FIG. 3.

Rotational phenotypes. The six strains used for the analysis in Fig. 2 plus one with a deletion of chromosomal trg (CP177) but containing plasmid pAL1 carrying trg were tethered and analyzed for rotational phenotypes by observing at least 100 rotating cells, each for 10 to 15 s, and classifying the behavior into one of five categories (displayed from left to right in each histogram as follows: exclusively CW, predominantly CW with occasional reversals, reversing frequently with no evident directional bias, predominantly CCW with occasional reversals, and exclusively CCW) (31). The data are averages for two independent determinations that yielded very similar distributions. Patterns for strains harboring plasmid-borne genes coding for receptors with the ligand-binding domain of Trg (top row) and patterns for receptors with the ligand-binding domain of Tsr (bottom row) are shown.