DNA replication of single-stranded DNA of phage fd microinjected into Xenopus laevis eggs

Single-stranded circular DNA of phage fd was microinjected into Xenopus laevis eggs and DNA synthesis was analyzed after incubation. An efficient DNA synthesis occurred in the eggs: 2.7 ng of DNA was newly formed in an egg whose volume is approximately 900 nl during a 5-h incubation at 20 degrees C. The DNA synthesis was sensitive to aphidicolin, suggesting that DNA polymerase alpha participates in the synthesis. Agarose gel electrophoresis showed that full size of fd DNA is synthesized and that replicative form I of fd DNA is the major form of the newly produced DNAs. These results suggest that priming of DNA synthesis, elongation of DNA chain and ligation of DNA strands take place co-operatively in the egg with single-stranded DNA as a template.