13,787 research outputs found

    The Stable Association of Virion with the Triple-geneblockProtein 3-based Complex of Bamboo mosaic virus

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    The triple-gene-block protein 3 (TGBp3) of Bamboo mosaic virus (BaMV) is an integral endoplasmic reticulum (ER) membraneprotein which is assumed to form a membrane complex to deliver the virus intracellularly. However, the virus entity that isdelivered to plasmodesmata (PD) and its association with TGBp3-based complexes are not known. Results from chemicalextraction and partial proteolysis of TGBp3 in membrane vesicles revealed that TGBp3 has a right-side-out membranetopology; i.e., TGBp3 has its C-terminal tail exposed to the outer surface of ER. Analyses of the TGBp3-specificimmunoprecipitate of Sarkosyl-extracted TGBp3-based complex revealed that TGBp1, TGBp2, TGBp3, capsid protein (CP),replicase and viral RNA are potential constituents of virus movement complex. Substantial co-fractionation of TGBp2, TGBp3and CP, but not TGBp1, in the early eluted gel filtration fractions in which virions were detected after TGBp3-specificimmunoprecipitation suggested that the TGBp2- and TGBp3-based complex is able to stably associate with the virion. Thisnotion was confirmed by immunogold-labeling transmission electron microscopy (TEM) of the purified virions. In addition,mutational and confocal microscopy analyses revealed that TGBp3 plays a key role in virus cell-to-cell movement byenhancing the TGBp2- and TGBp3-dependent PD localization of TGBp1. Taken together, our results suggested that the cellto-cell movement of potexvirus requires stable association of the virion cargo with the TGBp2- and TGBp3-based membranecomplex and recruitment of TGBp1 to the PD by this complex

    Flood Damage Assessment in Taipei City Taiwan

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    In this study, we reviewed the literature on flood damage assessment and collected information for related research in Taiwan to analyze the relationships between direct flood damage, flood frequency, flood depth, and land-use. The procedure for flood damage assessment was then developed that includes the following steps: (a) Scenario simulation of inundation potential. (b) Establishment of the relationship between inundation depth and damage loss for varied land-use. (c) Risk analysis of inundation damage. Taipei City in north Taiwan was adopted as the case study to demonstrate the proposed algorithm. Flood events with return periods of 5, 10, 25, 50, 100 and 200 years were used for flood hazard analysis to cover possible flooding scenarios. The inundation hazard maps were first generated via hydraulic modelling. The regional flood damage was then estimated using a relationship between inundation depth and damage. The flood damage exceedance probability (EP) curve for Taipei City was constructed following the association of the loss with its probability of occurrence. The flood damage EP curve was further used to integrate the damage assessments for individual flood events for a full probability range presentation of the flood risk. The expected annual damage was calculated by integrating the area under the EP curve

    SEC24A deficiency lowers plasma cholesterol through reduced PCSK9 secretion.

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    The secretory pathway of eukaryotic cells packages cargo proteins into COPII-coated vesicles for transport from the endoplasmic reticulum (ER) to the Golgi. We now report that complete genetic deficiency for the COPII component SEC24A is compatible with normal survival and development in the mouse, despite the fundamental role of SEC24 in COPII vesicle formation and cargo recruitment. However, these animals exhibit markedly reduced plasma cholesterol, with mutations in Apoe and Ldlr epistatic to Sec24a, suggesting a receptor-mediated lipoprotein clearance mechanism. Consistent with these data, hepatic LDLR levels are up-regulated in SEC24A-deficient cells as a consequence of specific dependence of PCSK9, a negative regulator of LDLR, on SEC24A for efficient exit from the ER. Our findings also identify partial overlap in cargo selectivity between SEC24A and SEC24B, suggesting a previously unappreciated heterogeneity in the recruitment of secretory proteins to the COPII vesicles that extends to soluble as well as trans-membrane cargoes. DOI:http://dx.doi.org/10.7554/eLife.00444.001
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