Fig. 2. The SIN proteins are required during meiosis. (A) pat1-114/pat1-114 (control) and pat1-114/pat1-114 homozygous for the indicated SIN temperature-sensitive mutation were replica-plated onto EMM-NH₄Cl, shifted to 34°C for 3 hours and then shifted back to 25°C (25°C), or kept at 34°C for 24 hours (34°C). Plates were then exposed to iodine vapour to stain spore walls. (B) pat1-114/pat1-114 and pat1-114/pat1-114 cdc11-136/cdc11-136 were induced to sporulate at 33°C during 24 hours, fixed and stained with DAPI. Bar, 10 µm. Notice the absence of spores in the pat1-114 cdc11-136 mutant. (C) pat1-114/pat1-114 (control) and pat1-114/pat1-114 cells homozygous for the indicated SIN temperature-sensitive mutation were induced to sporulate at 34°C for 20 hours or for 3 hours and then shifted back to 25°C. Cells were then fixed, stained with DAPI and the percentage of tetranucleate cells containing spores was determined.