144 research outputs found

    A Lin28 homologue reprograms differentiated cells to stem cells in the moss Physcomitrella patens

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    Both land plants and metazoa have the capacity to reprogram differentiated cells to stem cells. Here we show that the moss Physcomitrella patens Cold-Shock Domain Protein 1 (PpCSP1) regulates reprogramming of differentiated leaf cells to chloronema apical stem cells and shares conserved domains with the induced pluripotent stem cell factor Lin28 in mammals. PpCSP1 accumulates in the reprogramming cells and is maintained throughout the reprogramming process and in the resultant stem cells. Expression of PpCSP1 is negatively regulated by its 3′-untranslated region (3′-UTR). Removal of the 3′-UTR stabilizes PpCSP1 transcripts, results in accumulation of PpCSP1 protein and enhances reprogramming. A quadruple deletion mutant of PpCSP1 and three closely related PpCSPgenes exhibits attenuated reprogramming indicating that the PpCSP genes function redundantly in cellular reprogramming. Taken together, these data demonstrate a positive role of PpCSP1 in reprogramming, which is similar to the function of mammalian Lin28

    Atendimento ao cliente.

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    The Selaginella Genome Identifies Genetic Changes Associated with the Evolution of Vascular Plants

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    Vascular plants appeared ~410 million years ago then diverged into several lineages of which only two survive: the euphyllophytes (ferns and seed plants) and the lycophytes (1). We report here the genome sequence of the lycophyte Selaginella moellendorffii (Selaginella), the first non-seed vascular plant genome reported. By comparing gene content in evolutionary diverse taxa, we found that the transition from a gametophyte- to sporophyte- dominated life cycle required far fewer new genes than the transition from a non-seed vascular to a flowering plant, while secondary metabolic genes expanded extensively and in parallel in the lycophyte and angiosperm lineages. Selaginella differs in post- transcriptional gene regulation, including small RNA regulation of repetitive elements, an absence of the tasiRNA pathway and extensive RNA editing of organellar genes

    Investigation of the effect of temper rolling on the texture evolution and mechanical behavior of IF steels using multiscale simulation

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    The main objective of this study is to simulate texture and deformation during the temper-rolling process. To this end, a rate-independent crystal plasticity model, based on the self-consistent scale-transition scheme, is adopted to predict texture evolution and deformation heterogeneity during temper-rolling process. For computational efficiency, a decoupled analysis is considered between the polycrystalline plasticity model and the finite element analysis for the temper rolling. The elasto-plastic finite element analysis is first carried out to determine the history of velocity gradient during the numerical simulation of temper rolling. The thus calculated velocity gradient history is subsequently applied to the polycrystalline plasticity model. By following some appropriately selected strain paths (i.e., streamlines) along the rolling process, one can predict the texture evolution of the material at the half thickness of the sheet metal as well as other parameters related to its microstructure. The numerical results obtained by the proposed strategy are compared with experimental data in the case of IF steels.French program “Investment in the future” operated by the National Research Agency (ANR)-11-LABX-0008-01, LabEx DAMAS (LST)

    A Study on the Propulsion Performance in the Actual Sea by means of Full-scale Experiments

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    The IMO has adopted Energy Efficiency Design Index (EEDI), Ship Energy Efficiency Management Plan (SEEMP) and Energy Efficiency Operational Indicator (EEOI) in order to reduce GHG emissions from international shipping. And, the shipping industry is required to develop and improve the energy saving ship operation technologies to meet the above IMO guideline. The weather routing is one of the energy saving navigation technologies and widely adopted by oceangoing merchant ships. The effectiveness of the weather routing mainly depends on the accuracy of weather forecast data and the ship’s propulsion performance prediction. The propulsion performance in the actual sea is usually predicted using the Self Propulsion Factors obtained by model tests. It is necessary to understand the propulsion performance characteristics in the actual sea conditions for the improvement of propulsion performance prediction. From the above points of view, the authors performed full‐scale experiments using a training ship in order to investigate the propulsion performance characteristics in the actual sea. This paper describes the analysis results on the characteristics of Power Curves and Self Propulsion Factors under various weather and sea conditions
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