the closed circular dna of bacteriophage pm2 has properties distinct from those of the other dnas of this study in that it has been shown to contain fractions which exist in the base-paired duplex form after neutralization of strongly alkaline solutions of this dna incubated at ambient temperature , while no duplex dna is observed after exposure to alkali and neutralization of solutions of closed circular dna from other sources .
C0012854
dna
C0012925
circular dna