Fig. 3
From: Efficient generation of influenza virus with a mouse RNA polymerase I-driven all-in-one plasmid
Homologous recombination of plasmid pYA4990. E. coli recA1 mutant strain EPI300 was transformed with plasmid pYA4990. A single colony was rotary cultured in LB media containing 25 μg/ml chloramphenicol at 37 °C for 12 h (passage 0). The culture was diluted at the ratio of 1:1000, and cultured at same condition for additional four passages. Plasmid DNA was extracted from each passage, and digested with EcoRI and KpnI. From an intact plasmid pYA4990, the size of five theoretical fragments are 8384 bp, 5166 bp, 3747 bp, 1944 bp, and 1798 bp