Cover photograph (Copyright © 2007, American Society for Microbiology. All Rights Reserved.): Tissue cysts of the parasite Toxoplasma gondii formed under stress conditions in vitro. The cyst wall is stained green with Dolichos biflorus lectin. Internal bradyzoites are stained red with antibodies to the protein BAG1. Nuclei are stained blue with 4′,6′-diamidino-2-phenylindole. The image was generated by a three-dimensional rendering of optical Z-stacks collected by confocal microscopy. (See related article on page 2580.)