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Accueil > Séminaires

Département Biologie des Génomes

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Agenda

  • Vendredi 24 mars 11:00-12:00 - Dr. Damien Devos - Center of Andalusian Biology of Development (CABD), Seville, Espagne

    Eukaryogenesis and microbiology’s platypus or how bacteria with membranes illuminate understanding the origin of our own cells

    Résumé : Invité par Bénédicte Michel, équipe Stabilité de l’ADN bactérien

    Lieu : Auditorium - Bâtiment 21, campus de gif


  • Vendredi 31 mars 11:00-12:00 - Dr Anca Segall - San Diego State University, USA

    Biological Dark Matter & the Contributions of Phages

    Résumé : Phages are the most abundant biological entities on Earth. They modulate bacterial populations either by lysing their hosts or by conferring selective advantages by contributing phage-encoded fitness factors. Consequently, phages play a critical role in host survival and pathogenicity, and in nutrient redistribution. The analysis of phage genomes in any environment provides insights into the physiological impact of viruses on the microbial community and human health. However, in most environments the function of over 70%, and sometimes greater than 95%, of phage-encoded genes cannot be predicted based on similarity to genes with known function currently in databases. This may be due either to extreme divergence from a common ancestor or to the presence of previously unidentified functions, structures, and/or protein folds. Accurate identification of viral-encoded functions would greatly improve annotation and understanding the contribution of phages in any environment.
    We have developed machine learning tools that predict gene function independently of amino acid sequence alignments. The resulting predictions are being validated using structural methods (X-ray crystallography and EM), which have unveiled new protein folds. We are combining these approaches with phenotypic responses, biochemistry, and metabolomics to probe the functions of non-structural proteins encoded by phages, and uncovering new contributions to bacterial lifestyles, with implications for microbial communities and human health.

    Lieu : Auditorium - Bâtiment 21, Campus de gif


  • Vendredi 21 avril 11:00-12:00 - Dr Kazufumi MOCHIZUKI - Institute of Human Genetics (IGH) CNRS-University of Montpellier UMR9002 Montpellier

    Small RNA-mediated trans-generational genome comparison and trans-recognition network in Tetrahymena DNA elimination

    Résumé : Small RNAs are used to silence transposable elements (TEs) in many eukaryotes, which use surprisingly diverse evolutionary solutions to identify TEs. We have previously reported that in the ciliated protozoan Tetrahymena thermophile, small RNA-mediated comparison of the germline and somatic genomes underlies identification of TE-related sequences, which are then eliminated from the soma. In addition, we recently found an additional layer of small RNA-mediated identification of TE-related sequences in Tetrahymena. We found that a limited set of Internal Eliminated Sequences (IESs) containing potentially active TEs produces a class of small RNAs that recognize not only the IESs from which they are derived but also other IESs in trans. This trans-recognition triggers the expression of yet another novel class of small RNAs that identify other IESs. Therefore, TE-related sequences in Tetrahymena are robustly targeted for elimination by a genome-wide trans-recognition network accompanied by a chain reaction of small RNA production. In this presentation, I will discuss our latest picture of small RNA-directed DNA elimination with two “trans” mechanisms : small RNA-mediated trans-generational genome comparison and trans-recognition network.

    Lieu : Auditorium - Bâtiment 21, campus de gif


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