FIG. 2.

Identification of vsp-related genomic fragments undergoing rearrangements during VspA or VspC phase variation. Chromosomal DNAs of the VspA variants (A) or of the VspC variants (B) were restricted with the HindIII restriction enzyme, subjected to Southern blot hybridization, and probed with a 2.3-kb HindIII fragment carrying the vspA gene in the OFF state (A) or with a 1.5-kb HindIII fragment carrying the vspC ON gene (B). Variable HindIII fragments present only in the VspA ON or in the VspC ON variants (A and B, lanes 1 and 3) are indicated by solid arrows. Invariant HindIII fragments (A and B) are indicated by open arrows. The names of the vsp genes corresponding to the HindIII genomic fragments are shown. Phenotypic transitions (ON→OFF→ON, lanes 1 to 3, respectively) are indicated at the top with arrows.