Figure 3.
Step induction of closed loop circuit. (A) aTc induction of Sc-RFP began 30 min after start of experiment and continued for the rest of the experiment. (B) scaffold–RFP/OD measurements for no induction (left), 37.5 nM induction (middle), and 75 nM induction (right). Response time (Tr) is quantified by finding the time needed for fluorescence to increase from 10% (gray dotted line) to 90% of the maximum value (blue dotted line). A 2-fold increase in aTc results in a 4-fold increase in scaffold expression and a 2-fold increase in response time. The insets show growth curves for each condition. (C) AS-YFP/OD measurements show 2.5-fold increase between the two inputs and a 3-fold increase in response time. Fluorescent measurements are normalized such that the maximum of the middle column (37.5 nM aTc) is 1 au to better visualize fold change.