Protein synthesis is required for rapid degradation of tubulin mRNA and other deflagellation-induced RNAs in Chlamydomonas reinhardi

1986 ◽  
Vol 6 (1) ◽  
pp. 54-61
Author(s):  
E J Baker ◽  
L R Keller ◽  
J A Schloss ◽  
J L Rosenbaum
Keyword(s):  
Protein Synthesis ◽  
Transcriptional Control ◽  
Protein S ◽  
Protein Synthesis Inhibitors ◽  
Control Factors ◽  
Flagellar Proteins ◽  
The Stability ◽  
And Control

After flagellar detachment in Chlamydomonas reinhardi, there is a rapid synthesis and accumulation of mRNAs for tubulin and other flagellar proteins. Maximum levels of these mRNAs (flagellar RNAs) are reached within 1 h after deflagellation, after which they are rapidly degraded to their predeflagellation levels. The degradation of alpha- and beta-tubulin RNAs was shown to be due to the shortening of their half-lives after accumulation (Baker et al., J. Cell Biol. 99:2074-2081, 1984). Deflagellation in the presence of protein synthesis inhibitors results in the accumulation of tubulin and other flagellar mRNAs by kinetics similar to those of controls. However, unlike controls, in which the accumulated mRNAs are rapidly degraded, these mRNAs are stabilized in cycloheximide. The stabilization by cycloheximide is specific for the flagellar mRNAs accumulated after deflagellation, since there is no change in the levels of flagellar mRNAs in nondeflagellated (uninduced) cells in the presence of cycloheximide. The kinetics of flagellar mRNA synthesis after deflagellation are shown to be the same in cycloheximide-treated and control cells by in vivo labeling and in vitro nuclear runoff experiments. These results show that protein synthesis is not required for the induced synthesis of flagellar mRNAs, and that all necessary transcriptional control factors are present in the cell before deflagellation, but that protein synthesis is required for the accelerated degradation of the accumulated flagellar mRNAs. Since cycloheximide prevents the induced synthesis and accumulation of flagellar proteins, it is possible that the product(s) of protein synthesis required for the accelerated decay of these mRNAs is a flagellar protein(s). The possibility that one or more flagellar proteins autoregulate the stability of the flagellar mRNAs is discussed.

scholarly journals Protein synthesis is required for rapid degradation of tubulin mRNA and other deflagellation-induced RNAs in Chlamydomonas reinhardi.

1986 ◽  
Vol 6 (1) ◽  
pp. 54-61 ◽  
Author(s):  
E J Baker ◽  
L R Keller ◽  
J A Schloss ◽  
J L Rosenbaum
Keyword(s):  
Protein Synthesis ◽  
Transcriptional Control ◽  
Protein S ◽  
Protein Synthesis Inhibitors ◽  
Control Factors ◽  
Flagellar Proteins ◽  
The Stability ◽  
And Control

After flagellar detachment in Chlamydomonas reinhardi, there is a rapid synthesis and accumulation of mRNAs for tubulin and other flagellar proteins. Maximum levels of these mRNAs (flagellar RNAs) are reached within 1 h after deflagellation, after which they are rapidly degraded to their predeflagellation levels. The degradation of alpha- and beta-tubulin RNAs was shown to be due to the shortening of their half-lives after accumulation (Baker et al., J. Cell Biol. 99:2074-2081, 1984). Deflagellation in the presence of protein synthesis inhibitors results in the accumulation of tubulin and other flagellar mRNAs by kinetics similar to those of controls. However, unlike controls, in which the accumulated mRNAs are rapidly degraded, these mRNAs are stabilized in cycloheximide. The stabilization by cycloheximide is specific for the flagellar mRNAs accumulated after deflagellation, since there is no change in the levels of flagellar mRNAs in nondeflagellated (uninduced) cells in the presence of cycloheximide. The kinetics of flagellar mRNA synthesis after deflagellation are shown to be the same in cycloheximide-treated and control cells by in vivo labeling and in vitro nuclear runoff experiments. These results show that protein synthesis is not required for the induced synthesis of flagellar mRNAs, and that all necessary transcriptional control factors are present in the cell before deflagellation, but that protein synthesis is required for the accelerated degradation of the accumulated flagellar mRNAs. Since cycloheximide prevents the induced synthesis and accumulation of flagellar proteins, it is possible that the product(s) of protein synthesis required for the accelerated decay of these mRNAs is a flagellar protein(s). The possibility that one or more flagellar proteins autoregulate the stability of the flagellar mRNAs is discussed.

Faster protein and ribosome synthesis in thyroxine-induced hypertrophy of rat heart

1985 ◽  
Vol 248 (3) ◽  
pp. C309-C319 ◽  
Author(s):  
D. Siehl ◽  
B. H. Chua ◽  
N. Lautensack-Belser ◽  
H. E. Morgan
Keyword(s):  
Protein Synthesis ◽  
Single Injection ◽  
Plasma Concentrations ◽  
Bicarbonate Buffer ◽  
Ribosomal Subunits ◽  
Ribosome Synthesis ◽  
And Control ◽  
Perfused Hearts

Rates of protein synthesis and degradation were measured in hearts from normal and thyroxine-injected rats that were perfused as working preparations with Krebs-Henseleit bicarbonate buffer containing 400 microU insulin/ml, 2 mM lactate, 10 mM glucose, and normal plasma concentrations of amino acids. Hearts were perfused after four daily injections (1 microgram/g body wt) of thyroxine. Protein synthesis was 24% greater in hypertrophying hearts compared with controls; ribosomal RNA content increased 25%. In addition, the proportion of total RNA in free ribosomal subunits in hypertrophying hearts was unchanged from perfused hearts of control rats and from unperfused normal hearts. These results indicated that increased protein synthetic machinery as monitored by content of ribosomes, rather than more efficient initiation or elongation of peptide chains, accounted for the faster rate of protein synthesis in hypertrophying hearts. Rates of protein degradation were the same in hearts from thyroxine-injected and control animals. When rates of ribosome production were measured in vitro at various times after a single injection of thyroxine in vivo, faster ribosome synthesis was detected within 8 h; no change in the rate of total protein synthesis occurred after a single injection of thyroxine. These studies indicated that accelerated ribosome formation was an early and quantitatively important factor in cardiac hypertrophy.

‘Unmasking’ of stored maternal mRNAs and the activation of protein synthesis at fertilization in sea urchins

Development ◽  
1991 ◽  
Vol 111 (2) ◽  
pp. 623-633 ◽  
Author(s):  
L.C. Kelso-Winemiller ◽  
M.M. Winkler
Keyword(s):  
Protein Synthesis ◽  
Sea Urchins ◽  
In Vitro Assay ◽  
Vitro Assay ◽  
Translational Machinery ◽  
Maternal Mrnas ◽  
Additional Support ◽  
And Control

The isolation and in vitro assay of maternal mRNPs has led to differing conclusions as to whether maternal mRNAs in sea urchin eggs are in a repressed or ‘masked’ form. To circumvent the problems involved with in vitro approaches, we have used an in vivo assay to determine if the availability of mRNA and/or components of the translational machinery are limiting protein synthesis in the unfertilized egg. This assay involves the use of a protein synthesis elongation inhibitor to create a situation in the egg in which there is excess translational machinery available to bind mRNA. Eggs were fertilized and the rate of entry into polysomes of individual mRNAs was measured in inhibitor-treated and control embryos using 32P-labeled cDNA probes. The fraction of ribosomes in polysomes and the polysome size were also determined. The results from this in vivo approach provide strong evidence for the coactivation of both mRNAs and components of the translational machinery following fertilization. The average polysome size increases from 7.5 ribosomes per message in 15 min embryos to approximately 10.8 ribosomes in 2 h embryos. This result gives additional support to the idea that translational machinery, as well as mRNA, is activated following fertilization. We also found that individual mRNAs are recruited into polysomes with different kinetics, and that the fraction of an mRNA in polysomes in the unfertilized egg correlates with the rate at which that mRNA is recruited into polysomes following fertilization.

Differential behaviour of 25-hydroxyvitamin D3 24-hydroxylase and 1-hydroxylase in response to protein synthesis inhibitors and cytochrome P-450 inhibitors

1988 ◽  
Vol 66 (5) ◽  
pp. 586-591 ◽  
Author(s):  
M. Kung ◽  
S. W. Kooh ◽  
W. Paek ◽  
D. Fraser
Keyword(s):  
Protein Synthesis ◽  
Enzyme Activities ◽  
Protein Synthesis Inhibitors ◽  
Hydroxylase Activity ◽  
Hydroxyvitamin D ◽  
Control Value ◽  
25 Hydroxyvitamin D ◽  
Cytochrome P 450

To characterize 25-hydroxyvitamin D3 24-hydroxylase and 25-hydroxyvitamin D3 1-hydroxylase, the activities of the two enzymes were measured in the presence of two types of inhibitors. The effect of protein synthesis inhibitors on 25-hydroxyvitamin D3-stimulated 24-hydroxylase activity in 1-hydroxylating rat kidneys perfused in vitro was tested. Actinomycin D (4 μM) and cytoheximide (10 μM) each abolished 25-hydroxyvitamin D3 24-hydroxylase synthesis when added at the start of perfusion but not when added 4 h later; they did not affect 25-hydroxyvitamin D3 1-hydroxylase activity. The effects of cytochrome P-450 inhibitors on the two enzyme activities were then studied in vivo. Metyrapone and SKF-525A (50 mg/kg body weight) each inhibited 25-hydroxyvitamin D3 24-hydroxylase at 6 and 24 h; in contrast 1-hydroxylase increased and was 5 times the control value at 24 h. Finally, the in vitro effects of six cytochrome P-450 inhibitors at concentrations ranging from 10−7 to 10−3 M on enzyme activities in renal mitochondrial preparations were compared. Both enzymes were inhibited by all of the inhibitors, but inhibition of 25-hydroxyvitamin D3 24-hydroxylase was consistently greater than that of 25-hydroxyvitamin D3 1-hydroxylase. These studies demonstrate that 24-hydroxylation and 1-hydroxylation respond differently to protein synthesis inhibitors and to cytochrome P-450 inhibitors. The findings are consistent with the hypothesis that the two enzyme activities are associated with different cytochrome P-450 moieties.

A comparison of the decontamination efficacy of foam-making blends based on cationic and nonionic tensides against organophosphorus compounds determinedin vitro and in vivo

2003 ◽  
Vol 22 (9) ◽  
pp. 507-514 ◽  
Author(s):  
J Cabal ◽  
J Kassa ◽  
J Severa
Keyword(s):  
Hydrogen Peroxide ◽  
Field Condition ◽  
Benzalkonium Chloride ◽  
Organophosphorus Compounds ◽  
Antagonistic Effects ◽  
In Vitro Methods ◽  
The Stability ◽  
And Control

The ability of foam-making blends to decontaminate the skin exposed to organophosphorus compounds was tested. The appropriate composition and rheological features (stability, grade of foaming) of tested blends were evaluated by in vitro methods and their ability to remove the contaminants from hard surface and to transform the contaminants into nontoxic compounds was evaluated byin vivo methods. The blends containing cationic and nonionic tensides as well as alkalized hydrogen peroxide seem to be the most efficacious to decontaminate the skin exposed to organophosphorus compounds according to the literature data. The composition of tested blends was optimized because particular components often have antagonistic effects. Cationic tensides support the reactivity of the blend and control the grade of foaming. Nonionic tensides control the stability of the foams but also react as retardants of the reactivity of the foams. Hydrogen peroxide is a real reacting component when it is transformed into hydrogen peroxide anion. It also acts as buffer if pH is higher than 11. Our in vivo results confirm that Desam OX (34 and 68%) and the foam-making blend containing benzalkonium chloride / Althosan MB (8%), Slovasol 2510 (2%) and hydrogen peroxide (3%) alkalized at pH 12 seem to be the most efficacious to remove contaminants (soman, VX) from the skin and transform them into nontoxic compounds. Therefore they could be used for primary decontamination of chemical casualties contaminated with nerve agents in the field condition.

scholarly journals ALTERATIONS IN POLYRIBOSOMES DURING ERYTHROID CELL MATURATION

1964 ◽  
Vol 22 (3) ◽  
pp. 599-611 ◽  
Author(s):  
Richard A. Rifkind ◽  
David Danon ◽  
Paul A. Marks
Keyword(s):  
Protein Synthesis ◽  
Quantitative Analysis ◽  
Morphological Study ◽  
Protein Biosynthesis ◽  
Cell Maturation ◽  
Erythroid Cell ◽  
Erythroid Cells ◽  
The Stability

This communication presents a morphological study of the changes in ribosome content and organization which occur during the maturation of erythroid cells of the phenylhydrazine-treated rabbit. Electron micrographs of thin sectioned nucleated and non-nucleated erythroid cells have been subjected to a quantitative analysis of the distribution of ribosomes as polyribosomes of various sizes and as single ribosomes. The ribosomes of nucleated erythroid cells of marrow are virtually all arranged in the polyribosome configuration consisting of clusters of 2 to 6 individual ribosomes. These cells are the most active in the erythroid series in protein biosynthesis. During maturation to the non-nucleated reticulocyte stage, found in the circulating blood, there is a decrease in protein synthesizing capacity, a fall in total ribosome content, and, more significantly, a decrease in the number and size of polyribosomes. Maturation to the ribosome-free erythrocyte, either under in vitro or in vivo conditions, entails a further decrease in protein synthesis which correlates with a progressive disaggregation of the biosynthetically active polyribosomes into smaller clusters and inactive single ribosomes. Possible models which may account for the stability of the polyribosome and for the mechanism of polyribosome dissociation are discussed.

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.

scholarly journals Modulation of Release of Proinflammatory Bacterial Compounds by Antibacterials: Potential Impact on Course of Inflammation and Outcome in Sepsis and Meningitis

2002 ◽  
Vol 15 (1) ◽  
pp. 95-110 ◽  
Author(s):  
Roland Nau ◽  
Helmut Eiffert
Keyword(s):  
Protein Synthesis ◽  
Bacterial Load ◽  
Animal Experiments ◽  
Sufficient Evidence ◽  
Bacterial Protein ◽  
Protein Synthesis Inhibitors ◽  
Number Of Patients ◽  
Bacterial Protein Synthesis

SUMMARY Several bacterial components (endotoxin, teichoic and lipoteichoic acids, peptidoglycan, DNA, and others) can induce or enhance inflammation and may be directly toxic for eukaryotic cells. Bactericidal antibiotics which inhibit bacterial protein synthesis release smaller quantities of proinflammatory/toxic bacterial compounds than Β-lactams and other cell wall-active drugs. Among the Β-lactams, compounds binding to penicillin-binding protein 2 (PBP-2) release smaller amounts of bacterial substances than antibacterials inhibiting PBP-3. Generally, high antibiotic concentrations (more than 10 times the MIC) induce the release of fewer bacterial proinflammatory/toxic compounds than concentrations close to the MIC. In several in vitro and in vivo systems, bacteria treated with protein synthesis inhibitors or Β-lactams inhibiting PBP-2 induce less inflammation than bacteria treated with PBP-3-active Β-lactams. In mouse models of Escherichia coli peritonitis sepsis and of Streptococcus pneumoniae meningitis, lower release of proinflammatory bacterial compounds was associated with reduced mortality. In conclusion, sufficient evidence for the validity of the concept of modulating the release of proinflammatory bacterial compounds by antibacterials has been accumulated in vitro and in animal experiments to justify clinical trials in sepsis and meningitis. A properly conducted study addressing the potential benefit of bacterial protein synthesis inhibitors versus Β-lactam antibiotics will require both strict selection and inclusion of a large number of patients. The benefit of this approach should be greatest in patients with a high bacterial load.

Formation and Structure of Casein Micelles in Lactating Mammary Tissue

1970 ◽  
Vol 28 ◽  
pp. 150-151
Author(s):  
Robert J. Carroll ◽  
Marvin P. Thompson ◽  
Harold M. Farrell
Keyword(s):  
Size Distribution ◽  
G Protein ◽  
Milk Proteins ◽  
Mammary Tissue ◽  
Colloidal System ◽  
Casein Micelles ◽  
The Stability

Milk is an unusually stable colloidal system; the stability of this system is due primarily to the formation of micelles by the major milk proteins, the caseins. Numerous models for the structure of casein micelles have been proposed; these models have been formulated on the basis of in vitro studies. Synthetic casein micelles (i.e., those formed by mixing the purified αsl- and k-caseins with Ca2+ in appropriate ratios) are dissimilar to those from freshly-drawn milks in (i) size distribution, (ii) ratio of Ca/P, and (iii) solvation (g. water/g. protein). Evidently, in vivo organization of the caseins into the micellar form occurs in-a manner which is not identical to the in vitro mode of formation.

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