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Département Biologie des Génomes

par EQYY - publié le , mis à jour le


  • Vendredi 1er décembre 11:00-12:00 - Pierre Amato - CNRS, UMR 6296, ICCF (Institut de Chimie de Clermont-Ferrand), Université Clermont Auvergne, France

    Structure and functioning of cloud microbiota

    Résumé : The atmosphere carries microorganisms and connects distant ecosystems. In addition of the underlying epidemiological issues associated with the presence of living microorganisms in the air, it was shown recently that they can contribute to atmospheric physico-chemical processes. Clouds are thus now considered in some aspects as habitats for microorganisms, albeit temporary by essence. Our first culture-based studies led on cloud microflora recovered from the atmospheric observatory at the puy de Dôme mountain summit (1465 m asl.), in the early 2000’s, revealed a high diversity in the microbial community, dominated by a few genera of bacteria and fungi. The advent of new DNA amplification methods (MDA), associated with next generation sequencing tools allows clarifying our vision of cloud biodiversity and its functioning, while overcoming the difficulties raised by the low biomass in these environments ( 104 cells m-3). Thereby, cloud water metagenomes, metatranscriptomes and amplicons libraries (16S and 18S rRNA genes) were investigated. The results showed a high taxonomic diversity in both prokaryotes and eukaryotes, but a very uneven distribution dominated by a few abundant OTUs. The large domination of Proteobacteria was confirmed, and the presence of noticeable groups such as viruses, Cyanobacteria and Archaea was observed. The active biodiversity was largely related to some groups of bacteria, notably Alpha- and Gamma-Proteobacteria. Metatranscriptomes showed a large overrepresentation of functions related to metabolic regulation, genome reorganization, access to substrates and defense against oxidants. These new pictures of cloud microbial communities indicate that these are environments open to numerous taxa, but where only a few can maintain and thus successfully disperse. They must rapidly adjust their functioning for surviving in these dynamic environments, suggesting that atmospheric transport probably operates strong selection on the microorganisms of outdoor surfaces, and thus drives to some extent microbial evolution.
    Contact : Jean-Luc Ferat <jean-luc.ferat>

    Lieu : Bibliothèque- bâtiment 34 - Campus CNRS de Gif-sur-Yvette

  • Vendredi 8 décembre 11:00-12:00 - Olivier Espeli - Collège de France

    Dealing with environmental stresses through bacterial cell cycle contortions

    Résumé : Abstract not available
    invited by Yoshi Yamaichi <yoshiharu.yamaichi>

    Lieu : Salle de séminaires - bâtiment 26 (TBA) - Campus CNRS de Gif-sur-Yvette

  • Vendredi 15 décembre 11:00-12:00 - Wouter de Laat - Biomedical genomics group, Hubrecht Institute, Utrecht, The Netherlands

    Genome structure-function relationships explored at new dimensions

    Résumé : Chromatin folding is increasingly recognized as a regulator of genomic processes such as gene activity. Chromosome conformation capture (3C) methods have been developed to unravel genome topology through the analysis of pair-wise chromatin contacts and have identified many genes and regulatory sequences that, in populations of cells, are engaged in multiple DNA interactions. I will describe our contributions to this field and will present novel Multi-Contact 4C (MC-4C), that applies Oxford Nanopore long-read single molecule sequencing to study multi-way DNA conformations of individual alleles for distinction between cooperative, random and competing interactions. Using this single molecule multi-contact analysis method, we uncover previously missed structures in sub-populations of cells, reveal single locus enhancer hubs and demonstrate the collision of CTCF-anchored architectural loops. Insight into single allele higher-order topological features will help understanding how the myriad of regulatory sequences spatially coordinate their actions on individual chromosomes and facilitate interpreting the consequences of natural and induced genetic variation. If time permits, I will also discuss how we explore the application of 3C-based methods in DNA diagnostics, oncogenetics and non-invasive prenatal diagnosis.
    Contact : Daan Noordermeer <daan.noordermeer>

    Lieu : Auditorium - bâtiment 21 - Campus CNRS de Gif-sur-Yvette

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