Fusion of the Dhfr/Mtx and IR/MAR Gene Amplification Methods Produces a Rapid and Efficient Method for Stable Recombinant Protein Production
Figure 5
Amplification and antibody expression using plasmid set
α. CHO DG44 cells were co-transfected with pMycLH (plasmid 2) and pΔBN AR1-Dhfr or pSFV-V-Dhfr (plasmid 1); cells were then selected by culture in the presence of 500 µg/ml G418, and the indicated concentrations of blasticidin (BS) and Mtx. The transfectant number (No.), Mtx concentration (nM), BS concentration (µg/ml), αMEM used (with (αMEM +) or without (αMEM−) nucleosides and deoxynucleosides), and amplification method, are indicated at the bottom of the figure. IR/MAR: IR/MAR method; Conv: conventional expression plasmid. Cells reached confluence at the indicated number of days after transfection (Days a Trf). Cytogenetic structures were analyzed by FISH (A) (cw: chromosome width). Antibody expression was quantified by real-time PCR (B), and ELISA (C). Cells prepared for ELISA were grown in the presence (+) or absence (−) of 10 mM sodium butyrate (But). Error bars represent mean +/− S.D.