FIGURE 2:

Meiotic phenotype of the ZHP3 deletion mutant. Meiotic progression in (A) wild-type (WT) and (B) zhp3Δ cells. At prophase, nuclear reorganization and chromosome dynamics are indistinguishable in WT and mutant cells. (C) Southern hybridization with a MIC-specific DNA probe to a PFGE gel shows transient DSB-generated DNA fragmentation. DSB formation and repair occur with similar dynamics in WT and zhp3Δ cells. Samples were run 0, 3, 4, 5, 6, and 7 h after induction of meiosis. DSB band intensity (a rough measure of the relative DSB abundance) was determined, normalized to the loading control (a 306-kb macronuclear chromosome), and plotted as the n-fold increase over background intensity. (D) Dmc1 foci in elongated meiotic prophase nuclei are similar in WT and zhp3Δ cells. (E) FISH was used to quantify homologous pairing in elongated meiotic prophase nuclei. Inset, examples of separate (top) and paired (bottom) homologous loci. Red bars indicate mean distances. (F) Schaudinn fixation and Giemsa staining were used to spread chromosomes and analyze bivalents in diakinesis or metaphase I. The WT has mainly ring bivalents, whereas zhp3Δ mostly has rod bivalents or univalents. Bars, 10 µm (A, B, D), 2 µm (F).