Simulations of stressosome activation emphasize allosteric interactions between RsbR and RsbT

<p>Abstract</p> <p>Background</p> <p>The stressosome is a bacterial signalling complex that responds to environmental changes by initiating a protein partner switching cascade, which leads to the release of the alternative sigma factor, σ^B. Stress perception increases the phosphorylation of the stressosome sensor protein, RsbR, and the scaffold protein, RsbS, by the protein kinase, RsbT. Subsequent dissociation of RsbT from the stressosome activates the σ^B cascade. However, the sequence of physical events that occur in the stressosome during signal transduction is insufficiently understood.</p> <p>Results</p> <p>Here, we use computational modelling to correlate the structure of the stressosome with the efficiency of the phosphorylation reactions that occur upon activation by stress. In our model, the phosphorylation of any stressosome protein is dependent upon its nearest neighbours and their phosphorylation status. We compare different hypotheses about stressosome activation and find that only the model representing the allosteric activation of the kinase RsbT, by phosphorylated RsbR, qualitatively reproduces the experimental data.</p> <p>Conclusions</p> <p>Our simulations and the associated analysis of published data support the following hypotheses: (i) a simple Boolean model is capable of reproducing stressosome dynamics, (ii) different stressors induce identical stressosome activation patterns, and we also confirm that (i) phosphorylated RsbR activates RsbT, and (ii) the main purpose of RsbX is to dephosphorylate RsbS-P.</p

Propuesta metodológica mediante diseños Box-Behnken para mejorar el rendimiento del análisis conjunto en estudios experimentales de mercado

ResumenEl análisis conjunto es una técnica utilizada para estudiar las preferencias de los consumidores en estudios de mercado. Uno de los aspectos más importantes relacionados con el desarrollo de dicha técnica, se centra en fijar el conjunto de elección que deben evaluar los entrevistados. De forma tradicional, se utilizan diseños factoriales para estimar los valores parciales de los factores. Sin embargo, si el investigador, además, está interesado en estimar las interacciones entre dos o más factores, estos diseños requieren un número tan elevado de alternativas que se hace difícil su evaluación, provocando que los entrevistados no utilicen criterios compensatorios. La utilización de diseños Box-Behnken agrupados en bloques permite reducir el esfuerzo cognitivo de los entrevistados y, a la vez, ajustar un modelo de segundo grado. Este trabajo ilustra, mediante un experimento, el uso y las ventajas de utilizar diseños Box-Behnken en estudios de mercado. Los resultados obtenidos muestran el mayor rendimiento de estos modelos en comparación con los diseños factoriales habituales.AbstractConjoint analysis is a technique used to study consumer preferences in market research. One of the most important issues is to determine the choice set which respondents must assess; usually factorial designs to estimate part-worth factors have been used. But, if the researcher is also interested in estimating two or more factor interactions, factorial designs require such a large number of alternatives that makes their evaluation very difficult, leading respondents to not use compensatory criteria. Using Box-Behnken designs in blocks reduce the cognitive effort made by respondents and, at the same time, it allows fitting a quadratic model. This paper illustrates, through an experiment, the properties and how to use Box-Behnken designs in market research. Results showed a better performance of these models when compared with standard factorial designs

Propuesta metodológica mediante diseños Box-Behnken para mejorar el rendimiento del análisis conjunto en estudios experimentales de mercado

El análisis conjunto es una técnica utilizada para estudiar las preferencias de los consumidores en estudios de mercado. Uno de los aspectos más importantes relacionados con el desarrollo de dicha técnica, se centra en fijar el conjunto de elección que deben evaluar los entrevistados. De forma tradicional, se utilizan diseños factoriales para estimar los valores parciales de los factores. Sin embargo, si el investigador, además, está interesado en estimar las interacciones entre dos o más factores, estos diseños requieren un número tan elevado de alternativas que se hace difícil su evaluación, provocando que los entrevistados no utilicen criterios compensatorios. La utilización de diseños Box-Behnken agrupados en bloques permite reducir el esfuerzo cognitivo de los entrevistados y, a la vez, ajustar un modelo de segundo grado. Este trabajo ilustra, mediante un experimento, el uso y las ventajas de utilizar diseños Box-Behnken en estudios de mercado. Los resultados obtenidos muestran el mayor rendimiento de estos modelos en comparación con los diseños factoriales habituales

Using response surface methodology to optimize factors in conjoint experiments

Identifying relevant attributes or variables is the first objective of conjoint analysis in market research. As a result of technological development, today it is common for researchers to use sequential experimental methods for adjusting design factors in successive phases. In particular, in the field of consumer behaviour these models are used predominantly for assessing subjective perceptions relating to the attributes of different products with high sensorial components (e.g. food, drinks and personal care products) ..

El papel del valor de la marca propia en la composición del surtido del minorista: su influencia sobre la lealtad al establecimiento

El objetivo del presente trabajo es conocer la influencia del valor de la MdD, en diferentes tipos de surtido, sobre la lealtad de los consumidores hacia el establecimiento, tanto para una categoría de producto como para la cesta de la compra. Para ello, consideramos surtidos con diferente tamaño y estructura (solo MdD y mixtos) y desarrollamos un experimento online con una muestra de 1.400 consumidores en España. A partir de un análisis ANOVA, los resultados solo muestran diferencias significativas en surtidos mixtos donde la MF de alto valor tiene poco peso, no encontrándose diferencias significativas en surtidos con solo MdD, ni en surtidos mixtos con mayor proporción de MF de alto valor. Estos resultados sugieren diferentes recomendaciones para los minoristas, dependiendo del tipo de surtido por el que optenThe objective of this work is to know the influence of the PL equity, in different structures of the assortment, on the consumer’s loyalty towards the store, for both a product category and the shopping basket. Thus, we consider assortments with different sizes and composition (PL-only and mixed) and develop an online experiment with a sample of 1,400 consumers in Spain. Through an ANOVA analysis, the results only show significant differences in mixed assortments where NBs high equity represent a low ratio, not finding significant differences in PL-only assortments, nor in mixed assortments with a higher ratio of NBs high equity. These results suggest different suggestions for retailers, depending on the type of assortmen

Quantitative isotope-dilution high-resolution-mass-apectrometry analysis of multiple intracellular metabolites in Clostridium autoethanogenum with uniformly 13C-labeled standards derived from Spirulina

We have investigated the applicability of commercially available lyophilized spirulina (Arthrospira platensis), a microorganism uniformly labeled with 13C, as a readily accessible source of multiple 13C-labeled metabolites suitable as internal standards for the quantitative determination of intracellular bacterial metabolites. Metabolites of interest were analyzed by hydrophilic-interaction liquid chromatography coupled with high-resolution mass spectrometry. Multiple internal standards obtained from uniformly (U)-13C-labeled extracts from spirulina were used to enable isotope-dilution mass spectrometry (IDMS) in the identification and quantification of intracellular metabolites. Extraction of the intracellular metabolites of Clostridium autoethanogenum using 2:1:1 chloroform/methanol/water was found to be the optimal method in comparison with freeze–thaw, homogenization, and sonication methods. The limits of quantification were ≤1 μM with excellent linearity for all of the calibration curves (R2 ≥ 0.99) for 74 metabolites. The precision and accuracy were found to be within relative standard deviations (RSDs) of 15% for 49 of the metabolites and within RSDs of 20% for all of the metabolites. The method was applied to study the effects of feeding different levels of carbon monoxide (as a carbon source) on the central metabolism and Wood–Ljungdahl pathway of C. autoethanogenum grown in continuous culture over 35 days. Using LC-IDMS with U-13C spirulina allowed the successful quantification of 52 metabolites in the samples, including amino acids, carboxylic acids, sugar phosphates, purines, and pyrimidines. The method provided absolute quantitative data on intracellular metabolites that was suitable for computational modeling to understand and optimize the C. autoethanogenum metabolic pathways active in gas fermentation

The role of online brand community engagement on consumer-brand relationship

The purpose of this study is to analyze the effects of online brand community (OBC) engagement on strategic aspects for the brand supporting the community. A total of 628 valid responses were collected through a self-administered questionnaire. The authors tested the proposed model using structural equation modeling. The results show that OBC engagement directly favors par-ticipation in the community, willingness to co-create with the brand and positive WOM; it also has an indirect positive influence on brand loyalty. At the same time, OBC engagement is directly influenced by OBC identification and, through this, indirectly influenced by brand identification. Likewise, brand trust directly influences brand co-creation, loyalty and positive WOM. However, OBC participation has been shown to have no significant effect on brand co-creation and positive WOM

Piperaquine Pharmacokinetic and Pharmacodynamic Profiles in Healthy Volunteers of Papua New Guinea after Administration of Three-Monthly Doses of Dihydroartemisinin–Piperaquine

Mass drug administration (MDA) with monthly dihydroartemisinin-piperaquine (DHA-PQP) appears useful in malaria control and elimination strategies. Determining the relationship between consecutive piperaquine phosphate (PQP) exposure and its impact on QT interval prolongation is a key safety consideration for MDA campaigns

Large-Scale Spatial Dynamics of Intertidal Mussel (<i>Mytilus edulis L.</i>) Bed Coverage in the German and Dutch Wadden Sea

Intertidal blue mussel beds are important for the functioning and community composition of coastal ecosystems. Modeling spatial dynamics of intertidal mussel beds is complicated because suitable habitat is spatially heterogeneously distributed and recruitment and loss are hard to predict. To get insight into the main determinants of dispersion, growth and loss of intertidal mussel beds, we analyzed spatial distributions and growth patterns in the German and Dutch Wadden Sea. We considered yearly distributions of adult intertidal mussel beds from 36 connected tidal basins between 1999 and 2010 and for the period 1968-1976. We found that in both periods the highest coverage of tidal flats by mussel beds occurs in the sheltered basins in the southern Wadden Sea. We used a stochastic growth model to investigate the effects of density dependence, winter temperature and storminess on changes in mussel bed coverage between 1999 and 2010. In contrast to expectation, we found no evidence that cold winters consistently induced events of synchronous population growth, nor did we find strong evidence for increased removal of adult mussel beds after stormy winter seasons. However, we did find synchronic growth within groups of proximate tidal basins and that synchrony between distant groups is mainly low or negative. Because the boundaries between synchronic groups are located near river mouths and in areas lacking suitable mussel bed habitat, we suggest that the metapopulation is under the control of larval dispersal conditions. Our study demonstrates the importance of moving from simple habitat suitability models to models that incorporate metapopulation processes to understand spatial dynamics of mussel beds. The spatio-dynamic structure revealed in this paper will be instrumental for that purpose