Cryo electron microscopy of vitreous sections revisited for high throughput tomographic imaging of tissue and cells
Event details
| Date | 05.05.2026 |
| Hour | 16:00 › 17:00 |
| Speaker | Amélie Leforestier | CNRS, France |
| Location | Online |
| Category | Conferences - Seminars |
| Event Language | English |
Cellular cryo electron tomography is experiencing spectacular developments, revealing with increasing resolution and complexity the structures and interactions of macromolecules at work in living matter. To obtain thin samples from biological tissue and cells in their flash-frozen native state, cryo-FIB milling is nowadays the most popular method, with impressive successes. The alternative, cryo-ultramicrotomy - also known as CEMOVIS - has been overshadowed because of (i) technical difficulties associated to cryo-section generation and collection - in particular the lack of control over adhesion; and (ii) crevasses and compression artefacts.
I will present recent developments with optimization of the experimental workflow, focusing on section adhesion and their support grids. These result in high throughput data acquisition, with typically several tens to hundreds of cryo-tomograms per sample. Revisiting cutting artefacts shows that crevasses alter but 10 % of the sample volume. Compression is heterogeneous, with scale and material-dependent effects. This is altogether a drawback – with no simple computational correction – and an advantage for projects dedicated to non-(or little)-affected objects such as nucleosomes and chromatin.
Altogether, it is time to revive CEMOVIS as a practical alternative to cryo-FIB milling, offering specific advantages: (i) imaging of large areas of any type of sample, from cells to tissues, organs or even entire organisms – and more generally all kinds of hydrated molecular systems ; (ii) the possibility of serial section approaches ; (iii) no beam damage ; and (iv) a specimen thickness that can be tuned down to 30-50 nm, which may be an advantage for high resolution imaging of small molecular complexes.
Biography
Amélie Leforestier is a CNRS research director at the Solid-State Physics Laboratory (LPS, Paris-Saclay, France). After a PhD in Life Sciences on liquid crystalline self-assembly of DNA, she learned cryo electron microscopy during her post-doctoral studies in the group of Jacques Dubochet in Lausanne. Back in France, she set up a cryo-EM facility for soft matter physics at LPS. She is part of an interdisciplinary team dedicated to self-assembly processes at work in living systems at the molecular level. Her work, combining concepts from soft matter physics (poly-electrolytes, liquid crystals, frustration) and structural biology, focuses on the geometry and interactions in condensed states of DNA and chromosomes in vitro and in situ.
Practical information
- General public
- Free
- This event is internal
Organizer
- CIME