Protein metabolism in cultured plant tissues. Calculation of an absolute rate of protein synthesis, accumulation, and degradation in tobacco callus in vivo

Biochemistry ◽  
1971 ◽  
Vol 10 (1) ◽  
pp. 81-88 ◽  
Author(s):  
John D. Kemp ◽  
Dennis W. Sutton
Keyword(s):  
Protein Synthesis ◽  
Protein Metabolism ◽  
Plant Tissues ◽  
Tobacco Callus ◽  
Absolute Rate

scholarly journals Protein metabolism in the mouse during pregnancy and lactation

1987 ◽  
Vol 248 (1) ◽  
pp. 251-257 ◽  
Author(s):  
P E Millican ◽  
R G Vernon ◽  
V M Pain
Keyword(s):  
Protein Synthesis ◽  
Protein Metabolism ◽  
Gastrocnemius Muscle ◽  
Mammary Glands ◽  
Whole Body ◽  
Absolute Rate ◽  
Pregnancy And Lactation ◽  
Day By Day ◽  
Stimulation Of

Protein synthesis was measured in vivo in the whole body and in a number of individual tissues in mice at various stages of pregnancy and lactation. The absolute rate of protein synthesis in the whole body increased from 640 mg/day in virgin mice to 1590 mg/day by day 18 of pregnancy, and to 2100 mg/day by day 15 of lactation. Large proportions of these increments were contributed by the rapidly growing foetuses and placentae in the pregnant animals and by protein synthesis in the mammary glands during lactation. In addition, a substantial stimulation of growth and protein synthesis was also observed in the liver and the gastrointestinal tract. Gastrocnemius muscle showed no changes in protein metabolism, indicating that in the well-fed mouse this tissue is not required to play a role as a protein reserve during pregnancy and lactation.

scholarly journals Comprehensive assessment of post-prandial protein handling by the application of intrinsically labelled protein in vivo in human subjects

2021 ◽  
pp. 1-9
Author(s):  
Jorn Trommelen ◽  
Andrew M. Holwerda ◽  
Philippe J. M. Pinckaers ◽  
Luc J. C. van Loon
Keyword(s):  
Protein Synthesis ◽  
Amino Acid ◽  
Stable Isotope ◽  
Dietary Protein ◽  
Protein Metabolism ◽  
Muscle Protein ◽  
Human Subjects ◽  
Whole Body ◽  
Body Protein

All human tissues are in a constant state of remodelling, regulated by the balance between tissue protein synthesis and breakdown rates. It has been well-established that protein ingestion stimulates skeletal muscle and whole-body protein synthesis. Stable isotope-labelled amino acid methodologies are commonly applied to assess the various aspects of protein metabolism in vivo in human subjects. However, to achieve a more comprehensive assessment of post-prandial protein handling in vivo in human subjects, intravenous stable isotope-labelled amino acid infusions can be combined with the ingestion of intrinsically labelled protein and the collection of blood and muscle tissue samples. The combined application of ingesting intrinsically labelled protein with continuous intravenous stable isotope-labelled amino acid infusion allows the simultaneous assessment of protein digestion and amino acid absorption kinetics (e.g. release of dietary protein-derived amino acids into the circulation), whole-body protein metabolism (whole-body protein synthesis, breakdown and oxidation rates and net protein balance) and skeletal muscle metabolism (muscle protein fractional synthesis rates and dietary protein-derived amino acid incorporation into muscle protein). The purpose of this review is to provide an overview of the various aspects of post-prandial protein handling and metabolism with a focus on insights obtained from studies that have applied intrinsically labelled protein under a variety of conditions in different populations.

Enhancement of tumor proteolysis by TNF-alpha: correlation of in vivo isotope estimates with growth

1991 ◽  
Vol 261 (1) ◽  
pp. R106-R116
Author(s):  
N. W. Istfan ◽  
P. R. Ling ◽  
G. L. Blackburn ◽  
B. R. Bistrian
Keyword(s):  
Protein Synthesis ◽  
Protein Metabolism ◽  
Whole Body ◽  
Independent Effect ◽  
Yoshida Sarcoma ◽  
Protein Breakdown ◽  
Body Protein ◽  
Breakdown Rates ◽  
Made In

To evaluate the accuracy of in vivo estimates of protein synthesis and breakdown, measurements of plasma and tissue leucine kinetics were made in rat tumor tissues at different conditions of growth by use of constant intravenous infusion of [14C]leucine. These measurements were made in Yoshida sarcoma tumors on days 10 and 13 after implantation, with and without tumor necrosis factor (TNF) infusion and on day 10 in Walker-256 carcinosarcoma. Expressed as micromoles of leucine per gram tissue, tumor protein breakdown increased (P less than 0.01) from 0.32 +/- 0.02 to 0.52 +/- 0.09 (SE) mumol/h, with progress of the Yoshida sarcoma tumor between days 10 and 13 after implantation. Similarly, TNF increased tumor proteolysis on day 10 (0.43 +/- 0.03 mumol.h-1.g-1, P less than 0.05 vs. day 10 control) but not on day 13 after implantation of the Yoshida tumor. Estimates of growth derived from the difference between protein synthesis and breakdown rates were not statistically different from those based on actual tumor volume changes in both tumor models. However, estimates of “whole body” protein metabolism (plasma leucine flux) were not affected either by tumor aging or by treatment with TNF. This study shows that in vivo estimates of tissue protein metabolism based on our [14C]leucine constant infusion model closely reflect the growth characteristic of that tissue. A cytotoxic perfusion-independent effect for intravenous TNF on growing tumor tissue is demonstrable as increased protein breakdown. Furthermore, the commonly used concept of whole body protein metabolism, derived solely from tracer dilution in plasma, is an oversimplification.

scholarly journals ALTERATIONS IN PROTEIN AND NUCLEIC ACID METABOLISM OF LYMPHOMA 6C3HED-OG CELLS IN MICE GIVEN GUINEA PIG SERUM

1966 ◽  
Vol 123 (1) ◽  
pp. 55-74 ◽  
Author(s):  
Leslie H. Sobin ◽  
John G. Kidd
Keyword(s):  
Protein Synthesis ◽  
Guinea Pig ◽  
Protein Metabolism ◽  
Acid Metabolism ◽  
Tritiated Thymidine ◽  
Lymphoma Cells ◽  
Cell Counter ◽  
Pig Serum

Lymphoma 6C3HED-OG cells, known from previous work to be susceptible to the effects of guinea pig serum in vivo and dependent upon extrinsic asparagine for protein synthesis and growth in vitro, remained for the most part morphologically intact and countable in the electronic cell counter following exposures of 1 and 2 hr to the effects of heated (56°C, 30 min) guinea pig serum injected into the peritoneal cavities of mice in which the lymphoma cells were growing rapidly; after exposures of 4 and 6 hr the bulk of the -OG cells remained still intact and countable in the cell counter, though by this time a small proportion of them (5 to 12%) proved stainable with eosin in wet preparations) hence were presumably nonviable. After 12, 16, and 24 hr of exposure, however, the bulk of the -OG cells were either lysed or fragmented, to the extent that they did not register in the cell counter. Morphologic studies of the cells exposed 16 and 24 hr to the effects of heated guinea pig serum in vivo, disclosed that most of the cells then remaining were either frankly necrotic or greatly altered otherwise, marked vacuolation of the cytoplasm being the most conspicuous alteration in cells not yet obviously necrotic. Long before the bulk of the Lymphoma 6C3HED-OG cells had become conspicuously changed morphologically following exposure to the effects of heated guinea pig serum in vivo, they manifested striking alterations in protein metabolism, as was disclosed by "pulse" studies with radioactive valine. For example, the protein metabolism of -OG cells, as measured by their incorporation of L-valine-C14, was sharply curtailed following 15 min of exposure to heated guinea pig serum in vivo, as compared with valine incorporation by cells labeled immediately after exposure to the guinea pig serum. Following exposure to heated guinea pig serum during 60 min, -OG cells incorporated less than half as much L-valine-C14 as did cells labeled immediately after exposure, and the incorporation of L-valine-C14 was still less after 120 min of exposure. By contrast, Lymphoma -RG1 cells, known from previous work to be wholly insusceptible to the effects of guinea pig serum in vivo and independent of need for extrinsic asparagine for protein synthesis and growth in vitro, showed no curtailment whatever of protein synthesis following exposures to the effects of heated guinea pig serum in vivo during periods of 15, 60, and 120 min. Reasons are given for considering the prompt inhibition of protein synthesis in the asparagine-dependent -OG cells a direct result of asparagine-deprivation induced in vivo by the injected guinea pig serum, the L-asparaginase of which presumably converted the available L-asparagine of the host to L-aspartic acid that was not taken up by the -OG cells. The synthesis of deoxyribonucleic acid by Lymphoma 6C3HED-OG cells, as measured by the incorporation of thymidme-H3, determined with the aid of liquid scintillation counting and autoradiography, was also altered by exposure of the lymphoma cells to the effects of heated guinea pig serum in vivo, though not during exposures of 15 and 60 min; only after an exposure of 120 min did the population of -OG cells incorporate notably less thymidine-H3 than did control populations, though after 240 min of exposure the -OG cells incorporated less than one-fifth as much tritiated thymidineas had -OG cells exposed to heated guinea pig serum for 60 min or to heated horse serum for periods up to 240 min. Autoradiographs indicated that DNA synthesis by -OG cells normally proceeds at an intense level that leads to some 60% of these cells being heavily labeled in autoradiographs at any given time; after exposure to the effects of heated guinea pig serum during 2 and 4 hr in vivo, however, the lymphoma cells lost their ability to incorporate enough tritiated thymidine to become heavily labeled, but approximately the same proportion of them (56 to 58%) retained their ability to incorporate sufficient tritiated thymidine to become lightly labeled. The possibility is considered that the inhibition of DNA synthesis in the asparagine-dependent -OG cells exposed to the effects of heated guinea pig serum in vivo may be secondary to the previously manifest inhibition of protein synthesis. Further, in tests of ribonucleic acid metabolism of Lymphoma 6C3HED-OG cells after exposure to the effects of heated guinea pig serum in vivo during periods of 15, 60, 120, and 240 min, the findings indicated that the ability of the lymphoma cells to synthesize RNA, as measured by their capacity to incorporate uridine-5-H3, remained unaltered during the exposures of 15, 60, and 120 min, but was substantially reduced following 240 min of exposure. The findings are considered in relation to the probability, disclosed in part by previous studies, that heated guinea pig serum brings about its effects upon Lymphoma 6C3HED-OG cells in vivo by providing active L-asparaginase in large amounts, which presumably converts the available (extracellular) asparagine of the host to aspartic acid, the latter not being taken up by the lymphoma cells in vivo or in vitro. Hence it seems likely that heated guinea pig serum in this way brings about a state of asparagine deprivation that is responsible for the sequential metabolic and morphologic alterations that become manifest in asparagine-dependent Lymphoma 6C3HED-OG cells following their exposure to the effects of guinea pig serum in vivo, as here described.

scholarly journals PROTEIN METABOLISM IN TUMOR CELLS AT VARIOUS STAGES OF GROWTH IN VIVO

1974 ◽  
Vol 62 (3) ◽  
pp. 585-593 ◽  
Author(s):  
Massimo Olivotto ◽  
Francesco Paoletti
Keyword(s):  
Protein Synthesis ◽  
Amino Acid ◽  
Tumor Cells ◽  
Protein Metabolism ◽  
Protein Turnover ◽  
Specific Activity ◽  
Cell Mass ◽  
Ascites Hepatoma ◽  
Two Phases

Protein metabolism of Yoshida ascites hepatoma cells was studied in the early phase of logarithmic proliferation and in the following stage in which cell mass remains constant (resting phase). The rate of protein synthesis was measured by a short-time incorporation of [8H]lysine, while degradation was concurrently assessed by following the decrease of specific activity of [14C]lysine-labeled proteins. Most of the labeled amino acid injected intraperitoneally into the animal was immediately available for the tumor cells, with only a minor loss towards the extra-ascitic compartment. It was thus possible to calculate the dilution of the isotope in the ascitic pool of the lysine, which increased concurrently with the ascitic plasma volume. Amino acid transport capacity did not change in the log vs. the resting cells. This fact permitted the correction of the specific activity of the proteins synthesized by tumors in the two phases, taking into account the dilution effect. Protein synthesis was found to proceed at a constant rate throughout each of the two phases, although it was 30% lower during the resting as compared to the log phase. When cell mass attained the steady-state, protein degradation occurred at such a level as to balance the synthesis. Throughout the resting phase the amount of lysine taken up by the cells and renewed from the blood remained unchanged. Protein turnover, as studied in subcellular fractions, exhibited a similar rate in nuclei and microsomes, where it proceeded at a higher level than in mitochondria. On the whole, the results encourage the use of the Yoshida ascites hepatoma as a suitable model for studying protein turnover in relation to cell growth in vivo.

scholarly journals Effect of hypophysectomy on the rates of protein synthesis and degradation in rat liver

1979 ◽  
Vol 178 (3) ◽  
pp. 725-731 ◽  
Author(s):  
R D Conde
Keyword(s):  
Protein Synthesis ◽  
Protein Degradation ◽  
Rat Liver ◽  
Protein Metabolism ◽  
Plasma Proteins ◽  
Degradation Rates ◽  
Hypophysectomized Rats ◽  
Protein Synthesis And Degradation ◽  
Synthesis And Degradation

The effect of hypophysectomy on the protein metabolism of the liver in vivo was studied. Fractional rates of protein synthesis and degradation were determined in the livers of normal and hypophysectomized rats. Synthesis was measured after the injection of massive amounts of radioactive leucine. Degradation was estimated either as the balance between synthesis and accumulation of stable liver proteins or from the disappearance of radioactivity from the proteins previously labelled by the injection of NaH14CO3. The results indicate that: (1) hypophysectomy diminishes the capacity of the liver to synthesize proteins in vivo, mainly of those that are exported as plasma proteins; (2) livers of both normal and hypophysectomized rats show identical protein-degradation rates, whereas plasma proteins are degraded slowly after hypophysectomy.

Protein metabolism by rat lung: influence of fasting, glucose, and insulin

1977 ◽  
Vol 43 (3) ◽  
pp. 463-467 ◽  
Author(s):  
L. A. Thet ◽  
M. D. Delaney ◽  
C. A. Gregorio ◽  
D. Massaro
Keyword(s):  
Protein Synthesis ◽  
Protein Content ◽  
Protein Metabolism ◽  
Specific Radioactivity ◽  
Rat Lung ◽  
Synthetic Process ◽  
In Vitro System ◽  
Other Substances

We studied protein metabolism by rat lung slices. We found that phenylalanine is not metabolized to other substances by the lung and that the rate of incorporation of L-[U-14C]phenylalanine into protein, calculated using its intracellular specific radioactivity, reached a maximum within 20 min and remained stable for the rest of a 3-h incubation. The rate of protein degradation, determined using [12C]phenylalanine as a marker, was linear over a 3-h incubation. Fasting for 3 days slowed the increase in lung protein content of fasted compared to nonfasted rats; there was also a decrease in protein synthesis and an increase in proteolysis. In fed rats, glucose, insulin, and glucose plus insulin did not alter protein synthesis. Glucose, insulin alone, and glucose plus insulin decreased proteolysis. We conclude that the in vitro system reflected changes in the in vivo protein content of the lung. Fasting decreases protein synthesis and increases proteolysis. Glucose and insulin alone modulate protein metabolism in the lung by acting on the degradative rather than the synthetic process.

Cardiac protein content and synthesis in vivo after voluntary running or head-down suspension

1994 ◽  
Vol 76 (6) ◽  
pp. 2814-2819 ◽  
Author(s):  
E. J. Henriksen ◽  
K. A. Munoz ◽  
A. T. Aannestad ◽  
M. E. Tischler
Keyword(s):  
Protein Synthesis ◽  
Protein Content ◽  
Protein Metabolism ◽  
Wheel Running ◽  
Weight Bearing ◽  
Normal Weight ◽  
Body Growth ◽  
Whole Body ◽  
Sprague Dawley

The adaptive responses of myocardial protein metabolism to chronic increases in work load were evaluated in juvenile female Sprague-Dawley rats. Rats were studied under four conditions: normal weight bearing (N), voluntary wheel running (WR) for < or = 4 wk, head-down-tilt suspension for 7 days (HS), or wheel running (2 or 3 wk) followed by 7 days of suspension (WR-HS). WR activity plateaued after 2 wk at 16 km/day and was maintained through week 4. WR did not affect normal whole body growth. Protein metabolism was studied by measuring heart protein content and in vivo fractional rate of protein synthesis with the [3H]phenylalanine “flooding dose” method. Two weeks of WR increased (P < 0.05) absolute heart protein content (22%) and protein synthesis (21%) relative to age-matched N group values. These differences in protein content and synthesis were maintained for > or = 4 wk. Rats failed to gain significant body weight during suspension. Heart protein content increased (P < 0.05) by 12% to 26% as did protein synthesis (14% to 22%) in HS compared with N group. In WR-HS group, cardiac protein content and protein synthesis were maintained at significantly elevated levels. These findings indicate that 1) high-volume WR by young rats provides a convenient noninvasive method for producing rapid and substantial cardiac hypertrophy, which results, at least in part, from enhanced cardiac protein synthesis; and 2) head-down suspension of sedentary juvenile rats leads to increased cardiac protein synthesis, which helps to increase cardiac protein content despite a lack of whole body growth.

The influence of carbon dioxide on protein synthesis in etiolated coleoptiles of Arena sativa

1972 ◽  
Vol 50 (9) ◽  
pp. 1937-1942
Author(s):  
A. W. Bown ◽  
W. W. Lampman
Keyword(s):  
Carbon Dioxide ◽  
Protein Synthesis ◽  
Avena Sativa ◽  
Protein Metabolism ◽  
Protein Fraction ◽  
Carbon Dioxide Concentration ◽  
Electrophoretic Analysis ◽  
Plant Tissues ◽  
Atmospheric Concentration ◽  
Profound Influence

Various concentrations of carbon dioxide have been used to assess the influence of carbon dioxide on protein metabolism in etiolated coleoptiles of Avena sativa. Increases in carbon dioxide concentration from 0% to 0.03% to 3% result in dramatic increases in both the total level of protein and the incorporation of radioactive leucine into protein. In addition an electrophoretic analysis indicates that as the carbon dioxide concentration is raised from 0% to 0.03% there is both an increased synthesis of most proteins plus a pronounced synthesis of one particular protein fraction. These results indicate that the normal atmospheric concentration of carbon dioxide has a profound influence on protein metabolism in Avena sativa coleoptiles and are discussed in connection with the well-documented phenomenon of carbon dioxide stimulated growth in etiolated plant tissues.

The anabolic actions of growth hormone and thyroxine on protein metabolism in Snell dwarf and normal mice

1988 ◽  
Vol 119 (1) ◽  
pp. 31-41 ◽  
Author(s):  
P. C. Bates ◽  
A. T. Holder
Keyword(s):  
Protein Synthesis ◽  
Growth Rates ◽  
Protein Metabolism ◽  
Bone Growth ◽  
Gh Treatment ◽  
Degradation Rates ◽  
The Individual ◽  
Dwarf Mice ◽  
Rna Concentration

ABSTRACT The individual effects of GH and thyroxine (T4) on protein metabolism were determined in dwarf and normal mice in vivo. The hormone deficiencies of dwarf mice (low serum concentrations of GH and T4) resulted in decreased protein synthesis rates in skeletal muscle and liver, but no difference in synthesis rates in heart. The efficiency of synthesis (g protein/g RNA per day; KRNA) was lower in all three tissues in dwarf compared with normal mice, but effects on RNA concentration were not consistent; there was no change in muscle, a decrease in liver and an increase in heart. Treatment of dwarf mice for 9 days with either human GH or T4 caused increases in body weight and length. Protein synthesis rates were increased in muscle, liver and heart by either hormone, though much more so with T4 than GH. In muscle and liver both GH and T4 treatment resulted in an increased RNA concentration, but T4 treatment also increased KRNA. In heart, both GH and T4 increased KRNA with no change in RNA concentration. GH caused no significant changes in protein degradation rates so that growth rates were increased. T4 increased degradation rates so that there was no increased net growth in muscle or liver; in heart, T4 did induce increased growth despite the large increase in degradation rate. Tibial length was increased by both hormones; GH treatment of dwarf mice also increased cartilage sulphate incorporation on day 9, but T4 treatment did not, suggesting that bone growth is transient with T4 treatment. Normal mice showed no changes in growth or tissue protein metabolism in response to GH, but following T4 treatment there was increased protein turnover due to higher tissue RNA concentrations, although only heart growth was increased. Thus normal mice showed almost no net response to GH or T4, but dwarf mice showed a large response to both hormones. The response was different, however, in that GH caused concomitant increases in growth rates whereas T4 altered body tissue proportions. J. Endocr. (1988) 119, 31–41

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