Early compacting mouse morulae were placed in alpha-amanitin at various times after HCG and the effect of this transcriptional inhibitor during formation of the blastocyst was noted. No cavitation was observed in those embryos transferred into alpha-amanitin before 77 h after HCG but the percentage of cavitation increased dramatically in those embryos transferred after 80 h post HCG. The large ...

Lacking an RNA-dependent RNA polymerase, hepatitis delta virus (HDV), which contains a circular RNA of 1.7 kilobases, is nonetheless able to replicate its RNA by use of cellular transcription machineries. Previously, we have shown that the replications of genomic- and antigenomic-strand HDV RNAs have different sensitivities to alpha-amanitin, suggesting that these two strands are synthesized in...

Three peaks of DNA-dependent RNA polymerase (RNA nucleotidyltransferase) activity are resolved by chromatography of a sonicated yeast cell extract on DEAE-Sephadex. The enzymes, which are named RNA polymerases I, II, and III in order of elution, show similar catalytic properties to the vertebrate class I, class II, and class III RNA polymerases, respectively. Yeast RNA polymerase III is readily...

The 2-cell stage of mouse embryogenesis is characterized by two phases of alpha-amanitin-sensitive polypeptide synthetic activity, which appear to mark the first major expression of the embryonic genome, as assessed by examination of in vitro translates of mRNA. Using populations of embryos synchronized to the first cleavage division, we have established that DNA replication takes place over th...

Our laboratory has developed methods for transient state kinetic analysis of human RNA polymerase II elongation. In these studies, multiple conformations of the RNA polymerase II elongation complex were revealed by their distinct elongation potential and differing dependence on nucleoside triphosphate substrate. Among these are conformations that appear to correspond to different translocation ...

New protein synthesis is essential in sheep oocytes for the progression of the meiotic cycle to metaphase. Inhibition of transcription by alpha-amanitin, a specific inhibitor of RNA polymerase II, arrests meiosis in the G2 phase in cumulus enclosed oocytes but denuded oocytes progress to M-phase. Denuded oocytes injected with alpha-amanitin also undergo maturation. Cumulus-enclosed and denuded ...

Nuclear run-on assays carried out in the presence and absence of the RNA polymerase II inhibitor, alpha-amanitin, were used to determine the exact timing of the switch from inhibitor-sensitive transcription catalysed by host RNA polymerase II, to inhibitor-resistant transcription catalysed by the baculovirus-induced RNA polymerase. These studies revealed that the onset of alpha-amanitin-resista...

a-Amanitin, a toxic substance from the mushroom Amanita phalloides, is a potent inhibitor of DNA-dependent RNA polymerase II (the nucleoplasmic form) from sea urchin, rat liver, and calf thymus. This compound exerts no effect on the activity of polymerase I (nucleolar form) or polymerase III (also nucleoplasmic). The inhibition is due to a specific interaction with polymerase II or with a compl...

1. alpha-Amanitin inhibits in vitro the activity of RNA polymerase II of rat brain nuclei. 2. The toxin does not pass the blood-brain barrier, but when injected intracerebrally is highly toxic for rats, and causes inhibition of RNA polymerase II of isolated brain nuclei. 3. Intracerebral injection of alpha-amanitin 6h before training to a passive avoidance task is followed by impaired performan...