Physics-Biology interface seminar

Held every second Wednesday at 11am at LPTMS in room 201 (our previous location, LPS, is under renovation) in Orsay, this seminar series aims to be a central forum for the Physics/Biology interface in the south of Paris.

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Other seminars and conferences you might be interested in:

Paris-Saclay Biomechanics seminar - last Thu. of the month in Palaiseau (subscribe to their announcements)
Seminar of the Physical Chemistry Laboratory - in Orsay

Informations for speakers
Past seminars
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Whole-brain imaging during vestibular stimulation in zebrafish with a novel rotatable light-sheet microscope

Volker Bormuth (Laboratoire Jean Perrin, Université Pierre et Marie Curie)

Light-sheet microscopy allows cell resolved whole-brain calcium imaging at several brain scans per second in zebrafish larvae. Currently this technique is not compatible with dynamic stimulation of the vestibular system. We developed an ultra-stable miniaturized light-sheet microscope that can be rotated while performing whole-brain recordings. Rotating the microscope rotates the fish and stimulates the vestibular system while imaging always the same plane in the brain. We demonstrate volumetric whole-brain neuronal activity recordings during vestibular stimulation. We mapped the brain activity with cellular resolution of the vestibule-ocular reflex (VOR) which drives compensatory eyes movements to maintain clear vision during body rotation. Our long-term goal is study with this system multisensory signal processing by the vertebrate brain by combining visual with vestibular stimuli.

Location: LPTMS, salle 201, 2ème étage, Bât 100, Campus d'Orsay

Julien Husson (LadHyX, École polytechnique, France)

Location: LPTMS, salle 201, 2ème étage, Bât 100, Campus d'Orsay

Ribosome assembly studied by single-molecule force measurements

Thierry Bizebard (IBPC, Paris)

Ribosomes belong to the most complicated structures in biology. Their assembly is a question of fundamental interest, but is still poorly understood. In vitro reconstitution studies have shown that the ribosome assembly process is highly cooperative and starts with the binding of a few ribosomal (r-) proteins to rRNA, but how these early binders act is unknown. Our work focuses on the initial phase of the assembly of the large subunit (50S) of the E. coli ribosome, which involves 23S rRNA, five r-proteins and a selection of assembly “helper” proteins. Our force measurements on single RNA molecules have allowed us to pinpoint several important properties of the early-binding r-proteins we have studied:

- These proteins bind with high cooperativity to the rRNA (as would be expected to obtain a high yield of fully assembled and active ribosomes).
- The r-proteins act as molecular clamps, stabilising the RNA 3D structure.
- As such, they afford a strong mechanical and energetical stabilisation of the ribonucleoprotein structure (which is also probably necessary for optimum activity).

In the near future, we intend to further improve the potential of our single-molecule measurements by implementing combined force/fluorescence manipulations, and apply this methodology to our study of the early phase of E. coli large ribosomal subunit assembly.

Location: LPTMS, salle 201, 2ème étage, Bât 100, Campus d'Orsay

Ivo Sbalzarini (Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany)

Location: LPTMS, salle 201, 2ème étage, Bât 100, Campus d'Orsay