Pds5 interacts with cohesin in meiotic chromosome morphogenesis. (A–D) Yeast cultures were induced to undergo synchronous meiosis. Protein extracts were prepared at the indicated times for immunoblotting (A) and meiotic nuclear spread for immunofluorescence (B–D). (A) Ectopic production of Mcd1 during meiosis. To induce P_CUP1MCD1 expression, we added 60 µM (final concentration) CuSO₄ to the sporulation medium after induction of meiosis. Mcd1 was detected with a polyclonal anti-Mcd1 antibody. β-Tubulin served as a loading control. WT, wild type. (B) Cohesin is required for Pds5 localization to chromosomes. Pds5 (green) was detected with anti-Pds5 antibody, microtubules (blue) by a monoclonal anti–α-tubulin antibody, and DNA (red) with DAPI. (C) Localization of ectopically expressed Mcd1 during meiosis. Mcd1 bound to meiotic chromosomes, but the SC component Zip1 (green) was present in the polycomplex (PC; arrows). (D) Quantitative analysis of chromosome V compaction in rec8Δ P_CUP1MCD1 and rec8Δ P_CUP1MCD1 P_CLB2PDS5 cells. SD is shown in parentheses.