REGULATION OF THE INITIATION OF HEMOGLOBIN SYNTHESIS IN THE BLOOD ISLAND CELLS OF CHICK EMBRYOS: III. QUALITATIVE STUDIES OF THE EFFECTS OF 8-AZAGUANINE AND PREPARATIONS OF TRANSFER RNAs

1967 ◽  
Vol 45 (2) ◽  
pp. 255-265 ◽  
Author(s):  
S. D. Wainwright ◽  
Lillian K. Wainwright
Keyword(s):  
Messenger Rna ◽  
Rna Synthesis ◽  
Actinomycin D ◽  
Aminolevulinic Acid ◽  
Leucine Incorporation ◽  
Transfer Rnas ◽  
Blood Island ◽  
Stage Of Development ◽  
High Concentrations ◽  
Active Preparation

High concentrations of actinomycin D caused markedly greater inhibition of the incorporation of 3H-uridine than concentrations adequate to totally inhibit synthesis of all RNAs of high molecular weight during short periods of incubation.8-Azaguanine markedly inhibited the formation of hemoglobin and the incorporation of leucine into protein by blastodiscs explanted prior to the 6-somite stage of development. This inhibition took place at later stages of development than the inhibition by actinomycin resulting in total arrest of messenger RNA synthesis. Inhibition of hemoglobin formation by 8-azaguanine was reversed by δ-aminolevulinic acid, without reversal of the inhibition of leucine incorporation.Preparations of amino-acylated bacterial transfer RNAs and of yeast and mammalian transfer RNAs partly or largely reversed the inhibition of hemoglobin formation by high concentrations of actinomycin. Preparations of "stripped" bacterial transfer RNAs were inactive. An active preparation of "charged" bacterial transfer RNA did not reverse inhibition of leucine incorporation by actinomycin. This preparation reversed the inhibition of hemoglobin formation by 8-azaguanine and partly reversed the inhibition of leucine incorporation due to the analogue.

Einfluß von Actinomycin auf die Vermehrung von Myxoviren

1964 ◽  
Vol 19 (4) ◽  
pp. 316-323 ◽  
Author(s):  
Rudolf Rott ◽  
Christoph Scholtissek
Keyword(s):  
Rna Synthesis ◽  
Actinomycin D ◽  
Viral Rna ◽  
Tissue Cultures ◽  
Virus Rna ◽  
High Concentrations

Actinomycin D (5 γ/ml) inhibits the synthesis of fowl plague virus RNA, S-antigen, hemagglutinin, neuraminidase and infectious particles. Even high concentrations (40 γ/ml) of the antibiotic do not inhibit the synthesis of the corresponding components of NDV. Although purified suspensions of these viruses can be inactivated by actinomycin in the presence of light, this photoeffect does not play an important role in the inhibition of fowl plague virus synthesis. If in the case of fowl plague virus actinomycin is added to tissue cultures at a time after infection when viral RNA synthesis has already started (1½—2 hours p. i.) further synthesis of viral RNA is stopped, while the S-antigen titer continues to rise.

scholarly journals EFFECT OF ACTINOMYCIN D ON RNA SYNTHESIS AND ANTIBODY FORMATION IN THE ANAMNESTIC RESPONSE IN VITRO

1964 ◽  
Vol 119 (6) ◽  
pp. 881-893 ◽  
Author(s):  
J. Donald Smiley ◽  
John G. Heard ◽  
Morris Ziff
Keyword(s):  
Messenger Rna ◽  
Rna Synthesis ◽  
Actinomycin D ◽  
Lymphoid Cells ◽  
Limiting Factor ◽  
High Concentration ◽  
Antibody Synthesis ◽  
Anamnestic Response ◽  
Low Concentrations

Antibody synthesis in anamnestic lymphoid cells, measured by incorporation of leucine-C14 into specific antibody, was inhibited at moderate concentrations of actinomycin D. This was accompanied by marked inhibition of synthesis of RNA as measured by incorporation of H3-cytidine monophosphate. However, at low concentrations of actinomycin D, antibody synthesis was unaffected or even increased while RNA synthesis continued to be inhibited. The results obtained suggest that messenger RNA for antibody synthesis, either because it is relatively stable or present in excess, does not become a limiting factor until its synthesis is maximally inhibited. Puromycin, an inhibitor of amino acid coupling, abolished antibody synthesis in low concentration. 6-Mercaptopurine had no effect on the synthesis of antibody or RNA even at high concentration. The data obtained support the view that antibody synthesis follows pathways similar to those utilized for the formation of other types of proteins.

scholarly journals REFORMATION OF NUCLEOLUS-LIKE BODIES IN THE ABSENCE OF POSTMITOTIC RNA SYNTHESIS

1971 ◽  
Vol 48 (3) ◽  
pp. 443-454 ◽  
Author(s):  
A. R. Stevens ◽  
D. M. Prescott
Keyword(s):  
Rna Synthesis ◽  
Actinomycin D ◽  
Amoeba Proteus ◽  
Nucleolar Protein ◽  
Fibrillar Material ◽  
Azure B ◽  
Late Anaphase ◽  
High Concentrations

The dependence of nucleolar reformation on RNA synthesis that resumes in late anaphase or early telophase has been investigated in synchronously dividing Amoeba proteus. RNA synthesis was completely inhibited throughout all stages of mitosis and the early hours of interphase with high concentrations of actinomycin D. In such cells, nucleolus-like bodies that bind azure B and pyronin were apparent in the reformed nuclei. The bodies appear as dense, fibrous masses with loosely associated, finely fibrillar material. There are no characteristic granular regions in the reformed structures. It is suggested that the bodies probably represent mainly nucleolar protein and residual RNA which can bring about the reorganization of nucleoli in the absence of postmitotic RNA synthesis.

scholarly journals SYNTHESIS OF MESSENGER-LIKE RIBONUCLEIC ACID AND PROTEIN DURING MEIOSIS IN ISOLATED CELLS OF TRILLIUM ERECTUM

1963 ◽  
Vol 19 (1) ◽  
pp. 45-58 ◽  
Author(s):  
Yasuo Hotta ◽  
Herbert Stern
Keyword(s):  
Messenger Rna ◽  
Rna Synthesis ◽  
Actinomycin D ◽  
Morphological Changes ◽  
Reaction Rates ◽  
Meiotic Stage ◽  
Isolated Cells ◽  
Rna Analysis ◽  
Protein And Rna Synthesis

The synthesis of RNA and protein by cultures of isolated microsporocytes has been demonstrated. The variation in capacities of such cultures to perform syntheses is a function of meiotic stage and parallels the pattern of changes observed for microsporocytes in situ. A principal feature of this pattern is the induction of syntheses during pachytene and diplotene, stages at which the chromosomes are partly contracted. By use of Actinomycin D, chloramphenicol, pulse-labeling with P32-phosphate, and nucleotide analyses of RNA digests, part of the RNA synthesized has been shown to correspond to messenger RNA. Analysis of reaction rates and the overlappings of protein and RNA synthesis indicates that the spread of cytological events in Trillium is not purely a function of the low temperature at which it occurs but, presumably, arises from a complement of regulatory devices which govern the periodic onset of reactions within the cells. The main conclusion drawn from the whole of these studies is that the sequence of morphological changes associated with chromosome contraction and movement during meiosis is accompanied by a set of gene transcriptions. Although comparatively few genes are presumed to be active during meiosis, the action of such genes may be essential to a translation of some of the information embodying the meiotic sequence which has been stored in the genome in the course of evolution.

Suppression of floral induction by actinomycin D — An inhibitor of ‘messenger’ RNA synthesis

Life Sciences ◽  
1964 ◽  
Vol 3 (8) ◽  
pp. 911-915 ◽  
Author(s):  
Esra Galun ◽  
Jonathan Gressel ◽  
Alex Keynan
Keyword(s):  
Messenger Rna ◽  
Rna Synthesis ◽  
Actinomycin D ◽  
Floral Induction

scholarly journals Nucleolar necklaces in chick embryo fibroblast cells. I. Formation of necklaces by dichlororibobenzimidazole and other adenosine analogues that decrease RNA synthesis and degrade preribosomes.

1975 ◽  
Vol 65 (2) ◽  
pp. 398-417 ◽  
Author(s):  
D Granick
Keyword(s):  
Chick Embryo ◽  
Messenger Rna ◽  
Rna Synthesis ◽  
28S Rrna ◽  
Chick Embryo Fibroblast ◽  
Adenosine Analogues ◽  
Biochemical Alterations ◽  
High Concentrations ◽  
Precursor Rna ◽  
Extensive Degradation

A number of chemicals, mostly adenosine analogues, cause the nucleolus of the chick embryo fibroblast to lose material and unravel over a period of several hours into beaded strands termed nucleolar necklaces (NN). The results of analyses of the fibroblasts, treated with the NN-forming chemical dichlororibobenzimidazole (DRB), suggests that the following biochemical alterations occur: DRB almost completely prevents the increase in both messenger RNA (mRNA) and heterogeneous nuclear RNA. It interferes with ribosome synthesis by decreasing the rate of 45S ribosomal RNA (rRNA) accumulation by 50%, slowing the rate of 18S rRNA appearance by 50%, and causing an extensive degradation (80%) of the 32S and 28S rRNA-containing preribisomes. Most of this preribosome degration probably occurs at or before the 32S rRNA preribosome stage. The degradation of these preribosomes appears to be due to the formation of defective 45S rRNA preribosomes rather than to a direct DRB interference with preribosome processing enzyme action. DRB inhibits total cellular RNA synthesis in less than 15 min, suggesting a direct interference with RNA synthesis. DRB also inhibits the uptake of nucleosides into the cell. DRB in the concentrations used does not appear to directly interfere with the translation of mRNA (i.e., protein synthesis). Other NN-forming adenoside analogues and high concentrations of adenosine (2 mM) cause biochemical alterations similar to those produced by DRB. To explain the preribosome degradation, we propose the hypothesis that DRB inhibits the synthesis of mRNA; as a consequence, some of the preribosomal proteins that normally coat the 32S rRNA portion of the 45S precursor RNA become limiting, and this defective portion is then subject to degradation by nucleases.

Effect of Some Metabolic Inhibitors on Vinblastine-Induced Ribosomal-Granular Material Complexes

1971 ◽  
Vol 29 ◽  
pp. 548-549
Author(s):  
Awtar Krishan ◽  
Dora Hsu
Keyword(s):  
Granular Material ◽  
Rna Synthesis ◽  
Culture Medium ◽  
Actinomycin D ◽  
Metabolic Inhibitors ◽  
Protein And Rna Synthesis ◽  
Apparent Reduction ◽  
Plant Alkaloids ◽  
In Cells

Cells exposed to antitumor plant alkaloids, vinblastine and vincristine sulfate have large proteinacious crystals and complexes of ribosomes, helical polyribosomes and electron-dense granular material (ribosomal complexes) in their cytoplasm, Binding of H3-colchicine by the in vivo crystals shows that they contain microtubular proteins. Association of ribosomal complexes with the crystals suggests that these structures may be interrelated.In the present study cultured human leukemic lymphoblasts (CCRF-CEM), were incubated with protein and RNA-synthesis inhibitors, p. fluorophenylalanine, puromycin, cycloheximide or actinomycin-D before the addition of crystal-inducing doses of vinblastine to the culture medium. None of these compounds could completely prevent the formation of the ribosomal complexes or the crystals. However, in cells pre-incubated with puromycin, cycloheximide, or actinomycin-D, a reduction in the number and size of the ribosomal complexes was seen. Large helical polyribosomes were absent in the ribosomal complexes of cells treated with puromycin, while in cells exposed to cycloheximide, there was an apparent reduction in the number of ribosomes associated with the ribosomal complexes (Fig. 2).

CONTRIBUTION TO THE EXISTENCE OF REGULATORY MECHANISMS AT THE ADRENAL LEVEL

1972 ◽  
Vol 70 (4) ◽  
pp. 741-757
Author(s):  
Otto Linèt
Keyword(s):  
Orotic Acid ◽  
Adrenal Glands ◽  
Actinomycin D ◽  
Delay Period ◽  
Regulatory Mechanisms ◽  
Leucine Incorporation ◽  
Total Period ◽  
Free Media

ABSTRACT Rat adrenal glands atrophied by the administration of cortisol acetate in vivo were used as a model for the study of early metabolic processes occurring in vitro. Atrophied adrenals incubated in the presence of 14C-leucine incorporated subnormal quantities of this amino acid per mg of protein for the first 120 min. When the incubation lasted for a total period of 180 or 240 min a supranormal rise in the 14C-leucine incorporation was observed. Similar changes occurred with some delay with regard to corticosterone production as expressed per 100 mg of tissue. No differences in 14C-leucine incorporation were observed between the control and atrophied adrenals in vivo. Homogenates from atrophied glands incorporated 14C-leucine to a greater extent than the control homogenates. The in vitro incorporation of 14C-orotic acid into the RNA was also higher in atrophied adrenals. The in vitro use of actinomycin D, cycloheximide and amphenone indicated that corticosterone production depended on the incorporation of 14C-leucine. The addition of cortisol to the incubation media markedly decreased the enhancement of 14C-lysine incorporation into the protein of atrophied adrenals. These, as well as additional results suggest rebound phenomena: once atrophic adrenals are transferred to cortisol-free media, reparative processes begin after a delay period. Such phenomena seem to be mediated by regulatory mechanisms at the adrenal level.

EFFECT OF ACTINOMYCIN D ON TSH-INDUCED STIMULATION OF THYROIDAL PROTEIN SYNTHESIS IN THE RAT

1974 ◽  
Vol 77 (1) ◽  
pp. 64-70 ◽  
Author(s):  
Gustav Wägar
Keyword(s):  
Protein Synthesis ◽  
Actinomycin D ◽  
The Other ◽  
Leucine Incorporation ◽  
Short Term ◽  
Other Hand ◽  
Thyroid Glands ◽  
Translational Level ◽  
Stimulation Of

ABSTRACT Whether the short-term regulation of thyroidal protein synthesis by TSH occurs at the transcriptional or the translational level was tested by measuring the effect of actinomycin D (act D) on the TSH-induced stimulation of L-14C-leucine incorporation into the thyroidal proteins of rats. TSH was injected 6 h before the rats were killed. The thyroid glands were then removed and incubated in vitro in the presence of L-14C-leucine for 2 h. The pronounced stimulation of leucine incorporation in the TSH-treated animals was depressed as compared with controls but still significant even when the animals had been pre-treated with 100 μg act D 24 and 7 h before sacrifice. On the other hand, act D strongly decreased incorporation of 3H-uridine into RNA. Short-term regulation of thyroidal protein synthesis by TSH appears to be partly but not wholly dependent on neosynthesis of RNA. Hence regulation may partly occur at the translation level of protein synthesis.

scholarly journals Biosynthesis of growth hormone in the rat anterior pituitary gland. Stimulation of biosynthesis in vitro by insulin

1973 ◽  
Vol 134 (4) ◽  
pp. 1103-1113 ◽  
Author(s):  
A. Betteridge ◽  
M. Wallis
Keyword(s):  
Growth Hormone ◽  
Anterior Pituitary ◽  
Rna Synthesis ◽  
Glucose Utilization ◽  
Actinomycin D ◽  
Hormone Synthesis ◽  
Pituitary Glands ◽  
Hormone Biosynthesis ◽  
Stimulation Of

The effect of insulin on the incorporation of radioactive leucine into growth hormone was investigated by using rat anterior pituitary glands incubated in vitro. A 50% stimulation over control values was observed at insulin concentrations above 2μm (280munits/ml). The effect was specific for growth hormone biosynthesis, over the range 1–5μm-insulin (140–700munits/ml). Lower more physiological concentrations had no significant effect in this system. Above 10μm (1.4 units/ml) total protein synthesis was also increased. The stimulation of growth hormone synthesis could be partially blocked by the addition of actinomycin D, suggesting that RNA synthesis was involved. Insulin was found to stimulate the rate of glucose utilization in a similar way to growth hormone synthesis. 2-Deoxyglucose and phloridzin, which both prevented insulin from stimulating glucose utilization, also prevented the effect of insulin on growth hormone synthesis. If glucose was replaced by fructose in the medium, the effect of insulin on growth hormone synthesis was decreased. We conclude that the rate of utilization of glucose may be an important step in mediating the effect of insulin on growth hormone synthesis.

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