Dynamic study of carbon nanotube growth and catalyst morphology evolution during acetylene decomposition on Co/SBA-15 in an environmental TEM

International @ SURFACES+FCA:MAO:ATUInternational audienceNon

Thousands of Rab GTPases for the Cell Biologist

Rab proteins are small GTPases that act as essential regulators of vesicular trafficking. 44 subfamilies are known in humans, performing specific sets of functions at distinct subcellular localisations and tissues. Rab function is conserved even amongst distant orthologs. Hence, the annotation of Rabs yields functional predictions about the cell biology of trafficking. So far, annotating Rabs has been a laborious manual task not feasible for current and future genomic output of deep sequencing technologies. We developed, validated and benchmarked the Rabifier, an automated bioinformatic pipeline for the identification and classification of Rabs, which achieves up to 90% classification accuracy. We cataloged roughly 8.000 Rabs from 247 genomes covering the entire eukaryotic tree. The full Rab database and a web tool implementing the pipeline are publicly available at www.RabDB.org. For the first time, we describe and analyse the evolution of Rabs in a dataset covering the whole eukaryotic phylogeny. We found a highly dynamic family undergoing frequent taxon-specific expansions and losses. We dated the origin of human subfamilies using phylogenetic profiling, which enlarged the Rab repertoire of the Last Eukaryotic Common Ancestor with Rab14, 32 and RabL4. Furthermore, a detailed analysis of the Choanoflagellate Monosiga brevicollis Rab family pinpointed the changes that accompanied the emergence of Metazoan multicellularity, mainly an important expansion and specialisation of the secretory pathway. Lastly, we experimentally establish tissue specificity in expression of mouse Rabs and show that neo-functionalisation best explains the emergence of new human Rab subfamilies. With the Rabifier and RabDB, we provide tools that easily allows non-bioinformaticians to integrate thousands of Rabs in their analyses. RabDB is designed to enable the cell biology community to keep pace with the increasing number of fully-sequenced genomes and change the scale at which we perform comparative analysis in cell biology

Polycomb repressive complex PRC1 spatially constrains the mouse embryonic stem cell genome.

The Polycomb repressive complexes PRC1 and PRC2 maintain embryonic stem cell (ESC) pluripotency by silencing lineage-specifying developmental regulator genes. Emerging evidence suggests that Polycomb complexes act through controlling spatial genome organization. We show that PRC1 functions as a master regulator of mouse ESC genome architecture by organizing genes in three-dimensional interaction networks. The strongest spatial network is composed of the four Hox gene clusters and early developmental transcription factor genes, the majority of which contact poised enhancers. Removal of Polycomb repression leads to disruption of promoter-promoter contacts in the Hox gene network. In contrast, promoter-enhancer contacts are maintained in the absence of Polycomb repression, with accompanying widespread acquisition of active chromatin signatures at network enhancers and pronounced transcriptional upregulation of network genes. Thus, PRC1 physically constrains developmental transcription factor genes and their enhancers in a silenced but poised spatial network. We propose that the selective release of genes from this spatial network underlies cell fate specification during early embryonic development

Surface and Bulk Structural and Chemical Modifications of Catalysts During Reaction Investigated within an Aberration-Corrected Environmental TEM

MICROSCOPIE+ATARI+FCA:MAOInternational audienceNon

Synthèse hydrothermale et caractérisation de catalyseurs Ce1-xZrxO2 pour la combustion du toluène

National @ ENERGIE+WHA:TCA:FCA:SBE:AAUInternational audienceNon

Synthèse hydrothermale et caractérisation de catalyseurs Ce1-xZrxO2 pour la combustion du toluène

National @ ENERGIE+WHA:TCA:FCA:SBE:AAUInternational audienceNon

Dynamic high-resolution study of the structural evolution of Ag nanoparticles during carbon gasification within an aberration-corrected environmental transmission electron microscope

MICROSCOPIE+ATARI:ECI2D:ING+FCA:MAO:SLO:ATUInternational audienceNon

Real-time in situ atomic-scale study of the surface termination of ceria nanoparticles under vacuum, O2 and CO2 pressures by environmental transmission electron microscopy.

MICROSCOPIE+ATARI:ING+FCA:MAO:CDA:FRM:DFAInternational audienceNon

Microwave hydrothermal synthesis of zirconia based catalysts for DeNOx applications

Internationa