Cover photograph (Copyright © 2007, American Society for Microbiology. All Rights Reserved.): A human fibroblast nucleus where three-color fluorescence in situ hybridization has been carried out. On the left is a maximum-intensity projection of the three-dimensional (3D) acquired image, and on the right is the image after segmentation and 3D surface rendering. Three different chromosomal domains (red, green, and blue) and the nucleus (cyan) are shown. (See related article on p. 4475.)