Staining for xanthine oxidase (A), xanthine dehydrogenase (B), and aldehyde oxidase (C) activities on native polyacrylamide gels. Lane 1, Rm1021 (wild type); lane 2, Rm11107 (bdhA1::Tn5); lane 3, Rm11262 (bdhA3::ΩSmSp). Cell extracts, equivalent to 85 μg of total protein, were loaded in each lane.