Quantitavive spectroscopy

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Shear flow induced transition from liquid-crystalline to polymer behavior in side-chain liquid crystal polymers

International audienceWe determine the structure and conformation of side-chain liquid-crystalline polymers subjected to shear flow in the vicinity of the smectic phase by neutron scattering on the velocity gradient plane. Below the nematic-smectic transition we observe a typical liquid-crystal behavior; the smectic layers slide, leading to a main-chain elongation parallel to the velocity direction. In contrast, a shear applied above the transition induces a tilted main-chain conformation which is typical for polymer behavior

Redefining the expressed prototype SICAvar gene involved in Plasmodium knowlesi antigenic variation

<p>Abstract</p> <p>Background</p> <p>The <it>SICAvar </it>gene family, expressed at the surface of infected erythrocytes, is critical for antigenic variation in <it>Plasmodium knowlesi</it>. When this family was discovered, a prototypic <it>SICAvar </it>gene was characterized and defined by a 10-exon structure. The predicted 205-kDa protein lacked a convincing signal peptide, but included a series of variable cysteine-rich modules, a transmembrane domain encoded by the penultimate exon, and a cytoplasmic domain encoded by the final highly conserved exon. The <it>205 SICAvar </it>gene and its family with up to 108 possible family members, was identified prior to the sequencing of the <it>P. knowlesi </it>genome. However, in the published <it>P. knowlesi </it>database this gene remains disjointed in five fragments. This study addresses a number of structural and functional questions that are critical for understanding <it>SICAvar </it>gene expression.</p> <p>Methods</p> <p>Database mining, bioinformatics, and traditional genomic and post-genomic experimental methods including proteomic technologies are used here to confirm the genomic context and expressed structure of the prototype <it>205 SICAvar </it>gene.</p> <p><b>Results</b></p> <p>This study reveals that the <it>205 SICAvar </it>gene reported previously to have a 10-exon expressed gene structure has, in fact, 12 exons, with an unusually large and repeat-laden intron separating two newly defined upstream exons and the <it>bona fide </it>5'UTR from the remainder of the gene sequence. The initial exon encodes a PEXEL motif, which may function to localize the SICA protein in the infected erythrocyte membrane. This newly defined start of the 205 <it>SICAvar </it>sequence is positioned on chromosome 5, over 340 kb upstream from the rest of the telomerically positioned <it>SICAvar </it>gene sequence in the published genome assembly. This study, however, verifies the continuity of these sequences, a 9.5 kb transcript, and provides evidence that the 205 <it>SICAvar </it>gene is located centrally on chromosome 5.</p> <p>Conclusion</p> <p>The prototype <it>205 SICAvar </it>gene has been redefined to have a 12-exon structure. These data are important because they 1) address questions raised in the <it>P. knowlesi </it>genome database regarding <it>SICAvar </it>gene fragments, numbers and structures, 2) show that this prototype gene encodes a PEXEL motif, 3) emphasize the need for further refinement of the <it>P. knowlesi </it>genome data, and 4) retrospectively, provide evidence for recombination within centrally located <it>SICAvar </it>sequences.</p

A small-angle neutron scattering study of sodium dodecyl sulfate-poly(propylene oxide) methacrylate mixed micelles

cited By 3International audienceMixed micelle of protonated or deuterated sodium dodecyl sulfate (SDS and SDSd25, respectively) and poly(propylene oxide) methacrylate (PPOMA) are studied by small-angle neutron scattering (SANS). In all the cases the scattering curves exhibit a peak whose position changes with the composition of the system. The main parameters which characterize mixed micelles, i.e., aggregation numbers of SDS and PPOMA, geometrical dimensions of the micelles and degree of ionisation are evaluated from the analysis of the SANS curves. The position qmax of the correlation peak can be related to the average aggregation numbers of SDS-PPOMA and SDSd25-PPOMA mixed micelles. It is found that the aggregation number of SDS decreases upon increasing the weight ratio PPOMA/SDS (or SDSd25). The isotopic combination, which uses the "contrast effect" between the two micellar systems, has allowed us to determine the mixed micelle composition. Finally, the SANS curves were adjusted using the RMSA for the structure factor S(q) of charged spherical particles and the form factor P(q) of spherical core-shell particle. This analysis confirms the particular core-shell structure of the SDS-PPOMA mixed micelle, i.e., a SDS "core" micelle surrounded by the shell formed by PPOMA macromonomers. The structural parameters of mixed micelles obtained from the analysis of the SANS data are in good agreement with those determined previously by conductimetry and fluorescence studies. © 2005 Elsevier Inc. All rights reserved

Performance modeling of ultraviolet Raman lidar systems for daytime profiling of atmospheric water vapor

We describe preliminary results from a comprehensive computer model developed to guide optimization of a Raman lidar system for measuring daytime profiles of atmospheric water vapor, emphasizing an ultraviolet, solar-blind approach

Serologic and cytokine signatures in children with multisystem inflammatory syndrome and coronavirus disease 2019

Background: The serologic and cytokine responses of children hospitalized with multisystem inflammatory syndrome (MIS-C) vs coronavirus disease 2019 (COVID-19) are poorly understood. Methods: We performed a prospective, multicenter, cross-sectional study of hospitalized children who met the Centers for Disease Control and Prevention case definition for MIS-C (n = 118), acute COVID-19 (n = 88), or contemporaneous healthy controls (n = 24). We measured severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike receptor-binding domain (RBD) immunoglobulin G (IgG) titers and cytokine concentrations in patients and performed multivariable analysis to determine cytokine signatures associated with MIS-C. We also measured nucleocapsid IgG and convalescent RBD IgG in subsets of patients. Results: Children with MIS-C had significantly higher SARS-CoV-2 RBD IgG than children with acute COVID-19 (median, 2783 vs 146; Conclusions: MIS-C was associated with high titers of SARS-CoV-2 RBD IgG antibodies and acute hypercytokinemia with IL-6, IL-10, IL-17A, and IFN-γ

A Positive Relationship Between Religious Faith and Forgiveness: Faith in the Absence of Data?

Religious faith and beliefs appear to play an important role in the lives of many individuals and are the topic of much research. The present study investigated the relationship between religious faith and forgiveness in a sample (n = 196) of college students. Students were asked to complete the Heartland Forgiveness Scale and the Santa Clara Strength of Religious Faith Questionnaire. Analyses of scores on both measures revealed a positive, significant correlation between these constructs, suggesting that there is a meaningful relationship between religious faith and the tendency to forgive. Implications and directions for further research are discussed

The Bioinformatics Open Source Conference (BOSC) 2013

Contact: [email protected]