Figure 6. End-Point RT-PCR and SYBR-Green qRT-PCR of select genes from the asb and bac operons in iron-depleted, iron-supplemented, and iron-rich conditions.

Ethidium bromide stained agarose gels from endpoint RT-PCR of the second gene in the asb operon (asbB), the second gene in the bac operon (dhbC) and a constitutively expressed elongation factor (fusA) from B. anthracis Sterne 34F₂ grown in different media with various iron concentrations. –Fe is Iron-Depleted Medium (IDM); +Fe is IDM with 20 µM Fe(II)SO₄ supplementation; LB is Luria Bertani Broth (∼7.6 µM iron concentration). High O₂ and low O₂ are cultures grown in high or low aeration respectively. LB cultures were grown under high O₂ conditions (see Methods). Numbers are approximations of fold differences in transcript abundance as assayed by SYBR-Green qRT-PCR representing the following comparisons: ¹ asbB is ∼11-fold more highly expressed in IDM with high aeration than in IDM+Fe with high aeration. ² asbB is ∼37 fold more highly expressed in IDM with low aeration than in IDM+Fe with low aeration. ³ asbB is ∼21 fold less abundant in LB medium than in IDM with high aeration. Note that there is less than a 2-fold difference in transcript abundance between LB and IDM+Fe. ⁴ dhbC is greater than 500 fold more highly expressed in IDM with high aeration than in IDM+Fe with high aeration. ⁵ dhbC is greater than 500 fold more highly expressed in IDM with low aeration than in IDM+Fe with low aeration. ⁶ dhbC is more than 500 fold less abundant in LB medium than in IDM with high aeration. Note that the abundance of transcript in LB medium as compared to IDM+Fe is approximately the same.