Post-synapsis incorporation of Zip1 or Zip1-GFP suppresses sporulation arrest triggered by SC built with Zip1-4LA.

<p>(A) Cartoon outlines the induction experiment carried out using K29 and K30. Meiotic cells expressing Zip1-4LA, instead of Zip1, arrest in late prophase with full-length SCs. At 24 hours of sporulation, most <i>zip1-4LA/P_GAL1[ZIP1-GFP] GAL4-ER/+</i> meiotic prophase-arrested cells exhibit full-length SC. <i>ZIP1</i> or <i>ZIP1-GFP</i> expression was induced in such cells at 24 hours, and then either processed for chromosome spreads (at 1 hour post-induction) or scored for spore formation (at 16 hours post-induction). (B) Nuclei from uninduced (upper panels) and induced (two examples, lower panels) K30 cells, were surface-spread and labeled with DAPI (white), anti-Zip1 (red), anti-GFP (green) following 1 hour of <i>ZIP1-GFP</i> induction; lower panels show that SC built with Zip1-4LA readily incorporates induced Zip1-GFP. Scale, 1 µm. (C) Bar graph depicting quantitation of spore production by uninduced cells expressing only Zip1-4LA and following induction of Zip1 or Zip1-GFP. Cells containing <i>P_GAL1[ZIP1]</i> or <i>P_GAL1[ZIP1-GFP]</i> and <i>GAL4-ER</i> were exposed to β–estradiol for indicated time periods before washing in sporulation media; spore formation was assayed approximately 16 hours later. While uninduced cells produced less than 0.5% spores, cells exposed to induced Zip1 or Zip1-GFP after 24 hours of sporulation produced between 30–50% spores, which is near wild-type for this BR1919 strain background. 1000 meiotic cells were assayed for each strain at each time point; shown are data from three independent experiments.