FIG. 5.

Increased abundance of Fox1, Ftr1, and Atx1 transcipts as medium iron is reduced. A 100-ml culture of C. reinhardtii was adapted to low iron (0.1 μM in copper-free TAP medium) at late log phase and was used to inoculate cultures with the indicated iron concentrations and copper to either 6 μM (normal copper-supplemented TAP medium), 0.4 μM (saturating for Cyc6 repression and plastocyanin biosynthesis [76]), or 0 μM. RNA was harvested the following day when the cultures were at mid-log phase (2 × 10⁶ to 3 × 10⁶ cells ml⁻¹) and analyzed by RNA hybridization. Parallel samples were probed for RbcS2 expression for quantitation of the data (tabulated). The relative intensities were obtained after object average background correction. The values in the table represent the signal for each sample relative to the maximum intensity for each probe, which was arbitrarily set at 100.