50 research outputs found

    Methylated DNA recognition during the reversal of epigenetic silencing is regulated by cysteine and cerine residues in the Epstein-Barr Virus lytic switch protein

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    Epstein-Barr virus (EBV) causes infectious mononucleosis and is associated with various malignancies, including Burkitt's lymphoma and nasopharyngeal carcinoma. Like all herpesviruses, the EBV life cycle alternates between latency and lytic replication. During latency, the viral genome is largely silenced by host-driven methylation of CpG motifs and, in the switch to the lytic cycle, this epigenetic silencing is overturned. A key event is the activation of the viral BRLF1 gene by the immediate-early protein Zta. Zta is a bZIP transcription factor that preferentially binds to specific response elements (ZREs) in the BRLF1 promoter (Rp) when these elements are methylated. Zta's ability to trigger lytic cycle activation is severely compromised when a cysteine residue in its bZIP domain is mutated to serine (C189S), but the molecular basis for this effect is unknown. Here we show that the C189S mutant is defective for activating Rp in a Burkitt's lymphoma cell line. The mutant is compromised both in vitro and in vivo for binding two methylated ZREs in Rp (ZRE2 and ZRE3), although the effect is striking only for ZRE3. Molecular modeling of Zta bound to methylated ZRE3, together with biochemical data, indicate that C189 directly contacts one of the two methyl cytosines within a specific CpG motif. The motif's second methyl cytosine (on the complementary DNA strand) is predicted to contact S186, a residue known to regulate methyl-ZRE recognition. Our results suggest that C189 regulates the enhanced interaction of Zta with methylated DNA in overturning the epigenetic control of viral latency. As C189 is conserved in many bZIP proteins, the selectivity of Zta for methylated DNA may be a paradigm for a more general phenomenon

    The normalization of online campaigning in the web.2.0 era

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    This article is based on a comparative study of online campaigning and its effects by country and over time, using four of the largest European Union member states (France, Germany, Poland and the United Kingdom) as a case study. Our research explores the extent of embeddedness of online campaigning, the strategic uses of the whole online environment and in particular the use of the interactive features associated with web.2.0 era. However, our research goes beyond studies of online campaigning as we also determine whether online campaigning across platforms matters in electoral terms. Our data support the normalization hypothesis which shows overall low levels of innovation but that the parties with the highest resources tend to develop online campaigns with the highest functionality. We find that there is a vote dividend for those parties which utilized web.2.0 features the most and so offered visitors to their web presence a more interactive experience

    In search of the authentic nation: landscape and national identity in Canada and Switzerland

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    While the study of nationalism and national identity has flourished in the last decade, little attention has been devoted to the conditions under which natural environments acquire significance in definitions of nationhood. This article examines the identity-forming role of landscape depictions in two polyethnic nation-states: Canada and Switzerland. Two types of geographical national identity are identified. The first – what we call the ‘nationalisation of nature’– portrays zarticular landscapes as expressions of national authenticity. The second pattern – what we refer to as the ‘naturalisation of the nation’– rests upon a notion of geographical determinism that depicts specific landscapes as forces capable of determining national identity. The authors offer two reasons why the second pattern came to prevail in the cases under consideration: (1) the affinity between wild landscape and the Romantic ideal of pure, rugged nature, and (2) a divergence between the nationalist ideal of ethnic homogeneity and the polyethnic composition of the two societies under consideration

    Evaluation of knowledge levels amongst village AIDS committees after undergoing HIV educational sessions: results from a pilot study in rural Tanzania

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    ABSTRACT: BACKGROUND: Village AIDS committees (VAC) were formed by the Tanzanian government in 2003 to provide HIV education to their communities. However, their potential has not been realised due to their limited knowledge and misconceptions surrounding HIV, which could be addressed through training of VAC members. In an attempt to increase HIV knowledge levels and address common misconceptions amongst the VACs, an HIV curriculum was delivered to members in rural north western Tanzania. METHODS: An evaluation of HIV knowledge was conducted prior to and post-delivery of HIV training sessions, within members of three VACs in Kisesa ward. Quantitative surveys were used with several open-ended questions to identify local misconceptions and evaluate HIV knowledge levels. Short educational training sessions covering HIV transmission, prevention and treatment were conducted, with each VAC using quizzes, role-plays and participatory learning and action tools. Post-training surveys occurred up to seven days after the final training session. RESULTS: Before the training, "good" HIV knowledge was higher amongst men than women (p = 0.041), and among those with previous HIV education (p = 0.002). The trade-centre had a faster turn-over of VAC members, and proximity to the trade-centre was associated with a shorter time on the committee.Training improved HIV knowledge levels with more members achieving a "good" score in the post-training survey compared with the baseline survey (p = < 0.001). The training programme was popular, with 100% of participants requesting further HIV training in the future and 51.7% requesting training at three-monthly intervals. CONCLUSIONS: In this setting, a series of HIV training sessions for VACs demonstrated encouraging results, with increased HIV knowledge levels following short educational sessions. Further work is required to assess the success of VAC members in disseminating this HIV education to their communities, as well as up-scaling this pilot study to other regions in Tanzania with different misconceptions

    Searches for the Zγ decay mode of the Higgs boson and for new high-mass resonances in pp collisions at √s=13 TeV with the ATLAS detector

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    This article presents searches for the Zγ decay of the Higgs boson and for narrow high-mass resonances decaying to Zγ, exploiting Z boson decays to pairs of electrons or muons. The data analysis uses 36.1 fb−1 of pp collisions at √s=13 recorded by the ATLAS detector at the CERN Large Hadron Collider. The data are found to be consistent with the expected Standard Model background. The observed (expected — assuming Standard Model pp → H → Zγ production and decay) upper limit on the production cross section times the branching ratio for pp → H → Zγ is 6.6. (5.2) times the Standard Model prediction at the 95% confidence level for a Higgs boson mass of 125.09 GeV. In addition, upper limits are set on the production cross section times the branching ratio as a function of the mass of a narrow resonance between 250 GeV and 2.4 TeV, assuming spin-0 resonances produced via gluon-gluon fusion, and spin-2 resonances produced via gluon-gluon or quark-antiquark initial states. For high-mass spin-0 resonances, the observed (expected) limits vary between 88 fb (61 fb) and 2.8 fb (2.7 fb) for the mass range from 250 GeV to 2.4 TeV at the 95% confidence level

    Identification of boosted, hadronically decaying W bosons and comparisons with ATLAS data taken at √s = 8 TeV

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    This paper reports a detailed study of techniques for identifying boosted, hadronically decaying W bosons using 20.3 fb −¹ of proton–proton collision data collected by the ATLAS detector at the LHC at a centre-of-mass energy √s = 8 TeV. A range of techniques for optimising the signal jet mass resolution are combined with various jet substructure variables. The results of these studies in Monte Carlo simulations show that a simple pairwise combination of groomed jet mass and one substructure variable can provide a 50 % efficiency for identifying W bosons with transverse momenta larger than 200 GeV while maintaining multijet background efficiencies of 2–4 % for jets with the same transverse momentum. These signal and background efficiencies are confirmed in data for a selection of tagging techniques

    Identification of a BRCA2-Specific Modifier Locus at 6p24 Related to Breast Cancer Risk

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