Friday 12th June 2015
Amphithéâtre Jean Perrin, Laboratoire Chimie Physique Matière et Rayonnement,
11 rue Pierre et Marie Curie,
For more information, please contact: Ludovic.Jullien [at] ens.fr
Light has recently emerged as the trigger of choice to perturb and read-out the state of living cells. The symposium will start with the introduction of recent views on the essence of Life relying on experiments dealing with the emergence of the living state from inert matter. It will then illustrate which molecular tools making use of light and optical instruments can be used to interrogate cells, organs, and organisms.
Ludovic Jullien (ENS-UPMC)
13:35-14:35: Prof. Dieter Braun, Ludwig Maximilians-Universität München, Allemagne
Nonequilibrium Mechanisms for the Onset of Life
The Origin of Life is one of the fundamental, unsolved riddles of modern science. Life as we know it is a stunningly complex non-equilibrium process, keeping its entropy low against the second law of thermodynamics. Therefore it is straightforward to argue that first living systems had to start in a natural non-equilibrium settings. Recent experiments with non-equilibrium microsystems suggest that geological conditions should be able to drive molecular evolution, i.e. the combined replication and selection of genetic molecules towards ever increasing complexity.
14:40-15:40: Andrey Klymchenko, Université de Strabourg, France
Molecular and nanoparticle probes with on/off response to external stimuli for biomolecular detection and imaging
On/off response of fluorescent molecular probes enables detection and imaging of biological targets with minimal background noise. Examples of turn-on probes developed in our group for imaging membrane receptors will be presented. Further improvement of the signal to noise ratio could be achieved by using ultrabright organic nanoparticles. Our recent progress in the design of these nanoparticles and their on/off switching by external stimuli will be also shown.
15:40-16:00: Coffee break
16:00-17:00: Dominique Bourgeois, Institut de Biologie Structurale, Grenoble, France
Phototransformable fluorescent proteins: structural insight into switching, blinking and bleaching
Phototransformable fluorescent proteins (PTFPs) change their photophysical state upon light illumination and are thus markers of choice in single-molecule based localization microscopy techniques such as PALM. However, the complex photophysics of PTFPs also deteriorate the quality of super-resolution images and cause artifacts in their quantitative evaluation. It is therefore crucial to understand the photophysical mechanisms driving processes such as photoswitching, photoblinking and photobleaching, in order to facilitate the design of future variants with improved performances. I will show how these processes can be directly visualized at the structural level by using kinetic crystallography approaches.
17:05-18:05: Emmanuel Beaurepaire, Ecole Polytechnique, France
Advances in multiphoton tissue imaging: multicolor and light-sheet approaches
Multiphoton microscopy is now the reference method for cell-resolution fluorescence imaging of thick/live samples. However established methods remain limited in terms of imaging speed and ability to simultaneously probe multiple parameters. This lecture will discuss some recent advances (efficient combination of fluorescence with coherent contrasts (THG, SHG), multicolor two-photon excitation using wavelength mixing and its application to brainbow tissue imaging, and high-throughput two-photon imaging using light-sheet excitation) for high-information content imaging of developing tissues and embryos.