Inhibition of rRNA synthesis following incorporation of 5-bromodeoxyuridine into DNA of Tetrahymena pyriformis

1975 ◽  
Vol 17 (3) ◽  
pp. 495-502
Author(s):  
A.E. Lykkesfeldt ◽  
H.A. Andersen
Keyword(s):  
Dna Replication ◽  
Ribosomal Rna ◽  
Rna Synthesis ◽  
Nuclear Dna ◽  
Tetrahymena Pyriformis ◽  
Growth Conditions ◽  
Defined Medium ◽  
Rrna Synthesis ◽  
Chemically Defined Medium ◽  
Dividing Cells

Tetrahymena pyriformis was grown on chemically defined medium in the presence of 5-bromodeoxyuridine (BUdR). Under these growth conditions more than 60% of the thymidine sites in DNA were substituted with BUdR. It was found that RNA synthesis was strongly inhibited by the presence of BUdR in DNA. To assure that incorporation of BUdR into DNA was a prerequisite of the effect observed, BUdR was added to synchronously dividing cells. BUdR had no effect on the cells when present outside the period of nuclear DNA replication, whereas RNA synthesis was strongly inhibited as soon as the genes coding for ribosomal RNA had replicated in the presence of BUdR.

Regulation of ribosomal RNA synthesis in Tetrahymena pyriformis

1978 ◽  
Vol 31 (1) ◽  
pp. 13-23
Author(s):  
J. Keiding ◽  
H.A. Andersen
Keyword(s):  
Cell Cycle ◽  
Dna Replication ◽  
Ribosomal Rna ◽  
Rna Synthesis ◽  
Tetrahymena Pyriformis ◽  
Rrna Synthesis ◽  
Constant Rate ◽  
Normal Increase ◽  
S Period ◽  
Dosis Effect

Ribosomal RNA is synthesized at constant rate during most of the cell cycle in heat-shock synchronized populations of Tetrahymena pyriformis. Early in each macronuclear S-period the rate of synthesis increases abruptly, concomitant with replication of the genes coding for ribosomal RNA. The increase is prevented by inhibitors of DNA replication, added prior to the S-period. Similarly, in cultures synchronized by starvation/refeeding, inhibition of DNA replication, at the time when the rDNA is replicated, will prevent the normal increase in rate of RNA synthesis which follows refeeding. We conclude that inhibition of rDNA replication interferes with the synthesis of rRNA, and we suggest that with respect to rRNA synthesis a gene dosis effect is operating in fast-growing Tetrahymena cells.

On the role of small peptides in the regulation of RNA synthesis in Tetrahymena pyriformis

1980 ◽  
Vol 45 (1) ◽  
pp. 31-39
Author(s):  
H.A. Andersen ◽  
A.E. Lykkesfeldt ◽  
S.J. Nielsen
Keyword(s):  
Ribosomal Rna ◽  
Rna Synthesis ◽  
Tetrahymena Pyriformis ◽  
Defined Medium ◽  
Specific Factor ◽  
Small Peptides ◽  
In Vitro Synthesis

Tetrahymena cells secrete a factor which inhibits RNA synthesis in vivo and in vitro. The factor is a relatively small peptide with a molecular weight between 300 and 1500 Daltons. Other, non-specific peptides in the broth medium or added to a chemically defined medium have a stimulatory effect on RNA synthesis in vivo and such peptides also stimulate the in vitro synthesis of RNA in a r-chromatin preparation. On the basis of these results we conclude that such extracellular small peptides compete with a specific factor which is part of the intracellular regulatory mechanism controlling the rate of RNA synthesis. The consequence of such competition is a high overproduction of ribosomal RNA in cells inoculated on peptide-rich broth media.

scholarly journals THE EFFECT OF 5-BROMODEOXYURIDINE ON DNA REPLICATION AND CELL DIVISION IN TETRAHYMENA PYRIFORMIS

1974 ◽  
Vol 62 (2) ◽  
pp. 316-321 ◽  
Author(s):  
Anne E. Lykkesfeldt ◽  
H. A. Andersen
Keyword(s):  
Cell Division ◽  
Structural Change ◽  
Dna Replication ◽  
First Generation ◽  
Normal Growth ◽  
Tetrahymena Pyriformis ◽  
Defined Medium ◽  
Chemically Defined Medium ◽  
Normal Hybrid ◽  
Hybrid Dna

Populations of Tetrahymena pyriformis were grown in a chemically defined medium containing the thymidine analogue 5-bromodeoxyuridine (BUdR). About 65% of the thymidine sites in DNA were substituted by BUdR. During the first generation in the presence of BUdR, all DNA became hybrid. After the following cell division, in about 80% of the cells the second DNA replication round was initiated but no further cell division took place. The cells could be rescued by removing BUdR and adding thymidine. New replication took place before the first cell division. However, although the cells contained double heavy as well as hybrid DNA, only the hybrid DNA was replicated. After a full replication of the hybrid DNA, normal growth was restored. Melting profiles of normal, hybrid, and double heavy DNA indicated a structural change of the double heavy DNA.

Preferential inhibition of rDNA transcription by 5-bromodeoxyuridine

1977 ◽  
Vol 25 (1) ◽  
pp. 95-102
Author(s):  
A.E. Lykkesfeldt ◽  
H.A. Andersen
Keyword(s):  
Growth Medium ◽  
Ribosomal Rna ◽  
Rna Synthesis ◽  
Tetrahymena Pyriformis ◽  
Degree Of Substitution ◽  
Rdna Transcription ◽  
Total Rna

On a chemically defined growth medium the degree of substitution of thymidine with 5-bromodeoxyuridine (BUdR) in DNA of Tetrahymena pyriformis was controlled by the concentration of tetrahydrofiolic acid, BUdR and thymidine in the medium. A correlation between the degree of BUdR substitution in DNA and the reduction in rate of total RNA synthesis has been established. It was found that the reduction of total RNA synthesis results from inhibition of transcription of all RNA species which have been measured. However, independent of the degree of BUdR substitution in DNA, a preferential inhibition of the synthesis of 25s and 17s ribosomal RNA was found. It is concluded that the various genes may respond differently to BUdR substitution with respect to transcription.

scholarly journals REGULATION OF RIBOSOMAL RNA AND 5s RNA SYNTHESIS IN DROSOPHILA MELANOGASTER: I. BOBBED MUTANTS

Genetics ◽  
1972 ◽  
Vol 72 (2) ◽  
pp. 267-276
Author(s):  
Roberto Weinmann
Keyword(s):  
Drosophila Melanogaster ◽  
Developmental Delay ◽  
Ribosomal Rna ◽  
Gel Electrophoresis ◽  
Rna Synthesis ◽  
Rrna Synthesis ◽  
Wild Type ◽  
5S Rna ◽  
Wild Type Level

ABSTRACT Analysis of the rates and amounts of rRNA and 5s RNA synthesized in Drosophila melanogaster bobbed mutants was done by using acrylamide-gel electrophoresis. The results show that the amounts of rRNA synthesized are constant, although the rates of rRNA synthesis in bb's are reduced to 30% of the wild-type level. The rates of synthesis of 5s RNA were constant. The rate of synthesis of the two kinds of molecules that enter in equimolar amounts into the mature ribosome is non-coordinated.—The rates of rRNA synthesis were shown to be proportional to the length of the scutellar bristles, supporting the notion that in trichogen cells there is no developmental delay, but the size of the bristle depends directly on the rate of rRNA synthesis.

Dynamics and thermal sensitivity of ribosomal RNA maturation paths in plants

2021 ◽  
Author(s):  
Thiruvenkadam Shanmugam ◽  
Deniz Streit ◽  
Frank Schroll ◽  
Jelena Kovacevic ◽  
Enrico Schleiff
Keyword(s):  
High Temperature ◽  
Ribosomal Rna ◽  
Ribosome Biogenesis ◽  
Thermal Sensitivity ◽  
Normal Growth ◽  
Growth Conditions ◽  
High Temperature Stress ◽  
High Temperature Treatment ◽  
Rrna Synthesis ◽  
Rrna Maturation

Abstract Ribosome biogenesis is a constitutive fundamental process for cellular function. Its rate of production depends on the rate of maturation of precursor ribosomal RNA (pre-rRNA). The rRNA maturation paths are marked by four dominant rate-limiting intermediates with cell-type variation of the processivity rate. We have identified that high temperature stress in plants, while halting the existing pre-rRNA maturation schemes, also transiently triggers an atypical pathway for 35S pre-rRNA processing. This pathway leads to production of an aberrant precursor rRNA, reminiscent of yeast 24S, encompassing 18S and 5.8S rRNA that do not normally co-occur together at sub-unit levels; this response is elicited specifically by high and not low temperatures. We show this response to be conserved in two other model crop plant species (Rice and Tomato). This pathway persists even after returning to normal growth conditions for 1 hour and is reset between 1-6 hours after stress treatment, likely, due to resumption of normal 35S pre-rRNA synthesis and processing. The heat-induced ITS2 cleavage-derived precursors and stalled P-A2-like precursors were heterogeneous in nature with a fraction containing polymeric (A) tails. Furthermore, high temperature treatment and subsequent fractionation resulted in polysome and precursor rRNA depletion.

scholarly journals Expression of Virulence Factors by Staphylococcus aureus Grown in Serum

2011 ◽  
Vol 77 (22) ◽  
pp. 8097-8105 ◽  
Author(s):  
Yuichi Oogai ◽  
Miki Matsuo ◽  
Masahito Hashimoto ◽  
Fuminori Kato ◽  
Motoyuki Sugai ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Virulence Factors ◽  
Iron Acquisition ◽  
Calf Serum ◽  
Growth Conditions ◽  
Defined Medium ◽  
Chemically Defined Medium ◽  
Regulatory Factor ◽  
Content Type

ABSTRACTStaphylococcus aureusproduces many virulence factors, including toxins, immune-modulatory factors, and exoenzymes. Previous studies involving the analysis of virulence expression were mainly performed byin vitroexperiments using bacterial medium. However, whenS. aureusinfects a host, the bacterial growth conditions are quite different from those in a medium, which may be related to the different expression of virulence factors in the host. In this study, we investigated the expression of virulence factors inS. aureusgrown in calf serum. The expression of many virulence factors, including hemolysins, enterotoxins, proteases, and iron acquisition factors, was significantly increased compared with that in bacterial medium. In addition, the expression of RNA III, a global regulon for virulence expression, was significantly increased. This effect was partially restored by the addition of 300 μM FeCl3into serum, suggesting that iron depletion is associated with the increased expression of virulence factors in serum. In chemically defined medium without iron, a similar effect was observed. In a mutant withagrinactivated grown in serum, the expression of RNA III,psm, andsec4was not increased, while other factors were still induced in the mutant, suggesting that another regulatory factor(s) is involved. In addition, we found that serum albumin is a major factor for the capture of free iron to prevent the supply of iron to bacteria grown in serum. These results indicate thatS. aureusexpresses virulence factors in adaptation to the host environment.

scholarly journals Dependence of nucleus-directed rRNA synthesis upon mitochondrial protein synthesis in Tetrahymena.

1982 ◽  
Vol 2 (5) ◽  
pp. 508-516 ◽  
Author(s):  
L Ruben ◽  
A B Hooper
Keyword(s):  
Protein Synthesis ◽  
Rna Synthesis ◽  
Mitochondrial Protein ◽  
Tetrahymena Pyriformis ◽  
Cellular Protein ◽  
Rrna Synthesis ◽  
Mitochondrial Protein Synthesis ◽  
Mitochondrial Rrna ◽  
Polyadenylated Rna ◽  
Nuclear Rna

The antibiotic chloramphenicol selectively inhibited mitochondrial protein synthesis in the ciliate protozoan Tetrahymena pyriformis GL. Secondary to the inhibition of mitochondrial protein synthesis was an inhibition of nuclear RNA synthesis at a time before inhibition of cellular protein and DNA synthesis. Of the stable non-polyadenylated RNA species in Tetrahymena, the addition of chloramphenicol resulted specifically in the inhibition of synthesis of 28S + 17S and 5S rRNA transcripts. By contrast, syntheses of 4S tRNA and 21S mitochondrial rRNA were not as extensively inhibited. The addition of 60 microM hemin before the addition of chloramphenicol partially protected against the inhibition of RNA synthesis. These data indicate that continued synthesis of nucleus-directed rRNA is linked to the synthesis of mitochondrial proteins in Tetrahymena.

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