26 research outputs found

    Politics of Aedification, Sensation and Ruination at the Brussels Wiertz Museum

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    This paper seeks to explain why party candidates and their party leadership have congruent policy positions or not. Despite its importance as a way through which parties are able to behave as a unitary actor, this congruence has never been studied as a dependent variable. We seek to fill this void in the literature. Our results suggest that leadership-candidate congruence comes about through two mechanisms: selection and learning. With selection, the party leadership aims to get those candidates elected whose policy preferences are congruent with the party line. Learning occurs through the process of socialization in which candidates assume the views of the party they work and candidate for as their own under. This happens under the pressure of cognitive dissonance. If a candidate learns about the position of the leadership and notices that they are incongruent, they may feel discomfort and change their opinion to be congruent with the party

    Non-cellulosic polysaccharides from cotton fibre are differently impacted by textile processing.

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    Cotton fibre is mainly composed of cellulose, although non-cellulosic polysaccharides play key roles during fibre development and are still present in the harvested fibre. This study aimed at determining the fate of non-cellulosic polysaccharides during cotton textile processing. We analyzed non-cellulosic cotton fibre polysaccharides during different steps of cotton textile processing using GC-MS, HPLC and comprehensive microarray polymer profiling to obtain monosaccharide and polysaccharide amounts and linkage compositions. Additionally, in situ detection was used to obtain information on polysaccharide localization and accessibility. We show that pectic and hemicellulosic polysaccharide levels decrease during cotton textile processing and that some processing steps have more impact than others. Pectins and arabinose-containing polysaccharides are strongly impacted by the chemical treatments, with most being removed during bleaching and scouring. However, some forms of pectin are more resistant than others. Xylan and xyloglucan are affected in later processing steps and to a lesser extent, whereas callose showed a strong resistance to the chemical processing steps. This study shows that non-cellulosic polysaccharides are differently impacted by the treatments used in cotton textile processing with some hemicelluloses and callose being resistant to these harsh treatments

    Metabolism of polysaccharides in dynamic middle lamellae during cotton fibre development

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    Main conclusion: Evidence is presented that cotton fibre adhesion and middle lamella formation are preceded by cutin dilution and accompanied by rhamnogalacturonan-I metabolism. Cotton fibres are single cell structures that early in development adhere to one another via the cotton fibre middle lamella (CFML) to form a tissue-like structure. The CFML is disassembled around the time of initial secondary wall deposition, leading to fibre detachment. Observations of CFML in the light microscope have suggested that the development of the middle lamella is accompanied by substantial cell-wall metabolism, but it has remained an open question as to which processes mediate adherence and which lead to detachment. The mechanism of adherence and detachment were investigated here using glyco-microarrays probed with monoclonal antibodies, transcript profiling, and observations of fibre auto-digestion. The results suggest that adherence is brought about by cutin dilution, while the presence of relevant enzyme activities and the dynamics of rhamnogalacturonan-I side-chain accumulation and disappearance suggest that both attachment and detachment are accompanied by rhamnogalacturonan-I metabolism

    Efficient Translation of Pelargonium line pattern virus RNAs Relies on a TED-Like 3 '-Translational Enhancer that Communicates with the Corresponding 5 '-Region through a Long-Distance RNA-RNA Interaction

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    [EN] Cap-independent translational enhancers (CITEs) have been identified at the 3'-terminal regions of distinct plant positive-strand RNA viruses belonging to families Tombusviridae and Luteoviridae. On the bases of their structural and/or functional requirements, at least six classes of CITEs have been defined whose distribution does not correlate with taxonomy. The so-called TED class has been relatively under-studied and its functionality only confirmed in the case of Satellite tobacco necrosis virus, a parasitic subviral agent. The 3' untranslated region of the monopartite genome of Pelargonium line pattern virus (PLPV), the recommended type member of a tentative new genus (Pelarspovirus) in the family Tombusviridae, was predicted to contain a TED-like CITE. Similar CITEs can be anticipated in some other related viruses though none has been experimentally verified. Here, in the first place, we have performed a reassessment of the structure of the putative PLPV-TED through in silico predictions and in vitro SHAPE analysis with the full-length PLPV genome, which has indicated that the presumed TED element is larger than previously proposed. The extended conformation of the TED is strongly supported by the pattern of natural sequence variation, thus providing comparative structural evidence in support of the structural data obtained by in silico and in vitro approaches. Next, we have obtained experimental evidence demonstrating the in vivo activity of the PLPV-TED in the genomic (g) RNA, and also in the subgenomic (sg) RNA that the virus produces to express 3'-proximal genes. Besides other structural features, the results have highlighted the key role of long-distance kissing-loop interactions between the 3'-CITE and 5'-proximal hairpins for gRNA and sgRNA translation. Bioassays of CITE mutants have confirmed the importance of the identified 5'-3' RNA communication for viral infectivity and, moreover, have underlined the strong evolutionary constraints that may operate on genome stretches with both regulatory and coding functions.This work was supported by grants BFU2009-11699 and BFU2012-36095 from the Ministerio de Investigacion, Ciencia e Innovacion (MICINN, Spain, www.micinn.es) and the Ministerio de Economia y Competitividad (MINECO, Spain, http://www.mineco.gob.es), respectively, and ACOMP/2012/100 from the Generalitat Valenciana (http://www.gva.es) (to C.H.). MBP and LR were the recipients of a predoctoral and postdoctoral (Juan de la Cierva program) contract, respectively, from MICINN, and MPC was the recipient of a predoctoral contract from MINECO.Blanco Pérez, M.; Pérez Cañamás, M.; Ruiz, L.; Hernandez Fort, C. (2016). Efficient Translation of Pelargonium line pattern virus RNAs Relies on a TED-Like 3 '-Translational Enhancer that Communicates with the Corresponding 5 '-Region through a Long-Distance RNA-RNA Interaction. PLoS ONE. 11(4):1-24. https://doi.org/10.1371/journal.pone.0152593S12411

    Features of the autonomous function of the translational enhancer domain of satellite tobacco necrosis virus.

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    The RNA of satellite tobacco necrosis virus (STNV) is a monocistronic messenger that lacks both a cap and a poly(A) tail. Translation of STNV RNA in vitro is promoted by a 120-nt translational enhancer domain (TED) in the 3'-untranslated region. TED also stimulates translation of heterologous mRNAs. In this study, we show that TED stimulates translation of a cat mRNA by increasing translation efficiency to the level of capped mRNA. This stimulatory activity is not impaired by translation through TED. TED stimulates translation efficiency from different positions within the mRNA, varying from the 5' end to 940 nt downstream of the coding region. Duplication of TED has an additive effect on translation stimulation only when located at both ends of the mRNA. On dicistronic RNAs, TED stimulates translation of both cistrons to the same extent. These data suggest that TED acts primarily by recruiting the translational machinery to the RNA

    Subgenomic RNAs mediate expression of cistrons located internally on the genomic RNA of tobacco necrosis virus strain A.

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    Upon infection of tobacco protoplasts, the genomic RNA of tobacco necrosis virus strain A (TNV-A) accumulates linearly in time. The accumulation patterns of the two subgenomic RNAs resemble those of endogenous mRNAs in that the peak levels are reached after several hours. The accumulation of the 1.3-kb subgenomic RNA is delayed by 1 h compared with that of the 1.6-kb subgenomic RNA, which illustrates the important role of the subgenomic RNAs in the regulation of TNV-A gene expression. The locations of the 5' nucleotides of the subgenomic RNAs reveal that the 5'-proximal cistrons of the 1.6- and 1.3-kb RNAs encode an 8-kDa protein from open reading frame (ORF) 3 and the coat protein from ORF 5, respectively. In a wheat germ translation system, a synthetic transcript resembling the 1.6-kb RNA expresses both ORFs 3 and 4. Moreover, the synthesis of the 6-kDa protein from ORF 4 depends on the translation efficiency of ORF 3, suggesting that in vivo, ORFs 3 and 4 are both expressed from the 1.6-kb RNA. The major in vitro translation product of TNV-A genomic RNA is the coat protein. We show that the region upstream of the coat protein promotes internal initiation of translation in vitro. However, this region is functionally inactive in vivo, suggesting that TNV-A genomic RNA is not important for coat protein synthesis in plants

    Heteromannan and heteroxylan cell wall polysaccharides display different dynamics during the elongation and secondary cell wall deposition phases of cotton fiber cell development

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    The roles of non-cellulosic polysaccharides in cotton fiber development are poorly understood. Combining glycan microarrays and in situ analyses with monoclonal antibodies, polysaccharide linkage analyses and transcript profiling the occurrence of heteromannan and heteroxylan polysaccharides and related genes in developing and mature cotton (Gossypium spp.) fibers have been determined. Comparative analyses on cotton fibers at selected days post anthesis indicate different temporal and spatial regulation of heteromannan and heteroxylan during fiber development. The LM21 heteromannan epitope was more abundant during the fiber elongation phase and localized mainly in the primary cell wall. On the contrary, the AX1 heteroxylan epitope occurred at the transition phase and during secondary cell wall deposition and localized in both the primary and the secondary cell walls of the cotton fiber. These developmental dynamics were supported by transcript profiling of biosynthetic genes. Whereas our data suggest a role for heteromannan in fiber elongation, heteroxylan is likely to be involved in the regulation of cellulose deposition of secondary cell walls. In addition, the relative abundance of these epitopes during fiber development varied between cotton lines with contrasting fiber characteristics from four species (G. hirsutum, G. barbadense, G. arboreum, G. herbaceum), suggesting that these non-cellulosic polysaccharides may be involved in determining final fiber quality and suitability for industrial processing

    The 3' untranslated region of satellite tobacco necrosis virus RNA stimulates translation in vitro.

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    The RNA of satellite tobacco necrosis virus (STNV) is a monocistronic messenger that lacks both a 5' cap structure and a 3' poly(A) tail. We show that in a cell-free translation system derived from wheat germ, STNV RNA lacking the 600-nucleotide trailer is translated an order of magnitude less efficiently than full-size RNA. Deletion analyses positioned the translational enhancer domain (TED) within a conserved hairpin structure immediately downstream from the coat protein cistron. TED enhances translation when fused to a heterologous mRNA, but the level of enhancement depends on the nature of the 5' untranslated sequence and is maximal in combination with the STNV leader. The STNV leader and TED have two regions of complementarity. One of the complementary regions in TED resembles picornavirus box A, which is involved in cap-independent translation but which is located upstream of the coding region
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