Figure 6.

In vivo transposition assays in isogenic hns⁺/hns⁻ E. coli strains. (A) Relative transposition frequency of mini-Tn5-lacZ in isogenic hns⁺ and hns⁻ strains as measured using a papillation assay. Three colonies of isogenic hns⁺ and hns⁻ strains transformed with a plasmid encoding HA transposase are shown. The dark spots are LacZ⁺ papillae; the number of papillae formed per colony provides a measure of the relative frequency of transposition of a mini-Tn5-lacZ transposon within the colony. Note that the photographs were taken when colonies were roughly the same size, which corresponded to 50 and 90 h of growth, respectively, for the hns⁺ versus the hns⁻ strain. (B) Box diagram showing the fold-changes in transposition frequency in cis as measured by mating out for hns⁺ and hns⁻ strains expressing HA transposase or MA/LP transposase. Transposition frequencies were calculated by dividing the number of Sm^RCm^R colonies (transposition events) by the number of Sm^R colonies (total exconjugants) obtained per 0.1 ml of mating mix. Transposition frequencies represent an average from at least two independent experiments. The transposition frequency for the hns⁺/HA transposase is shown. Arrows point in the direction of the fold-decrease (e.g. hns⁺/HA transposase supported transposition at a 3.1-fold higher level relative to hns⁻/HA transposase).