Cover photograph (Copyright © 2002, American Society for Microbiology. All Rights Reserved.): Atomic-force microscopic image showing the effect of the human SWI/SNF ATP-dependent chromatin remodeling complex (yellow) on 5S ribosomal DNA polynucleosomal arrays. The normally well-spaced array of nucleosomes has been disorganized by the complex. Photograph width, 0.4 m. (See related article in December 2000, issue 24: vol. 21, p. 8504.)