Analysis of meiotic landmarks in spo19 during sporulation. Isogenic wild type and spo19Δ were monitored for (A) dityrosine at 23° and 34° (see text), (B) meiotic recombination detected by Leu+ per 104 total CFU, (C) haploidization detected by canR per total CFU, and (D) completion of MI (squares), MII (triangles), and ascus formation (circles). In B–D wild type is shown by solid symbols and solid lines, and spo19Δ is shown by open symbols and dotted lines. The assays in B–D were done at 30°.