14C In Amino Acids Research Articles

Absorption des substances dissoutes dans le milieu, des particules et des produits de la digestion extracellulaire chez Actinia equina (Cnidaria, Actiniaria)

The results of nutrition experiments with glucose 14C, leucine 3H, amino acids 14C, cyanophyceae 14C and lipids have permitted me to enlarge our present knowledge of actinian nutrition. Ectodermal absorption.--Glucose and amino acids dissolved in the sea-environment were rapidly absorbed by the ectoderm. The multiple tentacles of Actinia and their cell microvilli enlarged the ectodermal surface. There is no preoral digestion, and the macromolecules were not absorbed since the ectoderm does not possess phagocytic cells. Digestion and endodermal absorption.--Macromolecules, particles and prey were carried into the coelenteron. The prey were enclosed in the convoluted lower part of mesenteries where they were divided into fragments and molecules by enzymes secreted by the zymogen cells of the mesenterial filaments. The macromolecules, particles and prey fragments (up to a few micrometers) produced by this extracellular digestion, or collected in the environment, were absorbed by the phagocytic cells. The lipids were pinocyted by the same cells concentrated in some parts of the endoderm, but the smallest molecules (carbohydrates and amino acids) were immediately absorbed by the mesenterial filament cells in contact with the prey. The transfer (in both directions) of the different absorbed substances between the ectoderm and the endoderm was slow. Glucose seemed to diffuse through the mesoglea, while the amino acids and the macromolecules would be transferred by the mobile cells of the mesoglea.

Intestinal absorption of palmitate and 2-aminoisobutyric acid in piglets infected with Strongyloides ransomi

Piglets were infected with 5000 or 15,000 third stage larvae of Strongyloides ransomi/kg of body weight. On the 15th day post infection absorption of the amino acid 14C alpha-amino-isobutyric acid (AIB) and the fatty acid 3H palmitic acid were studied. It was found that the onset of absorption of amino and fatty acids was delayed in the infected animals. Defective absorption of the amino acid was found in heavily infected piglets, whereas in moderate infection there was no failure of absorption from the entire small intestine. There was no difference in the rates of absorption of 3H-palmitic acid between infected and control piglets.

カンキツ類果実の生理および貯蔵に関する研究

To study the organic acid and carbohydrate metabolism of mandarin fruit after harvest, the metabolic processes of citrate-1, 5-14C (pH 3.49), glucose-1-14C (pH 7.0; G-1-14C) and glucose-6-14C (pH 7.0; G-6-14C) which were injected with a disposable syringe into a segment through the rind of the fruit were investigated during storage at 7±3°C for 50 days after injection.1. The injected citrate-14C was incorporated into 14CO2 immediately after injection. The cumulative radioactivity of respired 14CO2 continued to increase rapidly and attained to 28.8% of total radioactivity after 10 days and 33.5% after 50 days. Meanwhile, the cumulative radioactivity of 14CO2 from G-1-14C and G-6-14C continued increase slowly and attained to 6.5% and 6.3% of total activity of the substrates after 50 days, respectively.2. The rate of cumulative radioactivity of 14CO2 from the injected G-6-14C and G-1-14C was 0.34 for subsequent 2 days, 0.63 for 5 days, 0.68 for 10 days and 1.02 for 50 days after injection, respectively. These results may show that the hexose monophosphate pathway is the major pathway in the early stages of glycolysis of injected glucose and the glycolysis tends to shift to the Embden-Meyerhof Parnas pathway from HMP pathway in the latter period of the experiment.3. The injected citrate-14C could be incorporated rapidly into the carbohydrates, amino acids, proteins and pectic substances. There remained only a half amount of the substrate in the anionic fraction after 10 days. The metabolic activity of glucose-14C was considerably low as compared with that of citrate-14C. Therefore, the remaining of glucose-14C in the neutral fraction was about 80% after 50 days. The rate of incorporation into organic acid-14C and amino acid-14C from the moiety of injected glucose-14C attained to about 20% of total radioactivity of the ethanol soluble fraction at the end of experimental period.From these results, it may be concluded that the rate of turnover of citric acid in mandarin fruit can be considerably high, even after harvest.

Structure, Carbon Dioxide Fixation and Metabolism of Stomata

Studies were made of the structure and rates of CO2 fixation of epidermis and of changes in organic metabolites in Commelina cyanea during transition to light and dark in both normal and CO2-free air. Guard cells of C. cyanea and Vicia faba contain numerous highly developed mitochondria and starch-forming chloroplasts (mitochondria: chloroplast ratios of 3 : 1) in comparison to other epidermal cells with few mitochondria and rudimentary plastids without starch. Their rates of photosynthesis per chloroplast appeared to be at least as high as those of the mesophyll, but circumstantial evidence suggested that about half of current photosynthate was respired. The rate of CO2 fixation in the dark was about 0.2–0.4% of that in the light. Illumination caused an increase, and darkening a decrease, of aperture, malate, and organic acid 1% within the epidermis of C. cyanea. Darkening in CO2-free air was accompanied by only slight decreases in aperture and malate. There were close positive correlations between aperture and concentration of malate and between aperture and organic acid 14C. During opening, the rise in organic acid 14C was associated with a decline in amino acid 14C. It is suggested that organic acids may be formed through aspartate and possibly also from sugars and other amino acids entering the tricarboxylic acid cycle. Concentrations of sugars were not related to aperture although they increased on illumination and declined about 2 h after darkening. Polysaccharide concentrations in the epidermis of darkened leaves were similar to those in illuminated leaves.

Stimulation by ICSH of protein biosynthesis in isolated Leydig cells from hypophysectomized rats.

Leydig cells were prepared from testes of hypophysectomized rats by dissection and incubated in vitro with amino acids-14C. ICSH (100 μg/100 g body weight), administered intraperitoneally as a single injection, increased the incorporation in vitro of amino acids-14C into Leydig cell protein. This response was specific for ICSH and for the placental gonadotrophins HCG and PMS; FSH was without effect. The response to ICSH was seen within 5 days of hypophysectomy and within 5 hr of injection of the hormone. Glucose was without effect upon amino acid incorporation into Leydig cell protein by cells from either intact or hypophysectomized rats. Incorporation by Leydig cells of hypophysectomized rats was maximal at 34 C. A single intraperitoneal injection of N6,O2-dibutyryl adenosine-3′,5′-cyclic monophosphate increased incorporation of phenylalanine into Leydig cell protein in vitro. Isolated Leydig cells provide a useful system for studying the action of ICSH upon these cells and the possible relationship betw...

Concomitant synthesis of membrane protein and exportable protein of the secretory granule in rat parotid gland.

After enzyme secretion the membrane of the secretory granule, which had been fused to the cell membrane, was resorbed into the cell. Experiments were therefore carried out to test whether formation of new secretory granules involves reutilization of the resorbed membrane or synthesis of a new membrane, de novo, from amino acids. Incorporation of amino acids-(14)C into proteins of various cell fractions was measured in vivo, 30, 120, and. 300 min after labeling. At all times the specific radioactivity of the secretory granule membrane was about equal to that of the granule's exportable content. At 120 and 300 min the specific radioactivity of the granule membrane and of the granule content was much higher than that of any other subcellular fraction. It is therefore concluded that the protein of the membrane is synthesized de novo concomitantly with the exportable protein. The proteins of the granule membrane could be distinguished from those of the granule content by gel electrophoresis. All major bands were labeled proportionately to their staining intensity. The amino acid composition of the secretory granule membrane was markedly different from that of the granule's content and also from that of the mitochondrial membrane. The granule membrane showed a high proline content, 30 moles/100 moles amino acids. The analyses show that the radioactivity of the granule membrane is indeed inherent in its proteins and is not due to contamination by other fractions. The possibility is considered that the exportable protein leaves the endoplasmic reticulum already enveloped by the newly synthesized membrane.

Studies on the metabolism of nuclear basic proteins after radiation in vitro.

Exposure of isolated rabbit lymphocytes to 1000 R γ-radiation results in an increased rate of incorporation of amino acids-14C into cellular proteins during the first hour after irradiation. Fractionation of the proteins showed that the synthesis of basic proteins extracted from the nucleus was most affected. Two factors contributed to this apparent stimulation of protein synthesis by irradiation: (a) a transient increase in the amount of amino acid-14C available for protein synthesis in the cell; and (b) an increase in concentration of sodium ions in the cell. It is suggested that much of the observed increase in amino acid incorporation after irradiation of the lymphocytes is caused by radiation-induced changes in cell permeability.

Studies on the Fungicidal Action of Dithiocarbamates

The effect of sodium dimethyldithiocarbamate (NaDMDC) on Xanthomonas oryzae, a causative pathogen for bacterial leaf blight of rice plant, was investigated. The growth of X. oryzae in liquid medium was completely suppressed at a concentration of 50μg/ml when the fungicide was added immediately after inoculation, and at the mid-logarithmic growth it was also suppressed about 50 per cent at a concentration of 100μg/ml.Oxygen uptakes by endogenous respiration and substrate oxidation were slightly accelerated by the concentration less than 50μg/ml, whereas at the higher concentration, the oxygen uptakes were somewhat inhibited, among the several kinds of substrate, succinate oxidation was most markedly inhibited. But succinate dehydrogenase activity in cell-free extracts of X. oryzae was almost not inhibited by 10μg/ml NaDMDC.The incorporations of amino acids-14C into protein and of glucosamine-14C into cell wall were not inhibited even at a concentration of 100μg/ml. The incorporations of uridine-14C and thymidine-14C into RNA and DNA respectively were considerably inhibited by 100μg/ml NaDMDC, while adenine-14C, orotic acid-14C, glycine-14C and H332PO4 were not inhibited at the same concentration. Thus it is assumed that NaDMDC acts against incorporation of nucleosides into nucleic acids. However, the most remarkable inhibition was observed in the lipid synthesis. The incorporation of acetate-14C into lipid was inhibited approximately 50 per cent by 100μg/ml NaDMDC, and under the presence of glucose the inhibition reached to 90 per cent at the same concentration. Furthermore, the incorporations of pyruvate-14C and H332PO4 into lipid were remarkably inhibited.These results indicate clearly that the possible site of NaDMDC action against X. oryzae may be the process of lipid biosynthesis.

Fetal rat thyroid gland in organ culture

Using the organ culture technique, the action of TSH and of insulin on 131I metabolism and on amino acid 14C incorporation into protein was studied in fetal rat thyroid glands. By addition of TSH to the culture medium, nonfunctioning fetal thyroid could be made to initiate iodine metabolism. In functioning fetal thyroid, TSH greatly improved 131I utilization which is reflected primarily in its increased incorporation into thyroxine. Under similar conditions, it is found that TSH failed to influence the incorporation of 14C-leucine into protein and that puromycin, at a concentration that inhibited protein formation, failed to abolish the TSH-induced stimulation of 131I incorporation into protein-bound iodotyrosines and thyroxine. It seems, therefore, that TSH stimulation of thyroid hormone production is not dependent on increased synthesis of protein. We made use of perchlorate and tapazole to explore the mechanism of action of TSH. It is suggested that the effect of TSH on organ culture of embryonic thyroid glands is not dependent only on the stimulation of iodide concentrating ability of the explants since TSH accelerates the conversion of MIT to DIT and the formation of thyroid hormones. Insulin also has a pronounced effect on embryonic thyroid glands explanted into organ culture. Its presence as the only hormone in the culture medium enhanced significantly the incorporation of 131I into protein-bound iodotyrosines and thyroxine. When insulin was added to the TSH-containing medium, 131I utilization exceeded that observed in the presence of TSH alone; the formation of DIT and T 4 pas proportionately more affected than was that of MIT. The 14C of 14C-labeled amino acids was readily incorporated into thyroidal protein, and in each case the presence of insulin in the medium enhanced the incorporation. Addition of insulin to the culture medium stimulated also the incorporation of 14C of adenine-8- 14C into ribonucleic acid by the fetal glands. It is conceivable that insulin enhances protein formation in embryonic thyroid explants solely or partly via its influence on the metabolism of ribonucleic acid.

Inhibition of protein synthesis in noninfected L cells by partially purified interferon preparations.

Partially purified interferon preparations, obtained from L-cell monolayers infected with Newcastle disease virus (NDV), were shown to inhibit protein synthesis in noninfected L cells. The incorporation of several amino acids-(14)C was equally sensitive to the pretreatment of the cells with the interferon preparation. Treatment of L-cell monolayers for 24 hr with 800 units of interferon resulted in a 50% decrease in amino acid incorporation. The degree of inhibition was found to be a function of the interferon concentration and the time of exposure of the cells to the partially purified preparations. No inhibitory effect was detected in medium obtained from noninfected cells and purified in an identical manner. The inhibitory effect was shown to be cell specific in that the partially purified interferon from L cells did not reduce amino acid incorporation in heterospecific cell lines. Heating the interferon preparations at 60 degrees C destroyed their antiviral activity and their ability to inhibit valine-(14)C incorporation in L cells.

Hepatic Lipid Metabolism in Experimental Diabetes: IV. Incorporation of Amino Acid 14C Into Lipoprotein-Protein and Triglyceride

Abstract The incorporation of radioactive amino acids into serum proteins by isolated perfused livers from alloxan diabetic rats was depressed in comparison to the normal. The incorporation of amino acids into the major classes of serum lipoproteins (density l1.020; density 1.020 to 1.063; density 1.063 to 1.210) also was impaired in alloxan diabetes. The incorporation of 14C into the total serum proteins and into the lipoproteins was also depressed with livers from chronic alloxan diabetic rats maintained on insulin, and was not further depressed after withdrawal of the insulin from the animals. The incorporation of amino acids into serum proteins was not restored to normal levels upon treatment of the diabetic rats with insulin under our experimental conditions. The incorporation of amino acids into hepatic protein also appeared to be depressed below normal in livers from diabetic rats. The conversion of amino acid 14C to fatty acid carbon of liver and serum triglycerides was reduced with perfused livers from acute and chronic alloxan diabetic rats and was stimulated when the animals were treated with insulin. In diabetes, an increase in the incorporation of amino acid 14C into glyceride-glycerol and into water-soluble neutral compounds of the perfusate was observed, and production of urea and output of amino acid nitrogen were also elevated. The inhibition of synthesis and, possibly, release of the protein moiety of the density l1.020 serum lipoprotein (the carrier of the major proportion of the serum triglyceride) which was observed in perfused livers from acute and chronic alloxan diabetic rats may not be causally related to the inhibition of release of triglyceride in diabetes, since, upon administration of insulin to the diabetic animal, the release of triglyceride by the liver was stimulated even though the defect in the synthesis of serum lipoprotein-protein persisted.

Characteristics of a subcellular system from Cellvibrio gilvus for the incorporation of amino acids into protein.

SummaryA cell-free system which was active with respect to amino acid-14C incorporation into hot TCA insoluble material was derived from Cellvibrio gilvus and characterized. This amino-acid incorporation was typical in its requirement for ribosomes, pH 5 fraction, ATP, and magnesium ions, and in its inhibition by ribonuclease and puromycin. Deoxyribonuclease and actinomycin D had little effect, whereas chloramphenicol caused 65% inhibition. The optimal condition for incorporation was 30 min incubation at 30° and at pH 8.0. The addition of an exogenous source of a polyamine (spermidine, spermine, or putrescine) had little effect on this system. Poly-U dependent phenylalanine incorporation was observed with this system and found to be stimulated by an exogenous source of tRNA, although tRNA had no stimulatory effect on leucine incorporation.

Effect of FSH on protein biosynthesis in testes of the immature rat.

Incorporation of amino acid-14C into tricholoracetic acid-precipitable material by testis from 20-day-old rats was measured in vitro. It was concluded that this incorporation Was a measure of testicular protein biosynthesis in that it was time dependent, was abolished by heating the tissue, was neither altered by extracting the precipitate with hot NaCl nor decreased by alkaline hydrolysis, and was inhibited by addition of puromycin in vitro. Protein biosynthesis in the testis of the immature rat was stimulated by FSH administered as a single intraperitoneal injection. The response to FSH was observed with 3 amino acids (lysine-14C, leucine-14C and tyrosine-14C), was time dependent (significant Stimulation was observed 30 min following injection and maximal stimulation was reached after 1 hr), was dose dependent (within the range 0f 0.2 to 200 μg/rat), and was abolished by addition of puromycin in vitro. The stimulation of tiesticular protein biosynthesis by FSH proved to be specific for that hormone and ...

The incorporation of amino acids-14C into proteins by ribosomes of Bacillus cereus

The incorporation of amino acids-14C into proteins by ribosomes of Bacillus cereus