scholarly journals Effects of progesterone on protein metabolism in chicken oviduct tissue pretreated with oestrogen

1970 ◽  
Vol 120 (2) ◽  
pp. 337-344 ◽  
Author(s):  
K. R. Muller ◽  
R. F. Cox ◽  
N. H. Carey
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Free Amino ◽  
Specific Radioactivity ◽  
Dna And Rna ◽  
Progesterone Treatment ◽  
Chicken Oviduct ◽  
Total Dna

1. The effect of simultaneous injections of oestrogen benzoate and progesterone (0.5mg/day each) on immature chicken oviduct tissue pretreated with oestrogen benzoate (0.5mg/day) was studied. 2. After 3 days of treatment with both hormones, the weight of the tissue doubles as compared with tissue treated only with oestradiol benzoate. 3. The progesterone-induced weight increase had no effect on total DNA content of the tissue, but greatly increased the protein/DNA and RNA/DNA ratios. 4. Amino acid incorporation in vivo after progesterone treatment was elevated as measured by using 2h pulses of amino acids; this effect could be accounted for by observed alterations in the concentrations of free amino acids in the tissue. 5. With longer pulses of amino acid the specific radioactivity of total protein remained high in tissue treated with progesterone, at times when specific radioactivity of protein in oestrogen-treated animals was diminishing. 6. From a knowledge of the specific radioactivity of labelled amino acids in the free amino acid pool and in newly synthesized protein, the rate of protein synthesis was estimated in differently treated tissues. 7. The results suggest that progesterone treatment does not cause an increase in protein synthesis. It is concluded that the observed accumulation of oviduct protein is achieved via an effect of progesterone on protein catabolism.

scholarly journals An analysis of errors in estimation of the rate of protein synthesis by constant infusion of a labelled amino acid

1978 ◽  
Vol 176 (2) ◽  
pp. 402-405 ◽  
Author(s):  
P J Garlick
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Detailed Analysis ◽  
Free Amino Acid ◽  
Free Amino ◽  
Specific Radioactivity ◽  
Constant Infusion ◽  
Simplifying Assumptions

Rates of protein synthesis in tissues can be calculated from the specific radioactivity of free and protein-bound amino acids at the end of a constant infusion of a labelled amino acid (Garlick, Millward & James (1973) Biochem. J. 136, 935–945]. The simplifying assumptions used in these calculations have been criticized [Madsen, Everett, Sparrow & Fowkes (1977) FEBS Lett. 79, 313–316]. A more detailed analysis using a programmable desk-top calculator is described, which shows that the errors introduced by the simplifying assumptions are small, particularly when the specific radioactivity of the free amino acid rises rapidly to a constant value.

Aminoacyl-tRNA and tissue free amino acid pools are equilibrated after a flooding dose of phenylalanine

1999 ◽  
Vol 277 (1) ◽  
pp. E103-E109 ◽  
Author(s):  
Teresa A. Davis ◽  
Marta L. Fiorotto ◽  
Hanh V. Nguyen ◽  
Douglas G. Burrin
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Free Amino Acid ◽  
Free Amino ◽  
Specific Radioactivity ◽  
Isotopic Labeling ◽  
Precursor Pool ◽  
Free Amino Acid Pools

The flooding dose method, which is used to measure tissue protein synthesis, assumes equilibration of the isotopic labeling between the aminoacyl-tRNA pool and the tissue and blood free amino acid pools. However, this has not been verified for a phenylalanine tracer in an in vivo study. We determined the specific radioactivity of [3H]phenylalanine in the aminoacyl-tRNA and the tissue and blood free amino acid pools of skeletal muscle and liver 30 min after administration of a flooding dose of phenylalanine along with [3H]phenylalanine. Studies were performed in neonatal pigs in the fasted and refed states and during hyperinsulinemic-euglycemic-amino acid clamps. The results showed that, 30 min after the administration of a flooding dose of phenylalanine, there was equilibration of the specific radioactivity of phenylalanine among the blood, tissue, and tRNA precursor pools. Equilibration of the specific radioactivity of the three precursor pools for protein synthesis occurred in both skeletal muscle and liver. Neither feeding nor insulin status affected the aminoacyl-tRNA specific radioactivity relative to the tissue free amino acid specific radioactivity. The results support the assumption that the tissue free amino acid pool specific radioactivity is a valid measure of the precursor pool specific radioactivity and thus can be used to calculate protein synthesis rates in skeletal muscle and liver when a flooding dose of phenylalanine is administered.

scholarly journals The specific radioactivity of the tissue free amino acid pool as a basis for measuring the rate of protein synthesis in the rat in vivo

1974 ◽  
Vol 142 (2) ◽  
pp. 413-419 ◽  
Author(s):  
Edward B. Fern ◽  
Peter J. Garlick
Keyword(s):  
Protein Synthesis ◽  
Amino Acid ◽  
Free Amino Acid ◽  
Free Amino ◽  
Gastrocnemius Muscle ◽  
Specific Radioactivity ◽  
Amino Acid Pool ◽  
Free Amino Acid Pool ◽  
Acid Pool

1. Rats were infused in vivo with [U-14C]glycine for periods of 2–6h, during which time the specific radioactivity of the free glycine in plasma and tissue approached a constant value. 2. Free serine also became labelled. The ratio of specific radioactivity of serine to that of glycine in the protein of liver, kidney, brain, jejunum, heart, diaphragm and gastrocnemius muscle was closer to the ratio in the free amino acid pool of the tissue than that of the plasma. 3. The kinetics of incorporation of [14C]glycine and [14C]serine into the protein of gastrocnemius muscle further suggested that the plasma free amino acids were not the immediate precursors of protein. 4. Infusion of rats with [U-14C]serine resulted in labelling of free glycine. The ratio of specific radioactivity of glycine to serine in the protein of liver, kidney, brain, jejunum and heart again suggested incorporation from a pool similar to the free amino acid pool of the tissue. 5. Rates of tissue protein synthesis calculated from the incorporation into protein of both radioactive glycine and serine, either infused or derived, were very similar when the precursor specific radioactivity was taken to be that in the total free amino acids of the tissue. Except for gastrocnemius muscle and diaphragm during the infusion of radioactive serine, the rates of tissue protein synthesis calculated from the specific radioactivity of the free glycine and serine in plasma differed markedly.

scholarly journals BIOSYNTHESIS IN ISOLATED ACETABULARIA CHLOROPLASTS

1972 ◽  
Vol 54 (2) ◽  
pp. 279-294 ◽  
Author(s):  
David C. Shephard ◽  
Wendy B. Levin
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Technical Problems ◽  
Hydrolyzed Protein ◽  
Protein Amino Acids ◽  
Amino Acid Labeling ◽  
Labeling Pattern

The ability of chloroplasts isolated from Acetabulana mediterranea to synthesize the protein amino acids has been investigated. When this chloroplast isolate was presented with 14CO2 for periods of 6–8 hr, tracer was found in essentially all amino acid species of their hydrolyzed protein Phenylalanine labeling was not detected, probably due to technical problems, and hydroxyproline labeling was not tested for The incorporation of 14CO2 into the amino acids is driven by light and, as indicated by the amount of radioactivity lost during ninhydrin decarboxylation on the chromatograms, the amino acids appear to be uniformly labeled. The amino acid labeling pattern of the isolate is similar to that found in plastids labeled with 14CO2 in vivo. The chloroplast isolate did not utilize detectable amounts of externally supplied amino acids in light or, with added adenosine triphosphate (ATP), in darkness. It is concluded that these chloroplasts are a tight cytoplasmic compartment that is independent in supplying the amino acids used for its own protein synthesis. These results are discussed in terms of the role of contaminants in the observed synthesis, the "normalcy" of Acetabularia chloroplasts, the synthetic pathways for amino acids in plastids, and the implications of these observations for cell compartmentation and chloroplast autonomy.

Effect of Cycloheximide on In Vitro and In Vivo Protein Synthesis by Certain Tissues of Rats and Pigeons with Special Reference to Muscle

1973 ◽  
Vol 51 (12) ◽  
pp. 933-941 ◽  
Author(s):  
Njanoor Narayanan ◽  
Jacob Eapen
Keyword(s):  
Amino Acids ◽  
Body Weight ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Amino Acid Incorporation ◽  
Contrast Administration ◽  
Acid Incorporation ◽  
Tissue Homogenates

The effect of cycloheximide in vitro and in vivo on the incorporation of labelled amino acids into protein by muscles, liver, kidneys, and brain of rats and pigeons was studied. In vitro incorporation of amino acids into protein by muscle microsomes, myofibrils, and myofibrillar ribosomes was not affected by cycloheximide. In contrast, administration of the antibiotic into intact animals at a concentration of 1 mg/kg body weight resulted in considerable inhibition of amino acid incorporation into protein by muscles, liver, kidneys, and brain. This inhibition was observed in all the subcellular fractions of these tissues during a period of 10–40 min after the administration of the precursor. Tissue homogenates derived from in vivo cycloheximide-treated animals did not show significant alteration in in vitro amino acid incorporation with the exception of brain, which showed a small but significant enhancement.

scholarly journals Measurement of protein synthesis in rat lungs perfused in situ

1980 ◽  
Vol 188 (1) ◽  
pp. 269-278 ◽  
Author(s):  
Clyde A. Watkins ◽  
D. Eugene Rannels
Keyword(s):  
Protein Synthesis ◽  
Amino Acid ◽  
Free Amino ◽  
Plasma Concentrations ◽  
Specific Radioactivity ◽  
Sole Source ◽  
Bicarbonate Buffer ◽  
Normal Plasma ◽  
Rat Lungs

Compartmentalization of amino acid was investigated to define conditions required for accurate measurements of rates of protein synthesis in rat lungs perfused in situ. Lungs were perfused with Krebs–Henseleit bicarbonate buffer containing 4.5% (w/v) bovine serum albumin, 5.6mm-glucose, normal plasma concentrations of 19 amino acids, and 8.6–690μm-[U-14C]phenylalanine. The perfusate was equilibrated with the same humidified gas mixture used to ventilate the lungs [O2/CO2 (19:1) or O2/N2/CO2 (4:15:1)]. [U-14C]Phenylalanine was shown to be a suitable precursor for studies of protein synthesis in perfused lungs: it entered the tissue rapidly (t½, 81s) and was not converted to other compounds. As perfusate phenylalanine was decreased below 5 times the normal plasma concentration, the specific radioactivity of the pool of phenylalanine serving as precursor for protein synthesis, and thus [14C]phenylalanine incorporation into protein, declined. In contrast, incorporation of [14C]histidine into lung protein was unaffected. At low perfusate phenylalanine concentrations, rates of protein synthesis that were based on the specific radioactivity of phenylalanyl-tRNA were between rates calculated from the specific radioactivity of phenylalanine in the extracellular or intracellular pools. Rates based on the specific radioactivities of these three pools of phenylalanine were the same when extracellular phenylalanine was increased. These observations suggested that: (1) phenylalanine was compartmentalized in lung tissue; (2) neither the extracellular nor the total intracellular pool of phenylalanine served as the sole source of precursor for protein; (3) at low extracellular phenylalanine concentrations, rates of protein synthesis were in error if calculated from the specific radioactivity of the free amino acid; (4) at high extracellular phenylalanine concentrations, the effects of compartmentalization were negligible and protein synthesis could be calculated accurately from the specific radioactivity of the free or tRNA-bound phenylalanine pool.

scholarly journals Amino acid regulation of synthesis of ribonucleic acid and protein in the liver of rats

1971 ◽  
Vol 124 (2) ◽  
pp. 385-392 ◽  
Author(s):  
R. W. Wannemacher ◽  
C. F. Wannemacher ◽  
M. B. Yatvin
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Free Amino Acids ◽  
Free Amino ◽  
Cellular Protein ◽  
Deficient Diet ◽  
Cellular Protein Content ◽  
Regulate Protein

Weanling (23-day-old) rats were fed on either a low-protein diet (6% casein) or a diet containing an adequate amount of protein (18% casein) for 28 days. Hepatic cells from animals fed on the deficient diet were characterized by markedly lower concentrations of protein and RNA in all cellular fractions as compared with cells from control rats. The bound rRNA fraction was decreased to the greatest degree, whereas the free ribosomal concentrations were only slightly less than in control animals. A good correlation was observed between the rate of hepatic protein synthesis in vivo and the cellular protein content of the liver. Rates of protein synthesis both in vivo and in vitro were directly correlated with the hepatic concentration of individual free amino acids that are essential for protein synthesis. The decreased protein-synthetic ability of the ribosomes from the liver of protein-deprived rats was related to a decrease in the number of active ribosomes and heavy polyribosomes. The lower ribosomal content of the hepatocytes was correlated with the decreased concentration of essential free amino acids. In the protein-deprived rats, the rate of accumulation of newly synthesized cytoplasmic rRNA was markedly decreased compared with control animals. From these results it was concluded that amino acids regulate protein synthesis (1) by affecting the number of ribosomes that actively synthesize protein and (2) by inhibiting the rate of synthesis of new ribosomes. Both of these processes may involve the synthesis of proteins with a rapid rate of turnover.

Correlation between osmoregulation and cell volume regulation

1987 ◽  
Vol 252 (4) ◽  
pp. R768-R773
Author(s):  
M. A. Lang
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Osmotic Pressure ◽  
Cell Volume ◽  
Free Amino Acids ◽  
Volume Regulation ◽  
Free Amino ◽  
Cell Volume Regulation

The euryhaline crab, Callinectes sapidus, behaves both as an osmoregulator when equilibrated in salines in the range of 800 mosM and below and an osmoconformer when equilibrated in salines above 800 mosM. There exists a close correlation between osmoregulation seen in the whole animal in vivo and cell volume regulation studied in vitro. Hyperregulation of the hemolymph osmotic pressure and cell volume regulation both occurred in salines at approximately 800 mosM and below. During long-term equilibration of the crabs to a wide range of saline environments, the total concentration of hemolymph amino acids plus taurine remained below 3 mM. During the first 6 h after an acute osmotic stress to the whole animal, the hemolymph osmotic pressure and Na activity gradually decreased, whereas the free amino acids remained below 3 mM. As the hemolymph osmotic pressure decreased below approximately 850 mosM, the amino acid level began to increase to 17-25 mM. This change was primarily due to increases in glycine, proline, taurine, and alanine. The likely source of the increase in hemolymph free amino acids in vivo is the free amino acid loss from muscle cells observed during cell volume regulation in vitro.

scholarly journals Amino acid infusion increases the sensitivity of muscle protein synthesis in vivo to insulin. Effect of branched-chain amino acids

1988 ◽  
Vol 254 (2) ◽  
pp. 579-584 ◽  
Author(s):  
P J Garlick ◽  
I Grant
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Branched Chain Amino Acids ◽  
Acid Infusion ◽  
Amino Acid Infusion ◽  
Branched Chain

Rates of muscle protein synthesis were measured in vivo in tissues of post-absorptive young rats that were given intravenous infusions of various combinations of insulin and amino acids. In the absence of amino acid infusion, there was a steady rise in muscle protein synthesis with plasma insulin concentration up to 158 mu units/ml, but when a complete amino acids mixtures was included maximal rates were obtained at 20 mu units/ml. The effect of the complete mixture could be reproduced by a mixture of essential amino acids or of branched-chain amino acids, but not by a non-essential mixture, alanine, methionine or glutamine. It is concluded that amino acids, particularly the branched-chain ones, increase the sensitivity of muscle protein synthesis to insulin.

scholarly journals The regulation of protein synthesis in the liver of rats. Mechanisms of dietary amino acid control in the immature animal

1968 ◽  
Vol 107 (5) ◽  
pp. 615-623 ◽  
Author(s):  
R. W. Wannemacher ◽  
W. K. Cooper ◽  
M. B. Yatvin
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Specific Radioactivity ◽  
Protein Diet ◽  
Low Protein Diet ◽  
Deficient Diet ◽  
Low Protein ◽  
Rna Content ◽  
Cytoplasmic Rna

Weanling (23-day-old) rats were fed either on an amino acid-deficient diet (6% of casein, which in effect represents an ‘amino acid-deficient’ diet) or on a diet containing an adequate amount of protein (18% of casein) for 28 days. The hepatic cells from the animals fed on the low-protein diet were characterized by low amino acid content, almost complete inhibition of cell proliferation and a marked decrease in cell volume, protein content and concentration of cytoplasmic RNA compared with cells from control rats. The lower concentration of cytoplasmic RNA was correlated with a decreased ribosomal-RNA content, of which a larger proportion was in the form of free ribosomes. The protein-synthetic competence and messenger-RNA content of isolated ribosomes from liver cells of protein-deprived animals were 40–50% of those noted in controls. At 1hr. after an injection of radioactive uridine, the specific radioactivity of liver total RNA was greater in the group fed on the low-protein diet, but the amount of label that was associated with cytoplasmic RNA or ribosomes was significantly less than that noted in control animals. From these data it was concluded that dietary amino acids regulate hepatic protein synthesis (1) by affecting the ability of polyribosomes to synthesize protein and (2) by influencing the concentration of cytoplasmic ribosomes. It is also tentatively hypothesized that the former process may be directly related to the concentration of cellular free amino acids, whereas the latter could be correlated with the ability of newly synthesized ribosomal sub-units to leave the nucleus.

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