Cover photograph (Copyright © 2001, American Society for Microbiology. All rights reserved.): Mycoplasma pneumoniae, a wall-less parasitic bacterium, has polarized cell morphology characterized by a membrane protrusion designated the attachment organelle. M. pneumoniae binds to and glides on glass, plastic, and animal cell surfaces. The cells bound to a glass surface were fluorescently labeled for chromosomal DNA (blue) and for the adhesion protein, densely located at the attachment organelle (red). (See related article on page 1621.)