FIG. 1.

Replication control parameters at different temperatures. Cultures of strain BBC119 were grown under conditions of balanced growth in AB-thiamine-glucose-Casamino Acids supplemented medium at the indicated temperatures. Samples were taken for flow cytometric analysis of DNA, origins, and light scatter (LS), for immunoblot analysis of DnaA protein, and for determination of DnaA–β-galactosidase specific activity. The indicated values are averages of two (30 and 21°C) or three (14°C) independent experiments, and error bars indicate ranges for the different experiments. All values have been normalized to those determined in parallel for the 37°C cultures. The actual values for DNA per cell and origins per cell are shown in Table 1. We found that the cells at 37°C contained approximately 25 ng of DnaA per ml at OD₄₅₀ = 1, which is in accordance with previous determinations (16), and that the specific activity of DnaA–β-galactosidase was 17 to 20 Miller units.