FIG. 3.

Reverse transcription-PCR was performed on total RNA harvested from cultures of B. anthracis. The reactions used primers specific for an internal fragment of the purD gene (approximately 380 bp). Lane 1, wild-type RNA; lane 2, RNA collected from the ΔpurH strain; lane 3, RNA collected from the ΔpurD mutant strain; lane 4, RNA collected from the ΔpurH + purH strain. Lane 5, 1 KB Plus ladder; bands shown, from bottom to top, are 200 bp, 300 bp, and 400 bp. Lanes 6 to 9, corresponding negative controls to confirm the absence of DNA from the RNA samples. Additionally, positive controls (not shown) were run using primers specific for the pagA gene as an internal control to ensure the quality of the harvested RNA.