Fig 3.

Influence of RpoS and OspC production by Mn²⁺ and Zn²⁺ in B. burgdorferi strain 297. (A) Growth curves of wild-type B. burgdorferi strain 297 in standard or Chelex-treated BSK-II medium. The means with SD from two separate experiments are shown with duplicates of each sample. (B) Protein profiles of spirochetes grown in standard or Chelex-treated medium. Cells were harvested at the late log phase, and cell lysates were subjected to SDS-PAGE analysis. The bands corresponding to OspC are indicated by an arrow. Results are representative of the two separate experiments. (C and D) Effects of Mn²⁺ and Zn²⁺on RpoS and OspC levels. Strain 297 was grown at 37°C in Chelex-treated BSK-II medium (pH 7.5) with or without added 10 μM MnCl₂ and/or ZnSO₄ (C) or 100 μM ZnSO₄ (D). Equivalent amounts of protein were separated by SDS-PAGE (D, top panel) and immunoblotted with antibodies against FlaB, RpoS, or OspC (C and D, bottom panels). FlaB served as a loading control. *, a 10-fold dilution of each sample was used in this immunoblot assay to avoid saturation of the OspC signal. Data shown in panels C and D are representative from two separate experiments performed with samples in triplicate.