Fig. 9. sid2⁺ overexpression rescues the sporulation defect caused by deletion of slk1. (A) Schematic representation of the P41nmt1-sid2 construction. Endogenous sid2 was under the control of the P41nmt1 promoter, repressed by thiamine. (B) Homothallic strain slk1 P41nmt1-sid2 (S1890) was spotted onto MEA (sid2 expression high) and MEA+thiamine (sid2 expression low). DIC images of asci were taken after 2 days of incubation at 25°C. As controls, images of wild-type (S1478) and slk1 (S1883) asci are shown. Note that sid2⁺ overexpression improves the sporulation of slk1, but sid2 shut-off does not enhance the sporulation defect of the slk1 mutant, indicating that sid2 is still expressed in the presence of thiamine. Scale bars: 10 µm. (C) The MEA plates of the experiment shown in B were stained with iodine vapour after 2 days of incubation at 25°C.