More evidence for replication-transcription-coupling in Physarum polycephalum

1980 ◽  
Vol 41 (1) ◽  
pp. 105-113
Author(s):  
G. Pierron ◽  
H.W. Sauer
Keyword(s):  
Ionic Strength ◽  
Rna Polymerase ◽  
Physarum Polycephalum ◽  
Mitotic Cycle ◽  
Polymerase Activity ◽  
S Phase ◽  
Isolated Nuclei ◽  
Rna Polymerase Activity ◽  
High Level ◽  
Alpha Amanitin

Endogenous RNA polymerase activity of isolated nuclei from Physarum polycephalum was determined at high (400 mM KCl) and low (5–100 mM KCl) ionic strength. The activity of RNA polymerase B (alpha-amanitin-sensitive UMP incorporation) and of RNA polymerase A (plus C) (alpha-amanitin-resistant UMP incorporation) was compared in accurately sized nuclear samples derived from macroplasmodia at distinct points of the mitotic cycle. Minimum total RNA polymerase activity was detected in metaphase nuclei. A constant level of RNA polymerase B activity was detected at all other stages of the mitotic cycle, if nuclei were assayed at high ionic strength. However, a high level in S-phase, a low level in G2-phase and again a high level in early prophase were measured, if nuclei were assayed at low ionic strength. Inhibition of DNA synthesis by hydroxyurea in vivo had a selective and drastic effect on in vitro RNA polymerase activity of isolated nuclei derived from S-phase plasmodia, yielding up to 100% inhibition in early S-phase.

In vitro transcription of RNA in nuclei, nucleoli and chromatin from physarum polycephalum

1977 ◽  
Vol 26 (1) ◽  
pp. 267-279
Author(s):  
K.E. Davies ◽  
I.O. Walker
Keyword(s):  
Rna Polymerase ◽  
Physarum Polycephalum ◽  
Rna Synthesis ◽  
In Vitro Transcription ◽  
Polymerase Activity ◽  
Controlled Conditions ◽  
Rna Polymerase Activity ◽  
Alpha Amanitin

Methods for isolating nuclei, nucleoli and chromatin from Physarum polycephalum which retain high levels of endogenous RNA polymerase activity are described. Under carefully controlled conditions with respect to mono- and divalent cation concentrations RNA synthesis in nuclei displayed linear kinetics for at least 30 min and the RNA products had a similar size distribution to nuclear RNA synthesis observed in vivo. Chromatin showed 60% of the nuclear transcriptional activity but no conditions were found where faithful transcription of the template occurred. Isolated nucleoli were 5-fold more active than nuclei and the endogenous RNA polymerase activity was insensitive to alpha-amanitin. Under carefully controlled conditions, the nucleoli appeared to support the accurate transcription, re-initiation and processing of rRNA chains in vitro.

Chromosomale Strukturen von Pseudomonas testosteroni. II. Aktivität der endogenen RNA-Polymerase /Chromosomal Structure of Pseudomonas testosteroni. II. Activity of the Endogenous RNA-Polymerase

1976 ◽  
Vol 31 (9-10) ◽  
pp. 601-605 ◽  
Author(s):  
Günter Reimer ◽  
Dusan Drahovsky
Keyword(s):  
Ionic Strength ◽  
Rna Polymerase ◽  
Protein Complexes ◽  
Polymerase Activity ◽  
Chromosomal Dna ◽  
Chromosomal Structure ◽  
Dna Structures ◽  
Rna Polymerase Activity ◽  
Pseudomonas Testosteroni

Abstract After careful lysis the nucleoid of Pseudomonas testosteroni can be isolated in three different forms with compact and unfolded DNA structures 1. The released nucleoids contain endogenous DNA-dependent RNA-polymerase activity using the chromosomal DNA as a template. RNA syn­ thesis is proportional to duration of RNA-polymerase reaction and amount of DNA-protein-complexes. The sensitivity towards ionic strength and rifampicin indicates that a part of RNA-polymerase activity is tightly bound to the chromosomal DNA.

scholarly journals Inhibition of hepatic deoxyribonucleic acid-dependent ribonucleic acid polymerases by the exotoxin of Bacillus thuringiensis in comparison with the effects of α-amanitin and cordycepin

1972 ◽  
Vol 129 (1) ◽  
pp. 153-166 ◽  
Author(s):  
Edward A. Smuckler ◽  
Asen A. Hadjiolov
Keyword(s):  
Bacillus Thuringiensis ◽  
Rna Polymerase ◽  
Competitive Inhibition ◽  
Polymerase Activity ◽  
Rna Polymerases ◽  
Similar Action ◽  
Isolated Nuclei ◽  
Nuclear Rna ◽  
Rna Polymerase Activity

The action of Bacillus thuringiensis exotoxin, a structural analogue of ATP, on mouse liver DNA-dependent RNA polymerases was studied and its effects were compared with those of α-amanitin and cordycepin. (1) Administration of exotoxin in vivo caused a marked decrease in RNA polymerase activity of isolated nuclei at various concentrations of Mg2+, Mn2+and (NH4)2SO4. A similar action was recorded after addition of exotoxin to isolated nuclei from control or exotoxin-treated mice. (2) Chromatographic separation of nuclear RNA polymerases from mice treated in vivo with exotoxin showed a drastic decrease of the peak of nucleoplasmic RNA polymerase, whereas the peak of nucleolar RNA polymerase remained unaltered. The same effect was observed after administration of α-amanitin in vivo, but cordycepin did not alter the relative amounts of the two main RNA polymerase peaks. (3) Administration of exotoxin in vivo did not alter the template activity of isolated DNA or chromatin tested with different fractions of RNA polymerase from control or exotoxin-treated mice. (4) Addition of exotoxin to isolated liver RNA polymerases inhibited both enzyme fractions. However, the α-amanitin-sensitive RNA polymerase was also 50–100-fold more sensitive to exotoxin inhibition than was the α-amanitin-insensitive RNA polymerase. Kinetic analysis indicated the exotoxin produces a competitive inhibition with ATP on the nucleolar enzyme, but a mixed type of inhibition with nucleoplasmic enzyme. The results obtained indicate that the B. thuringiensis exotoxin inhibits liver RNA synthesis by affecting nuclear RNA polymerases, showing a preferential inhibition of the nucleoplasmic α-amanitin-sensitive RNA polymerase.

scholarly journals Modification of the template capacity of liver chromatin for form-B ribonucleic acid polymerase by food intake in rats under controlled feeding schedules

1975 ◽  
Vol 146 (3) ◽  
pp. 687-696 ◽  
Author(s):  
B Barbiroli ◽  
B Tadolini ◽  
M S Moruzzi ◽  
M G Monti
Keyword(s):  
Ionic Strength ◽  
Food Intake ◽  
Rna Polymerase ◽  
Dark Period ◽  
Polymerase Activity ◽  
Nuclear Chromatin ◽  
Feeding Period ◽  
Period 2 ◽  
Liver Chromatin ◽  
Rna Polymerase Activity

Nuclei from liver of rats accustomed to eating during the first 8h of a daily 12h dark period demonstrate an increased capacity to synthesize RNA 6H after the beginning of the feeding period. 2. This increase is accompanied by a higher yield of extractable form-B DNA-dependent RNA polymerase activity. 3. The endogenous RNA polymerase activity associated with nuclear chromatin is also stimulated by food intake. Both purified and chromatin-associated form-B enzyme activities exhibit different ionic strength requirements after food intake. 4. The sensitivity of exogenous (added) form-B-enzyme to changes in ionic strength changes after feeding when chromatin is used as template. 5. Chromatin extracted from the liver of fed rats is a better template for form-B-enzyme than chromatin extracted from starved rats.

Stimulation of Protein Synthesis and of RNA Polymerase Activity in the Liver of 3-Methylcholanthrene-Treated Rats

1973 ◽  
Vol 59 (2) ◽  
pp. 119-127
Author(s):  
Claudia Greco ◽  
Umberto Ferrini
Keyword(s):  
Protein Synthesis ◽  
Single Dose ◽  
Rna Polymerase ◽  
Rat Liver ◽  
Transport Mechanism ◽  
Polymerase Activity ◽  
Isolated Nuclei ◽  
Rna Polymerase Activity ◽  
Stimulation Of

Following a single dose of 3-methylcholanthrene in rat liver the RNA polymerase activity of Mg++ and Mn++/(NH4)2SO4 - dependent forms is stimulated in isolated nuclei and particularly in the chromatin of extranucleolar fraction. The early enhancement of N-2-fluorenylacetamide microsomal hydroxylating activity does not parallel the shift of the monomer-polysome equilibrium to more aggregated forms. It is suggested that the rate of synthesis and the transport mechanism of RNA messengers into the cytoplasm can be selectively regulated by 3-methylcholanthrene and its metabolites.

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