FIGURE 1.

Cpc2 is a positive regulator of G₂/M transition during the cell cycle. A, cell morphology and size at division (micrometers ± S.D.) in strains MM2 (control) and AN002 (cpc2Δ), growing in YES medium at 28 °C and stained with Calcofluor white. B, cells from strains PPG148 (cdc25-22) and AN-CC18 (cdc25-22 cpc2Δ) were grown to an A₆₀₀ of 0.3 at 25 °C, shifted to 37 °C for 3.5 h, and then released from the growth arrest by transfer back to 25 °C. Aliquots were taken at different time intervals, and Cdc2 phosphorylation at Tyr¹⁵ or total Cdc2 was detected by immunoblotting with anti-Cdc2 pY15 and anti-Cdk1/Cdc2 (PSTAIR) antibodies, respectively. Lower, corresponding percentages of septated cells, binucleated cells, and Tyr¹⁵ phosphorylation for cdc25-22 (filled bars) and cdc25–22 cpc2Δ (open bars) cells (n = 4). C, samples containing 10⁴, 10³, 10², or 10¹ cells of strains MM2 (control), PPG148 (cdc25-22), and AN-CC18 (cdc25-22 cpc2Δ) grown in YES medium were spotted onto Bacto Agar supplemented YES plates and incubated for 3 days at either 25 °C, 28 °C, 34 °C, and 37 °C before being photographed. D, cell morphology and size at division in strains PPG148 (cdc25-22) and AN-CC18 (cdc25-22 cpc2Δ) growing at 28 °C determined as described in A.