A Polycomb complex remains bound through DNA replication in the absence of other eukaryotic proteins

Propagation of chromatin states through DNA replication is central to epigenetic regulation and can involve recruitment of chromatin proteins to replicating chromatin through interactions with replication fork components. Here we show using a fully reconstituted T7 bacteriophage system that eukaryotic proteins are not required to tether the Polycomb complex PRC1 to templates during DNA replication. Instead, DNA binding by PRC1 can withstand passage of a simple replication fork.Molecular and Cellular Biolog

Expression of synaptotagmin and syntaxin associated with N-type calcium channels in small cell lung cancer

AbstractThe presence of synaptic proteins involved in excitation/secretion coupling was examined in ten small cell lung cancer lines. N-Type calcium channels (ω)-conotoxin receptors), synaptotagmin (p65) and syntaxin (HPC-1) were detected in eight. Co-immunoprecipitation experiments indicated that syntaxin can form a complex with synaptotagmin and calcium channels. The expression of synaptotagmin in small cell lung cancer may elicit an autoimmune response that reduces transmitter release at the nerve terminal

The signaling pathway of Campylobacter jejuni-induced Cdc42 activation: Role of fibronectin, integrin beta1, tyrosine kinases and guanine exchange factor Vav2

<p>Abstract</p> <p>Background</p> <p>Host cell invasion by the foodborne pathogen <it>Campylobacter jejuni </it>is considered as one of the primary reasons of gut tissue damage, however, mechanisms and key factors involved in this process are widely unclear. It was reported that small Rho GTPases, including Cdc42, are activated and play a role during invasion, but the involved signaling cascades remained unknown. Here we utilised knockout cell lines derived from fibronectin^-/-, integrin-beta1^-/-, focal adhesion kinase (FAK)^-/-and Src/Yes/Fyn^-/-deficient mice, and wild-type control cells, to investigate <it>C. jejuni</it>-induced mechanisms leading to Cdc42 activation and bacterial uptake.</p> <p>Results</p> <p>Using high-resolution scanning electron microscopy, GTPase pulldowns, G-Lisa and gentamicin protection assays we found that each studied host factor is necessary for induction of Cdc42-GTP and efficient invasion. Interestingly, filopodia formation and associated membrane dynamics linked to invasion were only seen during infection of wild-type but not in knockout cells. Infection of cells stably expressing integrin-beta1 variants with well-known defects in fibronectin fibril formation or FAK signaling also exhibited severe deficiencies in Cdc42 activation and bacterial invasion. We further demonstrated that infection of wild-type cells induces increasing amounts of phosphorylated FAK and growth factor receptors (EGFR and PDGFR) during the course of infection, correlating with accumulating Cdc42-GTP levels and <it>C. jejuni </it>invasion over time. In studies using pharmacological inhibitors, silencing RNA (siRNA) and dominant-negative expression constructs, EGFR, PDGFR and PI3-kinase appeared to represent other crucial components upstream of Cdc42 and invasion. siRNA and the use of Vav1/2^-/-knockout cells further showed that the guanine exchange factor Vav2 is required for Cdc42 activation and maximal bacterial invasion. Overexpression of certain mutant constructs indicated that Vav2 is a linker molecule between Cdc42 and activated EGFR/PDGFR/PI3-kinase. Using <it>C. jejuni </it>mutant strains we further demonstrated that the fibronectin-binding protein CadF and intact flagella are involved in Cdc42-GTP induction, indicating that the bacteria may directly target the fibronectin/integrin complex for inducing signaling leading to its host cell entry.</p> <p>Conclusion</p> <p>Collectively, our findings led us propose that <it>C. jejuni </it>infection triggers a novel fibronectin→integrin-beta1→FAK/Src→EGFR/PDGFR→PI3-kinase→Vav2 signaling cascade, which plays a crucial role for Cdc42 GTPase activity associated with filopodia formation and enhances bacterial invasion.</p

Facial phenotypes in subgroups of prepubertal boys with autism spectrum disorders are correlated with clinical phenotypes

<p>Abstract</p> <p>Background</p> <p>The brain develops in concert and in coordination with the developing facial tissues, with each influencing the development of the other and sharing genetic signaling pathways. Autism spectrum disorders (ASDs) result from alterations in the embryological brain, suggesting that the development of the faces of children with ASD may result in subtle facial differences compared to typically developing children. In this study, we tested two hypotheses. First, we asked whether children with ASD display a subtle but distinct facial phenotype compared to typically developing children. Second, we sought to determine whether there are subgroups of facial phenotypes within the population of children with ASD that denote biologically discrete subgroups.</p> <p>Methods</p> <p>The 3dMD cranial System was used to acquire three-dimensional stereophotogrammetric images for our study sample of 8- to 12-year-old boys diagnosed with essential ASD (<it>n </it>= 65) and typically developing boys (<it>n </it>= 41) following approved Institutional Review Board protocols. Three-dimensional coordinates were recorded for 17 facial anthropometric landmarks using the 3dMD Patient software. Statistical comparisons of facial phenotypes were completed using Euclidean Distance Matrix Analysis and Principal Coordinates Analysis. Data representing clinical and behavioral traits were statistically compared among groups by using χ²tests, Fisher's exact tests, Kolmogorov-Smirnov tests and Student's <it>t</it>-tests where appropriate.</p> <p>Results</p> <p>First, we found that there are significant differences in facial morphology in boys with ASD compared to typically developing boys. Second, we also found two subgroups of boys with ASD with facial morphology that differed from the majority of the boys with ASD and the typically developing boys. Furthermore, membership in each of these distinct subgroups was correlated with particular clinical and behavioral traits.</p> <p>Conclusions</p> <p>Boys with ASD display a facial phenotype distinct from that of typically developing boys, which may reflect alterations in the prenatal development of the brain. Subgroups of boys with ASD defined by distinct facial morphologies correlated with clinical and behavioral traits, suggesting potentially different etiologies and genetic differences compared to the larger group of boys with ASD. Further investigations into genes involved in neurodevelopment and craniofacial development of these subgroups will help to elucidate the causes and significance of these subtle facial differences.</p

W/Z Bremsstrahlung as the Dominant Annihilation Channel for Dark Matter, Revisited

We revisit the calculation of electroweak bremsstrahlung contributions to dark matter annihilation. Dark matter annihilation to leptons is necessarily accompanied by electroweak radiative corrections, in which a $W$ or $Z$ boson is also radiated. Significantly, while many dark matter models feature a helicity suppressed annihilation rate to fermions, bremsstrahlung process can remove this helicity suppression such that the branching ratios Br($\ell \nu W$), Br($\ell^+\ell^-Z$), and Br($\bar\nu \nu Z$) dominate over Br($\ell^+\ell^-$) and Br($\bar\nu \nu$). We find this is most significant in the limit where the dark matter mass is nearly degenerate with the mass of the boson which mediates the annihilation process. Electroweak bremsstrahlung has important phenomenological consequences both for the magnitude of the total dark matter annihilation cross section and for the character of the astrophysical signals for indirect detection. Given that the $W$ and $Z$ gauge bosons decay dominantly via hadronic channels, it is impossible to produce final state leptons without accompanying protons, antiprotons, and gamma rays.Comment: 8 pages, 6 figures; replaced to match published versio

Facial Structure Analysis Separates Autism Spectrum Disorders Into Meaningful Clinical Subgroups

Varied cluster analysis were applied to facial surface measurements from 62 prepubertal boys with essential autism to determine whether facial morphology constitutes viable biomarker for delineation of discrete Autism Spectrum Disorders (ASD) subgroups. Earlier study indicated utility of facial morphology for autism subgrouping (Aldridge et al. in Mol Autism 2(1):15, 2011). Geodesic distances between standardized facial landmarks were measured from three-dimensional stereo-photogrammetric images. Subjects were evaluated for autism-related symptoms, neurologic, cognitive, familial, and phenotypic variants. The most compact cluster is clinically characterized by severe ASD, significant cognitive impairment and language regression. This verifies utility of facially-based ASD subtypes and validates Aldridge et al.\u27s severe ASD subgroup, notwithstanding different techniques. It suggests that language regression may define a unique ASD subgroup with potential etiologic differences

Binding of Ala-scanning analogs of ω-conotoxin MVIIC to N- and P/Q-type calcium channels

Abstractω-Conotoxin MVIIC binds to P/Q-type calcium channels with high affinity and N-type channels with low affinity. To reveal the residues essential for subtype selectivity, we synthesized Ala-scanning analogs of MVIIC. Binding assays using rat cerebellar P2 membranes suggested that Thr11, Tyr13 and Lys2 are essential for binding to both N- and P/Q-type channels, whereas Lys4 and Arg22 are important for binding to P/Q-type channels. These results suggest that MVIIC interacts with P/Q-type channels via a large surface, in good agreement with previous observations using chimeric analogs

W/Z Bremsstrahlung as the Dominant Annihilation Channel for Dark Matter

Dark matter annihilation to leptons, $\chi \chi \rightarrow l \bar{l}$, is necessarily accompanied by electroweak radiative corrections, in which a W or Z boson is radiated from a final state particle. Given that the W and Z gauge bosons decay dominantly via hadronic channels, it is thus impossible to produce final state leptons without accompanying protons, antiprotons, and gamma rays. Significantly, while many dark matter models feature a helicity suppressed annihilation rate to fermions, radiating a massive gauge boson from a final state fermion removes this helicity suppression, such that the branching ratios Br(l \nu W), Br(l^+l^- Z), and Br(\nu\nubar Z) dominate over Br(l\bar{l}). W/Z-bremsstrahlung thus allows indirect detection of many WIMP models that would otherwise be helicity-suppressed, or v^2 suppressed. Antiprotons and even anti-deuterons become consequential final state particles. This is an important result for future DM searches. We discuss the implications of W/Z-bremsstrahlung for "leptonic" DM models which aim to fit recent cosmic ray positron and antiproton data.Comment: 19 pages, 5 figures. Updated to include Erratum, and changes made to PRD versio

Interaction of a synaptobrevin (VAMP)-syntaxin complex with presynaptic calcium channels

AbstractNerve terminal protein complexes implicated in exocytosis were examined by immuno-isolation from rat brain synaptosomes. Immunoprecipitation with anti-syntaxin or anti-VAMP antibodies revealed a syntaxin-SNAP25-VAMP-synaptotagmin complex. Anti-VAMP antibodies also trapped a distinct VAMP-synaptophysin complex. A similar fraction (about 70%) of N-type calcium channels ([125I]ω conotoxin GVIA receptors), was immunoprecipitated by either anti-syntaxin or anti-VAMP antibodies, but not by anti-synaptophysin antibodies (< 4%). The majority of N- but not L-type calcium channels ([3H]PN200-110 receptors), appear to be associated with a synaptic vesicle prefusion complex

The Gamma-Ray Imager/Polarimeter for Solar Flares (GRIPS)

The balloon-borne Gamma-Ray Imager/Polarimeter for Solar flares (GRIPS) instrument will provide a near-optimal combination of high-resolution imaging, spectroscopy, and polarimetry of solar-flare gamma-ray/hard X-ray emissions from approximately 20 keV to greater than approximately 10 MeV. GRIPS will address questions raised by recent solar flare observations regarding particle acceleration and energy release, such as: What causes the spatial separation between energetic electrons producing hard X-rays and energetic ions producing gamma-ray lines? How anisotropic are the relativistic electrons, and why can they dominate in the corona? How do the compositions of accelerated and ambient material vary with space and time, and why? The spectrometer/polarimeter consists of sixteen 3D position-sensitive germanium detectors (3D-GeDs), where each energy deposition is individually recorded with an energy resolution of a few keV FWHM and a spatial resolution of less than 0.1 cubic millimeter. Imaging is accomplished by a single multi-pitch rotating modulator (MPRM), a 2.5-centimeter thick tungsten alloy slit/slat grid with pitches that range quasi-continuously from 1 to 13 millimeters. The MPRM is situated 8 meters from the spectrometer to provide excellent image quality and unparalleled angular resolution at gamma-ray energies (12.5 arcsec FWHM), sufficient to separate 2.2 MeV footpoint sources for almost all flares. Polarimetry is accomplished by analyzing the anisotropy of reconstructed Compton scattering in the 3D-GeDs (i.e., as an active scatterer), with an estimated minimum detectable polarization of a few percent at 150-650 keV in an X-class flare. GRIPS is scheduled for a continental-US engineering test flight in fall 2013, followed by long or ultra-long duration balloon flights in Antarctica