Thin layer chromatography (TLC) of alkaline-stable lipids from GPL mutants of 920A6. GPL were isolated from each strain and 100 μg of lipid was applied to each lane on a silica gel TLC plate, developed in CHCl3:CH3OH:H2O (65:35:4), and sprayed with H2SO4 in ethanol. Lane 1, 920A6 SmO; Lane 2, 920A6 SmT; Lane 3, ΔrtfA mutant 213R.4; Lane 4, 227R.1; Lane 5, 233R.1. Wild-type strains 920A6 SmT and 920A6 SmO both expressed ssGPL and nsGPL whereas 213R.4 did not express serovar-8 specific GPL (arrow). Complementation of rtfA with a single copy integrant restored ssGPL expression for 233R.1 to a pattern similar to wild-type M. avium. Strain 227R.1 complemented with rtfA on an episomal plasmid expressed ssGPL but did not express nsGPL.