Fig. 4. Requirement of fkh2⁺, sep1⁺ and the PCB sequence for M/G1-specific transcription. (A) A cdc15⁺ promoter fragment containing the PCB sequence confers M/G1-specific transcription. cdc25-22 (GG 308) cells containing pSP178.15UAS (Anderson et al., 2002) were synchronised by transient temperature arrest and samples taken every 15 minutes upon release to the permissive temperature. RNA was analysed by northern blot using lacZ, cdc15⁺ and adh1⁺ as probes, the latter as a loading control. Quantification of each transcript against adh1⁺ is shown. Septation indices were counted microscopically and are plotted to indicate the synchrony of the culture. (B) Loss of PCB-regulated periodic transcription in fkh2 cells. fkh2 cdc25-22 (JM 2285) cells containing pSP178.15UAS (Anderson et al., 2002) were synchronised by transient temperature arrest and samples taken every 15 minutes upon release to the permissive temperature. RNA was analysed by northern blot using lacZ, cdc15⁺ and adh1⁺ as probes, the latter as a loading control. Quantification of each transcript against adh1⁺ is shown. Septation indices were counted microscopically and are plotted to indicate the synchrony of the culture. (C) Loss of PCB-regulated periodic transcription in sep1 cells. sep1 cdc25-22 (JM 2805) cells containing pSP178.15UAS (Anderson et al., 2002) were synchronised by transient temperature arrest and samples taken every 15 minutes upon release to the permissive temperature. RNA was analysed by northern blot using lacZ, cdc15⁺ and adh1⁺ as probes, the latter as a loading control. Quantification of each transcript against adh1⁺ is shown. Septation indices could not be counted for this culture, because of sep1 septation defect. (D) PCB sequence is required for M/G1-specific transcription in fission yeast. cdc25-22 (GG 308) cells containing pSP178.15UAS.MUT (GB 344) were synchronised by transient temperature arrest and samples taken every 15 minutes upon release to the permissive temperature. RNA was analysed by northern blot using lacZ, cdc15⁺ and adh1⁺ as probes, the latter as a loading control. Quantification of each transcript against adh1⁺ is shown. Septation indices were counted microscopically and are plotted to indicate the synchrony of the culture.