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Electron microscopy of frozen biological suspensions

Electron microscopy of frozen biological suspensions The methodology for preparing specimens in the frozen, hydrated state has been assessed using crystals and T4 bacteriophages. The methods have also been demonstrated with lambda bacteriophages, purple membrane of Halobacterium halobium and fibres of DNA. For particles dispersed in an aqueous environment, it is shown that optimum structural preservation is obtained from a thin, quench‐frozen film with the bulk aqueous medium in the vitreous state. Crystallization of the bulk water may result in solute segregation and expulsion of the specimen from the film. Contrast measurements can be used to follow directly the state of hydration of a specimen during transition from the fully hydrated to the freeze‐dried state and permit direct measurement of the water content of the specimen. By changing the concentration and composition of the aqueous medium the contrast of particles in a vitreous film can be controlled and any state of negative, positive or zero contrast may be obtained. At 100 K, frozen‐hydrated, freeze‐dried or sugar embedded crystals can withstand a three‐ to four‐fold increase in electron exposure for the same damage when compared with similar sugar‐embedded or freeze‐dried samples at room temperature. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Microscopy Wiley

Electron microscopy of frozen biological suspensions

Journal of Microscopy , Volume 129 (1) – Jan 1, 1983

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References (20)

Publisher
Wiley
Copyright
Copyright © 1983 Wiley Subscription Services, Inc., A Wiley Company
ISSN
0022-2720
eISSN
1365-2818
DOI
10.1111/j.1365-2818.1983.tb04163.x
Publisher site
See Article on Publisher Site

Abstract

The methodology for preparing specimens in the frozen, hydrated state has been assessed using crystals and T4 bacteriophages. The methods have also been demonstrated with lambda bacteriophages, purple membrane of Halobacterium halobium and fibres of DNA. For particles dispersed in an aqueous environment, it is shown that optimum structural preservation is obtained from a thin, quench‐frozen film with the bulk aqueous medium in the vitreous state. Crystallization of the bulk water may result in solute segregation and expulsion of the specimen from the film. Contrast measurements can be used to follow directly the state of hydration of a specimen during transition from the fully hydrated to the freeze‐dried state and permit direct measurement of the water content of the specimen. By changing the concentration and composition of the aqueous medium the contrast of particles in a vitreous film can be controlled and any state of negative, positive or zero contrast may be obtained. At 100 K, frozen‐hydrated, freeze‐dried or sugar embedded crystals can withstand a three‐ to four‐fold increase in electron exposure for the same damage when compared with similar sugar‐embedded or freeze‐dried samples at room temperature.

Journal

Journal of MicroscopyWiley

Published: Jan 1, 1983

Keywords: ; ; ; ; ; ; ;

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