Effects of actinomycin D on ribosomal RNA and protein synthesis as revealed by high resolution autoradiography

1979 ◽  
Vol 31 (1) ◽  
pp. 251-257
Author(s):  
A. Martinez-Ramón
Keyword(s):  
Protein Synthesis ◽  
High Resolution ◽  
Ribosomal Rna ◽  
Actinomycin D ◽  
Rna And Protein Synthesis ◽  
High Resolution Autoradiography

Regulation of K+ Influx in Barley Roots: Evidence for Direct Control by Internal K+

1977 ◽  
Vol 4 (2) ◽  
pp. 313 ◽  
Author(s):  
ADM Glass
Keyword(s):  
Protein Synthesis ◽  
Cell Division ◽  
Actinomycin D ◽  
Direct Control ◽  
Pretreatment Period ◽  
Rna And Protein Synthesis ◽  
Lag Period ◽  
Limited Protein ◽  
K Concentration ◽  
Gamma Irradiated

Values for plasmalemma influx of K+ into excised barley roots, from solutions containing 0.05 mM KCl plus 0.5 mM CaSO4, were reduced by 50-60% following a 6-h pretreatment period in 50 mM KCl plus 0.05 mM CaSO4 solution. This reduction of influx, associated with increased internal K+ concentration, was independent of DNA, RNA and protein synthesis during the pretreatment period as indicated by its insensitivity to the presence of 5-fluorodeoxyuridine, actinomycin D, cycloheximide, p-fluorophenylalanine or anisomycin in the pretreatment solutions. Roots of plantlets grown from gamma-irradiated barley seeds, which were incapable of under-going cell division and capable of only limited protein synthesis, were nevertheless able to reduce K+ influx values in response to increased internal K+ concentration. The measurement of K+ influx from 0.05 mM KCl solutions following pretreatment periods as short as 15 min in 50 mM KCl gave no evidence of any lag period in the development of reduced influx associated with increased internal K+ status. The above experiments are discussed in terms of a model for the regulation of K+ influx which ascribes a direct 'allosteric' role to internal K+ in controlling influx.

scholarly journals THE EFFECTS OF INHIBITORS OF RNA AND PROTEIN SYNTHESIS ON THE RECOVERY OF CHLOROPLAST RIBOSOMES, MEMBRANE ORGANIZATION, AND PHOTOSYNTHETIC ELECTRON TRANSPORT IN THE ac-20 STRAIN OF CHLAMYDOMONAS REINHARDI

1971 ◽  
Vol 50 (1) ◽  
pp. 50-62 ◽  
Author(s):  
Ursula W. Goodenough ◽  
R. P. Levine
Keyword(s):  
Protein Synthesis ◽  
Electron Transport ◽  
Chloroplast Dna ◽  
Ribosomal Rna ◽  
Structural Integrity ◽  
Photosynthetic Electron Transport ◽  
Rna And Protein Synthesis ◽  
Low Levels ◽  
Inhibitor Of Protein Synthesis ◽  
Secondary Consequence

The ac-20 strain of Chlamydomonas reinhardi is characterized by low levels of chloroplast ribosomes when grown mixotrophically. Cells can be transferred to minimal medium and their ribosome levels increase. If, at the time of transfer, cells are exposed to chloramphenicol, an inhibitor of protein synthesis in the chloroplast, or cycloheximide, an inhibitor of protein synthesis in the cytoplasm, ribosome recovery is not affected; however, recovery is blocked by exposure to rifampicin, an inhibitor of chloroplast DNA-dependent RNA polymerase. It is therefore concluded that ac-20 cells suffer from an impaired chloroplast ribosomal RNA synthesis. Mixotrophic ac-20 cells are also characterized by low rates of photosynthetic electron transport, disorganized chloroplast membranes, and a small pyrenoid. If chloramphenicol is applied to transferred cells whose chloroplast ribosome levels have already recovered, recovery of photosynthetic electron transport and of structural integrity does not occur. Under the same conditions, cycloheximide has no effect on recovery. It is concluded that the structural and photosynthetic lesions in ac-20 are a secondary consequence of the low levels of chloroplast ribosomes. Finally, we present evidence that recovery of photosynthetic electron transport requires the transcription of chloroplast DNA. This transcription is apparently triggered by light.

scholarly journals Analysis of the survival of mature human eosinophils: interleukin-5 prevents apoptosis in mature human eosinophils

Blood ◽  
1991 ◽  
Vol 78 (10) ◽  
pp. 2542-2547 ◽  
Author(s):  
Y Yamaguchi ◽  
T Suda ◽  
S Ohta ◽  
K Tominaga ◽  
Y Miura ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Dna Fragmentation ◽  
Culture System ◽  
Actinomycin D ◽  
Agar Gel ◽  
Interleukin 5 ◽  
Liquid Culture System ◽  
Rna And Protein Synthesis ◽  
Agar Gel Electrophoresis

Abstract We and other groups have previously shown that interleukin-5 (IL-5) maintained the viability of mature eosinophils in an in vitro liquid culture system. Mature eosinophils did not proliferate but their survival was maintained in the presence of IL-5. Using this culture system, we investigated the mechanism of IL-5-mediated survival. In the absence of human IL-5 (hIL-5) mature eosinophils succumbed after 4 days, while in the presence of hIL-5 they survived up to 10 days. When DNA extracts of cultured eosinophils were analyzed on an agar gel electrophoresis, marked DNA fragmentation was observed in the absence of hIL-5, while no significant DNA fragmentation was observed in the culture with hIL-5 for 48 hours. The DNA fragmentation appeared as early as 6 to 12 hours after hIL-5 deprivation. Concomitantly, IL-5 stimulated total RNA and protein synthesis, but did not induce DNA synthesis in mature eosinophils. Because cycloheximide or actinomycin D impeded the protection of apoptosis by hIL-5, some new RNA and protein synthesis appeared to be required in this phenomena. These findings indicate that IL-5 maintains survival of mature eosinophils with induction of new RNA and protein synthesis, thus leading to the inhibition of apoptosis.

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.

Changes in Ribosome Organization and Messenger RNA Abundance in Ripening Tomato Fruits

1984 ◽  
Vol 11 (3) ◽  
pp. 225 ◽  
Author(s):  
J Spiers ◽  
CJ Brady ◽  
D Grierson ◽  
E Lee
Keyword(s):  
Protein Synthesis ◽  
Ribosomal Rna ◽  
Messenger Rna ◽  
In Vitro Translation ◽  
Translation System ◽  
Active Protein ◽  
Tomato Fruits ◽  
Rna And Protein Synthesis ◽  
Early Ripening

The involvement of RNA and protein synthesis in fruit ripening was investigated. Mature-green tomato fruits were found to contain about 30% of their ribosomal RNA in polyribosomes. At the 'breaker' or early ripening stage, about 50% of rRNA was in polyribosomes and this distribution of rRNA was maintained until fruits were fully ripe. The continued presence of polyribosomes is consistent with active protein synthesis persisting through and beyond the climacteric period when the wall-hydrolysing enzyme polygalacturonase accumulates and fruits soften, synthesize lycopene and undergo other ripening related changes. Poly(A)-containing RNA purified from polyribosomes extracted from individual fruits was used to prime the synthesis of [35S]methionine-labelled polypeptides by a wheat germ in vitro translation system. The pattern of polypeptides synthesized in response to RNA from mature-green fruits differed from that given by RNA from ripening fruits. The majority of changes were found to occur within approximately 48 h of the increase of ethylene synthesis and were apparent in all fruits with any pink or red colour. Similar results were obtained by translating total cellular RNA and total polyribosomal RNA indicating that the major RNA species shown in this study to change in abundance during ripening are polyadenylated, and hence most probably cytoplasmic, and do not accumulate as 'stored messages' outside of the polyribosomes. The differences between green and ripening fruits in polyribosome profiles were demonstrated in two cultivars of tomato. Differences in mRNA populations between green and ripe fruits were found in three cultivars.

PRIMING EFFECT OF LUTEINIZING HORMONE RELEASING FACTOR: IN-VITRO AND IN-VIVO EVIDENCE CONSISTENT WITH ITS DEPENDENCE UPON PROTEIN AND RNA SYNTHESIS

1976 ◽  
Vol 69 (3) ◽  
pp. 373-379 ◽  
Author(s):  
A. J. M. C. PICKERING ◽  
G. FINK
Keyword(s):  
Protein Synthesis ◽  
Priming Effect ◽  
Actinomycin D ◽  
Protein S ◽  
In Vivo Studies ◽  
Protein And Rna Synthesis ◽  
Rna And Protein Synthesis ◽  
Secretory Apparatus

SUMMARY The aim of this study was to determine whether the priming effect of LH-RF depends upon RNA and protein synthesis. In in-vivo studies saline, actinomycin D, or cycloheximide was administered i.p. 3·5–4 h before the first i.v. injection of synthetic LH-RF into pro-oestrous rats anaesthetized with sodium pentobarbitone at 13.30 h. The LH-response to the second injection of LH-RF (given 60 min after the first) was markedly reduced by the inhibitors, but the response to the first injection was not significantly affected. Studies with cycloheximide given i.v. showed that the inhibition of protein synthesis up to the second injection of LH-RF reduced the magnitude of the priming effect, the reduction being greatest when the inhibitor was administered up to 30 min after the first LH-RF injection. Pituitary incubation studies showed that the priming effect could also be elicited in vitro and that it could be significantly reduced by actinomycin D, cycloheximide and puromycin. As in vivo, the inhibitors had relatively little effect on the LH-response to the first exposure to LH-RF. The protein synthesized after an injection of LH-RF may be new LH, and/or a protein(s) concerned with 'activation' of the receptor or release components of the LH-secretory apparatus.

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