Figure 2. fio1⁺ transcript levels are constitutively repressed in a php4Δ strain lacking the fra2⁺ gene.

A, fio1⁺ steady-state mRNA levels were assessed in wild-type (WT) and php4Δ strains. Total RNA was extracted from culture aliquots and were incubated in the absence (-) or presence of Dip (250 µM) or FeCl₃ (100 µM) for 0 and 30 min. For simplicity, the time point 30 min is shown since the mRNA signals detected (fio1⁺ and act1⁺) at other time points (e.g. 45, 60 and 90 min) were sensibly identical. B, Isogenic wild-type (WT) and fra2Δ php4Δ strains were grown and samples of cultures were taken after 0, 30, 45, 60 and 90 min of Dip (250 µM) and FeCl₃ (100 µM) treatment. As controls, cultures were left untreated (-) during the time course of the experiments. Total RNA was extracted and analyzed by RNase protection assays. Arrows indicate signals corresponding to fio1⁺ and act1⁺ mRNA steady-state levels. Results are representative of three independent experiments.