DNA replication in synchronized cultured mammalian cells. V. The temporal order of synthesis of component alpha DNA during monkey DNA synthesis induced by SV40 virus.

Purified simian virus 40 (SV40) was used to induce host DNA replication in contact-inhibited monolayer cultures of African green monkey kidney cells. Approximately 20% of the nuclear DNA of these cells is the simple sequence, component α DNA (Maio, 1971). At the beginning of DNA synthesis induced by SV40 viral infection, the average ratio of the specific radioactivity of component α DNA to that of bulk DNA was 0.18. Similar low specific activity ratios are observed early during the DNA synthetic period following the trypsin release of monkey cells from contact inhibition. These results indicate that when host DNA replication is induced by SV40 viral infection, component α DNA synthesis does not shift to precede the replication of bulk DNA.