Cover photograph (Copyright © 2006, American Society for Microbiology. All Rights Reserved.): Confocal image of a Drosophila stage 17 breathless-Gal4 UAS-dysfusion embryo, in which the dysfusion gene is misexpressed throughout the entire trachea. The defective trachea shows a reduction in branching and lumen formation. Tracheal lumen (red) is stained with monoclonal antibody 2A12, all tracheal nuclei (green) with anti-Trachealess, and ectopic Dysfusion (blue) with anti-Dysfusion. (See related article on page 6547.)