FIG. 2.

⁵⁵Fe³⁺-ExMB uptake. H37Rv and ST73 were cultured in LIMM and incubated with ⁵⁵Fe³⁺-ExMB at 0 or 37°C. At the indicated time points, an aliquot of cells was collected, washed as described in Materials and Methods, and resuspended in scintillation liquid. The radioactivity incorporated was measured in a Beckman scintillation counter. Symbols: □, H73Rv; ○, ST73. The data show the radioactivity incorporated at 37°C after subtraction of the radioactivity incorporated at 0°C. The average and standard deviation are derived from three experiments.