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At least 1,549 records · Page 86Linked to original sources
PubMed1967

Virus-specific ribonucleic acid synthesis in KB cells infected with herpes simplex virus.

The production of virus-specific ribonucleic acid (RNA) was investigated in KB cells infected with herpes simplex virus. A fraction of RNA annealable to virus deoxyribonucleic acid (DNA) was found in these cells as early as 3 hr after virus inoculation. Production of this species of RNA increased up to 6 or 7 hr after infection, at which time elaboration of virus messenger RNA (mRNA) declined. At 24 hr after infection, the rate of incorporation of uridine into this RNA was approximately one-half of the rate present at 6 hr after inoculation. Nucleotide analysis of the RNA annealable to virus DNA was compatible with that expected for virus mRNA. Centrifugation showed considerable spread in the size of the virus-induced nucleic acid, the bulk of this RNA sedimenting between 12 and 32S. Incorporation of uridine into cell mRNA, ribosomal precursor RNA, and soluble RNA was suppressed rapidly after infection. As is the case with most other cytocidal viruses investigated to date, virus-induced suppression of cell RNA synthesis appears to be a primary mechanism of cell injury.

Animals↗
PubMed1968

Effect of infection with ribonucleic acid bacteriophage R23 on the inducible synthesis of beta-galactosidase in Escherichia coli.

Infection by ribonucleic acid (RNA) bacteriophage R23 inhibited the synthesis of beta-galactosidase in Escherichia coli. The inhibition, although not complete, was apparent shortly after infection and was maximal after the first 20 min of infection. R23 diminished the beta-galactosidase-synthesizing capacity when inducer was added after phage infection, but not when infection followed inducer removal. These findings suggested that the primary effect of R23 on enzyme-forming capacity was limitation of synthesis of enzyme-specific messenger RNA. Studies with ultraviolet irradiated phage and amber mutants of R23 indicated that the inhibitory process could be separated into two phases. Early inhibition did not require the expression of the viral genome, whereas late inhibition required the expression of the viral RNA synthetase cistron.

Bacterial Proteins↗
PubMed1992

Comparison of flanking regions of the 5S ribosomal ribonucleic acid genes in Leptospira biflexa and Leptospira interrogans.

One of the genes encoding the 5S ribosomal ribonucleic acid (rRNA) for the Leptospira biflexa strain Patoc I was isolated and sequenced. The physical maps of the 5S rRNA genes in Leptospira were constructed. The strains of Leptospira biflexa had two genes on their chromosome; these two 5S rRNA genes were located several kb apart and sequences flanking these genes were divergent. In contrast to saprophytic leptospires, maps in parasitic leptospires that had only one gene for 5S rRNA on their genome were highly conserved and the physical maps of the genes in almost all strains were similar.

Base Sequence↗
PubMed1989

Chromogranin A and B messenger ribonucleic acids in pituitary and other normal and neoplastic human endocrine tissues.

The distribution of the messenger ribonucleic acids (mRNAs) for chromogranin A and B was analyzed by in situ hybridization in normal and neoplastic endocrine tissues using frozen and paraffin tissue sections. Combined in situ hybridization and immunochemical staining was also done on tissue sections from the same cases using a monoclonal antibody against chromogranin A (LK2H10). Most endocrine tumors expressed chromogranin A and B mRNAs as well as chromogranin A protein. Normal pituitary expressed chromogranin A and B mRNAs and chromogranin A protein in the anterior pituitary gland. Most of these cells were gonadotropic hormone-producing cells. Prolactinomas (5/5) did not express chromogranin A mRNA or protein, but contained chromogranin B mRNA. Null cell or nonfunctional adenomas (8/8) expressed chromogranin A and B mRNAs and reacted with antibody LK2H10. In some tumors such as Merkel cell carcinomas, insulinomas, and parathyroid adenomas, a stronger signal for chromogranin A mRNA was detected than for the immunoreactive proteins. These results indicate that in situ hybridization complements immunochemical techniques in the analysis of endocrine cells and neoplasms. The gene products for chromogranin A and B are widely distributed in many endocrine cells and tumors, but some neoplasms such as prolactinomas have a differential distribution of chromogranin A and B mRNA and proteins.

Blotting, Northern↗
PubMed1976

Human pancreatic-type ribonucleases with activity against double-stranded ribonucleic acids.

Purified acid-thermostable ribonuclease (Ribonucleate 3'-pyrimidino-oligonucleotidohydrolase, EC 3.1.4.22) from human pancreas degrades double-stranded RNA at 2% the rate for single-stranded RNA. The activities against single-stranded RNA and double-stranded RNA were shown to be due to a single enzyme with properties similar to bovine pancreatic RNAase A. For purposes of comparison the activities against double-stranded RNA of crystalline ribonucleases of the whale, rat and cow were assayed and found to be 0.4%, 0.03% and 0.003%, respectively, of their activities against single-stranded RNA. Both human serum and urine contain RNAse components of pancreatic origin which hydrolyze double-stranded RNA at 2% and 0.4%, respectively, of the rates against single-stranded RNA. By contrast, purified acid-thermostable RNAases from human spleen and liver hydrlyze double-stranded RNA at least 20-fold more slowly than human pancreatic RNAase, relative to the corresponding rates against single-stranded RNA. The human pancreatic and serum enzymes exhibit appreciable activity against the poly(C) component of the double-stranded poly(I)-poly(C); they also attack poly(C) itself at approximately 25 times the rate for poly(U) and at more than 50 times the rate for single-stranded RNA.

Animals↗
PubMed1987

Localization of neuropeptide Y messenger ribonucleic acid in rat and mouse brain by in situ hybridization.

The distribution of neuropeptide Y (NPY) messenger ribonucleic acid (mRNA) in the rat and mouse brain has been examined. A 28-mer oligonucleotide probe complementary to a distinctive region of NPY mRNA was 3'-end labeled with [35S]-deoxycytosine triphosphate ([35S]-dCTP) by using terminal transferase and was hybridized to fixed sections of rat and mouse brain. The hybridization of the labeled probe to the mRNA in the tissue section was then detected autoradiographically. A strong hybridization signal was seen corresponding to the arcuate nucleus of the hypothalamus. Scattered NPY-mRNA-containing cell bodies were seen throughout the cerebral cortex. Experiments which compared the distribution of NPY mRNA with immunohistochemically detected NPY indicated a similar distribution in the arcuate nucleus of the hypothalamus and cerebral cortex. These results indicate that active transcription of the NPY gene occurs within the brain and this transcription takes place in NPY-containing cell bodies.

Amino Acid Sequence↗
PubMed1997

Effect of antiretroviral combination therapy (zidovudine/didanosine or zidovudine/lamivudine) on quantitative plasma human immunodeficiency virus-ribonucleic acid in children and adolescents infected with human immunodeficiency virus.

OBJECTIVE: To assess human immunodeficiency virus (HIV) ribonucleic acid load in children and adolescents with HIV infection who are being treated with antiretroviral combination therapy. STUDY DESIGN: Five patients whose disease progressed with their prior antiretroviral therapy had treatment regimens changed to zidovudine (ZDV)/didanosine (DDI) (group A), and the regimens of six patients were changed to ZDV/lamivudine (3TC) (group B). Patients were followed every 4 to 8 weeks for an average period of 8.6 months. Serial determinations of viral copy numbers and CD4 cells were performed. RESULTS: In group A patients' mean relative changes in CD4 cells showed a 20% increase after 4 months (difference not significant (NS)) and a return to baseline after 8 months; in group B patients' mean relative increases of CD4 cells were 72% (p = 0.046) and 50% (NS), respectively. In group A mean relative viral load increased 21% (0.08 log10, NS) and 71% (0.23(10) log, NS), whereas in group B viral load decreased 22% (0.1 log10, NS) and 74% (0.58 log10, p = 0.03) after 4 and 8 months, respectively. After starting antiretroviral combination therapy in group A, there was a slight trend of a decreasing ratio of viral load per number of CD4 cells, whereas in group B this ratio significantly decreased, indicating a marked suppression of viral turnover with ZDV/3TC treatment. CONCLUSION: In a small cohort of pediatric patients, combination therapy with ZDV/3TC was well tolerated and had a strong and sustained effect on the decrease of viral loads similar to results obtained in adults. In patients with ZDV/DDI therapy the reduction of viral load was less pronounced, but treatment groups A and B were not comparable for statistic evaluation.

AIDS-Related Opportunistic Infections↗
PubMed1981

Chemical modification of ribonucleic acid. A direct study by carbon-13 nuclear magnetic resonance spectroscopy.

Direct study of the methylation of ribonucleic acid with methyl methanesulfonate by carbon-13 nuclear magnetic resonance spectroscopy has demonstrated the usefulness of this method in studying the chemical modification of biomacro-molecules and the interaction between nucleic acids and biologically active agents. This direct stable isotope method eliminated all tedious and questionable degradation processes for determining the reactive sites and the product distributions. Six methylated products, 7-methylguanosine, 1-methyladenosine, 3-methylcytidine, 1-methylguanosine, 3-methyluridine, and methyl phosphodiester, were identified by comparison with many model compounds and careful examination of spin-spin coupling and spin-lattice relaxation time. An extensive study of the interaction of phosphate buffer with methyl methansulfonate accounted for the sharp difference in the 13C spectra of the methylated RNA isolated from the reactions controlled by a pH-stat and phosphate buffer, respectively. The 13C-enriched agent significantly enhances the specificity and sensitivity of the method and provides better quantitative results.

Carbon Isotopes↗
PubMed1981

Alterations in polyadenylated messenger ribonucleic acid from free and total polysomes of a rat hepatoma.

We examined the homology between polysomal polyadenylated ribonucleic acid (mRNA) populations of hepatoma 252, a tumor which is deficient in the synthesis of plasma proteins, and those of normal and regenerating rat liver. Hybridization of polyadenylated mRNA populations with homologous or heterologous complementary deoxyribonucleic acids showed that mRNA from total and free polysomes from hepatoma 252 lack sequences which are present in normal or regenerating liver. Although there are obvious differences in the abundance of sequences between tumor and normal or regenerating liver polysomal mRNA, we did not detect, with the techniques used in this work, tumor-specific sequences. Analysis of hybridization curves using derivative plots did not reveal the presence in tumor mRNA of a high complexity class not present in normal liver. We conclude that alterations in mRNA populations of free and total polysomes of this tumor primarily reflect processes of genetic restriction rather than the derepression of previously unexpressed genes.

Animals↗
PubMed1974

Fingerprinting nonradioactive ribonucleic acid with the aid of polynucleotide phosphorylase.

We describe a method for obtaining radioactive fingerprints from nonradioactive ribonucleic acid. Fragments derived by T1 ribonuclease digestion of RNA are dephosphorylated with bacterial alkaline phosphatase. When these fragments are used as primers for the reaction of primer dependent polynucleotide phosphorylase with [alpha-(32)P]GDP in the presence of T1 ribonuclease the 3'-hydroxyl group of each fragment becomes phosphorylated. The degree of phosphorylation is reasonably uniform. The method has been applied to T1 ribonuclease digests of Escherichia coli tRNA(Met) (f); the oligonucleotides were further analyzed by spleen phosphodiesterase digestion. In a similar manner fingerprints of pancreatic ribonuclease digests of RNA can be obtained, when [alpha-(32)P]UDP, polynucleotide phosphorylase and pancreatic ribonuclease are used.

Alkaline Phosphatase↗
PubMed1971

Electrophoretic analysis of ribosomal and viral ribonucleic acids with a simple technique for slicing low-concentration polyacrylamide gels.

The electrophoretic mobilities of ribosomal ribonucleic acids (RNA) from cultured mammalian (HeLa, Vero, MDBK), avian (chick embryo), and bacterial (Escherichia coli) cells, and RNA species extracted from selected viruses (Sindbis, polio, tobacco mosaic, Sendai) were compared, employing a simple, inexpensive technique for slicing low-concentration polyacrylamide gels. The procedure provides for rapid fractionation of gels used for characterization of RNA, incorporating extrusion and serial sectioning of frozen gels. Among 28S ribosomal RNA species, Vero and MDBK were indistinguishable, whereas HeLA RNA had a slightly lower mobility (higher apparent molecular weight) and chick RNA had a higher mobility (lower apparent molecular weight). The 18S ribosomal RNA species of the three mammalian sources were indistinguishable, but chick 18S RNA had a slightly lower apparent molecular weight. The inverse relation between mobility and log-molecular weight among the ribosomal and viral RNA species, though not highly precise, demonstrates the applicability of the technique to the study of molecular weights of viral RNA species.

Animals↗
PubMed1970

Characterization of Labeled Residues from 5-Diazouracil-2-C Incorporated into Ribonucleic Acids of Filamentous Escherichia coli.

E. coli B, filamented with 5-diazouracil (DZU)-2-(14)C, yielded ribonucleic acid (RNA)-(DZU-2-(14)C) which was converted by pancreatic ribonuclease to (14)C-mono-and oligo-nucleotides. The mixed (14)C-mononucleotides isolated by diethylaminoethyl-cellulose fractionation were identified as cytidylic, uridylic, and hydroxyuridylic acids, by using a combination of paper chromatography and treatment with alkaline phosphatase and cytidine deaminase. Rifampin blocked incorporation of DZU-2-(14)C under conditions which inhibit RNA synthesis. Division inhibition by DZU-2-(14)C and the incorporation into Escherichia coli B were retarded by uracil but not by other RNA bases. In a pyrimidine-requiring E. coli, DZU substituted for uracil or cytosine to an extent limited by toxic effects. Cytosine and uracil retarded these effects and retarded the incorporation of DZU-2-(14)C into the pyrimidineless strain. A small proportion of DZU-2-(14)C was converted by the latter strain into hydroxyuridylic acid, but the bulk of the incorporated label was in cytidylic and uridylic acid, as in the wild strain.

Journal Article↗
PubMed1972

Specificity of interaction between the first enzyme for histidine biosynthesis and aminoacylated histidine transfer ribonucleic acid.

The specificity of the interaction between phosphoribosyltransferase and partially purified preparations of various species of transfer ribonucleic acid (tRNA) was investigated with the use of a filter binding assay. The enzyme showed a higher affinity for histidyl-tRNA than for arginyl- or glutamyl-tRNA. Competition experiments revealed that the enzyme does not distinguish between the aminoacylated and deacylated forms of arginine tRNA or glutamic acid tRNA, since all the binding of the aminoacylated tRNA could be inhibited by deacylated tRNA. The enzyme does, however, distinguish between the aminoacylated and deacylated forms of histidine tRNA. Approximately 70% of the binding of aminoacylated histidine tRNA is specific, since only 30% of the binding could be inhibited by deacylated tRNA. The possibility that the regulatory role of phosphoribosyltransferase is carried out as a complex with histidyl-tRNA is consistent with these data.

Acylation↗
PubMed1974

Decay of ribonucleic acid synthesis in amino acid-starved Escherichia coli after rifampin treatment.

The concentration of rifampin necessary to affect the initiation of ribonucleic acid (RNA) synthesis quickly in Escherichia coli strains K-12 and 15TAU was about 200 mug/ml, as determined by extrapolation of the effect of the drug on the induction of beta-galactosidase synthesis. A lag in the action of rifampin of about 10 s was confirmed. Rifampin was then used as a probe to compare RNA synthesis in growing and amino acid-starved E. coli. Restoring arginine to arginine-starved strain 15TAU immediately after rifampin inhibition did not detectably restore the rate of uracil uptake to that of uninhibited cells. The residual rate of RNA synthesis (corrected for acid-soluble triphosphate specific activities) after rifampin treatment of both growing and isoleucine-starved (valine-inhibited) cultures of strain K-12 showed similar decay kinetics. These findings support the notion that amino acid starvation blocks the initiation of some RNA transcription units, but do not rule out other possibilities.

Adenosine↗
PubMed1975

Transductional mapping of gene trmA responsible for the production of 5-methyluridine in transfer ribonucleic acid of Escherichia coli.

The gene trmA, responsible for the production of 5-methyluridine (ribothymidine) in transfer ribonucleic acid, has been located at 79 min on the chromosomal map of Escherichia coli K-12. In five-factor crosses the gene order was shown to be argH-trmA-rif-thiA-metA. The co-transduction frequency between argH and trmA was 65%. Furthermore, the trmA5 mutation was shown to be recessive, in agreement with the notion that the trmA gene is the structural gene for the transfer tibonucleic acid (5-methyluridine) methyltransferase.

Chromosome Mapping↗
PubMed1975

Unbalanced growth and the production of unique transfer ribonucleic acids in relaxed-control Escherichia coli.

The unique leucine-, arginine-, valine-, and phenylalanine-specific transfer ribonucleic acids (tRNA's) produced in relaxed-control (rel-) Escherichia coli during leucine or arginine starvation are chromatographically similar to those produced by chloramphenicol treatment. The major unique rel- leucine-specific and phenylalanine-specific tRNA's are heterogeneous, accumulate with time of starvation, and can account for up to 70% of the respective amino acid acceptor activities. The changes which occur in the isoacceptor profiles for tRNALeu and tRNAPhe as a function of starvation time suggest that the unique species are undermodified precursors to the major isoacceptor species observed in nonstarved cells. Analyses of the isoacceptor patterns of tRNA from cells recovering from starvation suggest that the unique species of tRNALeu and tRNAPhe may not be normally occurring precursors. When leucine-starved cells were incubated in fresh, fully supplemented medium, the major unique tRNALeu and tRNAPhe appeared to be converted to normal species only slowly or not at all. The results are consistent with the view that some of the events in the post-transcriptional modification of tRNA may occur in an ordered sequence. An examination of the subcellular distribution of the unique leucine and phenylalanine tRNA's revealed that these species occur on the ribosome at about the same frequency as the major, normally occurring isoacceptor species. This result provides additional evidence of a precursor-product relationship for the unique and normal tRNA's and further indicates that there is no discrimination against the unique species by the ribosome.

Arginine↗
PubMed1976

Turnover of polyadenylate-containing ribonucleic acid in Saccharomyces cerevisiae.

We examined the kinetics of incorporation of [3H]adenine into polyadenylate-containing ribonucleic acid [poly(A)-containing RNA] in yeast. The total poly(A)-containing RNA from spheroplasts and intact cells and the polysomal poly(A)-containing RNA exhibited similar incorporation kinetics. At 30 C half-saturation of the pool of poly(A)-containing RNA with label occurred in approximately 22 min. Since precursor pools appeared to require 5 min to saturate with label, we conclude that at 30 C messenger RNA molecules in yeast decay with an average half-life of 17 min.

Adenine↗
PubMed1976

Bacillus subtilis mutant temperature sensitive in the synthesis of ribonucleic acid.

A Bacillus subtilis temperature-sensitive mutant (PB1653) has been isolated in which the rate of ribonucleic acid (RNA) synthesis sharply decreases after shift to 45 degrees C. Both stable and unstable RNAs are affected by the mutation. The possibility that the block of transcription at high temperature could be due to a "stringent" effect, mediated by an increase in the concentration of "magic spot" nucleotides, has been ruled out. Treatment with chloramphenicol (or streptomycin) rapidly restores the rate of RNA synthesis at 45 degrees C. The synthesis of RNA in the mutant during the early phases of spore germination is not temperature sensitive. The phage-specific transcription during infection with SPP1 phage, at high temperature, is less affected than that of the bacterial chromosome. In vitro experiments indicate that, in the mutant at high temperature, RNA polymerase undergoes a change in template specificity. The rna-53 mutation has been located on the B. subtilis genetic map near the hisA locus.

Bacillus subtilis↗