scholarly journals Evidence that protein ingested by the rat visceral yolk sac yields amino acids for synthesis of embryonic protein

Development ◽  
1983 ◽  
Vol 73 (1) ◽  
pp. 307-315
Author(s):  
Stuart J. Freeman ◽  
John B. Lloyd
Keyword(s):  
Amino Acids ◽  
Free Amino ◽  
Polyacrylamide Gel Electrophoresis ◽  
Yolk Sac ◽  
Proteolytic Digestion ◽  
Pregnant Rats ◽  
Short Period ◽  
Visceral Yolk Sac ◽  
Rat Reticulocytes

[3H]Leucine-labelled haemoglobin was prepared from rat reticulocytes incubated in the presence of [3H]leucine. Conceptuses from 9·5-day pregnant rats were incubated in vitro for 48 h, with [3H]leucinelabelled haemoglobin present for the final 12, 8, 4, 2 or 0·5 hours. Radioactivity accumulated in visceral yolk sac and in embryonic tissue. When exposure to labelled haemoglobin was for only a short period before harvesting, all the radioactivity found in the embryo and most of that found in the visceral yolk sac was trichloroacetic acid-soluble (i.e. associated with free amino acid rather than with protein). After longer exposures the proportion of radioactivity that was acid-soluble decreased to minimum values of about 20 %. SDS-polyacrylamide gel electrophoresis of the protein-associated radioactivity in visceral yolk sac and embryo was performed. After exposure to labelled haemoglobin for 1 h only prior to harvesting, the yolk sac contained a single peak of radioactivity coincident in mobility with haemoglobin. The embryo contained no protein-associated radioactivity. After exposure to labelled haemoglobin for 12 h, many protein bands in both yolk sac and embryo were radiolabelled. Thus a single radiolabelled protein pinocytically captured by the visceral yolk sac can give rise to the presence of many labelled proteins in embryo and visceral yolk sac. These results indicate that the source protein underwent proteolytic digestion and that the amino acids generated were re-utilized for protein synthesis in both embryonic and visceral yolk-sac cells.

Effect of yolk-sac antibody on rat embryos grown in culture

Development ◽  
1972 ◽  
Vol 27 (3) ◽  
pp. 543-553
Author(s):  
D. A. T. New ◽  
R. L. Brent
Keyword(s):  
Direct Contact ◽  
Culture Medium ◽  
Gamma Globulin ◽  
Yolk Sac ◽  
Amniotic Cavity ◽  
Pregnant Rats ◽  
Rat Embryos ◽  
Visceral Yolk Sac ◽  
Primary Action

Rat embryos, explanted with their embryonic membranes during the early stages of organogenesis ( days gestation), were grown in culture in roller tubes. Yolk-sac antibody (sheep anti rat yolk-sac gamma globulin), known to be teratogenic when injected into pregnant rats, was added to the culture medium. At concentrations of 0·1 mg/ml or more the antibody caused gross retardation of growth and differentiation. Injection of antibody into the amniotic cavity so that it had direct contact with the embryo, or between the amnion and yolk sac so that it was in contact with the mesodermal surface of the yolk sac, had little or no effect on development of the embryo or its membranes. These in vitro experiments indicate that yolk-sac antibody has an effect on development independent of any immunological reaction of the mother, and the primary action is probably on the visceral yolk-sac endoderm.

The role of the visceral yolk sac in mediating protein utilization by rat embryos cultured in vitro

Development ◽  
1981 ◽  
Vol 66 (1) ◽  
pp. 223-234
Author(s):  
Stuart J. Freeman ◽  
Felix Beck ◽  
John B. Lloyd
Keyword(s):  
Serum Proteins ◽  
Yolk Sac ◽  
Rat Serum ◽  
Pregnant Rats ◽  
Digestion Product ◽  
Background Levels ◽  
Visceral Yolk Sac ◽  
Chorioallantoic Placenta

Conceptuses from 9·5-day pregnant rats have been cultured for 48 h in heat-inactivated homologous serum. Embryonic development was normal. The protein contents of embryos and visceral yolk sacs after different periods of culture were recorded. When 125-labelled polyvinylpyrrolidone or [3H]dextran were added to the culture serum, radioactivity was accumulated by the yolk sac, but only background levels were detected in the embryo itself. The amount of radioactivity found in the yolk sac varied with the length of the interval before harvesting during which 125 I-labelled PVP or [3H]dextran was present. When formaldehyde-denatured 125 I-labelled bovine serum albumin was added to the culture serum, little radioactivity accumulated in the yolk sac and only background levels were found in the embryo. Trichloroacetic acid-soluble radioactivity steadily appeared in the culture serum, however. When conceptuses were cultured in glucose- and vitamin-supplemented dialysed serum from rats injected 2 h previously with [3H]leucine, radioactivity was found in both embryos and yolk sacs. The amount of radioactivity in these tissues increased with duration of exposure to 3H-labelled serum proteins. After short exposures little of the yolk sac and embryonic radioactivity was acid-insoluble, but this proportion increased with duration of exposure. These results are interpreted as follows. Intact macromolecules cannot enter the cells of the embryo itself, but are captured by pinocytosis into the cells of the visceral yolk-sac endoderm. Indigestible macromolecules such as 125 I-labelled polyvinylpyrrolidone and [3H]- dextran accumulate within the yolk-sac lysosomes, but proteins are digested there by the lysosomal enzymes. The radiolabelled digestion product of 125 I-labelled bovine albumin is [125 I]iodotyrosine, which cells cannot utilize and so is excreted into the culture serum. The labelled digestion product of the 3H-labelled rat serum proteins is [3H]leucine, which is used for protein synthesis in both embryo and yolk sac. The experiments provide direct evidence for the long-suspected role of the yolk sac in mediating embryonic nutrition in the period of development prior to the establishment of a functional chorioallantoic placenta.

Methionine flux between a tapeworm (Hymenolepis diminuta) and its environment

Parasitology ◽  
1965 ◽  
Vol 55 (4) ◽  
pp. 653-666 ◽  
Author(s):  
C. A. Hopkins ◽  
L. L. Callow
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Environmental Conditions ◽  
Free Amino Acids ◽  
Free Amino ◽  
Hymenolepis Diminuta ◽  
Critical Importance ◽  
High Concentration ◽  
Short Period

In the course of work designed to measure the extent to which methionine absorbed in one region of a tapeworm became distributed throughout the strobila, it was observed that, whereas, in saline, Hymenolepis diminuta lost previously absorbed methionine slowly, in the intestine of a rat the methionine was lost very rapidly. The fact that two worms containing initially the same amount of free methionine should, after a short period in different environments, contain utterly different quantities of methionine indicated that the quantity of a free amino acid present at any time is not simply dependent on the amount previously absorbed less the amount metabolized.This observation has a bearing on several aspects of tapeworm physiology. Do tapeworms normally absorb amino acids from the intestine during periods of high concentration and release them when the concentration falls? If they do, the presence of tapeworms in the intestine could be beneficial to the host by extending the period over which an amino acid is available to the host, an important point as a mammal is unable to store amino acids for more than a few hours (Gitler, 1964). A knowledge of the environmental conditions which influence the level of free amino acids in a tapeworm, and thereby its ability to synthesize proteins, is obviously also of critical importance to workers attempting to grow worms in vitro.

The effect of teratogenic antiserum on yolk-sac function in rat embryos cultured in vitro

Development ◽  
1982 ◽  
Vol 71 (1) ◽  
pp. 63-74
Author(s):  
Stuart J. Freeman ◽  
Robert L. Brent ◽  
John B. Lloyd
Keyword(s):  
Embryonic Development ◽  
Yolk Sac ◽  
Rabbit Serum ◽  
Identical Result ◽  
Normal Rabbit Serum ◽  
Pregnant Rats ◽  
Homologous Serum ◽  
Visceral Yolk Sac ◽  
Parallel Control

The teratogenicity of rabbit anti-rat visceral yolk-sac antiserum, injected into pregnant rats at either 8·5 or 9·5 days of gestation, has been confirmed. Normal rabbit serum was found not to be teratogenic. When conceptuses from 9·5-day pregnant rats were cultured for 48 h in heat-denatured homologous serum, to which antiserum was added for the final (or the penultimate) 6 h of culture, embryonic development was normal. The protein contents of embryos and yolk sacs (at harvesting) were however decreased. When antiserum was present in cultures for the final 6 h, pinocytosis by the yolk sac, as measured by the uptake of 125I-labelled polyvinylpyrrolidone (PVP), was decreased to an extent related to the concentration of antiserum in the culture medium and to a minimum level of about 40%. The presence of antiserum in cultures for the penultimate 6 h only, with 125I-labelled PVP present for the final 6 h only, produced an identical result. No uptake of radioactivity into the embryo was observed, in either the absence or presence of antiserum. When conceptuses were cultured for the final 6 h in vitamin- and glucose-supplemented dialysed homologous serum whose proteins were [3H]leucine-labelled, the presence of antiserum for either the final or penultimate 6 h again resulted in a decrease in the uptake of radioactivity by conceptuses. Uptake of radioactivity into yolk sac and embryo was decreased by the same amount, indicating that proteolysis in yolk-sac lysosomes was not inhibited. In parallel control experiments in which normal rabbit serum replaced rabbit anti-rat visceral yolk-sac antiserum, no effects on embryonic development, on protein contents of yolk sacs and embryos at harvesting, or on the uptake of radioactivity by conceptuses were observed. These results are interpreted as providing evidence that teratogenic antibodies decrease pinocytosis of protein by visceral yolk sac at the early organogenesis stage and consequentially decrease the availability of amino acids and thus protein synthesis in both yolk sac and embryo. It is proposed that this effect constitutes the mechanism of action of teratogenic antisera.

scholarly journals Inhibition of proteolysis in rat yolk sac as a cause of teratogenesis. Effects of leupeptin in vitro and in vivo

Development ◽  
1983 ◽  
Vol 78 (1) ◽  
pp. 183-193
Author(s):  
Stuart J. Freeman ◽  
John B. Lloyd
Keyword(s):  
Amino Acids ◽  
Protein Content ◽  
Culture Medium ◽  
Specific Inhibitor ◽  
Yolk Sac ◽  
Cysteine Proteinases ◽  
Rat Serum ◽  
Pregnant Rats ◽  
Stage Of Development

Conceptuses from 9·5-day pregnant rats were cultured for 48 h in heat-inactivated homologous serum to which leupeptin, a specific inhibitor of the lysosomal cysteine-proteinases, was added for the final or the penultimate 6h. The presence of leupeptin (25 µg/ml or above) increased the protein content of yolk sacs at harvesting to approximately twice the control value. The protein content of the embryo at harvesting was lower than that of controls. When 125I-labelled polyvinylpyrrolidone was added to the culture serum for the final 6 h of culture, radioactivity was found in the yolk sac at harvesting, but not in the embryo. The presence of leupeptin did not affect the rate of uptake of the radiolabelled macromolecule by the yolk sac, nor facilitate its entry into the embryo. When formaldehyde-denatured 125I-labelled bovine serum albumin was added to the culture medium for the final 6 h of culture, little radioactivity was found in the yolk sac at harvesting, and barely any was found in the embryo. Trichloroacetic acid-soluble radioactivity was found in the culture serum. The presence of leupeptin sharply increased the levels of radioactivity in the yolk sac (but not the embryo) and sharply decreased the acid-soluble radioactivity of the culture medium. When rat serum whose proteins were labelled with [3H]leucine was used as culture medium, radioactivity was found in both yolk sac and embryo at harvesting. The presence of leupeptin increased the amount found in the yolk sac and decreased that found in the embryo. These results are interpreted as follows. Leupeptin enters the lysosomes of the yolk sac, inhibiting their cysteine proteinases. The digestion of proteins pinocytosed by the yolk sac is consequently inhibited, resulting in the accumulation of protein by the yolk sac and a decreased flow of amino acids to the embryo. Leupeptin (50 mg/kg), injected into pregnant rats at either 8·5 days or 9·5 days of gestation, induced congenital malformation in the offspring. It is proposed that leupeptin exerts its teratogenic action by inhibiting proteolysis in the lysosomes of the yolk sac, and so depriving the developing embryo of its supply of amino acids at a critical stage of development.

Turnover of total proteins and ornithine aminotransferase during liver regeneration in rats

1980 ◽  
Vol 238 (1) ◽  
pp. E46-E52
Author(s):  
S. L. Augustine ◽  
R. W. Swick
Keyword(s):  
Amino Acids ◽  
Liver Regeneration ◽  
Protein Degradation ◽  
Partial Hepatectomy ◽  
Free Amino ◽  
Liver Protein ◽  
Ornithine Aminotransferase ◽  
Fractional Rate

The recovery of approximately 40% of the total liver protein during the first day after partial hepatectomy was shown to be due to the near cessation of protein breakdown rather than to an increase in protein synthesis. The decrease in degradation of total protein was less if rats were adrenalectomized or protein-depleted prior to partial hepatectomy. The effect of these treatments originally suggested that changes in free amino acid levels in liver might be related to the rate of protein degradation. However, no correlation was found between levels of total free amino acids and rates of breakdown. Measurements of individual amino acids during liver regeneration suggested that levels of free methionine and phenylalanine, amino acids that have been found to lower rates of protein degradation in vitro, are not correlated with rates of breakdown in vivo. The difference between the fractional rate of ornithine aminotransferase degradation (0.68/day and 0.28/day in sham-hepatectomized and partially hepatectomized rats, respectively) was sufficient to account for the higher level of this protein 3 days after surgery in the latter group.

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.

Apolipoprotein expression by murine visceral yolk sac endoderm

Development ◽  
1984 ◽  
Vol 81 (1) ◽  
pp. 143-152
Author(s):  
Wei-Kang Shi ◽  
John K. Heath
Keyword(s):  
Culture Supernatant ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Yolk Sac ◽  
Apolipoprotein Ai ◽  
Visceral Endoderm ◽  
Ldl Particles ◽  
Visceral Yolk Sac ◽  
Specific Localization

Apolipoprotein expression was examined in the postimplantation mouse embryo. Antibodies directed against murine Apolipoprotein AI and human low-density lipoprotein (LDL) particles specifically immunoprecipitated metabolically labelled radioactive apolipoproteins from the culture supernatant of 10·5 days post coitum (days p.c.) yolk sac visceral endoderm cultured in vitro. No evidence for apolipoprotein expression by other embryonic or extraembryonic tissues at this stage was obtained. Immunohistochemical staining at sectioned 10·5 days p.c. embryos with anti-Apolipoprotein AI antibodies revealed specific localization of immunoreactive material in the yolk sac visceral endoderm. We conclude that the yolk sac visceral endoderm is a source of lipoproteins during postimplantation embryonic development.

scholarly journals The organization of the virus-tested planting material production for the grape varieties of the local and foreign selection in Kazakhstan

2020 ◽  
Vol 25 ◽  
pp. 01002
Author(s):  
Saule Kazybayeva ◽  
Svetlana Dolgikh ◽  
Shokan Kulshanov ◽  
Marina Urazayeva ◽  
Gulnaz Ushkempirova
Keyword(s):  
Amino Acids ◽  
Tissue Culture ◽  
Genetic Stability ◽  
Free Amino ◽  
Material Production ◽  
Planting Material ◽  
Propagation Factor ◽  
Nutritional Medium ◽  
Grape Varieties

The intensification of viniculture involves the organization of the virus-tested planting material production, establishment of the basic parent plantings, certification of the virus-tested planting material with the control of genetic stability of the grape plants propagated in tissue culture. The modified nutritional medium was developed for microclonal propagation of vine in vitro with the content of the free amino acids: glycine and glutamine, increasing propagation factor up to 15% and the number of nodes on microplant up to 27%.

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