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.

scholarly journals Nucleolar necklaces in chick embryo fibroblast cells. II. Microscope observations of the effect of adenosine analogues on nucleolar necklace formation.

1975 ◽  
Vol 65 (2) ◽  
pp. 418-427 ◽  
Author(s):  
D Granick
Keyword(s):  
Chick Embryo ◽  
Ribosomal Rna ◽  
Messenger Rna ◽  
Rna Synthesis ◽  
Rrna Synthesis ◽  
Fibroblast Cells ◽  
Chick Embryo Fibroblast ◽  
Adenosine Analogues ◽  
Nucleolar Apparatus ◽  
Extensive Degradation

The round nucleoli of chick embryo fibroblast cells, when exposed to adenosine (2 mM)or to a number of adenosine analogues, lose material and unravel over a period of several hours to become beaded strands, 20 mu M in length, termed nucleolar necklaces (NN). Light microscope observations on this process are described. Biochemical experiments have revealed that most of these analogues interfere with both messenger RNA synthesis and ribosome synthesis, causing extensive degradation of the preribosome species containing 32S RNA although most of the preribosomes containing 18S RNA survive. We suggest that it is the depletion from the nucleolus of the adhesive 32S and 28S RNA preribosomes which allows the remaining nucleolar apparatus to spread apart into the NN configuration. Also required for the maintenance of the NN structure is the synthesis of some ribosomal RNA (rRNA) possibly present as rRNA "feathers" on the DNA. The addition of inhibitors of rRNA synthesis such as actinomycin D to the NN-containing cells causes loss of rRNA. Then a contraction and collapse of the NN structure into small dense spheres is observed.

Analyse des Vermehrungsmechanismus des Newcastle disease Virus (NDV) mit Hilfe verschiedener Inhibitoren

1967 ◽  
Vol 22 (12) ◽  
pp. 1319-1330 ◽  
Author(s):  
Werner Schäfer ◽  
Liselotte Pister ◽  
Rita Schneider
Keyword(s):  
Chick Embryo ◽  
Viral Antigen ◽  
Rna Synthesis ◽  
Protein S ◽  
Viral Rna ◽  
Chick Embryo Fibroblast ◽  
Sensitive Material ◽  
Sensitive Phase ◽  
Antigenic Material ◽  
Structural Antigen

The reproduction of NDV in chick-embryo-fibroblast cultures was studied with 6-Azauridine, 8-Azaguanine, Parafluorophenylalanine (FPA) and Puromycine as inhibitors. The results suggest that no virus initiated FPA-sensitive material is needed for the uncoating of the infecting particles, and that viral parental RNA is able to induce the formation of protein (s) needed for viral RNA-synthesis (“RNA-protein“) as well as the production of viral structural antigen (s). Further antigenic material appears after the beginning of new viral RNA-synthesis. The “RNA-protein (s)“become (s) detectable between 2 and 3 hours after infection and is (are) stable in its function over several hours. According to the formation of viral antigenic material parental viral RNA can act as a messenger longer than 9 hours. The capacity for the production of hemagglutinating units appears after the viral antigen producing capacity, when viral RNA can already be synthesized. This capacity is separated from that to produce plaque forming particles by a FPA-sensitive phase. The character of the corresponding FPA-sensititve material is unknown.

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.

scholarly journals Action of dichlorobenzimidazole riboside on RNA synthesis in L-929 and HeLa cells.

1976 ◽  
Vol 69 (2) ◽  
pp. 229-240 ◽  
Author(s):  
I Tamm ◽  
R Hand ◽  
L A Caliguiri
Keyword(s):  
Hela Cells ◽  
Rna Synthesis ◽  
Dose Range ◽  
Inhibitory Effect ◽  
Mouse Fibroblast ◽  
L Cells ◽  
Uridine Uptake ◽  
High Concentrations ◽  
Precursor Rna ◽  
Ribosomal Precursor

5,6-Dichloro-1-beta-D-ribofuranosylbenzimidazole (DRB) inhibits RNA synthesis in L-929 cells (mouse fibroblast line) and HeLa cells (human epitheloid carcinoma line) within 2 min of addition of the compound to the medium. By removing DRB from the medium, the inhibition is promptly and completely reversed after treatment of cells for as long as 1 h or even longer. The inhibitory effect of DRB on the overall rate of RNA synthesis is similar in L and HeLa cells and is markedly concentration-dependent in the low dose range (5-20 muM or 1.6-6.4 mug/ml), but not as higher concentrations of DRB. At a concentration of 12 muM, DRB has a highly selective inhibitory effect on the synthesis of nuclear heterogenous RNA in L cells. At higher concentrations, there is also inhibition of 45 S ribosomal precursor RNA synthesis, but at all concentrations the effect on heterogeneous RNA synthesis in L cells in considerably greater than that on preribosomal RNA synthesis. In HeLa cells, too, DRB has a selective effect on heterogeneous RNA synthesis, but quantitatively the selectivity of action is somewhat less pronounced. In both L and HeLa cells, the inhibition of synthesis of nuclear heterogeneous RNA is incomplete even at very high concentrations of DRB (150 muM). Thus, while DRB is a selective inhibitor of nuclear heterogeneous RNA synthesis, not all such RNA synthesis is sensitive to inhibition. It is proposed that messenger precursor RNA synthesis may largely be sensitive to inhibition by DRB. In short-term experiments, DRB has no effect on protein synthesis in L or HeLa cells. DRB has a slight to moderate inhibitory effect on uridine uptake into L cells and a moderate to marked effect on uptake of uridine into HeLa cells.

scholarly journals Hydrocortisone requirement for the induction of glutamine synthetase in chick-embryo retinas

1968 ◽  
Vol 106 (2) ◽  
pp. 425-430 ◽  
Author(s):  
Liane Reif-Lehrer ◽  
Harold Amos
Keyword(s):  
Chick Embryo ◽  
Glutamine Synthetase ◽  
Messenger Rna ◽  
Active Component ◽  
Calf Serum ◽  
Synthetase Activity ◽  
Glutamine Synthetase Activity

Hydrocortisone has been found to induce glutamine synthetase activity in chick-embryo retinas in culture. Evidence is presented to show that the hydrocortisone is definitely required for transcription; its requirement for translation has not been ruled out. The possible identity of hydrocortisone with an active component of calf-serum diffusate reported earlier is discussed. The data also indicate that the glutamine synthetase messenger RNA is stable for at least several hours.

scholarly journals MESSENGER RNA SYNTHESIS BY A "COATED" VIRAL GENOME

1967 ◽  
Vol 57 (2) ◽  
pp. 314-320 ◽  
Author(s):  
J. R. Kates ◽  
B. R. McAuslan
Keyword(s):  
Viral Genome ◽  
Messenger Rna ◽  
Rna Synthesis

The effects of D- and L-threo-chloramphenicol on the early development of the chick embryo

Development ◽  
1965 ◽  
Vol 13 (3) ◽  
pp. 341-356
Author(s):  
F. S. Billett ◽  
Rosalba Collini ◽  
Louie Hamilton
Keyword(s):  
Protein Synthesis ◽  
Amino Acid ◽  
Chick Embryo ◽  
Messenger Rna ◽  
Mammalian Cells ◽  
Animal Cells ◽  
Inhibit Protein Synthesis ◽  
Acid Complex ◽  
Amino Acid Complex ◽  
Bacterial Systems

In many bacterial systems chloramphenicol has been shown to inhibit protein synthesis (Hahn & Wisseman, 1951; Gale & Folkes, 1953). The precise mechanism of this inhibition is not clear, although the evidence suggests that the interaction of the soluble RNA-amino acid complex with the ribosomes is prevented because the attachment of the messenger RNA to the ribosomes is itself impaired (Lacks & Gros, 1959; Nathans & Lipman, 1961; Jardetsky & Julian, 1964; Julian & Jardetsky, 1964). In contrast to its effect on bacterial systems, chloramphenicol has been reported to have little or no action on the protein synthesis by cell-free extracts of mammalian cells (Rendi, 1959; Ehrenstein & Lipmann, 1961). A basis for this resistance has been proposed by Vazquez (1964), who finds that whereas bacterial ribosomes bind chloramphenicol, ribosomes from other organisms do not. Nevertheless, it cannot be stated with any confidence that chloramphenicol has no effect on the protein synthesis of animal cells.

FURTHER STUDIES ON THE DUAL REQUIREMENT FOR PHENYLALANINE AND TYROSINE IN TISSUE CULTURE

1961 ◽  
Vol 39 (5) ◽  
pp. 925-932 ◽  
Author(s):  
Helen J. Morton ◽  
Joseph F. Morgan
Keyword(s):  
Amino Acids ◽  
Tissue Culture ◽  
Chick Embryo ◽  
Heart Cells ◽  
Present System ◽  
Chick Heart ◽  
High Concentrations ◽  
Chick Embryo Heart ◽  
Embryo Heart ◽  
Related Compounds

Seventeen structurally related compounds were tested for their ability to substitute for phenylalanine or tyrosine in the nutrition of chick embryo heart fragments. DL-Alanyl-DL-phenylalanine replaced phenylalanine. All other compounds had negligible effects, and most were toxic at high concentrations. β-Phenylserine, a phenylalanine antagonist, actually prolonged the survival of chick heart cells but only if both phenylalanine and tyrosine were present. Similarly, optimal reversal of β-phenylserine toxicity was dependent on the presence of both amino acids. Although phenylalanine and tyrosine are not interconvertible in the present system, it has been shown that three phenylalanine antagonists, p-fluorophenylalanine, β-2-thienylalanine, and β-phenylserine, can be identified by their relationship to tyrosine, rather than to phenylalanine.

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