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At least 127 records · Page 7Linked to original sources
PubMed1976

Synthesis of polyadenylic acid-containing ribonucleic acid during the germination of Neurospora crassa conidia.

Ribonucleic acid (RNA) synthesized during the first 1 h of conidial germination (15 to 20, 25 to 30, and 55 to 60 min) has been characterized by sucrose-sodium dodecyl sulfate gradient centrifugation, binding to polyuridylic acid filters, and oligo(dT)-cellulose chromatography. At all labeling periods examined, polyadenylic acid-containing RNA is synthesized, processed, and incorporated into polysomes. Approximately 40% of the labeled RNA sedimenting between 5 and 17S binds to polyuridylic acid filters. RNA which binds to oligo(dT)-cellulose displays a heterogeneous distribution in sucrose-sodium dodecyl sulfate gradients with a major, broad peak at 10-16S. In addition, some polyadenylic acid-containing RNA sediments beyond the 25S marker. Approximately 3% of the [3H]adenosine in pulse-labeled polysomal RNA is in polyadenylic acid segments resistant to pancreatic and T1 ribonucleases.

Neurospora↗
PubMed1977

Incorporation characteristics of uracil, uridine, and orotic acid into ribonucleic acid of neoplastic cells.

Incorporation of uracil and uridine into ribonucleic acid (RNA) was compared among the ascitic and solid forms of Ehrlich mouse tumor, Morris hepatoma, Rhodamine sarcoma, gastric cancer and ulcer from human patients, and several normal rat tissues. Of these cells tested, the cells of Ehrlich ascites and solid tumors, human gastric cancer and ulcer, and certain tissues of a normal rat showed a considerably high activity. Furthermore, Ehrlich ascites tumor cells indicating a high incorporation activity was also high in activities of both phosphorylase and kinase for uridine, while Rhodamine sarcoma as a representative having a low incorporation activity was considerably low in these two enzymic activities. RNA synthesis from uridine phosphates by Rhodamine sarcoma was maintained to a fairly high extent contrary to its low activities of the phosphorylase and the kinase. Consequently, the low utilization of uracil and uridine by certain tumors was suggested to be due to the extremely low activities of both enzymes.

Adult↗
PubMed1979

Regulation of the biosynthesis of aminoacyl-transfer ribonucleic acid synthetases and of transfer ribonucleic acid in Escherichia coli. V. Mutants with increased levels of valyl-transfer ribonucleic acid synthetase.

Spontaneous revertants of a temperature-sensitive Escherichia coli strain harboring a thermolabile valyl-transfer ribonucleic acid (tRNA) synthetase were selected for growth at 40 degrees C. Of these, a large number still contain the thermolabile valyl-tRNA synthetase. Three of these revertants contained an increased level of the thermolabile enzyme. The genetic locus, valX, responsible for the enzyme overproduction, is adjacent to the structural gene, valS, of valyl-tRNA synthetase. Determination (by radioimmunoassay) of the turnover rates of valyl-tRNA synthetase showed that the increased level of valyl-tRNA synthetase is due to new enzyme synthesis rather than decreased rates of protein degradation.

Amino Acyl-tRNA Synthetases↗
PubMed1980

Auxin-induced deoxyribonucleic acid dependent ribonucleic acid polymerase activities in mature soybean hypocotyl.

When 3-day-old etiolated soybean seedlings are treated with the synthetic auxin, 2,4-dichlorophenoxyacetic acid, cells of the mature hypocotyl swell and proliferate abnormally. By 48 h after auxin application ribonucleic acid (RNA) polymerase I and II levels increase by about 10-20- and 6-fold, respectively, on a fresh weight tissue basis and about 3-6- and 2-fold, respectively, on a tissue deoxyribonucleic acid (DNA) basis. [35S]Methionine incorporation into RNA polymerase subunits suggests that this increase in levels of RNA polymerases results from de novo synthesis of the enzymes. No alteration in subunit structure or patterns of incorporation of [35S]methionine into RNA polymerase subunits is detected following auxin treatment. No differences in the phosphorylation patterns of RNA polymerase subunits are detected after hormone treatment. These results indicate that although the levels of RNA polymerases I and II may regulate, in part, the rates of transcription during physiological or developmental transitions, alteration or modification of RNA polymerase subunit structure does not appear to be involved in transcriptional regulation in the auxin-induced soybean hypocotyl.

Chemical Phenomena↗
PubMed1970

Control of deoxyribonucleic acid and ribonucleic acid synthesis in pyrimidine-limited Escherichia coli.

The effects of pyrimidine limitation on chromosome replication and the control of ribosomal and transfer ribonucleic acid syntheses were investigated. Chromosome replication was studied by autoradiography of (3)H-thymine pulse-labeled cells. Pyrimidine limitation did not affect the fraction of cells incorporating radioactive thymine during a short pulse, indicating that when growth is limited by the supply of pyrimidine, the time required for chromosome duplication increases in proportion to the time required for cell duplication. Control of ribosomal RNA and transfer RNA syntheses was examined by chromatographing cell extracts on methylated albumin kieselguhr columns. When growth was controlled by carbon-nitrogen limitation, the ratio of tRNA to total RNA remained roughly constant at growth rates above 0.5 doublings per hour. During pyrimidine limitation, however, the control of rRNA synthesis was apparently dissociated from the control of tRNA synthesis: the ratio of tRNA to total RNA increased as the growth rate decreased.

Autoradiography↗
PubMed1984

Optically detected magnetic resonance of Escherichia coli glutamic acid specific transfer ribonucleic acid and its anticodon-anticodon complex with yeast phenylalanine-specific transfer ribonucleic acid.

The low-temperature phosphorescence and the optically detected magnetic resonance (ODMR) spectra of Escherichia coli tRNA2Glu and its anticodon-anticodon complex with yeast tRNAPhe are reported. The ODMR signals are assigned to the modified base 5-[(methylamino)-methyl]-2-thiouracil (mnm5S2U) located at the "wobble" position of the anticodon. The zero-field splittings (zfs) are larger than those found for 1-methyl-2-thiouracil previously studied in a 1-methyluracil host system by ODMR. They are comparable, however, to those found for neat, polycrystalline 1-methyl-2-thiouracil and for the latter dissolved in ethyl acetate solvent. In the polycrystalline sample, five traps with widely varying zfs are assigned. A very large (15-25%) reduction in the D parameter of mnm5S2U is found to occur on formation of the anticodon-anticodon complex with yeast tRNAPhe. Additional ODMR signals found in the complex are assigned to the wybutine base of yeast tRNAPhe. The extreme sensitivity of the zfs parameters of S2U to environmental perturbations is ascribed to the variable involvement of the heavy atom containing chromophore, C = S, in the triplet-state wave function, which is largely localized on the C = C - C = O portion of the molecule.

Anticodon↗
PubMed1975

The Isolation and Characterization of Adenosine Monophosphate-rich Polynucleotides Synthesized by Soybean Hypocotyl Cells: Their Relation to Messenger Ribonucleic Acid.

Plant ribonucleic acids which have high adenosine monophosphate concentrations were studied. Purified deoxyribonucleic acid-like ribonucleic acid and tenaciously bound ribonucleic acid fractions both contained poly-adenosine monophosphate sequences (those from the latter being longer than those from the former); without these poly-adenosine monophosphate sequences their base compositions were the same. The average poly-adenosine monophosphate sequence from purified tenaciously bound ribonucleic acid was 160 residues long, as measured by gel electrophoresis. However, base hydrolysis and chromatography indicated one 3'-nucleoside (adenosine) per 71 nucleotides, giving a chain length of 72 residues. The dominant species in the cytoplasm, as measured by radioactive precursor incorporation, was tenaciously bound ribonucleic acid, whereas deoxyribonucleic acid-like ribonucleic acid was present in greater amounts in the nucleus. This work provides evidence that deoxyribonucleic acid-like ribonucleic acid and tenaciously bound ribonucleic acid represent forms of messenger ribonucleic acid in soybean, with deoxyribonucleic acid-like ribonucleic acid residing in the nucleus, perhaps as the messenger ribonucleic acid precursor, and tenaciously bound ribonucleic acid residing, as the active messenger ribonucleic acid, in the cytoplasm.

Journal Article↗