Direct visualization and tracing of chromatin folding in the Drosophila embryo
Chromatin organization, through the assembly of DNA with histones and the folding of nucleosome chains, regulates DNA accessibility for transcription, DNA replication and repair. Although models derived from in vitro studies have proposed distinct nucleosome chain geometries, the organization of chromatin within the crowded cell nucleus remains elusive. Using cryo-electron tomography of thin vitreous sections, we directly observed the path of nucleosomal and linker DNA in situ from a flash-frozen organism - Drosophila embryos. We quantified linker length and curvature, characterizing an irregular zig-zag chromatin-folding motif, with a low degree of linker bending. Nucleosome conformations could be identified on individual particles in favorable orientations without structure averaging. Additionally, we observed particles that accommodate a number of DNA gyres ranging from less than one to up to three, which resemble previously proposed non-octameric nucleosomal particles with variable DNA wrapping.
Authors
- Amélie Leforestier (ORCID: https://orcid.org/0000-0002-0225-2776)
- Fadwa Fatmaoui (ORCID: https://orcid.org/0000-0003-2994-4729)
- Pascal Carrivain (ORCID: https://orcid.org/0000-0001-9683-1236)
- Burkhard Jakob
- Fatima Taiki
- Jean-Marc Victor
- Mikhail Eltsov
- Amina Iusupova
- Diana Grewe
- Wim Hagen
Institutions
- Goethe University Frankfurt (DE)
- Centre National de la Recherche Scientifique (FR)
- Inserm (FR)
- GSI Helmholtz Centre for Heavy Ion Research (DE)
- Université Paris-Saclay (FR)
- Laboratoire de physique des Solides (FR)
- Technische Universität Darmstadt (DE)
- Sorbonne Université (FR)
- Institut de génétique et de biologie moléculaire et cellulaire (FR)
- Thermo Fisher Scientific (Netherlands) (NL)
- European Molecular Biology Laboratory (DE)
- Laboratoire de Physique Théorique de la Matière Condensée (FR)
- Université de Strasbourg (FR)
Publication Details
- Journal
- The EMBO Journal
- Published
- 2026-02-09
- DOI
- https://doi.org/10.1038/s44318-026-00701-7
- Primary Topic
- Genomics and Chromatin Dynamics
- Type
- article
- Field-Weighted Citation Impact
- 0.00
Funders
- Deutsche Forschungsgemeinschaft
- Agence Nationale de la Recherche
- Bundesministerium für Bildung und Forschung
- Centre National de la Recherche Scientifique
- French Infrastructure for Integrated Structural Biology
- Horizon 2020 Framework Programme