scholarly journals Lifetime of messenger ribonucleic acid for penicillinase synthesis in several strains of bacilli

1968 ◽  
Vol 108 (4) ◽  
pp. 675-677 ◽  
Author(s):  
M D Yudkin
Keyword(s):  
Bacillus Cereus ◽  
Bacillus Licheniformis ◽  
Ribonucleic Acid ◽  
Messenger Rna ◽  
Enzyme Synthesis ◽  
Messenger Ribonucleic Acid ◽  
Back Mutation ◽  
Constitutive Mutant

1. Previous studies of penicillinase synthesis in Bacillus licheniformis showed that enzyme synthesis after the addition of actinomycin continues for far longer in the constitutive mutant 749/C than in the parental inducible strain (Yudkin, 1966). This result was interpreted as indicating a difference in the lifetime of specific messenger RNA in the two strains. Other bacilli have now been examined in an attempt to see whether this difference is general. 2. There was no difference in the lifetime of messenger RNA for penicillinase synthesis between an inducible and a constitutive strain of Bacillus cereus. 3. Three freshly isolated constitutive mutants of B. licheniformis also had short-lived messenger RNA, like their inducible parent. 4. A reinvestigation of mutant 749/C confirmed the original finding that, on treatment with actinomycin, it continued to synthesize penicillinase far longer than did its parent. 5. An inducible revertant of mutant 749/C was indistinguishable from the original inducible strain, and appeared to have lost both constitutivity and long-lived messenger RNA in the back mutation.

scholarly journals Synthesis and turnover of mitochondrial ribonucleic acid in HeLa cells: the mature ribosomal and messenger ribonucleic acid species are metabolically unstable.

1981 ◽  
Vol 1 (6) ◽  
pp. 497-511 ◽  
Author(s):  
R Gelfand ◽  
G Attardi
Keyword(s):  
Ribosomal Rna ◽  
Hela Cells ◽  
Ribonucleic Acid ◽  
Half Life ◽  
Messenger Rna ◽  
Specific Activity ◽  
Mitochondrial Rna ◽  
Messenger Rnas ◽  
Precursor Pool ◽  
Messenger Ribonucleic Acid

The synthesis rates and half-lives of the individual mitochondrial ribosomal ribonucleic acid (RNA) and polyadenylic acid-containing RNA species in HeLa cells have been determined by analyzing their kinetics of labeling with [5-3H]-uridine and the changes in specific activity of the mitochondrial nucleotide precursor pools. In one experiment, a novel method for determining the nucleotide precursor pool specific activities, using nascent RNA chains, has been utilized. All mitochondrial RNA species analyzed were found to be metabolically unstable, with half-lives of 2.5 to 3.5 h for the two ribosomal RNA components and between 25 and 90 min for the various putative messenger RNAs. A cordycepin "chase" experiment yielded half-life values for the messenger RNA species which were, in general, larger by a factor of 1.5 to 2.5 than those estimated in the labeling kinetics experiments. On the basis of previous observations, a model is proposed whereby the rate of mitochondrial RNA decay is under feedback control by some mechanism linked to RNA synthesis or processing. A short half-life was determined for five large polyadenylated RNAs, which are probably precursors of mature species. A rate of synthesis of one to two molecules per minute per cell was estimated for the various H-strand-coded messenger RNA species, and a rate of synthesis 50 to 100 times higher was estimated for the ribosomal RNA species. These data indicate that the major portion of the H-strand in each mitochondrial deoxyribonucleic acid molecule is transcribed very infrequently, possibly as rarely as once or twice per cell generation. Furthermore, these results are consistent with a previously proposed model of H-strand transcription in the form of a single polycistronic molecule.

Nutrient utilization in actinomycetes. Induction of α-glucosidases in Streptomyces venezuelae

1981 ◽  
Vol 27 (7) ◽  
pp. 639-645 ◽  
Author(s):  
S. Chatterjee ◽  
L. C. Vining
Keyword(s):  
Amino Acids ◽  
Organic Acids ◽  
Ribonucleic Acid ◽  
De Novo ◽  
Nutrient Utilization ◽  
Enzyme Synthesis ◽  
De Novo Synthesis ◽  
Streptomyces Venezuelae ◽  
Messenger Ribonucleic Acid ◽  
Glucosidase Activity

Streptomyces venezuelae contains intracellular α-glucosidases that are induced during growth on maltose, isomaltose, maltotriose, dextrin, starch, and other α-glucosides. Induction was prevented by rifampicin at 10 μg∙mL−1 and inhibited by chloramphenicol or streptomycin, indicating that de novo synthesis of messenger ribonucleic acid and protein was required. Glucose and other readily utilizable sugars did not repress induction of α-glucosidase activity whereas certain organic acids and amino acids effectively reduced enzyme synthesis. Extracts of mycelium grown in the presence of maltose as an inducer hydrolysed maltose and isomaltose rapidly. Sucrose and other α-glucosides were less suitable substrates whereas trehalose and starch were not hydrolysed. No activity was observed with β-glucosides, α-galactosides, or methyl α-mannoside.

scholarly journals The control of ribonucleic acid synthesis in bacteria. Steady-state content of messenger ribonucleic acid in Escherichia coli M.R.E. 600

1970 ◽  
Vol 120 (2) ◽  
pp. 279-288 ◽  
Author(s):  
W. J. H. Gray ◽  
J. E. M. Midgley
Keyword(s):  
Escherichia Coli ◽  
Ribosomal Rna ◽  
Ribonucleic Acid ◽  
Messenger Rna ◽  
Acid Synthesis ◽  
Growth Conditions ◽  
Transfer Rna ◽  
Average Lifetime ◽  
Messenger Ribonucleic Acid ◽  
Wide Range

1. The technique of DNA–RNA hybridization was used to follow changes in the amount and average lifetime of unstable messenger RNA in Escherichia coli M.R.E. 600 over a wide range of different growth conditions. The method of analysis was based on the kinetics of incorporation of exogenous labelled nucleic acid bases into the RNA of steadily growing cultures, as described by Bolton & McCarthy (1962). 2. The ratio of the average lifetime of messenger RNA to the mean generation time of E. coli cultures was constant over the temperature range 25–45°C in a given medium, but the constant varied with the nature of the growth medium. For cultures growing in sodium lactate–salts or glucose–salts media the ratio was 0.046±0.005 and in enriched broth it was 0.087±0.009. Measurements of the amounts of transfer RNA, ribosomal RNA and messenger RNA were also made. The results confirmed earlier reports that the ratio of the amount of messenger RNA to the amount of ribosomes in the cells is virtually constant. On the other hand, the ratio of the amount of transfer RNA to the amount of ribosomal RNA decreased with increasing growth rate at a given temperature. 3. In cultures at temperatures higher than necessary for optimum rates of growth the average lifetime of messenger RNA lengthened in harmony with the increased time required for cell division. It seems that suboptimum growth rates at higher temperatures cannot be explained simply as a combination of increased rates of synthesis and breakdown of messenger RNA with a grossly decreased efficiency of translation. The absolute rate of messenger RNA synthesis was lowered, and its amount in the cells was typical of all other cultures grown at lower temperatures in the same medium. 4. The rate of entry of exogenous labelled uracil into unstable messenger RNA and stable ribosomal RNA was constant in all media at all temperatures in the approximate ratio 1:2. In media supporting a lower rate of growth, e.g. lactate–salts or glucose–salts media, the messenger RNA fraction constituted 2.2±0.3% of the total cellular RNA. In enriched broth 3.6±0.3% of the total RNA was messenger.

Aflatoxin B1 effect on enzyme biosynthesis in Bacillus cereus and Bacillus licheniformis

1970 ◽  
Vol 16 (11) ◽  
pp. 1059-1065 ◽  
Author(s):  
Eivind B. Lillehoj ◽  
Alex Ciegler
Keyword(s):  
Bacillus Cereus ◽  
Bacillus Licheniformis ◽  
Enzyme Production ◽  
Actinomycin D ◽  
Inhibitory Effect ◽  
Enzyme Synthesis ◽  
Low Levels ◽  
Aflatoxin B ◽  
Mediated Reduction ◽  
Enzyme Biosynthesis

The effect of aflatoxin B1 on induced and constitutive enzyme synthesis was examined in strains of Bacillus cereus (NRRL B-569, NRRL B-3537) and Bacillus licheniformis (NRRL B-3560, NRRL B-3540). Although B1 partially blocked penicillinase elaboration in B. cereus after incubation with the toxin, the level of B1-mediated reduction in total protein synthesis was similar to the diminished production of penicillinase. Comparative studies on the effects of aflatoxin B1 and actinomycin D on enzyme synthesis and growth in B. licheniformis demonstrated that actinomycin D exerted a differential inhibitory effect on induction of penicillinase and α-glucosidase, whereas levels of reduction of enzyme production initiated by aflatoxin resembled toxin-mediated growth inhibition. Thus, the mode of action of aflatoxin B1 is not exclusively analogous to that of actinomycin D in B. licheniformis. However, induced-penicillinase production in B. licheniformis was enhanced by relatively low levels of both actinomycin D and aflatoxin B1.

scholarly journals Synthesis and turnover of mitochondrial ribonucleic acid in HeLa cells: the mature ribosomal and messenger ribonucleic acid species are metabolically unstable

1981 ◽  
Vol 1 (6) ◽  
pp. 497-511
Author(s):  
R Gelfand ◽  
G Attardi
Keyword(s):  
Ribosomal Rna ◽  
Hela Cells ◽  
Ribonucleic Acid ◽  
Half Life ◽  
Messenger Rna ◽  
Specific Activity ◽  
Mitochondrial Rna ◽  
Messenger Rnas ◽  
Precursor Pool ◽  
Messenger Ribonucleic Acid

The synthesis rates and half-lives of the individual mitochondrial ribosomal ribonucleic acid (RNA) and polyadenylic acid-containing RNA species in HeLa cells have been determined by analyzing their kinetics of labeling with [5-3H]-uridine and the changes in specific activity of the mitochondrial nucleotide precursor pools. In one experiment, a novel method for determining the nucleotide precursor pool specific activities, using nascent RNA chains, has been utilized. All mitochondrial RNA species analyzed were found to be metabolically unstable, with half-lives of 2.5 to 3.5 h for the two ribosomal RNA components and between 25 and 90 min for the various putative messenger RNAs. A cordycepin "chase" experiment yielded half-life values for the messenger RNA species which were, in general, larger by a factor of 1.5 to 2.5 than those estimated in the labeling kinetics experiments. On the basis of previous observations, a model is proposed whereby the rate of mitochondrial RNA decay is under feedback control by some mechanism linked to RNA synthesis or processing. A short half-life was determined for five large polyadenylated RNAs, which are probably precursors of mature species. A rate of synthesis of one to two molecules per minute per cell was estimated for the various H-strand-coded messenger RNA species, and a rate of synthesis 50 to 100 times higher was estimated for the ribosomal RNA species. These data indicate that the major portion of the H-strand in each mitochondrial deoxyribonucleic acid molecule is transcribed very infrequently, possibly as rarely as once or twice per cell generation. Furthermore, these results are consistent with a previously proposed model of H-strand transcription in the form of a single polycistronic molecule.

scholarly journals A method for measuring the content of a specific messenger ribonucleic acid in Escherichia coli

1971 ◽  
Vol 121 (1) ◽  
pp. 105-108 ◽  
Author(s):  
J. O. Bishop ◽  
M. I. Irving
Keyword(s):  
Escherichia Coli ◽  
Ribosomal Rna ◽  
Ribonucleic Acid ◽  
Messenger Rna ◽  
Model System ◽  
Total Rna ◽  
Messenger Ribonucleic Acid

A method is described for measuring the porportion of a specific messenger RNA in the total RNA extracted from pulse-labelled cells. A model system consisting of total ribosomal RNA and Escherichia coli DNA is used to validate the method and to define the conditions under which it can be used.

scholarly journals Differential Expression of Rat Insulin I and II Messenger Ribonucleic Acid after Prolonged Exposure of Islet β-Cells to Elevated Glucose Levels*

Endocrinology ◽  
1998 ◽  
Vol 139 (2) ◽  
pp. 491-495 ◽  
Author(s):  
Zhidong Ling ◽  
Harry Heimberg ◽  
André Foriers ◽  
Frans Schuit ◽  
Daniel Pipeleers
Keyword(s):  
Ribonucleic Acid ◽  
Messenger Rna ◽  
Prolonged Exposure ◽  
Pancreatic Tissue ◽  
Β Cells ◽  
Messenger Ribonucleic Acid ◽  
Glucose Levels ◽  
Fold Reduction ◽  
Elevated Glucose ◽  
Cells Cultured

Abstract Prolonged exposure of rat islet β-cells to 10 mmol/liter glucose has been previously shown to activate more cells into a glucose-responsive state (>90%) than has exposure to 6 mmol/liter glucose (50%). The present study demonstrates that this recruitment of more activated cells results in 4- to 6-fold higher levels of proinsulin I and proinsulin II messenger RNA (mRNA). However, only the rate of proinsulin I synthesis is increased. Failure to increase the rate of proinsulin II synthesis in the glucose-activated cells results in cellular depletion of the insulin II isoform, which can be responsible for degranulation of β-cells cultured at 10 mmol/liter glucose. Higher glucose levels (20 mmol/liter) during culture did not correct this dissociation between the stimulated insulin I formation and the nonstimulated insulin II formation. On the contrary, the rise from 10 to 20 mmol/liter glucose resulted in a 2-fold reduction in the levels of proinsulin II mRNA, but not of proinsulin I mRNA; this process further increased the ratio of insulin I over insulin II to 5-fold higher values than those in freshly isolated β-cells. The present data suggest that an elevated insulin I over insulin II ratio in pancreatic tissue is a marker for a prolonged exposure to elevated glucose levels. The increased ratio in this condition results from a transcriptional and/or a posttranscriptional failure in elevating insulin II formation while insulin I production is stimulated in the glucose-activated β-cells.

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