Amplification of a transgene within a long array of replication origins favors higher gene expression in animal cells
Fig 7
Plasmid-encoded d2EGFP expression in the stable transformants.
After transfection of the indicated DNA into COLO 320DM (A) or CHO DG44 (B) cells, the stable transformants were selected by blasticidin for 34 or 29 days, respectively. The d2EGFP expression was measured using flow cytometry, and the mean fluorescence intensity in arbitrary units was plotted. (C) The indicated COLO 320DM transformants were cultured for 34, 62, and 82 days after transfection, and analyzed by flow cytometry in the absence (blue filled line) or presence (unfilled line) of 2 mM sodium butyrate during the last 3 days. The mean fluorescence intensity for butyrate (-) and (+; parenthesized) culture was noted in each chart.