891 research outputs found

    The bornavirus-derived human protein EBLN1 promotes efficient cell cycle transit, microtubule organisation and genome stability.

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    It was recently discovered that vertebrate genomes contain multiple endogenised nucleotide sequences derived from the non-retroviral RNA bornavirus. Strikingly, some of these elements have been evolutionary maintained as open reading frames in host genomes for over 40 million years, suggesting that some endogenised bornavirus-derived elements (EBL) might encode functional proteins. EBLN1 is one such element established through endogenisation of the bornavirus N gene (BDV N). Here, we functionally characterise human EBLN1 as a novel regulator of genome stability. Cells depleted of human EBLN1 accumulate DNA damage both under non-stressed conditions and following exogenously induced DNA damage. EBLN1-depleted cells also exhibit cell cycle abnormalities and defects in microtubule organisation as well as premature centrosome splitting, which we attribute in part, to improper localisation of the nuclear envelope protein TPR. Our data therefore reveal that human EBLN1 possesses important cellular functions within human cells, and suggest that other EBLs present within vertebrate genomes may also possess important cellular functions

    Neutrinoless Double Beta Decay in Heavy Deformed Nuclei

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    The zero neutrino mode of the double beta decay in heavy deformed nuclei is investigated in the framework of the pseudo SU(3) model, which has provided an accurate description of collective nuclear structure and predicted half-lives for the two neutrino mode in good agreement with experiments. In the case of 238U^{238}U the calculated zero neutrino half-life is at least three orders of magnitude greater than the two neutrino one, giving strong support of the identification of the radiochemically determined half-life as being the two neutrino double beta decay. For 150Nd^{150}Nd the zero neutrino matrix elements are of the order of magnitude of, but lesser than, those evaluated using the QRPA. This result confirms that different nuclear models produce similar zero neutrino matrix elements, contrary to the two neutrino case. Using these pseudo SU(3) results and the upper limit for the neutrino mass we estimate the ββ0ν\beta\beta_{0\nu} half-lives for six nuclei. An upper limit for majoron coupling constant is extracted from the experimental data.Comment: 19 pages, LaTeX, 2 figures not included, availables as poscript files upon reques

    A new limit of T-violating transverse muon polarization in the K+π0μ+νK^{+}\to\pi^{0}\mu^{+} \nu decay

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    A search for T-violating transverse muon polarization (PTP_T) in the K+π0μ+νK^{+}\to \pi^{0}\mu^{+}\nu decay was performed using kaon decays at rest. A new improved value, PT=0.0017±0.0023(stat)±0.0011(syst)P_T= -0.0017\pm 0.0023 (stat)\pm 0.0011 (syst), was obtained giving an upper limit, PT<0.0050| P_T | < 0.0050. The T-violation parameter was determined to be Imξ=0.0053±0.0071(stat)±0.0036(syst)\xi = -0.0053 \pm 0.0071(stat)\pm 0.0036(syst) giving an upper limit, |Imξ<0.016\xi| <0.016.Comment: 5 pages, 4 figure

    Test of exotic scalar and tensor interactions in K_e3 decay using stopped positive kaons

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    The form factors of the decay K+ --> pi0 e+ nu (K_e3) have been determined from the comparison of the experimental and Monte Carlo Dalitz distributions containing about 10^5 K_e3 events. The following values of the parameters were obtained: lambda_+ = 0.0278 +- 0.0017(stat) +- 0.0015(syst), f_S/f_+(0) = 0.0040 +- 0.0160(stat) +- 0.0067(syst) and f_T/f_+(0) = 0.019 +- 0.080(stat) +- 0.038(syst). Both scalar f_S and tensor f_T form factors are consistent with the Standard Model predictions of zero values.Comment: 10 pages, 5 figures, contributed to the proceedings of NANP Conference, Dubna, June 19-23, 200

    No Evidence for Natural Selection on Endogenous Borna-Like Nucleoprotein Elements after the Divergence of Old World and New World Monkeys

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    Endogenous Borna-like nucleoprotein (EBLNs) elements were recently discovered as non-retroviral RNA virus elements derived from bornavirus in the genomes of various animals. Most of EBLNs appeared to be defective, but some of primate EBLN-1 to -4, which appeared to be originated from four independent integrations of bornavirus nucleoprotein (N) gene, have retained an open reading frame (ORF) for more than 40 million years. It was therefore possible that primate EBLNs have encoded functional proteins during evolution. To examine this possibility, natural selection operating on all ORFs of primate EBLN-1 to -4 was examined by comparing the rates of synonymous and nonsynonymous substitutions. The expected number of premature termination codons in EBLN-1 generated after the divergence of Old World and New World monkeys under the selective neutrality was also examined by the Monte Carlo simulation. As a result, natural selection was not identified for the entire region as well as parts of ORFs in the pairwise analysis of primate EBLN-1 to -4 and for any branch of the phylogenetic trees for EBLN-1 to -4 after the divergence of Old World and New World monkeys. Computer simulation also indicated that the absence of premature termination codon in the present-day EBLN-1 does not necessarily support the maintenance of function after the divergence of Old World and New World monkeys. These results suggest that EBLNs have not generally encoded functional proteins after the divergence of Old World and New World monkeys

    Reductive Metabolism of AGE Precursors: A Metabolic Route for Preventing AGE Accumulation in Cardiovascular Tissue

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    OBJECTIVE—To examine the role of aldo-keto reductases (AKRs) in the cardiovascular metabolism of the precursors of advanced glycation end products (AGEs). RESEARCH DESIGN AND METHODS—Steady-state kinetic parameters of AKRs with AGE precursors were determined using recombinant proteins expressed in bacteria. Metabolism of meth-ylglyoxal and AGE accumulation were studied in human umbil-ical vein endothelial cells (HUVECs) and C57 wild-type, akr1b3 (aldose reductase)-null, cardiospecific-akr1b4 (rat aldose reduc-tase), and akr1b8 (FR-1)-transgenic mice. AGE accumulation and atherosclerotic lesions were studied 12 weeks after streptozoto-cin treatment of C57, akr1b3-null, and apoE- and akr1b3-apoE– null mice. RESULTS—Higher levels of AGEs were generated in the cytosol than at the external surface of HUVECs cultured in high glucose

    New determination of the branching ratio of the structure dependent radiative K+e+νeγK^{+} \to e^{+} \nu_{e} \gamma decay

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    The branching ratio of the structure dependent (SD) radiative K+e+νeγK^{+} \to e^{+} \nu_{e} \gamma decay relative to that of the K+e+νe(γ)K^+\rightarrow e^+ \nu_{e} (\gamma) decay including the internal bremsstrahlung (IB) process (Ke2(γ)K_{e2(\gamma)}) has been measured in the J-PARC E36 experiment using plastic scintillator/lead sandwich detectors. In the analysis, the effect of IB was also taken into account in the SD radiative decay as Ke2γ(γ)SDK_{e2\gamma(\gamma)}^{\rm SD}. By combining the new data with the previously reported result of the E36 experiment using a CsI(Tl) calorimeter after revision for the IB correction for Ke2γ(γ)SDK_{e2\gamma(\gamma)}^{\rm SD}, a new value Br(Ke2γ(γ)SD)/Br(Ke2(γ))=1.20±0.07Br(K_{e2\gamma(\gamma)}^{\rm SD})/Br(K_{e2(\gamma)})=1.20\pm0.07 has been determined, which is consistent with a recent lattice QCD calculation, but larger than the expectation of Chiral Perturbation Theory (ChPT) at order O(p4)O(p^4) and the previous KLOE value. Also, using the method to relate form factor and branching ratio described in the KLOE paper, the present result is consistent with the form factor prediction based on a gauged nonlocal chiral quark model, but larger than ChPT at order O(p6)O(p^6).Comment: 19 page

    Suppressing molecular motions for enhanced room-temperature phosphorescence of metal-free organic materials

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    Metal-free organic phosphorescent materials are attractive alternatives to the predominantly used organometallic phosphors but are generally dimmer and are relatively rare, as, without heavy-metal atoms, spin-orbit coupling is less efficient and phosphorescence usually cannot compete with radiationless relaxation processes. Here we present a general design rule and a method to effectively reduce radiationless transitions and hence greatly enhance phosphorescence efficiency of metal-free organic materials in a variety of amorphous polymer matrices, based on the restriction of molecular motions in the proximity of embedded phosphors. Covalent cross-linking between phosphors and polymer matrices via Diels-Alder click chemistry is devised as a method. A sharp increase in phosphorescence quantum efficiency is observed in a variety of polymer matrices with this method, which is ca. two to five times higher than that of phosphor-doped polymer systems having no such covalent linkage.ope
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