Cover photograph (Copyright © 2000, American Society for Microbiology. All rights reserved.): Effect of overexpression of the sporulation gene ssgA on morphology of Streptomyces coelicolor hyphae. The frequency of septum formation is increased approximately sixfold in comparison to wild-type hyphae, resulting in spore-like compartments separated by irregular septa. Also note the ectopic deposits of cell wall material along the hyphal wall. Cultures were grown for 40 h in liquid TSBS medium. (See related article on page 5653.)