Figure 1.

Plasmid pRZTL1 (described in more detail in ref. 23). The two solid squares are the OE sequences of Tn5 which define the transposable element. The shorter DNA sequence between the ends encoding kanamycin resistance is a donor backbone. Along with a p15A origin of replication and the Cam^R gene, the transposon contains a promoterless Tet^R gene next to one OE. Tetracycline resistance can be activated after transposition in the proper orientation into a unit of transcription. Since the same Km^R gene was used as a target in two other in vivo systems, we were able to compare all sets of data. The location into which the synthetic targets were cloned is indicated.