FIG. 1.

pcl1⁺, sdh4⁺, and isa1⁺ gene expression is down-regulated under conditions of iron depletion. (A) Wild-type strain FY435 was grown to mid-logarithmic phase in yeast extract plus supplements. Total RNA from Dip (250 μM), control (−), or FeCl₃ (Fe) (100 μM) cultures was isolated. Shown is a representative RNase protection assay of pcl1⁺, sdh4⁺, isa1⁺, and act1⁺ (as control) mRNA steady-state levels. Results shown are representative of three independent experiments. (B) Quantification of lacZ levels after treatments shown in panel A. Values are the averages of triplicate determinations ± standard deviations. (C) Representative RNase protection assay of fio1⁺ (used as a control gene known to be induced under conditions of iron starvation) and pcl1⁺ mRNA steady-state levels. (Bottom) act1⁺ mRNA as an internal control. Total RNA was extracted from aliquots of cultures incubated in the absence (−) or presence of 250 μM Dip or 100 μM FeCl₃ (Fe) for 90 min at 30°C. (D) Graphic representation of quantification of three independent RNase protection assays, including the experiment shown in panel C. The values are the means of three replicates ± standard deviations.