Norfloxacin treatment causes formation of shortened simple-Y molecules. DNA was isolated from JH39 cells carrying pBR322 and digested with EcoRI. The samples were as follows:
A. DNA was isolated under cleavage conditions (CLV) from untreated cells (UTR).
B. DNA was isolated under cleavage conditions from norfloxacin-treated cells (NOR).
C. DNA was isolated under resealing conditions (RSL) from norfloxacin-treated cells.
The illustrations below indicate the various arcs seen after EcoRI digestion, where B, bubble; LM, linear monomer; SSY, shortened simple-Y; Y, simple-Y; DY, double-Y; AY, asymmetric-Y; and OC, open circular monomer.