rac-3,9-Bis(3-chloro­phen­yl)-2,4,8,10-tetra­oxaspiro­[5.5]undeca­ne

In the title compound, C19H18Cl2O4, the two non-planar six-membered heterocycles passing through the spiro-C atom both adopt chair conformations, and the dihedral angle between the two benzene rings is 7.2 (1)°. In the crystal, the enanti­omers with R and S configurations are generated by the symmetry elements of the centrosymmetric space group, forming a racemic crystal. Inter­molecular C—H⋯π and weak C—H⋯O inter­actions link the mol­ecules in the crystal structure

Fast Computation of Single Scattering in Participating Media with Refractive Boundaries using Frequency Analysis

International audienceMany materials combine a refractive boundary and a participating media on the interior. If the material has a low opacity, single scattering effects dominate in its appearance. Refraction at the boundary concentrates the incoming light, resulting in an important phenomenon called volume caustics. This phenomenon is hard to simulate. Previous methods used point-based light transport, but attributed point samples inefficiently, resulting in long computation time. In this paper, we use frequency analysis of light transport to allocate point samples efficiently. Our method works in two steps: in the first step, we compute volume samples along with their covariance matrices, encoding the illumination frequency content in a compact way. In the rendering step, we use the covariance matrices to compute the kernel size for each volume sample: small kernel for high-frequency single scattering, large kernel for lower frequencies. Our algorithm computes volume caustics with fewer volume samples, with no loss of quality. Our method is both faster and uses less memory than the original method. It is roughly twice as fast and uses one fifth of the memory. The extra cost of computing covariance matrices for frequency information is negligible

Fabrication and Thermoelectric Properties of Graphene/ Bi

Graphene/Bi2Te3 thermoelectric materials were prepared by spark plasma sintering (SPS) using hydrothermal synthesis of the powders as starting materials. The X-ray diffraction (XRD) and field emission scanning electron microscope (FE-SEM) were used to investigate the phase composition and microstructure of the as-prepared materials. Electrical resistivity, Seebeck coefficient, and thermal conductivity measurement were applied to analyze the thermoelectric properties. The effect of graphene on the performance of the thermoelectric materials was studied. The results showed that the maximum dimensionless figure of merit of the graphene/Bi2Te3 composite with 0.2 vol.% graphene was obtained at testing temperature 475 K, 31% higher than the pure Bi2Te3

Harpin-induced expression and transgenic overexpression of the phloem protein gene AtPP2-A1 in Arabidopsis repress phloem feeding of the green peach aphid Myzus persicae

<p>Abstract</p> <p>Background</p> <p>Treatment of plants with HrpN_Ea, a protein of harpin group produced by Gram-negative plant pathogenic bacteria, induces plant resistance to insect herbivores, including the green peach aphid <it>Myzus persicae</it>, a generalist phloem-feeding insect. Under attacks by phloem-feeding insects, plants defend themselves using the phloem-based defense mechanism, which is supposed to involve the phloem protein 2 (PP2), one of the most abundant proteins in the phloem sap. The purpose of this study was to obtain genetic evidence for the function of the <it>Arabidopsis thaliana </it>(Arabidopsis) PP2-encoding gene <it>AtPP2-A1 </it>in resistance to <it>M. persicae </it>when the plant was treated with HrpN_Eaand after the plant was transformed with <it>AtPP2-A1</it>.</p> <p>Results</p> <p>The electrical penetration graph technique was used to visualize the phloem-feeding activities of apterous agamic <it>M. persicae </it>females on leaves of Arabidopsis plants treated with HrpN_Eaand an inactive protein control, respectively. A repression of phloem feeding was induced by HrpN_Eain wild-type (WT) Arabidopsis but not in <it>atpp2-a1</it>/E/142, the plant mutant that had a defect in the <it>AtPP2-A1 </it>gene, the most HrpN_Ea-responsive of 30 <it>AtPP2 </it>genes. In WT rather than <it>atpp2-a1</it>/E/142, the deterrent effect of HrpN_Eatreatment on the phloem-feeding activity accompanied an enhancement of <it>AtPP2-A1 </it>expression. In PP2OETAt (<it>AtPP2-A1</it>-overexpression transgenic <it>Arabidopsis thaliana</it>) plants, abundant amounts of the <it>AtPP2-A1 </it>gene transcript were detected in different organs, including leaves, stems, calyces, and petals. All these organs had a deterrent effect on the phloem-feeding activity compared with the same organs of the transgenic control plant. When a large-scale aphid population was monitored for 24 hours, there was a significant decrease in the number of aphids that colonized leaves of HrpN_Ea-treated WT and PP2OETAt plants, respectively, compared with control plants.</p> <p>Conclusions</p> <p>The repression in phloem-feeding activities of <it>M. persicae </it>as a result of <it>AtPP2-A1 </it>overexpression, and as a deterrent effect of HrpN_Eatreatment in WT Arabidopsis rather than the <it>atpp2-a1</it>/E/142 mutant suggest that <it>AtPP2-A1 </it>plays a role in plant resistance to the insect, particularly at the phloem-feeding stage. The accompanied change of aphid population in leaf colonies suggests that the function of <it>AtPP2-A1 </it>is related to colonization of the plant.</p

Dynamic placement of the linker histone H1 associated with nucleosome arrangement and gene transcription in early Drosophila embryonic development

The linker histone H1 is critical to maintenance of higher-order chromatin structures and to gene expression regulation. However, H1 dynamics and its functions in embryonic development remain unresolved. Here, we profiled gene expression, nucleosome positions, and H1 locations in early Drosophila embryos. The results show that H1 binding is positively correlated with the stability of beads-on-a-string nucleosome organization likely through stabilizing nucleosome positioning and maintaining nucleosome spacing. Strikingly, nucleosomes with H1 placement deviating to the left or the right relative to the dyad shift to the left or the right, respectively, during early Drosophila embryonic development. H1 occupancy on genic nucleosomes is inversely correlated with nucleosome distance to the transcription start sites. This inverse correlation reduces as gene transcription levels decrease. Additionally, H1 occupancy is lower at the 5\u27 border of genic nucleosomes than that at the 3\u27 border. This asymmetrical pattern of H1 occupancy on genic nucleosomes diminishes as gene transcription levels decrease. These findings shed new lights into how H1 placement dynamics correlates with nucleosome positioning and gene transcription during early Drosophila embryonic development

The Combination of CD8αα and Peptide-MHC-I in a Face-to-Face Mode Promotes Chicken γδT Cells Response.

The CD8αα homodimer is crucial to both thymic T cell selection and the antigen recognition of cytotoxic T cells. The CD8-pMHC-I interaction can enhance CTL immunity via stabilizing the TCR-pMHC-I interaction and optimizing the cross-reactivity and Ag sensitivity of CD8+ T cells at various stages of development. To date, only human and mouse CD8-pMHC-I complexes have been determined. Here, we resolved the pBF2*1501 complex and the cCD8αα/pBF2*1501 and cCD8αα/pBF2*0401 complexes in nonmammals for the first time. Remarkably, cCD8αα/pBF2*1501 and the cCD8αα/pBF2*0401 complex both exhibited two binding modes, including an "antibody-like" mode similar to that of the known mammal CD8/pMHC-I complexes and a "face-to-face" mode that has been observed only in chickens to date. Compared to the "antibody-like" mode, the "face-to-face" binding mode changes the binding orientation of the cCD8αα homodimer to pMHC-I, which might facilitate abundant γδT cells to bind diverse peptides presented by limited BF2 alleles in chicken. Moreover, the forces involving in the interaction of cCD8αα/pBF2*1501 and the cCD8αα/pBF2*0401 are different in this two binding model, which might change the strength of the CD8-pMHC-I interaction, amplifying T cell cross-reactivity in chickens. The coreceptor CD8αα of TCR has evolved two peptide-MHC-I binding patterns in chickens, which might enhance the T cell response to major or emerging pathogens, including chicken-derived pathogens that are relevant to human health, such as high-pathogenicity influenza viruses

NLRP3 Inflammasome as a Molecular Marker in Diabetic Cardiomyopathy

Diabetic cardiomyopathy (DCM), a common consequence of longstanding diabetes mellitus, is initiated by death of cardiomyocyte. Hyperglycemia-induced reactive oxygen species (ROS) overproduction is a major contributor of the chronic low-grade inflammation that characterizes as the DCM. ROS may promote the activation of nucleotide-binding oligomerization domain like receptor (NLR) pyrin domain containing 3 (NLRP3) inflammasome, a novel regulator of inflammation and cell death, by nuclear factor-kB (NF-κB) and thioredoxin interacting/inhibiting protein (TXNIP). NLRP3 inflammasome regulates the death of cardiomyocyte and activation of fibroblast in DCM, which is involved in the structural and functional disorder of DCM. However, comprehensive understanding of molecular mechanisms linking NLRP3 inflammasome and disorder of cardiomyocyte and fibroblast in DCM is lacking. Here, we review the molecular mechanism(s) of NLRP3 inflammasome activation in response to hyperglycemia in DCM

The Arabidopsis thaliana nucleotide sugar transporter GONST2 is a functional homolog of GONST1.

Glycosylinositolphosphorylceramides (GIPCs) are the predominant lipid in the outer leaflet of the plasma membrane. Characterized GIPC glycosylation mutants have severe or lethal plant phenotypes. However, the function of the glycosylation is unclear. Previously, we characterized Arabidopsis thaliana GONST1 and showed that it was a nucleotide sugar transporter which provides GDP-mannose for GIPC glycosylation. gonst1 has a severe growth phenotype, as well as a constitutive defense response. Here, we characterize a mutant in GONST1's closest homolog, GONST2. The gonst2-1 allele has a minor change to GIPC headgroup glycosylation. Like other reported GIPC glycosylation mutants, gonst1-1gonst2-1 has reduced cellulose, a cell wall polymer that is synthesized at the plasma membrane. The gonst2-1 allele has increased resistance to a biotrophic pathogen Golovinomyces orontii but not the necrotrophic pathogen Botrytis cinerea. Expression of GONST2 under the GONST1 promoter can rescue the gonst1 phenotype, indicating that GONST2 has a similar function to GONST1 in providing GDP-D-Man for GIPC mannosylation