Fig. 2. Phenotypes of meu14 cells. (A) The meu14 disruptant is defective in spore formation. Shown are DIC (differential interference contrast) and fluorescence photographs of Hoechst 33342-stained cells of the wild-type (TP4D-5A/TP4D-1D) and the meu14 mutant (YDO100) strains after 16 hours of nitrogen starvation. Bar, 10 µm. (B) Absence of spore walls in meu14 cells induced to sporulate. Wt and meu14 cells were streaked on a sporulation plate (EMM-N) and incubated at 28°C for 4 days. They were then exposed for 5 minutes to iodine vapor, which stains cells that have sporulated dark brown. (C) Progression of meiosis in wild-type and meu14 cells. Up to 1x10⁷ cells/ml cultured overnight in liquid growth medium (EMM2) were incubated with shaking at 30°C in liquid sporulation medium (EMM-N). A portion of the culture was taken every 2 hours and stained with DAPI. Cells were classified based on the numbers of nuclei. , interphase (mononucleate); , Horse-tail; , binucleate; , tetranucleate. For each sample, approximately 200 cells were counted. Values depict one representative result of four independent experiments. (D) The meu14 cells frequently produce abnormal tetranucleate cells. Tetranucleate cells were classified according to the number and position of the four nuclei per cell. 1, normal pattern; 2, unequally segregated nuclei; 3, missegregated nuclei; 4, unsegregated nuclei; 5, abnormally distributed nuclei; 6, distorted nuclei. The percentages of Wt and meu14 cells in each category after 12 hours of nitrogen starvation were compared. At least 200 cells were counted.