Linked Life Data

16978880

Source:http://linkedlifedata.com/resource/pubmed/id/16978880

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
2006-11-6
pubmed:abstractText
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.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:status
MEDLINE
pubmed:month
Nov
pubmed:issn
1047-8477
pubmed:author
pubmed:issnType
Print
pubmed:volume
156
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
246-54
pubmed:meshHeading
pubmed:year
2006
pubmed:articleTitle
Transmission electron microscopy of the bacterial nucleoid.
pubmed:affiliation
Laboratoire d'Analyse Ultrastructurale, Université de Lausanne, Lausanne, Switzerland. Mikhail.Eltsov@unil.ch
pubmed:publicationType
Journal Article, Review, Research Support, Non-U.S. Gov't