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Biomedical subjects

J R Warner

Publications and source records attributed to J R Warner.

121 records · Page 7Linked to original sources
PubMed1968

The turnover of nuclear DNA-like RNA in HeLa cells.

The subcellular distribution of various types of RNA in HeLa cells is described. In addition, the relative rate of synthesis of the major classes of nuclear RNA has been determined. From these experiments it can be deduced that the heterogeneous nuclear RNA fraction is rapidly synthesized and degraded within the cell nucleus.

Carbon Isotopes↗
PubMedDate not supplied

Termination of transcription of ribosomal RNA in Saccharomyces cerevisiae.

We have attempted to determine the site of termination of transcription of ribosomal RNA in the yeast, Saccharomyces cerevisiae. While a quantitative description of the termination sites of RNA polymerase I is not possible using presently available methods, we conclude that transcription of most molecules continues through a large portion of the adjacent enhancer region. There are two potential termination sites within the enhancer, one of which is near the binding site of the DNA binding protein REBI. In addition there is an apparently fail-safe termination site approximately 950 nucleotides beyond the 3' end of 35S ribosomal precursor RNA. Processing at the end of 35S RNA influences the choice of downstream termination site. Conversely downstream sequences also influence the site of termination.

Blotting, Northern↗
PubMedDate not supplied

The 5S rRNA and the rRNA intergenic spacer of the two varieties of Cryptococcus neoformans.

The intergenic spacers (IGS) separating the 23S-like and 16S-like rDNAs of the two varieties of the human pathogenic fungus Cryptococcus neoformans were amplified, cloned and sequenced. The C. neoformans var. neoformans IGS was 2421 nt with 5S rRNA at positions 1228-1345 3' of the 23S-like rRNA. The C. neoformans var. gattii IGS was 2480 nt with 5S rRNA at positions 1268-1385 3' of the 23S-like rRNA. For both varieties the 5S rDNA genes were in the same orientation as the 16S-5.8-23S genes and encode a 118 nt molecule of identical sequence. Phylogenetic comparison of C. neoformans 5S rDNA with that of other fungi placed this fungus in close relationship with other basidiomycetes including Tremella mesenterica, Bullera alba, and Cryptococcus laurentii. A secondary structure model for the deduced 5S rRNA was constructed by comparative sequence analysis. Polymerase chain reaction-amplified IGS of 12 C. neoformans var. neoformans strains revealed extensive size variation ranging from 100 to 300 nt. Size variation between strains in the length of the IGS may be useful for distinguishing strains. Structurally, the IGS were characterized by the presence of occasional short direct GC-rich 19-nt repeats. Overall IGS sequence identity between the C. neoformans varieties was only 78.5%, in sharp contrast to the identical or nearly identical sequences for the rDNA genes, and suggests rapid evolution for IGS sequences.

Base Sequence↗