Figure 4From: The constancy of global regulation across a species: the concentrations of ppGpp and RpoS are strain-specific in Escherichia colippGpp levels of ECOR strains starved for carbon or amino acid. Cells were treated as in the legend of Figure 3, except that samples were withdrawn 30 minutes following the addition of α-MG or SH. ECORs 50, 51, 53 and 63 carry a T13N substitution in spoT. Bars represent the mean ± SD of three independent measurements.Back to article page