Fig. 5. Cdc2-YFP accumulates on the SPB of cells arrested at the G₂/M transition or treated with HU. (A) Cdc2-YFP (AD185, a-e) fluorescence is very low on the SPB of septated cycling cells growing at 32°C in YES medium (c-e). SPB fluorescence was not observed in binucleate cells before septation (a-b). Bar, 5 µm. (B) Cdc2-YFP (AD185, a) and cdc13-YFP (AD112, b) accumulate in the nucleus and on the SPB of cells treated with 11 mM HU for 4 hours at 32°C. YFP-cig2 fluorescence was also enriched on the SPB of cells grown for 16 hours in the absence of thiamine at 32°C and incubated with 11 mM HU for 4 hours (AD179, c). Bar, 5 µm. (C) SPB accumulation of cdc2-YFP (AD189, a) and cdc13-YFP (AD226, b) is stronger in cdc25-22 ts cells after incubation for 4 hours at 36°C. Aggregation of cytoplasmic cdc2-YFP is observed at 36°C (see Fig. 4 legend). Bar, 5 µm. (D) cdc25-22 cells were arrested at the G₂/M transition by incubation for 4 hours at 36°C and released into mitosis at RT: cdc13-YFP (AD226, a-e), cdc2-YFP (AD189, f-j), GFP-2-tubulin (AD244, k-o) or both cdc2-YFP and GFP-2-tubulin (AD268, p-t). G₂/M boundary (a f,k,p) and mitosis (b-e,g-j,l-o,q-t). Bar, 5 µm.