Figure 2

Enhancer-blocking assay using two reporter transgenes. Reporter expression in S2 cells cotransfected with separate RFP and GFP transgenes. A. Left, diagrams of MT-RFP (top) and MT-GFP (bottom). Right, FACS chart of GFP and RFP induction in S2 cells cotransfected with both transgenes. Level of GFP or RFP is shown in logarithm scale (Y or X axis, respectively). The lower-left quadrant contains cell with both GFP and RFP levels <80 (double-negative cells); and the top-right quadrant contains cells with both GFP and RFP levels >80. Percentage of cells indicated at the corner in each quadrant. B. Induction of S2 cells cotransfected with MT-RFP and MT-sp-GFP, which contains a spacer (grey box) between MT and the eve promoter. Right: FACS chart of GFP and RFP induction in S2 cells cotransfected with both plasmids. C. Induction of S2 cells cotransfected with MT-RFP and the MT-suHw-GFP, which contains the 340-bp suHw element (red oval) between MT and the eve promoter. Right: FACS chart of GFP and RFP induction in S2 cells cotransfected with both plasmids. D. Relative induction level (I') of the RFP (red bars) and GFP (green bars) in cotransfection experiments in Panels A-C, see Methods).