Figure 5.

Histone H1 kinase activity in strains undergoing synchronous sporulation. Wild-type and spo12 strains homozygous for gene replacements of CLB1HA, CLB3HA, CLB4HA, and CLB5HA (CLB1/CLB1 [A], CLB1/CLB1 spo12Δ/spo12Δ [B], CLB3/CLB3 [C],CLB3/CLB3 spo12Δ/spo12Δ [D], CLB4/CLB4 [E], CLB4/CLB4 spo12Δ/spo12Δ [F], CLB5/CLB5 [G], and CLB5/CLB5 spo12Δ/spo12Δ [H]) were induced to undergo synchronous meiosis. Aliquots were collected at hourly or half-hourly intervals as indicated. Active Clb-Cdc28p kinase complexes were immunoprecipitated from the same amount of total protein in each lane with the use of anti-HA antibodies. Kinase activity of these complexes was measured by an in vitro kinase assay with histone H1 as a substrate. Progress through meiosis was monitored by DAPI staining (Table 5). In each case, the onset of histone H1 kinase activity corresponded to the onset of the meiotic divisions. Strains were YMG654, YMG655, YMG624, YMG659, YMG522, YMG632, YMG998, and YMG999.