Degradation of ribonucleic acid in mouse fibroblasts treated with actinomycin.

The cellular RNA content of mouse fibroblasts incubated with actinomycin decreases at a rate of about 1 to 1.5 per cent per hour, while DNA and protein content remain unchanged. This degradation affects nuclear and cytoplasmic RNA, ribosomal and soluble RNA.

Base specificity in the interaction of polynucleotides with antibiotic drugs.

Echinomycin, daunomycin, ethidium bromide, nogalamycin, chromomycin, mithramycin, and olivomycin inhibit RNA synthesis by RNA polymerase by interacting with the DNA template. Chromomycin and olivomycin form complexes with DNA, preferably in the helical form, but not with RNA. These complexes require guanine in DNA and the addition of a stoichiometric amount of bivalent cation.

ACTINOMYCIN: CORRELATION OF STRUCTURE AND FUNCTION OF ITS COMPLEXES WITH PURINES AND DNA.

Actinomycin inhibits strand separation of helical DNA at concentrations corresponding to those which inhibit DNA polymerase activity in vitro. This report proposes first that actinomycin affects DNA polymerase indirectly by way of the changed physical properties of the template and that it functions in the major groove of helical DNA; second, that RNA polymerase functioning in the minor groove is subject to direct steric inhibition by bound actinomycin; and third, that the reaction of actinomycin with free purines is unrelated to its reaction with DNA.

Effect of actinomycin D on cellular nucleic acid synthesis and virus production.

Actinomycin D inhibits the synthesis of ribonucleic acid in L cells and the yield of vaccinia virus containing deoxyribonucleic acid, but it does not inhibit cellular deoxyribonucleic acid synthesis or the multiplication of Mengo virus containing ribonucleic acid. These observations serve to distinguish the replication of viral ribonucleic from ribonucleic acid synthesis which is controlled by viral or cellular deoxyribonucleic acid.