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  • Génomes

    • Mardi 21 mai 11:00-12:00 - Silvia BULGHERESI - Environmental Cell Biology, University of Vienna, Austria

      Unconventional breakups - the extraordinary reproductive strategies of animal-attached bacteria

      Résumé : Up to now, the study of bacterial growth and division focused on model organisms grown in the laboratory and therefore isolated from their “natural” environment. As a consequence, cell biological research on bacterial symbionts - including those thriving on animal surfaces - is scarce. The spatial disposition of Gammaproteobacteria (Candidatus genus Thiosymbion) on the surface of their marine nematode hosts is species-specific, transgenerationally transmitted from mother to offspring, and likely facilitated by extraordinary reproductive strategies. We are studying their molecular underpinning and seek to understand why they evolved.

      Lieu : Salle des séminaires - bâtiment 26 - campus de Gif-sur-yvette

      Article

  • Virologie

    • Lundi 6 mai 14:30-15:30 - Dorian McIlroy - UMR 1064, INSERM, Centre de Recherche en Transplantation et Immunologie, Nantes

      Evolution de la capside des polyomavirus BK et JC à court et à long terme.

      Lieu : Salle des séminaires, Bât. 14C - Campus de Gif-sur-Yvette

      Notes de dernières minutes : Candidature au poste de Professeur de Virologie

      Article

    • Mardi 7 mai 14:30-15:30 - Alessia Zamborlini - Institut Universitaire d’Hématologie - IUH -, St Louis, Paris

      Rôle de la SUMOylation dans l’immunité innée : régulation de l’activité antivirale de SAMHD1

      Lieu : Salle des séminaires, Bât. 14C - Campus de Gif-sur-Yvette

      Notes de dernières minutes : Candidature au poste de Professeur de Virologie

      Article

    • Jeudi 9 mai 14:30-15:30 - Gaël Belliot - Centre National de Référence des virus des gastro-entérites, CHU, Dijon

      Interactions virus-hôte. Exemple des relations chez l’homme entre le norovirus et les antigènes de groupe sanguin

      Résumé : Candidature au poste de Professeur de Virologie

      Lieu : Salle des séminaires, Bât. 14C - Campus de Gif-sur-Yvette

      Article

  • Microbiologie

    • Mardi 14 mai 11:30-12:30 - Victor Kreis - ARNCLO team, Microbiology department, I2BC

      Role of noncoding RNAs in the pathogenesis of infections related to an emerging human enteropathogen, Clostridium difficile

      Résumé : Clostridium difficile is the leading cause of diarrhea associated with adult care in industrialized countries. The incidence of these infections continues to increase and this trend is accentuated by the general aging of the population. C. difficile represents today a real danger for human and animal health. Better understanding the regulation of colonization process of the digestive tract seems essential for the study of this emerging pathogen. We have recently discovered the existence of a large number of regulatory RNAs in C. difficile. We will use high throughput approaches to identify RNAs induced during infection as important virulence factors. We have already identified several regulatory RNAs specific to a particularly virulent strain that can contribute to this phenotype. Their detailed study will make possible to anticipate the emergence of new hypervirulent strains and better understand the adaptation mechanisms developed by this pathogen. This project will also allow uncovering the role of RNAs in the regulatory network controlling critical processes for the development of C. difficile in the host. These data will be used to develop new diagnostic and therapeutic approaches.

      Lieu : Salle Kalogeropoulos - Bât. 400, Campus d’Orsay

      Article

    • Mardi 21 mai 11:30-12:30 - Hilde De Reuse - Institut Pasteur, Département de Microbiologie, Unité Pathogenèse de Helicobacter, ERL CNRS 6002 PARIS (FRANCE)

      Evolution of Helicobacter and nickel metabolism

      Résumé : Metal acquisition and intracellular trafficking are crucial for all cells and metal ions have been recognized as virulence determinants in bacterial pathogens.
      Helicobacter pylori colonizes the acidic stomach of about half of the human population worldwide and is associated with gastric cancer that is responsible for 800,000 deaths every year. Virulence of Helicobacter pylori depends on the metal nickel, cofactor of two enzymes essential for in vivo colonization. In our group, we are studying the transport, storage and distribution of nickel in H. pylori. I will present the functional characterization of unique nickel-binding proteins of H. pylori that act as nickel stores and are essential for colonization. In addition, I will show our identification of a novel nickel transporter that is also required for colonization. Phylogenomics were applied to study the distribution of these proteins in the Helicobacter genus that is divided into two categories, enterohepatic species and gastric species (such as H. pylori) that exclusively colonize the stomach of mammals.
      Our data show that, during evolution of the Helicobacter genus, acquisition by gastric Helicobacter species of proteins involved in nickel transport and trafficking constituted a decisive evolutionary event to allow Helicobacter to colonize the hostile gastric environment and to become an amazingly successful pathogen.

      Lieu : Salle Kalogeropoulos - Bât. 400, Campus d’Orsay

      Article

  • B3S

    • Vendredi 10 mai 11:00-12:30 - Slavica Jonic - IMPMC - UMR 7590, Sorbonne Université/CNRS/MNHN, Paris

      Cryo-EM image analysis methods to study biomolecular conformational variability

      Résumé : Cryo electron microscopy (cryo-EM) has become comparable to X-ray crystallography with regards to the obtainable resolution of structures of biomolecular complexes, which are now increasingly determined at near-atomic resolution. To achieve such high resolutions, the classical approach is to collect a large number of cryo-EM images of complexes (particles) at random (unknown) orientations within a thin layer of vitreous ice, then, perform 2D and 3D classifications into an initially set number of classes and, finally, remove all those particles that do not contribute to the highest-resolution class averages (keep only particles with the most consistent views and conformations). Such “selection” of particles may obscure the information on a possibly larger conformational variability. More precisely, some conformational states may be thrown away blindly instead of being clearly elucidated while the characterization of different coexisting conformations may be essential for understanding how the complexes function and develop new drugs. Many classification-based image analysis methods exist and allow studying conformational changes assuming countable numbers of possible states (referred to as discrete-state methods) and the development of non-classification-based methods (referred to as continuous-state methods) is in progress. The latter methods assume uncountable numbers of states and aim at visualizing the full distribution of states. In this talk, I will review these different methods and describe in more detail the continuous-state method based on combining image analysis and normal mode analysis that has been developed in my lab.

      Lieu : Salle 102f - Bâtiment 14, Campus de Gif-sur-Yvette

      Article

    • Lundi 27 mai 11:00-12:00 - Jérôme Gouge - Structural Biology Department, Institute of Cancer Research, London, UK.

      Human RNA polymerase III recruitment at the type 3 promoters

      Résumé : The RNA Polymerase III controls transcription of the short and untranslated RNA, such as the entire pool of tRNA. Its recruitment relies on 3 subunits : i) TBP, ii) Bdp1 that opens the DNA bubble and iii) either Brf1 or Brf2. While Brf1 is found across all eukaryotes at type 1 and 2 promoters, Brf2 is present only in higher metazoans at the type 3 promoters. Brf2 has been linked to tumorigenesis but the underlying mechanisms remain elusive. Integration of structural, biochemical and in vitro data provided a model explaining Brf2 activation in cancer and how the promoter can be opened in the Pol III system in absence of ATP hydrolysis.

      Lieu : Auditorium I2BC - Bât. 21, Campus de Gif-sur-Yvette

      Notes de dernières minutes : Candidature à une création d’équipe ATIP

      Article

  • cytoskeleton club

    • Mardi 14 mai 11:30-12:30 - Martin Lenz - Laboratoire de Physique Théorique et Modèles Statistiques (LPTMS), UMR CNRS 8626, Orsay

      Cytoskeleton club - Why does actomyosin contract ?

      Résumé : The motion of living cells is largely due to the interaction of semi-flexible actin filaments (F-actin) and myosin molecular motors. It is often assumed that the relative sliding of these two components is sufficient to account for all actomyosin-based motion. While this is correct in our highly organized striated muscle, we question the application of this dogma to less ordered actomyosin systems, thus reexamining a cornerstone of our understanding of cellular motion.
      Contact : Christophe Le Clainche

      Lieu : Bibliothèque - bât. 34

      Article

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