Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “RIBONUCLEIC ACID”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,513 records · Page 84Linked to original sources
PubMed1981

Developmental biochemistry of cottonseed embryogenesis and germination: changing messenger ribonucleic acid populations as shown by in vitro and in vivo protein synthesis.

Changes in messenger ribonucleic acid (mRNA) populations during embryogenesis of cottonseed have been followed by cataloging (a) extant proteins, (b) proteins synthesized in vivo, and (c) proteins synthesized in vitro from extracted RNA, all at specific stages of embryogenesis. Evidence is presented for the existence of five mRNA subsets, all apparently under different regulatory regimes, that produce the abundant proteins of embryogenesis. One of these functions principally during the cell division phase of embryogenesis and encodes among its products the seed storage proteins whose mRNA is superabundant during this period. This subset has disappeared from the abundant group by the mature seed stage. Two other subsets appear in late embryogenesis, one of which may result from the removal of the embryo from the maternal environment, since it is inducible by excision of the young embryo from the seed. The other appears to be induced by the plant growth regulator abscisic acid, whose endogenous concentration increases at this stage. It can be induced by incubating excised young embryos in abscisic acid. The last two subsets exist throughout embryogenesis, but only one of them appears to function in germination.

Gossypium↗
PubMed1980

Changes in the hepatic levels of messenger ribonucleic acid for malic enzyme during induction by thyroid hormone or diet.

Levels of hepatic messenger ribonucleic acid (mRNA) for malic enzyme [L-malate:NADP oxidoreductase (decarboxylating), EC 1.1.1.40] were quantitated in different dietary and hormonal states of the rat. Polysomal or total cellular poly(A)-containing RNA was translated in the rabbit reticulocyte lysate system, which had been treated to reduce endogenous mRNA activity. The relative level of incorporation of radiolabeled amino acid into malic enzyme was determined by immunoprecipitation with antibody to malic enzyme and formaldehyde-fixed Staphylococcus aureus (Cowens I strain) as an immunoadsorbent. The immunoprecipitated product comigrated with purified malic enzyme on sodium dodecyl sulfate--polyacrylamide gel electrophoresis. No malic enzyme was detected when nonspecific antisera or an excess of unlabeled malic enzyme was added during immunoprecipitation. The level of malic enzyme mRNA was found to markedly increase relative to euthyroid, chow-fed rats when the animal was either fed a high carbohydrate, fat-free diet or made hyperthyroid. Animals receiving both treatments had a further increase in mRNA activity to a level which was approximately 0.2% of the total incorporation of [3H]leucine. Levels of malic enzyme activity and the relative rate of synthesis were found to increase roughly in proportion to mRNA levels in these three states. Thus, the induction of malic enzyme by thyroid hormone or high carbohydrate, fat-free diet is due largely to an increase in the mRNA coding for this enzyme.

Animals↗
PubMed1971

Ribosomal ribonucleic acid synthesis in Bacillus subtilis.

The mode of biosynthesis of the 16S and 23S ribosomal ribonucleic acids (rRNA) was studied in Bacillus subtilis 168thy(-). Three criteria were used to define the characteristics of the rRNA species: (i) the time required at 37 degrees C to synthesize 16S and 23S rRNA chains de novo in growing cultures; (ii) the degree of reactivity of the 3'-terminal groups of the rRNA molecules with periodate and [carbonyl-(14)C]isonicotinic acid hydrazide; and (iii) the reactivity of the 5'-terminal regions of the rRNA molecules with the bacterial exonuclease purified by Riley (1969). The 16S and 23S chains of B. subtilis were synthesized at rates of 22+/-2 and 21+/-2 nucleotides added/s. The periodate-[(14)C]isonicotinic acid hydrazide and the exonuclease techniques for estimating apparent chain lengths of RNA indicated that the chain length of the 23S rRNA was 1.8 times that of the 16S fraction. The apparent chain lengths of each rRNA species were: 16S rRNA, 1650+/-50 nucleotide residues; 23S rRNA, 3050+/-90 nucleotide residues. It appears that, the 16S and 23S rRNA molecules in B. subtilis are synthesized in the expected manner, by simple polymerization of the final products on independent cistrons.

Bacillus subtilis↗
PubMed1982

The transcription of various types of ribonucleic acid by hepatocytes isolated from rats of various ages.

The synthesis of various types of ribonucleic acid (RNA) isolated from 6- to 3-month-old female Fischer F344 rats was compared. The rate of RNA synthesis by freshly prepared hepatocytes was determined by dividing the amount of [3H]orotic acid incorporated into RNA as uridine-5'-monophosphate by the specific activity of the uridine-5'-triphosphate pool. The rate of total RNA synthesis by hepatocytes from 19-month-old rats was 40% less than the rate for hepatocytes from 12-month-old rats. No significant difference in the rate of total RNA synthesis was observed between 19 and 30 months of age. The percentage of [3H]orotic acid incorporated into poly(A) + RNA by 30-month-old rats was approximately 50% less than that observed for hepatocytes isolated from 6-month-old rats. The percentage of [3H]orotic acid incorporated into poly(A)-RNA as ribosomal RNA (38S, 18S, and 5S RNAs) or transfer RNA was similar for 12- and 30-month-old rats. The rate of poly(A) + RNA synthesis by hepatocytes isolated from 30-month-old rats was 65% less than that observed for hepatocytes from 6-month-old rats. In contrast to total RNA synthesis, the rate of poly(A) + RNA synthesis for the 30-month-old rats was significantly less than the rate for 19-month-old rats.

Age Factors↗
PubMed1969

Mutants of Escherichia coli with an altered tyrosyl-transfer ribonucleic acid synthetase.

We have isolated several mutants defective in the gene for tyrosyl-transfer ribonucleic acid (tRNA) synthetase (tyrS). One of these mutants is described in detail. It was isolated as a tyrosine auxotroph with defects both in the tyrosyl-tRNA synthetase and in the tyrosine biosynthetic enzyme, prephenate dehydrogenase. It also had derepressed levels of the tyrosine-specific 3-deoxy-d-arabinoheptulosonic acid-7-phosphate (DAHP) synthetase. The latter finding suggested that a wild-type tyrS gene was required for repression of the tyrosine biosynthetic enzymes. The following results demonstrated that this hypothesis was not correct. (i) When the defective tyrS gene was transferred to another strain, the tyrosine-specific DAHP synthetase in that strain was not derepressed, and (ii) two other mutants with defective tyrosyl-tRNA synthetases had repressed levels of the tyrosine biosynthetic enzymes. The tyrS gene was located near minute 32 on the Escherichia coli chromosome by interrupted mating experiments.

Amino Acids↗
PubMed1971

Small ribosomal ribonucleic acid species of Saccharomyces cerevisiae.

Yeast ribosomes contain two small molecular-weight species of ribonucleic acid (RNA), in addition to transiently associated transfer RNA. The 5S RNA species is part of the large ribosomal subunit and appears to be exactly the same size as 5S RNA from other organisms. There is another RNA molecule, approximately 5.8S or 150 nucleotides in size, which is noncovalently attached to the 25S ribosomal RNA and can be freed by gentle heating or urea treatment. Neither 5 nor 5.8S RNA are methylated. The 5.8S RNA is probably derived from a part of the 35S precursor RNA, whereas the 5S RNA is made de novo. These results substantiate the notion that ribosome biosynthesis in yeast is analogous to that of the higher eukaryotes.

Acrylates↗
PubMed1971

Gene dosage for 5S ribosomal ribonucleic acid in Escherichia coli ad Bacillus megaterium.

The number of gene copies for 5S ribosomal ribonucleic acid (rRNA), relative to that for 16 and 23S rRNA, has been determined by deoxyribonucleic acid (DNA)-RNA hybridization for Escherichia coli and Bacillus megaterium. In both cases, the number of 5S rRNA genes equals the number of 16 or 23S rRNA genes. Rapid procedures for preparing extremely highly purified DNA suitable for DNA-RNA hybridization experiments and chemically pure 5S rRNA are described.

Acrylates↗
PubMed1971

Regulation of synthesis of the aminoacyl-transfer ribonucleic acid synthetases for the branched-chain amino acids of Escherichia coli.

The regulation of synthesis of valyl-, leucyl-, and isoleucyl-transfer ribonucleic acid (tRNA) synthetases was examined in strains of Escherichia coli and Salmonella typhimurium. When valine and isoleucine were limiting growth, the rate of formation of valyl-tRNA synthetase was derepressed about sixfold; addition of these amino acids caused repression of synthesis of this enzyme. The rate of synthesis of the isoleucyl- and leucyl-tRNA synthetases was derepressed only during growth restriction by the cognate amino acid. Restoration of the respective amino acid to these derepressed cultures caused repression of synthesis of the aminoacyl-tRNA synthetase, despite the resumption of the wild-type growth rate.

Amino Acyl-tRNA Synthetases↗
PubMed1972

Different arginine transfer ribonucleic acid species prevalent in shaken and unshaken cultures of Neurospora.

When the arginyl-transfer ribonucleic acid (tRNA) species isolated from unshaken and from shaken cultures of Neurospora were compared by co-chromatography, a marked change in the relative abundance of the two main tRNA(arg) species was found. The two arginine tRNA species had different codon responses in ribosome binding assays. The tRNA(arg) eluting first (prevalent in shaken cultures) bound strongly to polyadenylic-guanylic acid [poly(A,G)] and to a lesser extent to polycytidylic-guanylic-adenylic acid [poly(C,G,A)]. The second tRNA(arg) species (prevalent in unshaken cultures) bound to poly(C,G,A) but not to poly(A, G). The possible significance of these observations is briefly discussed. Several modifications that improve the yield of tRNA from Neurospora were introduced in a standard isolation procedure.

Amino Acids↗
PubMed1973

Regulation of methionyl-transfer ribonucleic acid synthetase formation in Escherichia coli and Salmonella typhimurium.

The control of methionyl-transfer ribonucleic acid (tRNA) synthetase (l-methionine: soluble RNA ligase [adenosine monophosphate]) was studied in methionyl-tRNA synthetase mutants of Escherichia coli and Salmonella typhimurium. The results of activity determinations with crude extracts indicate that this enzyme of the E. coli mutant strain possessed a reduced affinity for methionine-tRNA, whereas this enzyme of the S. typhimurium mutant exhibited a decreased affinity for l-methionine. The differential rate of methionyl-tRNA synthetase formation in these two mutants was several-fold greater than that of the respective parental strains. On the other hand, the level of in vivo aminoacylation of methionine-tRNA was only about one-third that of the parent strains. These results suggest that aminoacylation of methionine-tRNA is a necessary step in repression control of methionyl-tRNA synthetase of both E. coli and S. typhimurium strains.

Amino Acyl-tRNA Synthetases↗
PubMed1974

Histidyl-transfer ribonucleic acid synthetase in positive control of the histidine operon in Salmonella typhimurium.

Histidyl-transfer ribonucleic acid (tRNA) synthetase (HRS), coded by the hisS gene, appears to play two roles in regulation of the histidine operon of Salmonella typhimurium: (i) in synthesis of a critical effector molecule, histidyl-tRNA, and (ii) a more direct effect elicited by the presence of the enzyme protein itself. The specific activity of HRS was elevated either by mutations in the strB locus or in hisS(+) merodiploids of Escherichia coli/S. typhimurium and S. abony/S. typhimurium. In each case, an increase in HRS was accompanied by an increase in histidine operon expression, indicating that HRS may be involved in positive control of the histidine operon. It is unlikely that HRS leads to increased histidine operon expression merely by acting as a "sponge" for charged tRNA. Rather, HRS appears to influence operon expression by interaction with some effector molecule other than charged tRNA or by a direct interaction with the histidine operator-promoter region. The functional level of histidine operon expression has no effect on HRS specific activity.

Alcohol Oxidoreductases↗
PubMed1974

Derepression of synthesis of the aminoacyl-transfer ribonucleic acid synthetases for the branched-chain amino acids of Escherichia coli.

The kinetics of derepression of valyl-, isoleucyl-, and leucyl-transfer ribonucleic acid (tRNA) synthetase formation was examined during valine-, isoleucine-, and leucine-limited growth. When valine was limiting growth, valyl-tRNA synthetase formation was maximally derepressed within 5 min, whereas the rates of synthesis of isoleucyl-, and leucyl-tRNA synthetases were unchanged. Isoleucine-restricted growth caused a maximal derepression of isoleucyl-tRNA synthetase formation in 5 min and derepression of valyl-tRNA synthetase formation in 15 min with no effect on leucyl-tRNA synthetase formation. When leucine was limiting growth, leucyl-tRNA synthetase formation was immediately derepressed, whereas valyl- and isoleucyl-tRNA synthetase formation was unaffected by manipulation of the leucine supply to the cells. These results support our previous findings that valyl-tRNA synthetase formation is subject to multivalent repression control by both isoleucine and valine. In contrast, repression control of iso-leucyl- and leucyl-tRNA synthetase formation is specifically mediated by the supply of the cognate amino acid.

Amino Acyl-tRNA Synthetases↗
PubMed1976

Evidence for the involvement of ribonucleic acid in the production of F pili.

The effects of rifampin and streptolydigin, inhibitors of ribonucleic acid (RNA) synthesis, on the production of F pili by Escherichia coli were studied by electron microscopy. The inhibition of RNA synthesis reduces the number of new pili produced by depiliated cells, but does not affect their length or the number of pili present at the time of inhibition or the retraction of pili. We suggest that the rifampin-sensitive step may be linked to the establishement of a site for pili production. Evidence is provided that chloramphenicol inhibits retraction. We suggest that retraction requires some protein whose pool size is limited.

Aminoglycosides↗
PubMed1968

Pyrogenic principle of the ribonucleic acid from the yeast Candida utilis.

Experiments were performed to characterize the pyrogenic principle of ribonucleic acid (RNA) from the yeast Candida utilis. It was shown that ribonuclease hydrolysis of the RNA does not lead to inactivation of the pyrogenicity. Pyrogenicity was, however, destroyed by treatment with sodium deoxycholate. On column chromatography with Biogel under sterile and pyrogen-free conditions, the pyrogenic principle of yeast RNA was eluted together with the RNA. After treatment of the RNA with ribonuclease, it was possible to separate the pyrogenic activity from the RNA (hydrolysis products) to a great extent. Column chromatography of Escherichia coli endotoxin showed that the endotoxin was eluted in the same fractions as the pyrogenic activity of yeast RNA. On the basis of the behavior of the pyrogen, it may very well be that the fever reaction is produced not by the nucleic acid but by pyrogenic contaminants of the RNA preparation.

Animals↗
PubMed1969

Chloramphenicol and the stimulation of ribonucleic acid synthesis in Escherichia coli.

Data have been obtained which imply that chloramphenicol stimulation of ribonucleic acid (RNA) synthesis is a result of the accumulation of aminoacyl transfer RNA (tRNA) molecules. The data also support the hypothesis that chloramphenicol exerts an additional effect upon the stimulation of RNA synthesis. This effect may be at the level of the ribosome or the aminoacyl tRNA, or of both. It is this effect combined with the presence of aminoacyl tRNA that results in stimulation by chloramphenicol of RNA synthesis.

Arginine↗
PubMed1969

Ribonucleic acid synthesis during the differentiation of sporangia in the water mold Achlya.

The role of ribonucleic acid (RNA) synthesis in the development of sporangia in the saprolegniaceous mold Achlya was studied. Methods were developed for growing and treating large populations of mycelia so that the hyphal tips would differentiate into sporangia with considerable synchrony. Under the starvation conditions imposed for the differentiation of sporangia, net RNA, deoxyribonucleic acid (DNA), and protein synthesis ceased. However, incorporation of radioactive precursors into RNA continued at a high rate throughout the period of differentiation, showing that the enzymatic mechanism for RNA synthesis was still in an active state. Actinomycin D inhibited the differentiation of sporangia and the incorporation of labeled precursors into RNA. The level of actinomycin used did not inhibit the normal outgrowth and branching of the mycelia that occurred during differentiation. Thus, DNA-dependent RNA synthesis was required for the differentiation of sporangia. Sucrose gradient analysis of newly synthesized RNA showed that only the ribosomal and soluble fractions of RNA were labeled during vegetative growth. During the differentiation of sporangia, ribosomal and soluble RNA fractions were also labeled, and, in addition, a heterodisperse fraction of labeled RNA which was heavier than ribosomal RNA appeared; this fraction was not evident in the newly synthesized RNA from vegetative mycelia.

Cell Differentiation↗