed mostly synonymous substitutions.

Proteins and Peptidases from Conidia and Mycelia of Scedosporium apiospermum Strain HLPB

The conidia-mycelia transformation is an essential step during the life cycle of the fungal human pathogens of the Pseudallescheria boydii complex. In the present study, we have analyzed the protein and peptidase profiles in two distinct morphological stages, conidia and mycelia, of Scedosporium apiospermum sensu stricto. Proteins synthesized by the mycelia, migrating at the ranges of 62-48 and 22-18 kDa, were not detected from the conidial extract. Conidia produced a single cellular peptidase of 28 kDa able to digest copolymerized albumin, while mycelia yielded 6 distinct peptidases ranging from 90 to 28 kDa. All proteolytic enzymes were active at acidic pH and fully inhibited by 1,10-phenanthroline, characterizing these activities as metallo-type peptidases. Quantitative peptidase assay, using soluble albumin, showed a high metallopeptidase production in mycelial cells in comparison with conidia. The regulated expression of proteins and peptidases in different morphological stages of S. apiospermum represents a potential target for isolation of stage-specific markers for biochemical and immunological analysis.

Selection of an ivermectin-resistant strain of Rhipicephalus microplus (Acari: Ixodidae) in Brazil

Resistance to ivermectin (IVM) in field Populations of Rhipicephalus microplus of Brazil has been observed since 2001 In this work, four selection methods (infestations with: (I) IVM-treated larvae, (2) larvae from IVM-treated adult female ticks, (3) larvae from IVM-treated adult female ticks on an IVM-treated host, and (4) larvae obtained from W-treated females that produced eggs with a high eclosion rate) were used oil a field population with an initial ivermectin (IVM) resistance ratio at LC50 (RR50) of 1 37 with the objective to obtain experimentally a highly-resistant strain After ten generations, using these methods combined, the final RR50 was 8 06 This work shows for the first time that it was possible to increase IVM resistance in R. microplus in laboratory conditions. The establishment of a drug resistant R microplus strain is a fundamental first step for further research into the mechanisms of ivermectin-resistance in R. microplus and potentially methods to control this resistance (C) 2009 Elsevier B V All rights reserved

Influence of quantum-dots density on average in-plane strain of optoelectronic devices investigated by high-resolution X-ray diffraction

High-resolution X-ray diffractometry is used to probe the nature of a diffraction-peak broadening previously noticed in quantum dots (QDs) systems with freestanding InAs islands on top of GaAs (001) substrates [Freitas et al., Phys. Status Solidi (A) 204, 2548 (2007)]. The procedure is hence extended to further investigate the capping process of InAs/GaAs QDs. A direct correlation is established between QDs growth rates and misorientation of lattice-planes at the samples surfaces. This effect provides an alternative too] for studying average strain fields on QDs systems in standard triple axis diffractometers running on X-ray tube sources, which are much more common than synchrotron facilities. (C) 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Inactivation of formyltransferase (wbkC) gene generates a Brucella abortus rough strain that is attenuated in macrophages and in mice

Rough mutants of Brucella abortus were generated by disruption of wbkC gene which encodes the formyltransferase enzyme involved in LPS biosynthesis. In bone marrow-derived macrophages the B. abortus Delta wbkC mutants were attenuated, could not reach a replicative niche and induced higher levels of IL-12 and TNF-alpha when compared to parental smooth strains. Additionally, mutants exhibited attenuation in vivo in C57BL/6 and interferon regulatory factor-1 knockout mice. Delta wbkC mutant strains induced lower protective immunity in C56BL/6 than smooth vaccine S19 but similar to rough vaccine RB51. Finally, we demonstrated that Brucella wbkC is critical for LPS biosynthesis and full bacterial virulence. (C) 2010 Elsevier Ltd. All rights reserved.

Lipopeptides Produced by a Soil Bacillus Megaterium Strain

A soil microorganism identified as Bacillum megaterium was found to produce several antibiotics substances after growth for 20 h at 37A degrees C in a mineral culture medium. Analysis both by electron spray ionization (ESI) and matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry (MS) identified these substances as lipopeptides. Predominant peaks at m/z 1,041 and m/z 1,065 revealed ions which are compatible with surfactins and lichenysins, respectively. Two other ions m/z 1,057 and m/z 1,464 were further studied by collision-induced dissociation (CID) unveiling an iturin A at the first and fengycins A and B at the second m/z peaks. The CID spectrum of the m/z 1,464 ion also suggests the existence of fengycins A and B variants in which Ile was changed to Val in the position 10 of the peptide moiety. Raw mixtures of all these compounds were also assayed for antibiotic features. The data enlighten the unusual diversity of the lipopeptide mixture produced by a sole Bacillus species.

Ring strain in boroxine rings: computational and experimental considerations

B3LYP/6-311+G(d) calculations indicate that (HBO)₃ (4) and (HBO)₄ (5) possess (zero-point energy corrected) strain enthalpies of 11.4 and 31.6 kJ mol⁻¹, respectively. The absence of eight-membered (RBO)₄ rings is attributed to a combination of ring strain and the lability of the B---O bond. The synthesis, characterization and molecular structure of (PhBO)₃·pyridine (1) are described and chemical phenomena related to the addition of amines to triorganoboroxine rings are rationalized in terms of relief of ring strain in 4.

The job strain model is enough for managers : no augmentation needed

This paper reports on the results of a study aimed at identifying the relative influence of generic and job-specific stressors experienced by a cohort of Australian managers. The results of a regression analysis revealed that both the generic components of the job strain model (JSM) and job-specific stressors were predictive of the strain experienced by participants. However, when looking at the total amount of variance that is explained by the predictor variables, the combined influence of job demand, job control and social support contributed 98 per cent of the explained variance in job satisfaction and 90 per cent of the variance in psychological health. The large amount of variance explained by the JSM suggests that this model provides an accurate account of the work characteristics that contribute to the strain experienced by managers and no augmentation is needed.

Prediction of stress-strain behaviors in steels using an integrated constitutive, FEM and ANN model

Austenitic steels with a carbon content of 0.0037 to 0.79 wt% C are torsion tested and modeled using a physically based constitutive model and an Integrated Phenomenological and Artificial neural Network (IPANN) model. The prediction of both the constitutive and IPANN models on steel 0.017 wt% C is then evaluated using a finite element (FEM) code ABAQUS with different reduction in the thickness after rolling through one roll stand. It is found that during the rolling process, the prediction accuracy of the reaction force from FEM simulation for both constitutive and IPANN models depends on the strain achieved (average reduction in thickness). By integrating FEM into IPANN model and introducing the product of strain and stress as an input of the ANN model, the accuracy of this integrated FEM and IPANN model is higher than either the constitutive or IPANN model.

Comparison of brood size and juvenile weight between a blue strain and normal-coloured strains of the Australian freshwater crayfish Cherax Destructor Clark (Decapoda: Parastacidae)

A blue strain of the yabby Cherax destructor albidus was compared to two normal-coloured strains of C. d. destructor and C. d. albidus for brood size and juvenile weight. Reproductive performance of the blue strain was found to be significantly poorer than the two normal-coloured strains. Similarly, the weight of newly independent juveniles was also found to be significantly lower for the blue strain. No differences were detected between the two normal-coloured strains in either reproductive performance or size of newly independent juveniles. The phenotypic differences between the blue strain and normal-coloured strains are most likely genetic. However, further studies are needed to investigate whether these differences are due to pleiotropy or inbreeding effects.

Predictors of the strain experienced by professional Australian footballers

The purpose of this model was to examine whether both the generic dimensions of the Job stress model (JSM) and job-specific stressors would be predictive of the strain experienced by professional Australian footballers. A football-specific stressor scale questionnaire was distributed and football specific stressors and their impact were identified.

The evolution of ultrafine ferrite formation through dynamic strain-induced transformation

Hot torsion testing of a C–Mn–V steel was used to study the evolution of  ultrafine ferrite (UFF) formation by dynamic strain-induced transformation (DSIT) in conjunction with air-cooling for two prior austenite grain sizes. This study evaluated not only the evolution of DSIT ferrite during straining, but also the grain growth behaviour of DSIT ferrite grains during post-deformation cooling. For both austenite grain sizes, the DSIT ferrite initially nucleated on/or near prior austenite grain boundaries at an early stage of transformation followed by the grain interiors. The prior austenite grain size affected the distribution of DSIT ferrite nucleation sites at an early stage of transformation and the subsequent coarsening behaviour of the grain boundary (GB) and the intragranular ferrite (IG) grains during post-deformation cooling. For the fine prior austenite grain size, the distribution of DSIT ferrite grains was more homogenous compared with the coarse austenite and the coarsening occurred not only in the GB ferrite grains but also in the IG ferrite grains. However, the ferrite coarsening mostly occurred for the IG ferrite rather than the GB ferrite grains in the coarse austenite. The result suggests that normal grain growth occurred during the overall transformation in the GB ferrite grains for the coarse initial austenite grain size.

Formation of ultrafine grained microstructures in steel through strain induced transformation during single pass hot rolling

In the present study, wedge-shape samples were used to study the effect of strain induced transformation on the formation of ultrafine grained structures in steel by single pass rolling. The results showed two different transition strains for bainite formation and ultrafine ferrite (UFF) formation in the surface layer of strip at reductions of 40% and 70%, respectively, in a plain carbon steel. The bainitic microstructure formed by strain induced bainitic transformation during single pass rolling was also very fine. The evolution of UFF formation in the surface layer showed that ferrite coarsening is significantly reduced through strain induced transformation combined with rapid cooling in comparison with the centre of the strip. In the surface, the ferrite coarsening mostly occurred for intragranular nucleated grains (IG) rather than grain boundary (GB) ferrite grains. The results suggest that normal grain growth occurred during overall transformation in the GB ferrite grains. In the centre of the strip, there was significantly more coarsening of ferrite grains nucleated on the prior austenite grain boundaries.