FIG. 3.

Dynamics of oxygen-responsive gene induction and repression during acclimatization to anaerobiosis and subsequent recovery. The numbers of genes that responded significantly (P < 0.01) to the shifts in O₂ availability in galactose (A and B) and glucose (C and D) media are plotted as a function of time (generations) after the shifts. Genes are divided into those that were significantly up-regulated and those that were significantly down-regulated. Black bars indicate the number of genes that were identified for the first time at that time point to exhibit a significant change in expression from that of the aerobic (A and C) or anaerobic (B and D) controls. Gray bars indicate the number of genes that were differentially expressed in the sample but that had already been identified to have responded significantly to the shift in O₂ concentration at an earlier time point. The combined height of the black and gray bars is the total number of genes at each time point that showed a significant difference in expression relative to controls.