scholarly journals A possible mechanism of inhibition of protein synthesis by dimethylnitrosamine

1967 ◽  
Vol 105 (2) ◽  
pp. 625-631 ◽  
Author(s):  
S. Villa-Treviño
Keyword(s):  
Protein Synthesis ◽  
Messenger Rna ◽  
Transfer Rna ◽  
The State ◽  
Leucine Incorporation ◽  
Mechanism Of Inhibition ◽  
Nuclear Rna ◽  
Inhibition Of Protein Synthesis ◽  
Hepatic Protein Synthesis

1. The incorporation of [14C]leucine into liver proteins of rats was measured in vivo at various times after treatment of the animals with dimethylnitrosamine and was correlated with the state of the liver ribosomal aggregates. Inhibition of incorporation ran parallel with breakdown of the aggregates. 2. Inhibition of leucine incorporation into protein and breakdown of ribosomal aggregates were not preceded by inhibition of incorporation of [14C]orotate into nuclear RNA of the liver. 3. Evidence was obtained of methylation of nuclear RNA in the livers of rats treated with [14C]dimethylnitrosamine. 4. Zonal centrifugation analysis of radioactive, nuclear, ribosomal and transfer RNA from livers of rats treated with [14C]dimethylnitrosamine revealed labelling of all centrifugal fractions to about the same extent. 5. It is suggested that methylation of messenger RNA might occur in the livers of dimethylnitrosamine-treated rats and the possible relation of this to inhibition of hepatic protein synthesis is discussed.

scholarly journals Inhibition of protein synthesis by N-methyl-N-nitrosourea in vivo

1973 ◽  
Vol 136 (2) ◽  
pp. 303-309 ◽  
Author(s):  
P. Kleihues ◽  
P. N. Magee
Keyword(s):  
Protein Synthesis ◽  
Direct Consequence ◽  
Maximum Effect ◽  
Adult Rat ◽  
Mechanism Of Inhibition ◽  
Weanling Rats ◽  
Inhibition Of Protein Synthesis ◽  
Hepatic Protein Synthesis

1. The intraperitoneal injection of N-methyl-N-nitrosourea (100mg/kg) caused a partial inhibition of protein synthesis in several organs of the rat, the maximum effect occurring after 2–3h. 2. In the liver the inhibition of protein synthesis was paralleled by a marked disaggregation of polyribosomes and an increase in ribosome monomers and ribosomal subunits. No significant breakdown of polyribosomes was found in adult rat brains although N-methyl-N-nitrosourea inhibited cerebral and hepatic protein synthesis to a similar extent. In weanling rats N-methyl-N-nitrosourea caused a shift in the cerebral polyribosome profile similar to but less marked than that in rat liver. 3. Reaction of polyribosomal RNA with N-[14C]methyl-N-nitrosourea in vitro did not lead to a disaggregation of polyribosomes although the amounts of 7-methylguanine produced were up to twenty times higher than those found after administration of sublethal doses in vivo. 4. It was concluded that changes in the polyribosome profile induced by N-methyl-N-nitrosourea may reflect the mechanism of inhibition of protein synthesis rather than being a direct consequence of the methylation of polyribosomal mRNA.

scholarly journals Effects of the hepatotoxic agents retrorsine and aflatoxin B1 on hepatic protein synthesis in the rat

1968 ◽  
Vol 109 (1) ◽  
pp. 87-91 ◽  
Author(s):  
S. Villa-Treviño ◽  
D. D. Leaver
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Rat Liver ◽  
Aflatoxin B1 ◽  
Plasma Proteins ◽  
Pyrrolizidine Alkaloid ◽  
Main Site ◽  
Nuclear Rna ◽  
Hepatic Protein Synthesis

1. Aflatoxin and the pyrrolizidine alkaloid retrorsine inhibited the incorporation of labelled amino acids into rat liver and plasma proteins in vivo. Inhibition was greater and detected earlier with retrorsine (1hr.) than with aflatoxin (3hr.). 2. Both toxins affected the liver ribosomal aggregates, causing increases in the proportion of monomers plus dimers. The effect of retrorsine was greater than that of aflatoxin. 3. Incorporation of labelled amino acids into proteins of cell-free preparations of liver from rats treated with aflatoxin was lower than in control preparations. The main site of inhibition appeared to be the ribosomes. 4. Both toxins inhibited the incorporation of orotate into liver nuclear RNA 1hr. after administration.

Role of the state of reduction of the nad system on the regulation of hepatic protein synthesis in the rat in vivo

1982 ◽  
Vol 14 (7) ◽  
pp. 615-620 ◽  
Author(s):  
Sebastian Cerdan Garcia-Esteller ◽  
SofÍa Sanchez Robles ◽  
Angeles Martin-Requero ◽  
Matilde S. Ayuso-Parrilla ◽  
Roberto Parrilla
Keyword(s):  
Protein Synthesis ◽  
The State ◽  
Role Of The State ◽  
Hepatic Protein Synthesis

Use of an in Vitro Protein Synthesizing System to Test the Mode of Action of Chloracetamides

Weed Science ◽  
1980 ◽  
Vol 28 (3) ◽  
pp. 334-340 ◽  
Author(s):  
Luanne M. Deal ◽  
J. T. Reeves ◽  
B. A. Larkins ◽  
F. D. Hess
Keyword(s):  
Protein Synthesis ◽  
Sand Culture ◽  
Leucine Incorporation ◽  
Insoluble Protein ◽  
In Vitro System ◽  
A Cell ◽  
Protein Incorporation ◽  
Vitro Protein

The effects of chloracetamides on protein synthesis were studied both in vivo and in vitro. Four chloracetamide herbicides, alachlor [2-chloro-2′,6′-diethyl-N-(methoxymethyl)acetanilide], metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide], CDAA (N–N-diallyl-2-chloroacetamide), and propachlor (2-chloro-N-isopropylacetanilide) were tested for inhibition of [3H]-leucine incorporation into protein. Incorporation of3H-leucine into trichloroacetic acid (TCA)-insoluble protein was inhibited in oat (Avena sativaL. ‘Victory’) seedlings grown in sand culture and treated 12 h at 1 × 10−4M with these chloracetamides. The herbicides were also tested in a cell-free protein synthesizing system containing polyribosomes purified from oat root cytoplasm. These herbicides had no effect on the rates of polypeptide elongation nor on the synthesis of specific polypeptides when herbicides (1 × 10−4M) were added directly to the system. Polypeptide formation was inhibited 89% when 1 × 10−4M cycloheximide was added during translation. Cytoplasmic polyribosomes were isolated from oat roots treated 12 h with 1 × 10−4M herbicide. Translation rates and products were not altered when these polyribosomes were added to the in vitro system. Protein synthesis is inhibited when tested in an in vivo system; however, the inhibition does not occur during the translation of mRNA into protein.

scholarly journals Effect of post-ischaemic recovery on albumin synthesis and relative amount of translatable albumin messenger RNA in rat liver

1982 ◽  
Vol 204 (1) ◽  
pp. 197-202 ◽  
Author(s):  
G Cairo ◽  
L Schiaffonati ◽  
M G Aletti ◽  
A Bernelli-Zazzera
Keyword(s):  
Protein Synthesis ◽  
Total Protein ◽  
Messenger Rna ◽  
Relative Proportion ◽  
Liver Homogenate ◽  
Albumin Synthesis ◽  
Specific Proteins ◽  
Membrane Bound ◽  
Albumin Mrna

In liver cells recovering from reversible ischaemia, total protein synthesis by postmitochondrial supernatant and membrane-bound and free polyribosomes is not different from that in sham-operated controls. However, the relative proportion of specific proteins is changed, since the incorporation of [3H]leucine in vivo into liver albumin, relative to incorporation into total protein, as determined by precipitation of labelled albumin with the specific antibody, decreases by 40-50% in post-ischaemic livers. Cell-free synthesis by membrane-bound polyribosomes and poly(A)-enriched RNA isolated from unfractionated liver homogenate shows that the decrease in albumin synthesis in liver of rats recovering from ischaemia is due to the relative decrease in translatable albumin mRNA.

Comparison of hepatic protein synthesis in vivo versus in vitro in the tumor-bearing rat

1987 ◽  
Vol 42 (1) ◽  
pp. 43-50 ◽  
Author(s):  
Robert S. Warren ◽  
M. Jeevanandam ◽  
Murray F. Brennan
Keyword(s):  
Protein Synthesis ◽  
Tumor Bearing ◽  
Hepatic Protein Synthesis

INDUCTION OF CYTOCHROME P-448 BY 3-METHYLCHOLANTHRENE IN THE RAT DURING INHIBITION OF PROTEIN SYNTHESIS IN VIVO

1977 ◽  
pp. 551-558 ◽  
Author(s):  
Georg F. Kahl ◽  
Bernd Zimmer ◽  
Teresa Galinsky ◽  
Hans G. Jonen ◽  
Regine Kahl
Keyword(s):  
Protein Synthesis ◽  
Inhibition Of Protein Synthesis
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