Centromere cohesin remained intact at the completion of meiosis I in the nup132Δ mutant. (A) An example of a wild-type cell undergoing meiosis I. Htb1-mCherry and Rec8-GFP were used to visualize histone H2B (red) and meiotic-specific cohesin (green), respectively. Meiotic stages are defined by the behavior of chromosomes. Karyogamy is the stage when the two haploid nuclei fuse. Prophase is the stage when the elongated horsetail-shaped nucleus moves back and forth. Metaphase I is defined by chromosome condensation, and anaphase I is the stage when the nucleus stretches and divides into two nuclei. The cyan arrows in anaphase I indicates the remaining GFP signals of centromeric Rec8. Bar, 5 µm. (B) Representative time-lapse images of a nup132Δ cell expressing Htb1-mCherry and Rec8-GFP during meiosis I. All the labels are described as in A. Bar, 5 µm. (C) Representative views of cells carrying homologous cen2-lacO/lacI-GFP (cen2-GFP) at meiosis I. The cen2-GFP signals can be seen as white dots inside the cells. Bright-field images were combined with the GFP fluorescence images so that the cell outline can be viewed. The mes1Δ background was used to stop the cells from entering meiosis II after completion of meiosis I. After meiosis I, the homologous cen2-GFP signals split into two, whereas the sister cen2-GFP remains together or closely adjacent. The bub1Δ strain was used as a negative control. The white arrowheads indicate separating sister cen2-GFP in mes1Δ bub1Δ cells. Bars, 5 µm. (D) The upper diagram illustrates two types of cells carrying homologous cen2-GFP after meiosis I. The type I cells are those with more than two separated dots of cen2-GFP in each of the divided nuclei (i.e., a split cen2-GFP). The type II cells are those with one dot or two closely adjacent dots in each of the divided nuclei (i.e., adjacent cen2-GFP). The lower diagram shows the percentage of type I and type II cells in the mes1Δ, mes1Δbub1Δ, or mes1Δnup132Δ mutant background (n = 75 for each strain).