The assembly of an RNA polymerase II initiation complex at a promoter is associated with the melting of the DNA template to allow the polymerase to read the DNA sequence and synthesize the corresponding RNA. Using the specific single-stranded modifying reagent KMnO4 and a new genomic sequencing technique, we have explored the melted regions of specific genes in genomic DNA of whole cells or of ...

In vitro transcription was used to analyze the promoter specificity of the alpha-amanitin-resistant RNA polymerase that is induced late during infection of Autographa californica multicapsid nuclear polyhedrosis virus. By modifying the preparation of crude nuclear extracts, we have established an assay that permits differentiation between weak late and strong very late viral promoters. The viru...

A transient decaribonucleotide (iRNA) is covalently linked to nascent eukaryotic DNA chains at their 5' end. Searching for the putative iRNA polymerase (primase), we detected in extracts from SV40-infected cells a DNA-dependent incorporation of UMP residues from UTP into free and DNA linked deca- or similarly sized ribonucleotides. Denatured salmon sperm DNA served as the standard template in t...

PURPOSE On reaching the surface position, corneal epithelial cells assemble a tight paracellular barrier rapidly. The purpose of this study was to identify at what maturation stage the cells acquire biochemical elements underpinning this ability. METHODS Rabbit corneas were subjected to a digitonin-exposure protocol that results in the devitalization and desquamation of the three outermost ce...

Hepatitis delta virus (HDV) contains a viroid-like circular RNA that is presumed to replicate via a rolling circle replication mechanism mediated by cellular RNA polymerases. However, the exact mechanism of rolling circle replication for HDV RNA and viroids is not clear. Using our recently described cDNA-free transfection system (L. E. Modahl and M. M. Lai, J. Virol. 72:5449-5456, 1998), we hav...