scholarly journals Comparison of the effects of zinc deprivation and actinomycin D on ribonucleic acid synthesis by stimulated lymphocytes

1975 ◽  
Vol 150 (2) ◽  
pp. 211-218 ◽  
Author(s):  
J K Chesters
Keyword(s):  
Actinomycin D ◽  
Soluble Fraction ◽  
Acid Synthesis ◽  
28S Rrna ◽  
Similar Time ◽  
Uridine Incorporation ◽  
Low Concentrations ◽  
Time Courses ◽  
Polymerase I ◽  
Stimulation Of

1. EDTA inhibited incorporation of [3H]uridine into RNA of lymphocytes, but did not decrease uptake into the cold-acid-soluble fraction of the cells. The inhibition by EDTA was largely reversible by simultaneous addition of Zn2+. 2. Low concentrations pf actinomycin D (3 ng/ml) added at the time of stimulation of the cells inhibited [3H]uridine incorporation into RNA, but concentrations of 50-100 ng/ml were required to produce the same degree of inhibition if addition of actinomycin D was delayed until just before the incorporation was measured. This difference in sensitivity did not reg within the cells. 3. When added immediately before phytohaemagglutinin, actinomycin D (3 ng/ml) and EDTA produced similar time-courses of inhibition of uridine incorporation. 4. Uridine incorporation at 32h was inhibited when actinomycin D (3 ng/ml) or EDTA was added just before stimulation of the cells, but was only slightly affected when they were added at 32h. At intermediate times the incorporation of uridine remained sensitive to addition of EDTA for longer than it was sensitive to actinomycin D. 5. Polyacrylamide-gel separation of RNA synthesized in EDTA-treated cultures in the presence or absence of added Zn2+ showed that lower availability of Zn2+ resulted in a decreased rate of transfer of radioactivity from 32S to 28S rRNA and decreased survival of 28S rRNA relative to 18S rRNA. 6. Close similarities have been shown to exist between the effects of EDTA and low concentrations of actinomycin D. Not all the effects of EDTA could be explained by postulating that Zn2+ was a constituent of RNA polymerase I, nor were the effects of actinomycin D readily explained by previously suggested mechanisms of action of this antibiotic.

Changes in protein and nucleic acid synthesis in rat gastric mucosa after pentagastrin.

1977 ◽  
Vol 232 (2) ◽  
pp. E223
Author(s):  
M R Enochs ◽  
L R Johnson
Keyword(s):  
Protein Synthesis ◽  
Gastric Mucosa ◽  
Messenger Rna ◽  
Actinomycin D ◽  
Acid Synthesis ◽  
Secreted Protein ◽  
Macromolecular Synthesis ◽  
Rat Gastric Mucosa ◽  
Ribosomal Rrna ◽  
Stimulation Of

The trophic effects of gastrin on gastrointestinal tissues have been shown to be physiologically important. This study was designed to investigate the sequence of changes in macromolecular synthesis in the rat gastric mucosa following a single dose of pentagastrin. The earliest response was an increase at 1-2 h of poly (A) messenger RNA (mRNA). This increase dropped after 4 h but remained slightly elevated even 12 h after pentagastrin. By 6 h there was a large increase in protein synthesis that lasted until 12 h. Accompanying this rise in protein synthesis was a large increase in ribosomal (rRNA) and transfer RNA (tRNA), which peaked at 12 h. The changes in both fractions of RNA and protein were over by 18 h. No significant increase in secreted protein was noted, but there was a slight, transient decrease at 1 h. Pentagastrin stimulated all forms of RNA, but the largest increase was seen in the rRNA fraction. After multiple doses, parallel increases in rRNA and tRNA were seen. The stimulation of protein synthesis could be abolished by actinomycin D, and was, therefore, RNA dependent.

scholarly journals The synthesis of ribonucleic acid in immature rat uterus responding to oestradiol-17β

1971 ◽  
Vol 125 (2) ◽  
pp. 605-614 ◽  
Author(s):  
J. T. Knowler ◽  
R. M. S. Smellie
Keyword(s):  
Rna Synthesis ◽  
Actinomycin D ◽  
Soluble Fraction ◽  
Rat Uterus ◽  
Immature Rat ◽  
Radioactive Precursor ◽  
Major Increase ◽  
Very High ◽  
Time Of Administration ◽  
Stimulation Of

Stimulation of incorporation of labelled precursors into the RNA of immature rat uterus is an early result of oestradiol-17β action. However, the extent of the increased incorporation varies with the mode of administration of the labelled precursors and with the weight of the rat. At the age and weight range normally used response is maximal at ten times control incorporation, 4h after the administration of 0.3μg or more of oestradiol-17β. Under these conditions the stimulation of incorporation into the acid-soluble fraction is only 2–2.5-fold. When the purified RNA is separated on polyacrylamide gels the major increase in incorporation of radioactive precursor is found in rRNA and 4S RNA; the formation of the former has been followed from the 45S precursor. Preceding these events by at least 30min, however, is an increase in the incorporation of precursor into RNA species of very high molecular weight, which remained in the first few slices of the gel. The possible significance of these findings is discussed. The increased synthesis of rRNA in response to oestradiol-17β is more strongly inhibited by actinomycin D than the synthesis of other RNA species. Cycloheximide, depending on time of administration and dosage, inhibits either RNA synthesis or the maturation of rRNA.

scholarly journals Stimulation of incorporation of nucleic acid precursors into HeLa cells caused by provaline

1969 ◽  
Vol 115 (4) ◽  
pp. 823-829
Author(s):  
J. W. Watts
Keyword(s):  
Nucleic Acid ◽  
Nucleic Acids ◽  
Hela Cells ◽  
Actinomycin D ◽  
Small Extent ◽  
Low Concentrations ◽  
High Concentrations ◽  
Stimulation Of

1. The effect of proflavine and other acridines on the incorporation of precursors into the nucleic acids of HeLa cells was examined. 2. Relatively low concentrations (50μm) of proflavine completely inhibited incorporation of precursors into DNA, but allowed a small extent of incorporation into RNA. 3. Acridine-resistant incorporation into RNA was unaffected by actinomycin D at 2μg./ml. and persisted even at high concentrations (500μm) of many acridines. 4. A few combinations of acridine and precursor, notably 250μm-proflavine and [14C]adenine, caused a stimulation of incorporation. 5. The proflavine-stimulated incorporation was into alkali-stable di- and tri-nucleotides. 6. It was concluded that the effect was due to the preferential inhibition of degradation of a fraction of RNA that normally turned over, thus allowing small radioactive oligonucleotides to accumulate in the cells.

ULTRASTRUCTURAL EVIDENCE FOR THE STIMULATION OF NUCLEAR RIBONUCLEIC ACID SYNTHESIS BY OESTRADIOL-17β IN THE VAGINAL EPITHELIUM OF THE OVARIECTOMIZED MOUSE

1970 ◽  
Vol 47 (2) ◽  
pp. 143-NP ◽  
Author(s):  
IRINA POLLARD
Keyword(s):  
Ribonucleic Acid ◽  
Rna Synthesis ◽  
Actinomycin D ◽  
Control Level ◽  
Staining Technique ◽  
Acid Synthesis ◽  
Vaginal Epithelium ◽  
Ovariectomized Mouse ◽  
Ultrastructural Evidence ◽  
Stimulation Of

SUMMARY The cytochemical nature of the ultrastructural nucleolar transformation previously observed in the vaginal epithelium of the ovariectomized mouse after local application of oestradiol-17β was investigated using a recently developed ultrastructural staining technique. Oestradiol treatment induced ribonucleic acid (RNA) synthesis, especially in the nucleolus but also in the nuclear chromatic region and ribosomes. Actinomycin D administered simultaneously with oestradiol reduced the oestrogen-induced nucleolar response to the control level. These findings are discussed with special reference to the mode of action of oestrogens.

scholarly journals Ribonucleic acid synthesis in vitro in primary spermatocytes isolated from rat testis

1977 ◽  
Vol 168 (1) ◽  
pp. 23-31 ◽  
Author(s):  
J. Anton Grootegoed ◽  
Anne H. Grollé-Hey ◽  
Focko F. G. Rommerts ◽  
Henk J. Van Der Molen
Keyword(s):  
Electrophoretic Mobility ◽  
Rna Synthesis ◽  
Actinomycin D ◽  
Marked Change ◽  
Acid Synthesis ◽  
Specific Pattern ◽  
28S Rrna ◽  
Phenol Extraction

The incorporation of [3H]uridine into RNA was studied quantitatively (by incorporation of [3H]uridine into acid-precipitable material) and qualitatively (by phenol extraction and electrophoretic separation of RNA in polyacrylamide gels) in preparations enriched in primary spermatocytes, obtained from testes of rats 26 or 32 days old. The rate of incorporation of [3H]uridine into RNA of isolated spermatocytes was constant during the first 8h of incubation, after which it decreased, but the decreased rate of incorporation was not reflected in a marked change in electrophoretic profiles of labelled RNA. In isolated spermatocytes, [3H]uridine was incorporated mainly into heterogeneous RNA with a low electrophoretic mobility. Most of this RNA was labile, as shown when further RNA synthesis was inhibited with actinomycin D. Spermatocytes in vivo also synthesized heterogeneous RNA with a low electrophoretic mobility. A low rate of incorporation of [3H]uridine into rRNA of isolated spermatocytes was observed. The cleavage of 32S precursor rRNA to 28S rRNA was probably retarded in spermatocytes in vitro as well as in vivo. RNA synthesis by preparations enriched in early spermatids or Sertoli cells was qualitatatively different from RNA synthesis by the spermatocyte preparations. It is concluded that isolated primary spermatocytes maintain a specific pattern of RNA synthesis, which resembles RNA synthesis in spermatocytes in vivo. Therefore isolated spermatocytes of the rat can be used for studying the possible regulation of RNA synthesis during the meiotic prophase.

EFFECT OF ACTINOMYCIN D ON TSH-INDUCED STIMULATION OF THYROIDAL PROTEIN SYNTHESIS IN THE RAT

1974 ◽  
Vol 77 (1) ◽  
pp. 64-70 ◽  
Author(s):  
Gustav Wägar
Keyword(s):  
Protein Synthesis ◽  
Actinomycin D ◽  
The Other ◽  
Leucine Incorporation ◽  
Short Term ◽  
Other Hand ◽  
Thyroid Glands ◽  
Translational Level ◽  
Stimulation Of

ABSTRACT Whether the short-term regulation of thyroidal protein synthesis by TSH occurs at the transcriptional or the translational level was tested by measuring the effect of actinomycin D (act D) on the TSH-induced stimulation of L-14C-leucine incorporation into the thyroidal proteins of rats. TSH was injected 6 h before the rats were killed. The thyroid glands were then removed and incubated in vitro in the presence of L-14C-leucine for 2 h. The pronounced stimulation of leucine incorporation in the TSH-treated animals was depressed as compared with controls but still significant even when the animals had been pre-treated with 100 μg act D 24 and 7 h before sacrifice. On the other hand, act D strongly decreased incorporation of 3H-uridine into RNA. Short-term regulation of thyroidal protein synthesis by TSH appears to be partly but not wholly dependent on neosynthesis of RNA. Hence regulation may partly occur at the translation level of protein synthesis.

scholarly journals Pseudo-streaming potentials in Necturus gallbladder epithelium. II. The mechanism is a junctional diffusion potential.

1992 ◽  
Vol 99 (3) ◽  
pp. 317-338 ◽  
Author(s):  
L Reuss ◽  
B Simon ◽  
C U Cotton
Keyword(s):  
Time Course ◽  
Bathing Solution ◽  
Intercellular Spaces ◽  
Similar Time ◽  
Streaming Potentials ◽  
Osmotic Water ◽  
Lateral Intercellular Spaces ◽  
Transepithelial Voltage ◽  
Time Courses ◽  
Good Agreement

The mechanisms of apparent streaming potentials elicited across Necturus gallbladder epithelium by addition or removal of sucrose from the apical bathing solution were studied by assessing the time courses of: (a) the change in transepithelial voltage (Vms). (b) the change in osmolality at the cell surface (estimated with a tetrabutylammonium [TBA+]-selective microelectrode, using TBA+ as a tracer for sucrose), and (c) the change in cell impermeant solute concentration ([TMA+]i, measured with an intracellular double-barrel TMA(+)-selective microelectrode after loading the cells with TMA+ by transient permeabilization with nystatin). For both sucrose addition and removal, the time courses of Vms were the same as the time courses of the voltage signals produced by [TMA+]i, while the time courses of the voltage signals produced by [TBA+]o were much faster. These results suggest that the apparent streaming potentials are caused by changes of [NaCl] in the lateral intercellular spaces, whose time course reflects the changes in cell water volume (and osmolality) elicited by the alterations in apical solution osmolality. Changes in cell osmolality are slow relative to those of the apical solution osmolality, whereas lateral space osmolality follows cell osmolality rapidly, due to the large surface area of lateral membranes and the small volume of the spaces. Analysis of a simple mathematical model of the epithelium yields an apical membrane Lp in good agreement with previous measurements and suggests that elevations of the apical solution osmolality elicit rapid reductions in junctional ionic selectivity, also in good agreement with experimental determinations. Elevations in apical solution [NaCl] cause biphasic transepithelial voltage changes: a rapid negative Vms change of similar time course to that of a Na+/TBA+ bi-ionic potential and a slow positive Vms change of similar time course to that of the sucrose-induced apparent streaming potential. We conclude that the Vms changes elicited by addition of impermeant solute to the apical bathing solution are pseudo-streaming potentials, i.e., junctional diffusion potentials caused by salt concentration changes in the lateral intercellular spaces secondary to osmotic water flow from the cells to the apical bathing solution and from the lateral intercellular spaces to the cells. Our results do not support the notion of junctional solute-solvent coupling during transepithelial osmotic water flow.

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.

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