Cover photograph (Copyright © 2003, American Society for Microbiology. All Rights Reserved.): Atomic force microscopic imaging of Escherichia coli expressing fimbrial adhesins. E. coli causing extraintestinal infections commonly carries polycistronic operons with fimbrial genes, and transcriptional analyses suggest that multiple mRNA processing events result in differential gene expression of importance to achieve the final stoichiometry of the different subunit proteins in biogenesis of the fimbriae. (See related article on page 620.)