title: Differential activity of a transposable element in Escherichia coli colonies.
abstract: In Escherichia coli colonies, patterns of differential gene expression can be visualized by the use of Mu d(lac) fusion elements. Here we report that patterned beta-galactosidase expression in colonies of strain MS1534 resulted from a novel mechanism, spatially localized replication of the Mu dII1681 element causing lacZ transposition to active expression sites. Mu dII1681 replication did not occur constitutively with a fixed probability but was dependent on the growth history of the bacterial population. The bacteria in which Mu dII1681 replication and lacZ transposition had occurred could no longer form colonies. These results lead to several interesting conclusions about cellular differentiation during colony development and the influence of bacterial growth history on gene expression and genetic change.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Chicago, Illinois 60637.
authors.forename: J A
authors.initials: JA
authors.lastname: Shapiro
authors.forename: N P
authors.initials: NP
authors.lastname: Higgins
mesh_terms: D015139:Blotting, Southern; D004251:DNA Transposable Elements; D004269:DNA, Bacterial / Q000235:genetics / Q000302:isolation & purification; D004926:Escherichia coli / Q000166:cytology / Q000201:enzymology / Q000235:genetics*; D005784:Gene Amplification; D015870:Gene Expression; D005798:Genes, Bacterial; D009693:Nucleic Acid Hybridization; D010957:Plasmids; D001616:beta-Galactosidase / Q000096:biosynthesis / Q000235:genetics
chemical_list: D004251:DNA Transposable Elements; D004269:DNA, Bacterial; D001616:beta-Galactosidase