FIG. 1.

Maps of plasmids pMDS28, carrying the transposon ThD28 (previously described in reference 6), and pMDS73, carrying the improved transposon ThD73 (described in this study). ThD73 consists of a halobacterial mevinolin-simvastatin resistance gene (Mev^r; accession no. M83531) (10) and the E. coli plasmid vector pUC19 (19), which includes parts of the lacZ and lacI genes, a pMB1 replicon, and an ampicillin resistance gene, Ap^r. These are flanked by ISH28 TIRs. The ISH28 transposase (Tpase) gene is located outside the transposon.