Asymmetric RNA was synthesized in vitro from SV4O form I DNA using Escherichia coli DNA-dependent RNA polymerase. Using this RNA, sheared 32P-SV4O DNA was separated into (+) and (-) DNA strands. (+) and (-) DNA was shown to be complementary strands of SV4O DNA. The separated strands were hybridized to nuclear, informosome, and polysome RNAs extracted at different times in the lytic infection, and to similar RNAs from transformed cells. Further, the size of the RNAs hybridizing to (+) and (-) DNAs was determined by sucrose gradient sedimentation. The results showed: (1) Nuclear, informosome and polysome RNA from transformed BSC-1-S cells, all hybridized to 20% with (-) DNA. These same RNAs failed to hybridize to (+) DNA. (2) SV4O (-) DNA hybridized to early lytic RNAs to different degrees: 70% with nuclear RNA, 70% with informosome RNA and 55% with polysome RNA. SV4O (+) DNA hybridized to 40% with early lytic nuclear, informosome and polysome RNAs. (3) Late lytic RNAs hybridized with (-) DNA to 100%, 80% and 50% with nuclear informosome and polysome RNAs respectively. SV40 (+) DNA hybridized to 80% with nuclear RNA, 70% with informosome RNA and 50% with polysome RNA. (4) The sizes of nuclear, informosome, and polysome SV40 RNAs extracted from cells during early and late times after infection were determined by sucrose gradient sedimentation. The SV40 RNAs were generally as large as expected for a single molecule that could represent the percentage of SV40 DNA transcribed These results imply post-transcriptional processing of SV40 pre-mRNA within the nucleus and independently within the cytoplasm of lytically infected BSC-1 cells.
Daniel Henderson (Thu,) studied this question.