Analysis of cryo-electron microscopy images does not support the existence of 30-nm chromatin fibers in mitotic chromosomes in situ.

Details

Serval ID
serval:BIB_7181F84A2278
Type
Article: article from journal or magazin.
Collection
Publications
Institution
Title
Analysis of cryo-electron microscopy images does not support the existence of 30-nm chromatin fibers in mitotic chromosomes in situ.
Journal
Proceedings of the National Academy of Sciences of the United States of America
Author(s)
Eltsov M., Maclellan K.M., Maeshima K., Frangakis A.S., Dubochet J.
ISSN
1091-6490 (Electronic)
ISSN-L
0027-8424
Publication state
Published
Issued date
16/12/2008
Peer-reviewed
Oui
Volume
105
Number
50
Pages
19732-19737
Language
english
Notes
Publication types: Journal Article ; Research Support, Non-U.S. Gov't
Publication Status: ppublish
Abstract
Although the formation of 30-nm chromatin fibers is thought to be the most basic event of chromatin compaction, it remains controversial because high-resolution imaging of chromatin in living eukaryotic cells had not been possible until now. Cryo-electron microscopy of vitreous sections is a relatively new technique, which enables direct high-resolution observation of the cell structures in a close-to-native state. We used cryo-electron microscopy and image processing to further investigate the presence of 30-nm chromatin fibers in human mitotic chromosomes. HeLa S3 cells were vitrified by high-pressure freezing, thin-sectioned, and then imaged under the cryo-electron microscope without any further chemical treatment or staining. For an unambiguous interpretation of the images, the effects of the contrast transfer function were computationally corrected. The mitotic chromosomes of the HeLa S3 cells appeared as compact structures with a homogeneous grainy texture, in which there were no visible 30-nm fibers. Power spectra of the chromosome images also gave no indication of 30-nm chromatin folding. These results, together with our observations of the effects of chromosome swelling, strongly suggest that, within the bulk of compact metaphase chromosomes, the nucleosomal fiber does not undergo 30-nm folding, but exists in a highly disordered and interdigitated state, which is, on the local scale, comparable with a polymer melt.
Keywords
Chromatin/ultrastructure, Chromosomes, Human/ultrastructure, Cryoelectron Microscopy, Cytoplasm/ultrastructure, HeLa Cells, Humans, Image Processing, Computer-Assisted, Mitosis, Nucleosomes/ultrastructure
Pubmed
Web of science
Open Access
Yes
Create date
29/01/2009 23:12
Last modification date
14/05/2024 8:58
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