抄録
Embryos of the silkworm, Bombyx mori L., were dispersed by trypsin and the dissociated cells were cultured for infection with nuclear polyhedrosis virus (NPV) of the silkworm. The monolayer and suspension cultures were infected with NPV. RNA and DNA syntheses in the normal and NPV-infected cells were measured by incorporation of 32P into RNA and DNA fractions. RNA and DNA syntheses in the cells after infection significantly increased over those in control cells (mock infection). The effects of actinomycin D, chloramphenicol and mitomycin C on RNA and DNA syntheses in infected cells were examined. The syntheses were inhibited by the antibiotics. It was suggested that the cellular DNA synthesis was inhibited by the viral infection, because the mitomycin C-resistant DNA synthesis was found in the normal cells but not in the infected cells treated with mitomycin C. The rate of DNA synthesis induced by NPV was immediately dropped to that of control cells by addition of chloramphenicol, while the RNA synthesis induced by NPV was not affected for 6 hr after the addition of chloramphenicol. If the antibiotic did not affect the size of precursor pools, this event suggested that the RNA polymerase concerned with viral RNA synthesis was more stable than the DNA polymerase participating in the viral DNA synthesis. The viral DNA as templates for RNA and DNA syntheses was decomposed by mitomycin C.
