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. 2010 Apr 12;38(11):e127. doi: 10.1093/nar/gkq178

Figure 1.

Figure 1.

Outline of experimental system. (a) The CRZ (top) and cHS4-CRZ (bottom) expression cassettes showing the 19 bp Tn5 mosaic ends, mRFP and zeocin mini-genes, and the cHS4 insulator sequences. (b) DHFR BAC map showing BAC vector backbone (black), mouse genomic sequence (gray), 256-mer lac operator transposon (green), and mRFP expression cassette transposon insertion sites (arrowheads) for C4 (orange) and C27 (red) clones. (c) mRFP expression levels (x-axis) measured by flow cytometry show higher and more uniform expression levels for NIH 3T3 mixed clonal populations of stable transformants after transfection with BAC transgenes (green and red) versus plasmid constructs with (blue) or without (yellow) cHS4 insulator sequences. Nontransfected cells (black) establish the background fluorescence level. (d–f) BAC transgenes produce more homogeneous expression within individual cell clones. Expression distribution for two stable cell clones with similar average expression levels selected from each transfection experiment: CRZ plasmid (d), cHS4-CRZ (e), BAC clone C4 (f). Controls (black) correspond to nontransfected cells. (c–f) Fluorescence measured in the same arbitrary units.