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Seminar of Csilla GERGELY

On October 7, 2020
11h, Lagrange Amphitheater

Seminar of Csilla Gergely Insight to severe muscular disorders by multiscale imaging: from atomic force microscopy to second harmonic generation microscopy study

2020_09_Csilla_Gegerly.jpg

2020_09_Csilla_Gegerly.jpg

Insight to severe muscular disorders by multiscale imaging: from atomic force microscopy to second harmonic generation microscopy study

 

by Csilla GERGELY, Laboratoire Charles Coulomb - L2C, UMR 5221 CNRS-Université de Montpellier, France

Csilla Gergely is currently professor in biophysics at the Charles Coulomb Laboratory of Montpellier University in France. She obtained her PhD in 1997 at the University of Szeged, Hungary, in the field of biophysics. C. Gergely is the leader of the Bionanophotonics team dealing with strongly multidisciplinary research developing various biophotonic tools to study molecular assemblies, living cells and tissues. The combination of advanced imaging techniques like atomic force microscopy, multiphoton an BCARS microscopy with molecular detection afforded by a novel generation of photonic biosensors is the strengths of our team addressing diagnosis and follow-up therapy.

The search for predictive indicators of disease has largely focused on molecular markers. However, biophysical markers, which can integrate multiple pathways, may provide a more global picture of pathophysiology. The adequacy of the chosen, mostly combined, advanced imaging techniques is often determined by their ability for multi-scale follow-up of molecular processes. I will present through two studies the different level of information we have obtained on the pathophysiological processes of two muscular illnesses that are the amyotrophic lateral sclerosis (ALS) and the Duchenne muscular dystrophy (DMD). Early symptoms of ALS usually include muscle weakness or stiffness. Therefore, mechanical response of differentiated myotubes from primary cultures of mice expressing the ALS-causing SOD1 mutation was examined by force mapping in atomic force microscopy. Wild type myotubes reveal a significant difference in elasticity between a narrow and a wide population, consistent with maturation occurring with higher actin expression. However, this is not true for SOD1 expressing myotubes, where a significant shift of thin population towards higher elastic modulus values was observed indicating that SOD1 mutation induces structural changes that occurs very early in muscle development.

Duchenne muscular dystrophy (DMD) is a severe and lethal disease linked to mutations in the dystrophin gene. However, the link between the dystrophin deficiency and the contractile dysfunction of the cardiomyocytes is unclear. Second harmonic generation (SHG) microscopy was used to acquire images on a mouse model of DMD (mdx mice) and control alive cardiomyocytes at different ages to study the cellular cytoskeleton and contractile apparatus organization. SHG makes functional imaging possible as without need of fluorescent staining, by measuring the SHG anisotropy important results are extracted on the myosin filament conformation and the organization of key sarcomeric cardiac proteins. Accurate image analysis of SHG signal allow monitoring several regional properties of the cardiomyocytes such as the orientation dispersion, sinusosity and organization of the myofibrils and the sarcomeres length.



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