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SUMMARY:Cryo electron microscopy of vitreous sections revisited for high t
 hroughput tomographic imaging of tissue and cells
DTSTART:20260505T160000
DTEND:20260505T170000
DTSTAMP:20260501T101207Z
UID:c98698425a233d97627f99ffe40ac5af24c2c1dea487d7d8e414f56a
CATEGORIES:Conferences - Seminars
DESCRIPTION:Amélie Leforestier | CNRS\, France\n\n\nCellular cryo electr
 on tomography is experiencing spectacular developments\, revealing with in
 creasing resolution and complexity the structures and interactions of macr
 omolecules at work in living matter. To obtain thin samples from biologica
 l tissue and cells in their flash-frozen native state\, cryo-FIB milling i
 s nowadays the most popular method\, with impressive successes. The altern
 ative\, cryo-ultramicrotomy - also known as CEMOVIS - has been overshadowe
 d because of (i) technical difficulties associated to cryo-section genera
 tion and collection - in particular the lack of control over adhesion\; an
 d (ii) crevasses and compression artefacts.\nI will present recent develop
 ments with optimization of the experimental workflow\, focusing on section
  adhesion and their support grids. These result in high throughput data ac
 quisition\, with typically several tens to hundreds of cryo-tomograms per 
 sample. Revisiting cutting artefacts shows that crevasses alter but 10 % o
 f the sample volume. Compression is heterogeneous\, with scale and materia
 l-dependent effects. This is altogether a drawback – with no simple comp
 utational correction – and an advantage for projects dedicated to non-(o
 r little)-affected objects such as nucleosomes and chromatin.\nAltogether\
 , it is time to revive CEMOVIS as a practical alternative to cryo-FIB mill
 ing\, offering specific advantages: (i) imaging of large areas of any type
  of sample\, from cells to tissues\, organs or even entire organisms – a
 nd more generally all kinds of hydrated molecular systems \; (ii) the pos
 sibility 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 a
 n advantage for high resolution imaging of small molecular complexes.\n\n\
 n\n\nBiography\n\nAmélie Leforestier is a CNRS research director at the S
 olid-State Physics Laboratory (LPS\, Paris-Saclay\, France). After a PhD i
 n Life Sciences on liquid crystalline self-assembly of DNA\, she learned c
 ryo electron microscopy during her post-doctoral studies in the group of J
 acques Dubochet in Lausanne. Back in France\, she set up a cryo-EM facilit
 y 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 mol
 ecular level. Her work\, combining concepts from soft matter physics (poly
 -electrolytes\, liquid crystals\, frustration) and structural biology\, fo
 cuses on the geometry and interactions in condensed states of DNA and chro
 mosomes in vitro and in situ.
LOCATION:https://epfl.zoom.us/j/65708791562
STATUS:CONFIRMED
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