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A Yannarell

Publications and source records attributed to A Yannarell.

8 recordsLinked to original sources
PubMed1977

Proflavine sensitivity of RNA processing in isolated nuclei.

The intercalating agent proflavine inhibits the processing and subsequent release of preformed messenger RNA and ribosomal RNA from isolated liver nuclei to surrogate cytoplasm. The direct effect of proflavine on these processes, as monitored in a reconstituted cell-free system, supports the theory that base-paired segments (i.e. hairpin loops) in the precursor RNA's are involved as recognition sites in nuclear RNA processing.

Acridines↗
PubMed1976

Nature of the facilitated messenger ribonucleic acid transport from isolated nuclei.

Cytoplasmic macromolecules were previously identified which regulate both qualitatively and quantitatively the release of messenger-like RNA from isolated nuclei. These macromolecules are now shown to be denatured at 45-50 degrees C and their synthesis is sensitive to pactamycin or cycloheximide. The putative regulatory proteins are essentially quantitatively precipitated with high specificity from the cytosol by streptomycin at a concentration 10-fold higher than that used to precipitate RNA. The nuclear concentration-dependence of RNA transport from successive samples of nuclei strongly suggests that the regulatory factors are recycled. Quantitative changes in the sequences transported at various dilutions of the cytosol suggest that not all the different classes of the putative regulatory macromolecules are present in an effective concentration at any one dilution.

Animals↗
PubMed1975

Effects of membrane ribonuclease and 3'-nucleotidase on the digestion of polyuridylic acid by rat liver plasma membrane.

1. Fragments of isolated rat liver plasma membrane possess a ribonuclease activity which at pH 7.8 in the presence of 10 mM EDTA can digest polyuridylic acid (poly(U)) and polycytidylic acid (poly(C)) but not polyadenylic acid (poly(A)) and polyguanylic acid (poly(G)). Under these conditions, the membrane preparation does not degrade native or denatured DNA. 2. The products of the reaction with poly(U) (10 mM EDTA present) can be separated on DEAE-Sephadex into oligonucleotides of increasing chain length. Most of the products are di- to hexa-nucleotides which contain terminal 3'-phosphate groups. 3. When EDTA is not present (pH 7.8 or 8.8) the plasma membrane preparation degrades both poly(A) and poly(U). With poly(A) the product is all nucleoside while with poly(U) as substrate most of the product is nucleoside, but also some oligonucleotides are produced. 4. The ribonuclease releases acid soluble products very slowly from high concentrations of poly(U) (mg/ml). 5. Uridine trinucleotide with and without a terminal 3'-phosphate group is degraded by rat liver plasma membrane. The trinucleotide diphosphate is rapidly hydrolyzed to nucleoside while the trinucleotide itself is slowly digested and yields intermediate products, including nucleoside.

Animals↗
PubMedDate not supplied

Age-dependence of nuclear RNA processing.

Following a 3 hour in vivo labelling of cytoplasmic RNA in rat liver with orotic acid-6-14C under conditions where ribosomal RNA synthesis was suppressed, the proportion of labelled messenger-like RNA released to the cytoplasm which contained polyadenylate (poly(A)) tracts was about 3.0 times higher in the livers of juvenile (50 day) as compared to adult (180 day) rats. This discrepancy was confirmed in a cell-free system which consisted of isolated prelabelled nuclei in fortified cytosol. Thus under conditions where approximately 80% of the released labelled RNA was messenger-like, the proportion of polyadenylated labelled RNA transported to the homologous cytosol was 3.4-fold greater in the systems derived from juvenile as compared to adult rat liver. Through comparisons of homologous and heterologous systems it was determined that the age-dependent change in the metabolism of polyadenylated messenger RNA resides in the nucleus and not in the cytoplasm. This change, furthermore does not involve the known ATP-dependence of nuclear RNA release. Rather it must involve other age-dependent changes in the processing or transport of polyadenylated messenger RNA.

Aged↗