Programme : séminaires et soutenances - Octobre 2014

Programme : séminaires et soutenances - Octobre 2014

Département de Microbiologie,
Institut Pasteur, 25 rue du Dr Roux - 75015 Paris
 

 

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Visitors have to present an identity document at the Welcome desk.

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. vend. 10 octobre à 11 h 30 : séminaire Thomas BERNHARDT (Harvard Medical School, Boston-USA)
 

. merc. 15 octobre à 14 h 00 : soutenance thèse Ambroise LAMBERT (Biologie Spirochètes, Institut Pasteur)

 

. vend. 17 octobre à 11 h 30 : séminaire conjoint Claudio BANDI (Univ. Milano, Italy)
 

. vend. 24 octobre à 11 h 30 : séminaire Nicolas DESPRAT (ENS, Paris)

 

 

 

Thomas BERNHARDT

Department of Microbiology & Immunobiology - Harvard Medical School, Boston (USA)


'Beta-lactam antibiotics induce a lethal malfunctioning of the bacterial cell wall synthesis machinery'


vendredi 10 octobre 2014 à 11 h 30

Amphi François Jacob - Centre François Jacob


contact : Nienke Buddelmeijer (nienke.buddelmeijer@pasteur.fr)



Abstract
Penicillin and related beta-lactams are one of our oldest and most widely used antibiotic therapies. These drugs have long been known to target the activity of enzymes called penicillin-binding proteins (PBPs) that build the bacterial cell wall. However, surprisingly little is understood about the downstream consequences of target inhibition and how they contribute to the lethal action of these important drugs. Elucidation of the events that follow PBP inhibition has been difficult because beta-lactams often target multiple PBPs in a given cell and elicit complex phenotypes that vary depending on the derivative used. To overcome these challenges, we studied the activity of mecillinam, a beta-lactam that is highly specific for a single PBP in the model gram-negative bacterium Escherichia coli. We demonstrate that mecillinam and other beta-lactams do more than just inhibit the PBPs as is commonly believed. Rather, like other bactericidal antibiotics, they induce a toxic malfunctioning of their target biosynthetic machinery that bolsters their killing activity. Characterization of this previously unappreciated property of beta-lactams has additionally revealed a novel quality-control function for enzymes that cleave bonds in the cell wall matrix. Our findings thus provide new insight into the cell wall assembly process in addition to uncovering the mechanism by which beta-lactam antibiotics induce cell death.

 

 

 

Soutenance de Thèse de Doctorat de l’Université Paris 7
Ecole doctorale B3MI

Ambroise LAMBERT


'Etude de la motilité et du chimiotactisme chez les leptospires'

mercredi 15 octobre 2014 à 14 h 00
Auditorium François Jacob – Bâtiment François Jacob

sous la direction de Mathieu Picardeau
unité Biologie des Spirochètes dirigée par Mathieu Picardeau

Contact : Ambroise Lambert (ambroise.lambert@pasteur.fr)

 

 

 

Séminaire conjoint organisé par les Départements :
'Parasites et Insectes vecteurs'  et  'Microbiologie'


Claudio BANDI


Professor of Parasitology and Parasitic Diseases, University of Milano (Italy)

'Gendercide parasites and other stories of sex, symbiosis and survival.

vendredi 17 octobre 2014 à 11 h 30
salle Jean-Paul Aubert - Bât. Fernbach

contacts :

Chetan Chitnis (chetan.chitnis@pasteur.fr) & Simonetta Gribaldo (simonetta.gribaldo@pasteur.fr)

Abstract
Symbiosis is a widespread biological phenomenon. High levels of integration are frequently observed between the partners of symbiotic associations, at the physiological, metabolic and even genetic and genomic levels. In insects and other arthropods, intracellular microbial symbionts are normally transmitted to the progeny of the host, through the female oocytes/reproductive apparatus. This uniparental type of transmission implies a conflict between the interests of the symbionts (whose reproductive success is linked to the success of females, or even to the success of those particular females that transmit them), and the interests of the host population as a whole (where males, or even uninfected females, are not useful to the symbiotic microorganisms). In these forms of symbiosis, characteristics that would be apparently ununderstandable (e.g. the generation of sterilized females, or the death of male embryos) can found an explanation if we focus our attention on the interests of the symbionts, rather than on the interest of the hosts.

 

 

 

Nicolas DESPRAT

LPS - Biomolecules CNRS UMR8550 - Ecole Normale Supérieure (Paris)

 

'Spatial interactions in bacterial colonies'.


vendredi 24 octobre 2014 à 11 h 30

Amphi François Jacob - Centre François Jacob


contact : Sven van Teeffelen (sven.van-teeffelen@pasteur.fr)


Abstract
The structure of the environment spatially confines bacteria inside groups where they live and evolve with their siblings. This population structure not only selects for individual abilities but also for group properties that eventually enhance the fitness of the colony. In media low in nutrients, we might think that maximizing the contact with the environment would maximize the fitness of individual cells. However, in media low in iron, we have shown that cell-cell contacts promote the use of secreted siderophores required to get iron from the environment. To further understand what set the degree of cellular contacts in micro-colonies attached to solid substrate, we recently developed experimental tools to measure the adhesion and the forces at play during the morphogenesis of bacterial micro-colonies.

 


 

Mis à jour le 09/10/2014

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