27 research outputs found

    Two Plant Viral Suppressors of Silencing Require the Ethylene-Inducible Host Transcription Factor RAV2 to Block RNA Silencing

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    RNA silencing is a highly conserved pathway in the network of interconnected defense responses that are activated during viral infection. As a counter-defense, many plant viruses encode proteins that block silencing, often also interfering with endogenous small RNA pathways. However, the mechanism of action of viral suppressors is not well understood and the role of host factors in the process is just beginning to emerge. Here we report that the ethylene-inducible transcription factor RAV2 is required for suppression of RNA silencing by two unrelated plant viral proteins, potyvirus HC-Pro and carmovirus P38. Using a hairpin transgene silencing system, we find that both viral suppressors require RAV2 to block the activity of primary siRNAs, whereas suppression of transitive silencing is RAV2-independent. RAV2 is also required for many HC-Pro-mediated morphological anomalies in transgenic plants, but not for the associated defects in the microRNA pathway. Whole genome tiling microarray experiments demonstrate that expression of genes known to be required for silencing is unchanged in HC-Pro plants, whereas a striking number of genes involved in other biotic and abiotic stress responses are induced, many in a RAV2-dependent manner. Among the genes that require RAV2 for induction by HC-Pro are FRY1 and CML38, genes implicated as endogenous suppressors of silencing. These findings raise the intriguing possibility that HC-Pro-suppression of silencing is not caused by decreased expression of genes that are required for silencing, but instead, by induction of stress and defense responses, some components of which interfere with antiviral silencing. Furthermore, the observation that two unrelated viral suppressors require the activity of the same factor to block silencing suggests that RAV2 represents a control point that can be readily subverted by viruses to block antiviral silencing

    Die Stoffwechselwirkungen der SchilddrĂĽsenhormone

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    A Consensus-Based Set of Measures for Oral Health Care

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    Increasingly more responsive and accountable health care systems are demanded, which is characterized by transparency and explicit demonstration of competence by health care providers and the systems in which they work. This study aimed to establish measures of oral health for transparent and explicit reporting of routine data to facilitate more patient-centered and prevention-oriented oral health care. To accomplish this, an intermediate objective was to develop a comprehensive list of topics that a range of stakeholders would perceive as valid, important, and relevant for describing oral health and oral health care. A 4-stage approach was used to develop the list of topics: 1) scoping of literature and its appraisal, 2) a meeting of experts, 3) a 2-stage Delphi process (online), and 4) a World Café discussion. The aim was to create consensus through structured conversations via a range of stakeholders (general dental practitioners, patients, insurers, and policy makers) from the Netherlands, Germany, the United Kingdom, Ireland, Hungary, and Denmark. The study was part of the ADVOCATE project, and it resulted in a list of 48 topics grouped into 6 clusters: 1) access to dental care, 2) symptoms and diagnosis, 3) health behaviors, 4) oral treatments, 5) oral prevention, and 6) patient perception. All topics can be measured, as they all have a data source with defined numerators and denominators. This study is the first to establish a comprehensive and multiple-stakeholder consented topic list designed for guiding the implementation of transparent and explicit measurement of routine data of oral health and oral health care. Successful measurement within oral health care systems is essential to facilitate learning from variation in practice and outcomes within and among systems, and it potentiates improvement toward more patient-centered and prevention-oriented oral health care
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