The structure of the DNA of bacteriophage φX174 VI. Pyrimidine sequences in the complementary strand of the replicative form

Partially synthetic duplex circles of φX174am3 DNA, specifically labeled in the pyrimidines of the complementary strand, were prepared in vitro using Escherichia coli DNA polymerase and a template of φX DNA. This material was degraded to pyrimidine tracts which were dephosphorylated and separated into fractions of uniform length by chromatography on DEAE-Sephadex. Chain lengths were assigned to the various isopliths by comparison with the profile obtained from labeled viral DNA tracts. By a combination of column Chromatographic and mapping techniques, a complete catalog of the pyrimidine tracts in the complementary strand of φX replicative form DNA (and thus, by complementarity, of the purine tracts of φX viral DNA) has been compiled