Quantitative 3D super-resolution imaging of chromatin ‘blobs’


Event details

Date and time 29.04.2021 13:3014:30  
Online https://epfl.zoom.us/s/88022434967
Speaker Lothar Schermelleh, Ph.D., Dept. Biochemistry University of Oxford
As affiliated member of the Micron Advanced Bioimaging Unit (www.micronoxford.com), he is driving the development of computational analysis and fluorescence labelling tools for super-resolution microscopy.
Lothar’s research aims at understanding the relationship between 3D nuclear organisation and genome activity in mammalian cells by combining genetic tools and advanced optical imaging methods.
Category Conferences - Seminars
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Three-dimensional (3D) chromatin organisation plays a key role in regulating genome function in higher eukaryotes. Despite recognition that the genome partitions into ~1Mb-sized topological associated domains (TADs) based on ensemble Hi-C measurements, many features of the physical organisation at the single cell level remain underexplored. In my talk I will present our recent progress in analysing functional chromatin topography and dynamics on the size scale of TADs using in vivo and in situ 3D super-resolution microscopy, supported by 3D scanning electron microscopy. We directly visualise curvilinear arrangements of globular/irregular shaped ~200-300 nm diameter nucleosomal condensates with viscoelastic properties (‘blobs’), that are juxtaposed to an RNA-populated chromatin-depleted interchromatin network. High-content mapping of functional marker reveal active/permissive chromatin marker to be confined to a narrow region at blob surfaces, whereas repressive marks are enriched towards blob interiors. This correlation between nanoscale topology and genome function is temporarily relaxed in postreplicative chromatin, but remarkably stable after inactivation of cohesin. Our findings establish TAD-sized nanodomains as physical modules of mesoscale genome organisation with functional chromatin states being defined by radial position and exposure to a (likely phase-separated) interchromatin space.

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superresolution microscopy nuclear organisation