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. 2001 May;8(3):489–495. doi: 10.1128/CDLI.8.3.489-495.2001

FIG. 1.

FIG. 1

Orientation of the switch-regulating phase variation in E. coli. (A) Schematic representation of the fim switch showing the positions of primers and restriction sites used in this study. The orientation of the fim switch can be determined by combined PCR and restriction analysis, since SnaBI cuts asymmetrically. IRL and IRR, left and right inverted repeats, respectively. The fimA promoter (Pfim) is indicated. (B) Agarose gel (2%) electrophoresis of SnaBI digests of PCR products. Lanes M, molecular weight markers; lanes 1 and 2, 96-7 (O157:H7); lanes 3 and 4, CL-49 (O157:H7); lanes 5 and 6, E333 (O157:H−); lanes 7 and 8, 96-11 (O157:H45); lanes 9 and 10, 97E12 (O26:H11); lanes 11 and 12, 97E2 (O111:H−); lanes 13 and 14, 70 (O55:H7); lanes 15 and 16, DH5α. Lanes 1, 3, 5, 7, 9, 11, 13, and 15 are from strains amplified at the start of this study (MSHA−); lanes 2, 4, and 6 (MSHA−) and lanes 8, 10, 12, 14, and 16 (MSHA+) are from strains amplified after 10 static serial passages.