Fig. 8. Genetic interactions between slk1 and SIN mutants. (A) sid2-250 and cdc7-24 alleles enhance the sporulation defect caused by the deletion of slk1. Homothallic sid2-250 (S1884), cdc7-24 (S1886), slk1 sid2-250 (S1885) and slk1 cdc7-24 (S1887) strains were sporulated on MEA plates, and DIC images were taken after 2 days of incubation at 25°C. Note that double mutants fail to sporulate at the permissive temperature. (B) MEA plates from the experiment shown in A were stained with iodine vapour and photographed. (C) In slk1 sid2-250 cells, forespore membrane growth around the nuclei is defective. h⁹⁰ slk1 sid2-250 cells carrying the plasmid pREP81-Psy1-GFP were sporulated on MEA plates for 2 days at 25°C, stained with Hoechst and photographed. Arrows highlight the abnormal distribution of DNA. (D) Time-lapse experiment showing forespore membrane growth in a sid2-250 slk1 strain (S1885) carrying plasmid pREP81-Psy1-GFP. Cells were sporulated on MEA plates and DNA was stained with Hoechst. Stacks of five images separated by 1 µm were taken every 5 minutes. GFP (green) and Hoechst (red) merged images were generated with ImageJ. The arrow marks a nucleus that is being cut by the forespore membrane upon closure. Scale bars: 10 µm.