Overabundant single-particle electron microscope views induce a three-dimensional reconstruction artifact

In the field of single-particles 3D reconstruction, the development of angular assignment techniques has allowed the collection of a large amount of cryoelectron microscope images of untilted-specimens. When particles have a preferential orientation within the ice layer, one type of electron microscope (EM) view is oversampled and produces a new type of 3D reconstruction artifact, This oversampling artifact is observed with simultaneous iterative reconstruction techniques (SIRT) but the theoretical analysis of the problem indicates that similar effects could also occur with other reconstruction algorithms. (C) 1998 Elsevier Science B.V. All rights reserved.