Site specific initiation of a DNA fragment

The first step in the replication cycle of the single-stranded DNA phages is the conversion of the infecting positive strand circle to a duplex ring. This event involves the de novo initiation of a negative strand, using the infecting positive strand cycle as a template. The synthesis of the negative strand is in many respects analogous to the formation of a fragment during cellular DNA replication. In this paper the authors describe the initiation of the negative strand of bacteriophage G4. The data establish that, in vivo, the synthesis of the G4 negative strand is initiated at a specific site, which the authors have mapped on the 5400-base viral chromosome.