FIG. 3.

PCR analysis of the repeated region in the spd0080 gene of D39 (spr0075 of R6). Primers III-F-036 and III-R-042 flanking the multiple 456-bp repeats of the SSURE domain (21) were used in PCRs to amplify the region as described in Materials and Methods. Amplification products from strains R6, D39 (Lilly), and D39 (NCTC) are shown next to a 1-kb molecular mass marker ladder (left lane) and the expected sizes of amplicons containing one to eight repeat units. The predominant species indicated repeats of eight or six SSURE units in this gene in R6 or D39, respectively. The faint ladder of bands differing by one repeat unit are likely a PCR amplification artifact and were not observed in Southern blots (see text). The extent to which this region was sequenced is indicated at the bottom of the figure. As was done previously (48), we inserted a placeholder sequence containing the five repeats reported previously for R6 into this region of the D39 genome sequence (see the text).