Spo5 localization to the cytoplasm facilitated by the mRNA export pathway does not involve global mRNA export. (A) Spo5–GFP accumulated in the nucleus in temperature-sensitive rae1-167 cells. Cells were incubated at 25°C for 6 h and then transferred to 36°C for 3 h. Cut11-4mRFP was used as a nuclear envelope marker. The Spo5–GFP signal was evident in cells undergoing meiotic prophase I through meiosis II. Scale bar, 5 μm. (B) To block RNA-polymerase II-dependent transcription of mRNAs, we used 1, 10-phenanthroline . Wild-type diploid cells were transferred to MM-N to induce meiosis, and after 3.5 hours (Time 0), 1,10-phenanthroline was added to half of the culture at a final concentration of 500 ng/μL. Microscopic observation of Spo5-GFP was carried out after 2 hours. Scale bar, 5 μm. (C) Quantitative analysis of Spo5-GFP localization in cells treated with 1,10-phenanthroline. The number of cells examined is as follows: 0 h, n = 152; 2 h(-), n = 239; and 2 h(+), n = 207. (D) Cells expressing Spo5–GFP (-LMB) were treated with 100 ng/mL LMB and observed after 1 h (+LMB). Mei2-mCherry served as a positive control since it accumulates in the nucleus upon LMB addition. Scale bar, 5 μm. (E) Pabp–GFP accumulated in the nucleus in rae1-167 cells, whereas it did not do so in spo5∆ cells. Scale bar, 5 μm.