Three-Dimensional Electron Microscopy of Individual Biological Objects

Abstract

In this paper methods and results of three-dimensional electron microscopy of individual molecules will be presented. Part I describes the general experimental and theoretical methods (microgoniometer, measuring scheme, two-dimensional and three-dimensional reconstruction, determination of the common origin of the projections). Special attention will be given to the image point shapes under different reconstruction conditions

Influence of Electron Noise on Three-dimensional Image Reconstruction

“…The reconstruction can be done in slices which are normal to the rotation axis (see e. g. 3 ). We define the ?/-axis as rotation axis and the z-axis as optical axis of the imaging instrument.…”

“…= -00 0 (5) We denote by P(x, ft) a projection of the object tilted about the angle ft. Between P(x, ft) and the object function q(x, z) exists the relation 00 Each point [u,'ft) from the region -oo<u<oo, 0 < ft<Ti corresponds uniquely to a point (R, 0) in the region 0 00, -ti 0<ti.…”

“…Thus it is possible to reconstruct a significant object from non-significant projections, if K is large. In practice there is only the additional condition that the determination of the tilt axis by correlation of successive projections must be significant (see 4 ).…”

“…Thus the Fourier space is only partially known (see [3][4][5] ). Further errors are caused by the fact that the image is finite 7 , by the transfer function which changes from projection to projection, by some approximations of the imaging theory and by radiation damage.…”

Three-Dimensional Electron Microscopy of Individual Biological Objects Part III. Experimental Results on Yeast Fatty Acid Synthetase

“…Conf. on Electron Microscopy at Canberra (1974) 3 and also reported in a short communication 4 . However, in this paper the results of three-dimensional reconstruction of FAS molecules will be discussed in more detail, mainly as an example of how to extract information from the reconstructions.…”