Cover photograph (Copyright © 2006, American Society for Microbiology. All Rights Reserved.): The filamentous cyanobacterium Anabaena sp. strain PCC 7120 expressing a fusion between the cell division rotein FtsZ and the green fluorescent protein (GFP). The filaments were visualized by epifluorescence excited by light at 465 nm. FtsZ-GFP forms a ring-like structure at the midcell position. (See related article on page 1396.)