498 research outputs found

    Early Cardiogenesis in the Newt Embryo

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    The migration of cardiogenic cells and the formation of a tubular heart in newt embryos were examined mainly by scanning electron microscopy (SEM). Cardiogenic cells are known to localize at the border region of lateral mesoderm migrating in the space between the ectoderm and the endoderm. They initially (before stage 20 or mid-neurula) appeared to attach to the basal surface of the ectoderm, whereas later (after stage 22 or late neurula) they changed their scaffold to the endoderm. On the scaffold cell surface, very fine fibrils of extracellular matrix (ECM) were found. These fibrils were proved to be composed partly of fibronectin by the immunofluorescence method as well as by immunoSEM using latex bead-labeled antibody, suggesting their seemingly important role in migration of cardiogenic cells. At stage 26 or the early tail bud stage, when the tips of bilateral cardiogenic areas begin to fuse under the foregut, several free vasoformative cells are seen there and the mesodermal sheet itself splits into two layers to produce a coelomic cavity. The splanchnic wall of the coelomic or pericardial cavity was recognized to form a trough consisting of cobblestone-like myocardial cells not yet covered with the epicardium

    Colletotrichum higginsianum extracellular LysM proteins play dual roles in appressorial function and suppression of chitin-triggered plant immunity

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    <p>The genome of the hemibiotrophic anthracnose fungus, Colletotrichum higginsianum, encodes a large repertoire of candidate-secreted effectors containing LysM domains, but the role of such proteins in the pathogenicity of any Colletotrichum species is unknown. Here, we characterized the function of two effectors, ChELP1 and ChELP2, which are transcriptionally activated during the initial intracellular biotrophic phase of infection. Using immunocytochemistry, we found that ChELP2 is concentrated on the surface of bulbous biotrophic hyphae at the interface with living host cells but is absent from filamentous necrotrophic hyphae. We show that recombinant ChELP1 and ChELP2 bind chitin and chitin oligomers in vitro with high affinity and specificity and that both proteins suppress the chitin-triggered activation of two immune-related plant mitogen-activated protein kinases in the host Arabidopsis. Using RNAi-mediated gene silencing, we found that ChELP1 and ChELP2 are essential for fungal virulence and appressorium-mediated penetration of both Arabidopsis epidermal cells and cellophane membranes in vitro. The findings suggest a dual role for these LysM proteins as effectors for suppressing chitin-triggered immunity and as proteins required for appressorium function.</p

    Twinning superlattices in indium phosphide nanowires

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    Here, we show that we control the crystal structure of indium phosphide (InP) nanowires by impurity dopants. We have found that zinc decreases the activation barrier for 2D nucleation growth of zinc-blende InP and therefore promotes the InP nanowires to crystallise in the zinc blende, instead of the commonly found wurtzite crystal structure. More importantly, we demonstrate that we can, by controlling the crystal structure, induce twinning superlattices with long-range order in InP nanowires. We can tune the spacing of the superlattices by the wire diameter and the zinc concentration and present a model based on the cross-sectional shape of the zinc-blende InP nanowires to quantitatively explain the formation of the periodic twinning.Comment: 18 pages, 4 figure

    Functional epigenetic approach identifies frequently methylated genes in Ewing sarcoma

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    Using a candidate gene approach we recently identified frequent methylation of the RASSF2 gene associated with poor overall survival in Ewing sarcoma (ES). To identify effective biomarkers in ES on a genome-wide scale, we used a functionally proven epigenetic approach, in which gene expression was induced in ES cell lines by treatment with a demethylating agent followed by hybridization onto high density gene expression microarrays. After following a strict selection criterion, 34 genes were selected for expression and methylation analysis in ES cell lines and primary ES. Eight genes (CTHRC1, DNAJA4, ECHDC2, NEFH, NPTX2, PHF11, RARRES2, TSGA14) showed methylation frequencies of>20% in ES tumors (range 24-71%), these genes were expressed in human bone marrow derived mesenchymal stem cells (hBMSC) and hypermethylation was associated with transcriptional silencing. Methylation of NPTX2 or PHF11 was associated with poorer prognosis in ES. In addition, six of the above genes also showed methylation frequency of>20% (range 36-50%) in osteosarcomas. Identification of these genes may provide insights into bone cancer tumorigenesis and development of epigenetic biomarkers for prognosis and detection of these rare tumor types

    Search for the Θ+\Theta^{+} pentaquark via the πpKX\pi^-p\to K^-X reaction at 1.92 GeV/cc

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    The Θ+\Theta^+ pentaquark baryon was searched for via the πpKX\pi^-p\to K^-X reaction in a missing-mass resolution of 1.4 MeV/c2c^2(FWHM) at J-PARC. π\pi^- meson beams were incident on the liquid hydrogen target with the beam momentum of 1.92 GeV/cc. No peak structure corresponding to the Θ+\Theta^+ mass was observed. The upper limit of the production cross section averaged over the scattering angle of 2^{\circ} to 15^{\circ} in the laboratory frame was obtained to be 0.26 μ\mub/sr in the mass region of 1.51-1.55 GeV/c2c^2.The upper limit of the Θ+\Theta^+ decay width using the effective Lagrangian approach was obtained to be 0.72 MeV/c2c^2 and 3.1 MeV/c2c^2 for JΘP=1/2+J^P_{\Theta}=1/2^+ and JΘP=1/2J^P_{\Theta}=1/2^-, respectively.Comment: 5 pages, 3 figures, 1 tabl

    Prediction of Anisotropic Single-Dirac-Cones in Bi1x{}_{1-x}Sbx{}_{x} Thin Films

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    The electronic band structures of Bi1x{}_{1-x}Sbx{}_{x} thin films can be varied as a function of temperature, pressure, stoichiometry, film thickness and growth orientation. We here show how different anisotropic single-Dirac-cones can be constructed in a Bi1x{}_{1-x}Sbx{}_{x} thin film for different applications or research purposes. For predicting anisotropic single-Dirac-cones, we have developed an iterative-two-dimensional-two-band model to get a consistent inverse-effective-mass-tensor and band-gap, which can be used in a general two-dimensional system that has a non-parabolic dispersion relation as in a Bi1x{}_{1-x}Sbx{}_{x} thin film system

    Gastric Ulcers in Middle-Aged Rats: The Healing Effect of Essential Oil from Citrus aurantium

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    The elderly population has experienced increased life expectancy as well as the increased incidence of gastric ulcers. The peels of fruits from Citrus aurantium L., popularly known in Brazil as orange bitter, are commonly used asatea form for the treatment of gastrointestinal tract disorders, such as ulcer and gastritis. We evaluated the healing effects of essential oil from the peels of Citrus aurantium fruits (OEC) on gastric ulcers in middle-aged rats. We examined the effects of a 14-day chronic OEC treatment on gastric mucosa in middle-aged male Wistar rats that were given acetic-acid-induced gastric lesions by morphometric and immunohistological analyses. Oral OEC treatment significantly reduced the lesion area (76%) within the gastric mucosa and significantly increased (P<.05) the height of regenerated mucosa (59%) when compared to the negative control group. Immunohistochemical analysis of the molecular markers such as COX-2, HSP-70, VEGF, and PCNA in the gastric mucosa confirmed that OEC treatment induced healing effects by increasing the number of new blood vessels and by augmenting gastric mucus in the mucosa glands. These results suggest that the oil from Citrus aurantium effectively heals gastric ulcers in middle-aged animals; however, safe use of OEC demands special care and precautions

    Endothelins are vascular-derived axonal guidance cues for developing sympathetic neurons

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    During development, sympathetic neurons extend axons along a myriad of distinct trajectories, often consisting of arteries, to innervate one of a large variety of distinct final target tissues. Whether or not subsets of neurons within complex sympathetic ganglia are predetermined to innervate select end-organs is unknown. Here we demonstrate in mouse embryos that the endothelin family member Edn3 (ref. 1), acting through the endothelin receptor EdnrA (refs 2, 3), directs extension of axons of a subset of sympathetic neurons from the superior cervical ganglion to a preferred intermediate target, the external carotid artery, which serves as the gateway to select targets, including the salivary glands. These findings establish a previously unknown mechanism of axonal pathfinding involving vascular-derived endothelins, and have broad implications for endothelins as general mediators of axonal growth and guidance in the developing nervous system. Moreover, they suggest a model in which newborn sympathetic neurons distinguish and choose between distinct vascular trajectories to innervate their appropriate end organs.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/62906/1/nature06859.pd
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