Mechanism of DNA chain growth. 3. Equal annealing of T4 nascent short DNA chains with the separated complementary strands of the phage DNA.

Nascent short DNA chains isolated from T4-infected E. coli under a variety of conditions anneal equally to the separated complementary phage DNA strands. The samples examined include: pulse-labeled short chains isolated by alkaline sucrose gradient sedimentation from the T4D (wild type)-infected cells in both the early and late stages of phage DNA synthesis; nascent chains accumulated during ligase inhibition of T4 ts B20-infected cells; and the single-stranded nascent short chains isolated from T4D-infected cells by mild procedures involving no denaturation treatment. The results are consistent with the hypothesis that both strands of DNA are synthesized discontinuously.