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.

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.

The Effect of Actinomycin D in Vivo Upon Peripheral Nucleoli and Other Nuclear Organelles in Oocytes of Triturus Cristatus

1972 ◽  
Vol 10 (3) ◽  
pp. 833-855
Author(s):  
M. H. L. SNOW
Keyword(s):  
Phase Contrast ◽  
Rna Synthesis ◽  
Actinomycin D ◽  
Triturus Cristatus ◽  
Granular Component ◽  
Azure B ◽  
Final Maturation ◽  
Ribosomal Precursor ◽  
20 Nm

Exposure of the ovaries of Triturus cristatus to actinomycin D at a concentration of 100 µg/ml causes characteristic changes in the peripheral nucleoli and other nuclear organelles in oocytes of 0.6-1.1 mm diameter. Viewed with the light microscope untreated oocytes contain nucleoli that stain uniformly with a variety of dyes. They also appear homogeneous tmder phase-contrast optics. After 2 or 4 h of in vivo incubation with actinomycin D, oocyte sections stained with Haidenhain's haematoxylin or viewed under phase-contrast optics show nucleoli composed of 2 regions. The more heavily stained or contrasted zone is crescent-shaped and directed away from the nuclear membrane. Neither sections stained with azure B bromide nor gallocyanin chrome alum show this feature. Ribonuclease digestion does not eliminate or alter it. Autoradiography with [3H]uridine indicates that all recently synthesized RNA is lost from the nucleolus during actinornycin D treatment. The zonation is not therefore a reflexion of RNA distribution. During recovery from actinomycin D poisoning there is a reduction in the degree of zonation shown by nucleoli which re-establish a normal appearance some 48 h after treatment. Electron microscopy of peripheral nucleoli in oocytes sampled during this treatment indicates that the zonation is not associated with reorganization of ultrastructural components. During incubation with actinomycin D the coarse granules (20 nm diameter) are completely lost from the nucleolus. There is associated shrinkage of the nucleolus which after treatment is found to consist entirely of fibrils (5 nm thick) and small granules. The reappearance of the coarse granules during recovery is completed in about 48 h. It is thought that the loss of the granular component during treatment represents the movement of the 30-S precursor and the 18-s ribosomal unit from the nucleolus. Some 20-30 µm inside the nucleus of untreated oocytes is a region containing many spheroidal bodies, less than 1.0 µm diameter. They have been termed micronucleoli and consist of granules 2.5-5 nm in diameter and fibrils of similar thickness. Actinomycin D treatment causes these components to segregate and eventually (within 24 h of treatment) the granular component is extruded. This component reappears during the second day after treatment. It is postulated that these micronucleoli represent the sites at which the 30-S ribosomal precursor undergoes its final maturation. The segregation of components induced by actinomycin D is probably the morphological manifestation of an abnormal metamorphosis of this precursor. Treatment with actinomycin D also induces the immediate formation within the nucleus of crystalline bodies composed of lamellae 16 nm wide, 4 nm thick and with a centre-to-centre spacing of 8-10 nm. They are not present 24 h after treatment. They are thought to represent a protein fraction normally associated with periods of intense RNA synthesis.

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.

Microsurgical Studies on the Formation of the Golgi Apparatus and Nuclear Envelope in Amebae

1974 ◽  
Vol 32 ◽  
pp. 310-311
Author(s):  
C. J. Flickinger
Keyword(s):  
Protein Synthesis ◽  
Golgi Apparatus ◽  
Nuclear Envelope ◽  
Rna Synthesis ◽  
Actinomycin D ◽  
Amoeba Proteus ◽  
Cytoplasmic Protein ◽  
Golgi Bodies ◽  
Nuclear Rna Synthesis ◽  
Nuclear Rna

The means of formation of the Golgi apparatus is uncertain. In beginning these studies, it seemed that an important first step was to determine the degree of dependence of the Golgi apparatus on the nucleus. This was investigated in Amoeba proteus because these cells are readily enucleated microsurgically. Normal amebae contained multiple Golgi bodies, which declined in size and number in the absence of the nucleus, indicating that the Golgi apparatus in amebae depends upon the nucleus. The influence of the nucleus on the Golgi apparatus may be mediated through nuclear RNA synthesis and cytoplasmic protein synthesis, since the ultrastructural effects of enucleation were mimicked by treating amebae with actinomycin D to inhibit RNA synthesis and, in part, by treating cells with emetine, which inhibits protein synthesis in amebae.

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).

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.

scholarly journals Cytophotometric analyses of myocardial RNA in rats exposed to altitude hypoxia.

1978 ◽  
Vol 26 (6) ◽  
pp. 459-467 ◽  
Author(s):  
A J Stere ◽  
N W Brister ◽  
A Anthony
Keyword(s):  
Coefficient Of Variation ◽  
Rna Synthesis ◽  
Prolonged Exposure ◽  
Progressive Increase ◽  
High Variability ◽  
Vascular Responses ◽  
Hypoxia Exposure ◽  
Azure B ◽  
Exposure Interval ◽  
Rna Levels

Analytical cytophotometry of azure B-stained heart sections was employed to investigate the pattern of myocardial ribonucleic acid (RNA) alterations in rats exposed to acute (1-2 days) and prolonged periods (1-8 weeks) of hypoxia exposure (380 torr). Data support the existence of a slight transient drop in myocardial RNA on day one of exposure followed by a restoration to levels slightly elevated over controls during a 1- to 8-week exposure interval. Because of the high variability in RNA levels among myocytes (coefficient of variation, ca 40%), a shift in the proportion of low and high RNA containing segments of the myocyte population proved to be a more sensitive indicator of suppression or augmentation of RNA synthesis than the use of average RNA levels of the cell population analyzed. Microscopic analyses revealed the presence of compensatory vascular responses which could be effective in ameliorating the extent of tissue hypoxemia, i.e., capillary vasodilation on day 1 with a progressive increase in vascularization with prolonged exposure.

Hormone-induced differentiation of antheridial branches in Achlya ambisexualis: dependence on ribonucleic acid synthesis

1974 ◽  
Vol 20 (7) ◽  
pp. 977-980 ◽  
Author(s):  
David K. Horowitz ◽  
Peter J. Russell
Keyword(s):  
Sexual Differentiation ◽  
Ribonucleic Acid ◽  
Rna Synthesis ◽  
Actinomycin D ◽  
Steroid Hormone ◽  
Acid Synthesis ◽  
Aquatic Fungus ◽  
Induced Differentiation ◽  
Sexual Steroid ◽  
Achlya Ambisexualis

Sexual differentiation in male strains of the aquatic fungus Achlya ambisexualis Raper is induced by antheridiol, a sexual steroid hormone secreted by female strains. Antheridiol-induced initiation of the morphologically distinct antheridial branches in male Achlya is completely prevented when DNA-dependent RNA synthesis is inhibited by actinomycin D. In addition antheridial branch elongation is inhibited to a degree proportional to the concentration of actinomycin D added. Thus, evidence indicates that RNA synthesis is required for antheridiol-induced initiation of antheridial branching and that continued RNA synthesis is required for elongation of antheridial branches.

scholarly journals Effect of DNA-interacting drugs on phage T7 RNA polymerase.

1998 ◽  
Vol 45 (1) ◽  
pp. 127-132 ◽  
Author(s):  
M Piestrzeniewicz ◽  
K Studzian ◽  
D Wilmańska ◽  
G Płucienniczak ◽  
M Gniazdowski
Keyword(s):  
Rna Polymerase ◽  
Rna Synthesis ◽  
Actinomycin D ◽  
T7 Rna Polymerase ◽  
Distamycin A ◽  
E Coli ◽  
Phage T7 ◽  
Drug Dependent ◽  
Dna Complex ◽  
Kinetics Of

9-Aminoacridine carboxamide derivatives studied here form with DNA intercalative complexes which differ in the kinetics of dissociation. Inhibition of total RNA synthesis catalyzed by phage T7 and Escherichia coli DNA-dependent RNA polymerases correlates with the formation of slowly dissociating acridine-DNA complex of time constant of 0.4-2.3 s. Their effect on RNA synthesis is compared with other ligands which form with DNA stable complexes of different steric properties. T7 RNA polymerase is more sensitive to distamycin A and netropsin than the E. coli enzyme while less sensitive to actinomycin D. Actinomycin induces terminations in the transcript synthesized by T7 RNA polymerase. Despite low dissociation rates of DNA complexes with acridines and pyrrole antibiotics no drug dependent terminations are observed with these ligands.

Synthesis of acid-soluble spore proteins by Bacillus subtilis

1982 ◽  
Vol 152 (3) ◽  
pp. 1117-1125
Author(s):  
J M Leventhal ◽  
G H Chambliss
Keyword(s):  
Bacillus Subtilis ◽  
Maximum Rate ◽  
Rna Synthesis ◽  
Actinomycin D ◽  
Sodium Dodecyl ◽  
Molecular Weights ◽  
Spore Proteins ◽  
Major Acid

The major acid-soluble spore proteins (ASSPs) of Bacillus subtilis were detected by immunoprecipitation of radioactively labeled in vitro- and in vivo-synthesized proteins. ASSP synthesis in vivo began 2 h after the initiation of sporulation (t2) and reached its maximum rate at t7. This corresponded to the time of synthesis of mRNA that stimulated the maximum rate of ASSP synthesis in vitro. Under the set of conditions used in these experiments, protease synthesis began near t0, alkaline phosphatase synthesis began at about t2, and refractile spores were first observed between t7 and t8. In vivo- and in vitro-synthesized ASSPs comigrated in sodium dodecyl sulfate-polyacrylamide gels. Their molecular weights were 4,600 (alpha and beta) and 11,000 (gamma). The average half-life of the ASSP messages was 11 min when either rifampin (10 micrograms/ml) or actinomycin D (1 microgram/ml) was used to inhibit RNA synthesis.

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