Figure 4

TIR selection in different media. The cells were grown in either LB (A, B, C, D), MOPS medium containing glucose, "MOPS Glc" (E, F, G, H), or MOPS containing sodium acetate, "MOPS NaAcetate" (I, J, K, L) at 37°C. mRNAs lacking enhancer (A, E, I), containing the weak enhancer (B, F, J) or containing the strong A/U-rich enhancer (C, G, K) were tested. The bacterial cultures were inoculated and aliquots were taken at the indicated time points. GFP expression was induced in these aliquots for one hour (LB, MOPS Glc) or 3 hours (MOPS NaAcetate) and the fluorescence was measured. Relative fluorescence was calculated by dividing the fluorescence values measured for cells containing particular constructs by the fluorescence measured for the GAGG SD sequence. In addition, growth curves in different media are shown (D, H, L).