Escherichia coli K-12 F' plasmids carrying insertion sequences IS1 and IS5

A simple method is described for the detection of the insertion elements IS1 and IS5 in Escherichia coli F' plasmids. Several of these insertion elements are normal constituents of the E. coli chromosome and are located on chromosomal regions carried by the F' plasmids, while several others were probably acquired during the isolation or propagation of the F' plasmids. The F' plasmids carrying copies of IS1 or IS5 have been transferred into Salmonella (a host lacking chromosomal copies of IS1 and IS5) where individual copies can be examined for a variety of properties, including structural similarities and ability to transpose to new sites.