Cover photograph (Copyright © 2005, American Society for Microbiology. All Rights Reserved.): Four-dimensional time-lapse microscopy of fluorescently tagged heterochromatin protein Swi6 in the nucleus of living Schizosaccharomyces pombe. Three-dimensional projections of stacks acquired every 5 s show that heterochromatin regions (yellow and red) move rapidly within the cell nucleus (blue). (See related article in April 2004, vol. 24: issue 8, p. 3157.)