scholarly journals CELL ELONGATION IN THE CULTURED EMBRYONIC CHICK LENS EPITHELIUM WITH AND WITHOUT PROTEIN SYNTHESIS

1972 ◽  
Vol 55 (1) ◽  
pp. 82-92 ◽  
Author(s):  
Joram Piatigorsky ◽  
Henry deF. Webster ◽  
Miriam Wollberg
Keyword(s):  
Protein Synthesis ◽  
Cell Elongation ◽  
Time Course ◽  
De Novo ◽  
Lens Epithelium ◽  
Cell Length ◽  
Continuous Exposure ◽  
Embryonic Chick ◽  
The Mean ◽  
Chick Lens

Previous studies have shown that cells in the 6-day old embryonic chick lens epithelium elongate in tissue culture. In the present study, the time course of elongation during the 1st day of cultivation has been examined histologically. Cultured epithelia were also treated with cycloheximide or colchicine in order to determine if cell elongation depends on new protein synthesis and on the utilization of microtubules, respectively. In the first 5 hr of culture, the mean cell length increased from 11 µ to 21 µ. Subsequently, elongation was slower; the mean cell length was 28 µ after 24 hr in culture. Continuous exposure to cycloheximide did not inhibit the initial doubling of cell length, but did prevent further elongation. By contrast, colchicine inhibited elongation almost immediately. When added after the cell length had doubled, cycloheximide and colchicine each inhibited further elongation; the treated cells remained columnar. Radioautographic and electrophoretic tests showed that protein synthesis was not appreciably affected by colchicine, but was suppressed by cycloheximide. Electron microscopic examination revealed that microtubules oriented along surface membranes were present in epithelia cultured with serum alone and with cycloheximide, but not in those incubated with colchicine. These results indicate that the early stages of cell elongation in the cultured lens epithelium require an initial assembly and organization of preexisting microtubular elements and that continued elongation depends, in addition, on the de novo synthesis of protein, possibly microtubule protein.

LPS induces late cardiac functional protection against ischemia independent of cardiac and circulating TNF-α

1997 ◽  
Vol 273 (4) ◽  
pp. H1894-H1902 ◽  
Author(s):  
Xianzhong Meng ◽  
Lihua Ao ◽  
James M. Brown ◽  
Daniel R. Meldrum ◽  
Brett C. Sheridan ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Time Course ◽  
De Novo ◽  
Ischemia Reperfusion ◽  
Enzyme Linked Immunosorbent Assay ◽  
Isolated Hearts ◽  
Tnf Α ◽  
Peak Increase ◽  
De Novo Protein Synthesis ◽  
Lps Treatment

Lipopolysaccharide (LPS) and tumor necrosis factor (TNF)-α independently induce cardioprotection against ischemia in the rat at 24 h after administration, suggesting that endogenously synthesized TNF-α may play a role in LPS-induced protection. The purposes of this study were 1) to delineate the time course of LPS-induced cardiac functional protection against ischemia and its relation with myocardial and circulating TNF-α profile, 2) to examine whether prior protein synthesis inhibition abrogates the protection, and 3) to assess the effects of TNF-α inhibition and neutralization on the protection. Rats were treated with LPS (0.5 mg/kg ip). Cardiac functional resistance to normothermic global ischemia-reperfusion was examined at sequential time points after LPS treatment in isolated hearts by the Langendorff technique. Myocardial and circulating TNF-α was determined by enzyme-linked immunosorbent assay at 1–24 h after LPS treatment. Protection was apparent at 24 h, 3 days, and 7 days but not at 2 or 12 h. Maximal protection at 3 days was abolished by cycloheximide pretreatment (0.5 mg/kg ip 3 h before LPS treatment). Increases in myocardial and circulating TNF-α preceded the acquisition of protection. Dexamethasone pretreatment (4.0 or 8.0 mg/kg ip 30 min before LPS treatment) abolished peak increase in myocardial TNF-α and substantially suppressed circulating TNF-α (54.3 and 85.9% inhibition, respectively) without an influence on the maximal protection. Similarly, maximal protection was not affected by TNF binding protein (40 or 80 μg/kg iv immediately after LPS treatment). The results suggest that LPS-induced cardiac functional protection against ischemia is a delayed and long-lasting protective response that may involve de novo protein synthesis. Although LPS-induced increase in myocardial and circulating TNF-α precedes the delayed protection, it may not be required for the delayed protection.

Nicotinamide as a rapid-acting inhibitor of renal brush-border phosphate transport

1988 ◽  
Vol 255 (1) ◽  
pp. F15-F21 ◽  
Author(s):  
K. I. Wu ◽  
R. A. Bacon ◽  
H. A. Al-Mahrouq ◽  
S. A. Kempson
Keyword(s):  
Protein Synthesis ◽  
Transport System ◽  
Brush Border ◽  
Time Course ◽  
De Novo ◽  
Phosphate Transport ◽  
Renal Brush Border Membrane ◽  
Dependent Inhibition ◽  
De Novo Protein Synthesis ◽  
Renal Brush Border

Administration of nicotinamide to rats produces specific dose-dependent inhibition of Na+-dependent phosphate transport across the renal brush-border membrane (BBM) and an increase in urinary excretion of phosphate. The intracellular mechanism of action of nicotinamide is not well established. As a step in this direction, the present studies determined whether nicotinamide was a rapid- or slow-acting regulator of the BBM phosphate transport system. Nicotinamide (0.5 g/kg) inhibited Na+-dependent BBM phosphate transport under conditions when de novo protein synthesis was inhibited by cycloheximide (1.0 mg/kg). Furthermore, the degree of inhibition was not different from that achieved by nicotinamide alone, suggesting that the action of nicotinamide does not require de novo protein synthesis. Studies on the time course of the onset of nicotinamide action revealed inhibition of BBM phosphate transport within 1 h after injection of nicotinamide, even in rats pretreated with cycloheximide. The rapid response to nicotinamide and its independence of de novo protein synthesis characterize nicotinamide as a rapid-acting regulator of the Na+-dependent phosphate transport system in renal BBM.

Protein synthesis and ultrastructure during the formation of embryonic chick lens fibers in vivo and in vitro

1972 ◽  
Vol 27 (2) ◽  
pp. 176-189 ◽  
Author(s):  
Joram Piatigorsky ◽  
Henry deF. Webster ◽  
Sydney P. Craig
Keyword(s):  
Protein Synthesis ◽  
Embryonic Chick ◽  
Lens Fibers ◽  
Chick Lens

scholarly journals Tetrodotoxin Desensitization in Aggregates of Embryonic Chick Heart Cells

1973 ◽  
Vol 62 (3) ◽  
pp. 286-302 ◽  
Author(s):  
Terence F. McDonald ◽  
Howard G. Sachs ◽  
Robert L. DeHaan
Keyword(s):  
Protein Synthesis ◽  
Time Course ◽  
Mean Value ◽  
Slow Inward Current ◽  
Heart Cell ◽  
Heart Cells ◽  
Initial Sensitivity ◽  
Chick Heart ◽  
Embryonic Chick Heart ◽  
The Mean

Spontaneous beating of heart-cell aggregates from 4-day chick embryos was initially blocked by 10-5 g/ml tetrodotoxin (TTX). With continued exposure to the drug, the fraction of blocked aggregates decreased from about 80% at 15 min to about 25% at 2–3 h, at which time, beating aggregates had become desensitized to the toxin, showing no response to a fresh dose. Aggregates from 5-day hearts were more sensitive to TTX, but fewer became desensitized in its presence. Desensitization to TTX was not seen in 6- and 7-day aggregates. Inhibition of protein synthesis by cycloheximide did not affect beating or initial sensitivity to TTX of 4-day aggregates, but desensitization failed to occur. Before TTX, the mean value of maximal upstroke velocity (Vmax) of the action potentials in 4-day aggregates was 33 V/s. After desensitization Vmax was 12 V/s. Activity of desensitized aggregates in the presence of TTX was augmented by elevated calcium levels, and suppressed by presumed inhibitors of slow inward current (manganese, D600). Desensitization was reversible; upon removal of TTX 10-5 g/ml, aggregates regained their responsiveness to a fresh dose of the drug with a 2–3 h time-course similar to that of desensitization. This was prevented by continued exposure to TTX at concentrations as low as 10-8 g/ml. These data suggest that (a) desensitization involves a change in the mode of action-potential generating from one involving Na-specific, TTX-sensitive channels to one utilizing slower Mn-sensitive channels; (b) the process of desensitization occurs over a period of 2–3 h and is dependent upon the products of protein synthesis; and (c) desensitization is reversible after removal of TTX over a 2–3 h time-course similar to its onset.

Alteration of gene expression in tomato plants (Lycopersicon esculentum) by drought and salt stress

Genome ◽  
1992 ◽  
Vol 35 (3) ◽  
pp. 385-391 ◽  
Author(s):  
R. D. Chen ◽  
Z. Tabaeizadeh
Keyword(s):  
Protein Synthesis ◽  
Salt Stress ◽  
Drought Stress ◽  
Lycopersicon Esculentum ◽  
Time Course ◽  
De Novo ◽  
Polyacrylamide Gel Electrophoresis ◽  
Control Level ◽  
Protein Patterns ◽  
Stress Injury

The effect of drought and NaCl treatments on polypeptide levels in both roots and leaves of tomato (Lycopersicon esculentum) seedlings was analyzed using two-dimensional polyacrylamide gel electrophoresis. In roots, comparison of silver-stained protein patterns showed that during drought treatment two proteins were highly accumulated and after rehydration they returned to the control level. The same changes were also observed under salinity stress. Moreover, salt treatment induced stress-specific proteins. In leaves, the in vivo labelling of intact leaves with 35S-labelled methionine showed that drought stress resulted in progressive changes in the protein pattern. There is de novo synthesis of proteins and repression of preexisting protein synthesis. The time course of appearance of newly synthesized proteins was different during water stress. The changes in proteins were usually reversible after rehydration of the seedlings. Leaves of NaCl-treated plants did not synthesize any salt stress specific polypeptides, but the synthesis of several drought-modulated proteins was affected. It is suggested that the quantitative and qualitative changes in protein synthesis may contribute to stress-resistant or stress-injury mechanisms.Key words: drought stress, Lycopersicon esculentum, protein synthesis, salt stress.

scholarly journals Protein-synthesis-dependent induction of annexin I by glucocorticoid

1991 ◽  
Vol 275 (2) ◽  
pp. 313-319 ◽  
Author(s):  
W T Wong ◽  
S C Frost ◽  
H S Nick
Keyword(s):  
Gene Expression ◽  
Protein Synthesis ◽  
Time Course ◽  
Actinomycin D ◽  
De Novo ◽  
Lung Epithelial Cells ◽  
Annexin I ◽  
Lung Epithelial ◽  
Maximal Induction ◽  
I Gene

We demonstrate that annexin I/lipocortin I (lipo I) gene expression is regulated by dexamethasone (DEX) in mouse 3T3-L1 fibroblasts and LA-4 lung epithelial cells. We have characterized this induction further in 3T3-L1 fibroblasts. At 24 h after addition of DEX, the levels of lipo I mRNA and protein increased 5-fold and 1.5-fold respectively. Time-course experiments revealed that the induction was delayed by 2-4 h after DEX addition. Half-maximal induction of both lipo I mRNA and protein was achieved with 10 nM-DEX. Both actinomycin D and cycloheximide blocked the DEX effect on lipo I mRNA expression. These results indicate that the induction of lipo I by DEX has a transcriptional component and requires protein synthesis de novo.

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