Beam-induced motion of vitrified specimen on holey carbon film.

Publication Type

Journal Article

Year of Publication

2012

Journal

J Struct Biol

Volume

177

Pagination

630-637

Date Published

2012 Feb 16

Abstract

The contrast observed in images of frozen-hydrated biological specimens prepared for electron cryo-microscopy falls significantly short of theoretical predictions. In addition to limits imposed by the current instrumentation, it is widely acknowledged that motion of the specimen during its exposure to the electron beam leads to significant blurring in the recorded images. We have studied the amount and direction of motion of virus particles suspended in thin vitrified ice layers across holes in perforated carbon films using exposure series. Our data show that the particle motion is correlated within patches of 0.3-0.5μm, indicating that the whole ice layer is moving in a drum-like motion, with accompanying particle rotations of up to a few degrees. Support films with smaller holes, as well as lower electron dose rates tend to reduce beam-induced specimen motion, consistent with a mechanical effect. Finally, analysis of movies showing changes in the specimen during beam exposure show that the specimen moves significantly more at the start of an exposure than towards its end. We show how alignment and averaging of movie frames can be used to restore high-resolution detail in images affected by beam-induced motion.

upload

Attachment Size
Brilot_JSB2012.pdf 1.25 MB
Movie_S1.gif 13.15 MB
Movie_S2.gif 14.68 MB
Movie_S3.gif 14.35 MB