Localization of Bqt2 and Sad1 in the absence of Bqt4. (A, left) Cells expressing Bqt2-GFP (red) and Taz1-mRFP (green) were observed after the induction of meiosis. The strain observed is CRLp83 (h⁹⁰ bqt4Δ::ura4⁺, taz1Δ::ura4⁺, lys1::taz1-mRFP, bqt2-GFP::kan). (right) Cells expressing Sad1-mRFP (red) and Taz1-GFP (green) were observed after induction of meiosis. The strain observed is CRLp85 (h⁹⁰ bqt4Δ::ura4⁺, taz1Δ::ura4⁺, lys1::taz1-GFP, sad1-mRFP::kan). Time-lapse images were recorded at intervals of 1 min. The image at each time point is a projection of optical section images. Numbers on the left of images indicate the time in minutes. (B) Localization of Sad1 (mRFP) and Rap1 (GFP) in vegetatively growing cells in which Bqt1 alone or both Bqt1 and -2 were ectopically expressed. In bqt4⁺ cells, Sad1 showed multiple foci, and many of these Sad1 foci colocalized with Rap1 when both bqt1 and -2 were expressed. The colocalization of Sad1 foci with Rap1 after ectopic expression was more extensive in bqt4⁺ than in bqt4Δ cells. Strains observed in each column are CRLs27 (bqt4⁺, CFP-bqt1), CRLs28 (bqt4⁺, CFP-bqt1, bqt2-myc), CRLs29 (bqt4Δ, CFP-bqt1), and CRLs30 (bqt4Δ, CFP-bqt1, bqt2-myc) from left to right. The graph shows the frequencies of colocalization of Sad1 and Rap1 in each strain. Numbers of Sad1 and Rap1 spots examined in each strain, from left to right, are 66 Sad1 spots and 153 Rap1 spots in 39 nuclei, 141 Sad1 spots and 187 Rap1 spots in 47 nuclei, 82 Sad1 spots and 141 Rap1 spots in 43 nuclei, and 89 Sad1 spots and 161 Rap1 spots in 51 nuclei. The green columns indicate the frequency with which Rap1 foci colocalized with Sad1 relative to total observed Rap1 foci. The red columns indicate the frequency with which Sad1 foci colocalized with Rap1 relative to total observed Sad1 foci. Bars: (A) 10 µm; (B) 1 µm.