DTC characterization of the model system. gfp (A), nptII (B), and cat (C) DTCs obtained from the series of model system plasmids (Figure 3C). The cumulative data presented were the result of two independent experiments. Constructs were tested in duplicate during each independent experiment. Three data points (and not four) are shown for the pSC101 construct in all panels because a replicate was lost during sample preparation. RNA and copy number values were normalized to that of the pSC101 construct, with each having been assigned a mean value of one. The piecewise-linear fits that minimized the sum of squared residual error are also shown.