Transmission electron microscopy of the bacterial nucleoid.

Eltsov, Mikhail; Zuber, Benoît (2006). Transmission electron microscopy of the bacterial nucleoid. Journal of structural biology, 156(2), pp. 246-254. Elsevier 10.1016/j.jsb.2006.07.007

[img] Text
1-s2.0-S1047847706002152-main.pdf - Published Version
Restricted to registered users only
Available under License Publisher holds Copyright.

Download (1MB) | Request a copy

Water-containing biological material cannot withstand the vacuum of the transmission electron microscope. The classical solution to this problem has been to dehydrate chemically fixed biological samples and then embed them in resin. During such treatment, the bacterial nucleoid is especially prone to aggregation, which affects its global shape and fine structure. Initial attempts to deal with aggregation by optimizing chemical fixation yielded contradictory results. Two decades ago, the situation improved with the introduction of freeze-substitution. This method is based on dehydration of unfixed cryo-immobilized samples at low temperature, which substantially reduces aggregation. As a result, the global shape of the nucleoid can be fairly well defined. Overall, in actively growing bacteria, the nucleoids are dispersed and "coralline" but become more confined when growth ceases. However, it is usually impossible to determine the molecular arrangement of DNA in the nucleoids of freeze-substituted bacteria because crystallization and the subsequent removal of water during substitution result in unavoidable distortions at the ultrastructural level. Recently, cryo-electron microscopy of vitreous sections has enabled the fully hydrated bacterial nucleoid to be studied close to the native state. Such studies have revealed aspects of bacterial nucleoid organization that are not preserved by freeze-substitution, including locally parallel or twisted bundles of DNA filaments, which are more frequently observed once bacterial growth has stopped, whereas in actively growing bacteria, the DNA is seen to be in a mostly disordered pattern.

Item Type:

Journal Article (Review Article)

Division/Institute:

04 Faculty of Medicine > Pre-clinic Human Medicine > Institute of Anatomy

UniBE Contributor:

Zuber, Benoît

Subjects:

500 Science > 570 Life sciences; biology
600 Technology > 610 Medicine & health

ISSN:

1047-8477

Publisher:

Elsevier

Language:

English

Submitter:

Benoît Zuber

Date Deposited:

28 Jan 2016 15:14

Last Modified:

01 Feb 2016 01:59

Publisher DOI:

10.1016/j.jsb.2006.07.007

PubMed ID:

16978880

BORIS DOI:

10.7892/boris.74798

URI:

https://boris.unibe.ch/id/eprint/74798

Actions (login required)

Edit item Edit item
Provide Feedback