Inhibition of Ribosomal RNA Synthesis in X-Irradiated HeLa Cells

1970 ◽  
Vol 44 (2) ◽  
pp. 456 ◽  
Author(s):  
R. Bases ◽  
F. Mendez ◽  
R. Nicolino
Keyword(s):  
Ribosomal Rna ◽  
Hela Cells ◽  
Rna Synthesis

Studies on the Control of Ribosomal RNA Synthesis in HeLa Cells

1975 ◽  
Vol 57 (1) ◽  
pp. 79-83 ◽  
Author(s):  
C. James CHESTERTON ◽  
Barbara E. H. COUPAR ◽  
Peter H. W. BUTTER WORTH ◽  
Janice BUSS ◽  
Melvin H. GREEN
Keyword(s):  
Ribosomal Rna ◽  
Hela Cells ◽  
Rna Synthesis

scholarly journals THE SELECTIVE INTERRUPTION OF NUCLEOLAR RNA SYNTHESIS IN HELA CELLS BY CORDYCEPIN

1969 ◽  
Vol 41 (2) ◽  
pp. 510-520 ◽  
Author(s):  
Moshe Siev ◽  
Robert Weinberg ◽  
Sheldon Penman
Keyword(s):  
Ribosomal Rna ◽  
Hela Cells ◽  
Rna Synthesis ◽  
Transfer Rna ◽  
Short Exposure ◽  
Low Concentrations ◽  
Dna And Protein Synthesis ◽  
Ribosomal Precursor ◽  
Precursor Molecules ◽  
Nucleolar Rna

Cordycepin is an analogue of adenosine lacking the 3'-OH. When incorporated into a growing RNA molecule, cordycepin prevents further elongation, thus producing a prematurely terminated RNA molecule. When HeLa cells are exposed to low concentrations of cordycepin, DNA and protein synthesis are unaffected during short exposure periods. The synthesis of completed ribosomal and ribosomal-precursor (45S) RNA is significantly depressed. Partially completed 45S ribosomal precursor molecules accumulate in the nucleolus. 18S ribosomal RNA can be cleaved from these incomplete precursors, while 32S ribosomal precursor cannot be produced from partially snythesized 45S molecules. The synthesis of transfer RNA is also reduced in the presence of cordycepin. The synthesis of the nuclear heterogeneous RNA species is unaffected by the drug while the cytoplasmic heterogeneous RNA is slightly reduced.

scholarly journals A comparative study of the effect of aflatoxin B1 and actinomycin D on HeLa cells

1969 ◽  
Vol 114 (2) ◽  
pp. 289-298 ◽  
Author(s):  
E. H. Harley ◽  
K. R. Rees ◽  
A. Cohen
Keyword(s):  
Protein Synthesis ◽  
Ribosomal Rna ◽  
Mechanism Of Action ◽  
Aflatoxin B1 ◽  
Hela Cells ◽  
Rna Synthesis ◽  
Actinomycin D ◽  
Inhibitory Effect ◽  
Cytotoxic Effects ◽  
Rna Precursor

1. The cytotoxic effects of aflatoxin B1 on HeLa cells were examined and effects of short exposures of the cells to the toxin were found to be reversible. 2. Aflatoxin B1 inhibited the synthesis of both ribosomal and heterodisperse RNA. It is proposed that the toxin's mechanism of action on ribosomal RNA synthesis is related to its inhibitory effect on the maturation of the 45s-ribosomal-RNA precursor. 3. Protein synthesis is inhibited to a greater extent by aflatoxin B1 than by actinomycin D. In contrast with actinomycin D, aflatoxin B1 was shown to disaggregate polyribosomes directly.

scholarly journals RNA SYNTHESIS IN HELA CELLS

1970 ◽  
Vol 47 (3) ◽  
pp. 734-744 ◽  
Author(s):  
Thoru Pederson ◽  
Elliott Robbins
Keyword(s):  
Ribosomal Rna ◽  
Hela Cells ◽  
Rna Synthesis ◽  
Close Correlation ◽  
Selective Inhibition ◽  
Transfer Rna ◽  
Extracellular Medium ◽  
Hypertonic Medium ◽  
Nuclear Rna ◽  
Ribosomal Precursor

Interphase HeLa cells manifest a stepwise shutoff of RNA synthesis when the tonicity of the extracellular medium is gradually increased. Synthesis of heterogeneous nuclear RNA is most sensitive and is selectively inhibited at 1.5 times isotonicity (450 milliosmols/liter), while 45S ribosomal RNA synthesis is not affected significantly below 2.0 times isotonicity. Transfer RNA synthesis is least sensitive to increased osmolarity and is not completely inhibited until the electrolyte concentration of the medium is elevated to 2.8 times isotonicity. Although the transcription and methylation of 45S ribosomal precursor is unaffected at 1.5 times isotonicity, there is pronounced impairment of its processing into 32S and 18S RNA. Using a refined cell synchronization technique, we have been able to compare these effects of hypertonicity with the shutoff of RNA synthesis which occurs during the G2-prophase interval of the cell division cycle. In this case, as with random cells in hypertonic medium, a selective inhibition of heterogeneous nuclear RNA synthesis and slowed processing of 45S ribosomal RNA were found, whereas synthesis of 45S and transfer RNA continued unabated throughout G2-prophase. While it is known that RNA synthesis essentially ceases during metaphase, we have noted that transfer RNA synthesis continues in metaphase at 10–15% of the interphase rate, which is of particular interest in view of the relative resistance of this species to hypertonicity. The close correlation between the patterns of cessation of RNA synthesis at mitosis and during exposure to hypertonic medium supports our earlier contention that alteration of intracellular electrolyte levels provides a useful model for studying the mechanism of mitosis.

scholarly journals Accelerated rates of ribosomal RNA synthesis during growth of contracting heart cells in culture

1989 ◽  
Vol 264 (30) ◽  
pp. 18220-18227
Author(s):  
P J McDermott ◽  
L I Rothblum ◽  
S D Smith ◽  
H E Morgan
Keyword(s):  
Ribosomal Rna ◽  
Rna Synthesis ◽  
Heart Cells ◽  
Cells In Culture ◽  
Contracting Heart
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