FIG. 6.

NDT80 promoter mutations bypass the sum1-ci block. (A) ndt80Δ or sum1-ci diploids harboring an NDT80 plasmid controlled by the wild-type promoter (WT), the promoter carrying a deletion of the MSE1 Sum1/Ndt80 binding site (M1Δ), or the plasmid lacking NDT80 (ø) were transferred to sporulation medium, and meiosis (MI) was scored at 24 h postinduction (n = 4). (B) sum1-ci diploids containing the indicated number of NDT80, NDT80::TRP1, or NDT80-M1Δ::TRP1 genes were analyzed as described for panel A (n = 3). (C) Strains a, d, and f from panel B were collected at 72 h postinduction, stained with DAPI, and analyzed using phase-contrast or fluorescence photomicrography. The arrows in the middle photomicrographs point to cells that have completed meiosis but have failed to form spores.