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Water, proteins and total free amino acids were estimated in different tissues of the euryhaline fish Tilapia mossambica after adaptation to various strenghts of sea water. The water content did not vary significantly in any tissue on salinity adaptation. The soluble and insoluble proteins displayed a general and considerable decrease in muscle, liver and heart; the decrease in the soluble fraction in the heart and the proteins of the muscle in 75% sea water (100% sea water=32.5‰ S) were significant. The gill proteins did not alter with salinity; the kidney proteins tended to increase slightly in 100% sea water (SW). The total free amino-acid content decreased insignificantly in all tissues on adaptation to 25% SW; in higher salinities, however, the content increased significantly. This increase was sudden and steep in 50% SW, and gradual and less steep in 75 and 100% SW. It is suggested that constancy in water content may contribute to the great adaptability of T. mossambica to heterosmotic media, and that the total free amino acids may be involved in isosmotic intracellular regulation. The possibility of amino acid increase as a result of protein breakdown is also indicated.

The previously suggested roles of protein synthesis and tRNA aminoacylation in the regulation of intracellular protein breakdown were examined in strains of E. coli temperature-sensitive for aminoacyl-tRNA synthetases. Direct measurements of tRNA aminoacylation show no correlation between the degree of tRNA charging and the rate of protein breakdown. Protein breakdown was accelerated by transfer from 30°C to 42°C to about the same degree in temperature-sensitive mutants as in related normal strains. Deprivation of inorganic phosphate at the high temperature stimulated further protein breakdown in normal, but not in temperature-sensitive strains. It is concluded that the regulation of protein breakdown requires concomitant protein synthesis and is not influenced by the level of aminoacylation of tRNA.

1. The rate of protein synthesis in rat tissues was measured by constant intravenous infusion of [14C]tyrosine. A modification has been developed for the method of calculating the rate of protein synthesis in individual tissues from the specific radioactivity of the free and protein-bound amino acid in tissue at the end of the infusion. This technique gives greater accuracy and allows a greater choice of labelled amino acids. The specific radioactivity of free tyrosine in plasma was used to calculate the plasma tyrosine flux, an index of the rate of protein synthesis in the whole body. 2. Young male Wistar rats were allowed access to food for only 4h in every 24h. The tyrosine flux and the rate of protein synthesis in liver and muscle at different periods of time after a single feed were estimated. 3. The tyrosine flux did not alter after feeding nor even after starvation for 48h. 4. The average fractional rate of protein synthesis in muscle was 7.2%/day, i.e. the proportion of the protein mass which is replaced each day. The rate rose after eating and declined during starvation for 48h. In addition the rate of muscle protein synthesis correlated with the growth rate of the rat. 5. In liver the average fractional rate of protein synthesis was 50%/day. There was no change in the rate after eating nor after starvation for 48h. In contrast with muscle this suggests that the changes in protein mass were accompanied by changes in the rate of protein breakdown rather than synthesis.

The effects of dexamethasone and insulin on the degradation of total cellular protein have been investigated in an established line of rat hepatoma cells (HTC) in suspension culture by measuring the release of acid-soluble radioactivity from previously labeled protein. When incubated in a chemically-defined, serum-free medium, HTC cells lose approximately 2 to 3% of their labeled protein per hour. Dexamethasone (0.1 μM) causes a 20% increase in the apparent rate of protein degradation. The addition of insulin (0.1 U/ml) to dexamethasone-treated cells causes a 26% decrease in the rate of protein degradation by a mechanism which does not require concomitant RNA synthesis. Since actinomycin D blocks the modest enhancement of amino acid incorporation into protein stimulated by insulin, but does not affect the inhibition of protein breakdown by insulin, it appears that the effect of insulin on protein degradation is independent of its effects on protein synthesis. Bovine serum (5%), which mimics the insulin st...

In the course of a study on urinary estriol levels in preterm and term infants, creatinine determinations were performed as reference values to calculate estriol-creatinine ratios [3], Since Information on creatinine levels in newborns is not available over a wide range of birth weight and gestational age, we considered it worthwhile to give a separate report of these data. Creatinine reaches the urine almost exclusively, by glomerular filtration [1]. Thus endogenous creatinine clearance has been used as a means of assessing glomerular filtration capacity both in health and disease [1], In utero metabolism is at a more steady state than postnatally: There is a steady influx of nourishment via the umbilical vessels, physical activity is limited and it may be assumed that protein catabolism also is more constant and even than after birth [4], If these assumptions are in fact correct, a single urinary creatinine level reflecting such steady inutero conditions, would be sufficient to yield Information about the state of glomerular filtration capacity. The first urine passed after birth, would meet these criteria. McCANCE reported that glomerular filtration rate is markedly reduced in preterm infants [6]. This should be reflected in the creatinine levels with which this paper is concerned.

These experiments were undertaken to determine the source of alanine released by skeletal muscle and to clarify the possible relationships between this process and the degradation of branched chain amino acids, the release of glutamine, and protein turnover in this tissue. During incubation in vitro, the rat diaphragm underwent net protein breakdown and released amino acids into the medium at a linear rate. The diaphragm released larger amounts of alanine and glutamine and lower amounts of leucine, isoleucine, and valine than would be expected from the average composition of muscle protein. Addition of the branched chain amino acids increased the production of alanine, glutamate, lysine, but not glutamine by the diaphragm in a concentration-dependent manner. At the same time, the branched chain amino acids inhibited net protein breakdown; therefore the increased amounts of alanine, glutamate, and lysine must have resulted from de novo synthesis or reduced catabolism of these amino acids. All the other amino acids together failed to increase the production of alanine or glutamate. Alanine production in muscle appears related to the rapid oxidation of the branched chain amino acids. In diaphragms from fasted rats, both processes occurred at increased rates. Amino groups released on oxidation of branched chain amino acids could account for all nitrogen recovered in alanine. Alanine production by diaphragms from fasted rats increased upon addition of glucose and even further when insulin was present. The muscle incorporated 14C from [U-14C]glucose into alanine, and addition of branched chain amino acids increased the production of [14C]alanine from [14C]glucose. Therefore, alanine production does not reflect protein degradation in muscle but instead appears to be synthesized de novo primarily from exogenous glucose and from amino groups released by catabolism of branched chain amino acids. These findings suggest the existence of a branched chain amino acid-alanine cycle in the organism. During fasting, enhanced oxidation of branched chain amino acids by muscle would provide energy for muscle, while the concomitant synthesis of alanine from glucose would serve to shuttle ammonia and gluconeogenic precursors back to the liver.

Plasma glucose, insulin and glucagon were measured in pregnant and age-matched virgin rats in the fed state and after fasting 6, 48 or 120 hours during day 16–21 of gestation. The fed state in pregnancy was characterized by a metabolic setting favoring anabolism. The lower plasma glucose in the fed pregnant rats was associated with higher insulin, slightly lower glucagon and higher insulin/glucose and insulin/glucagon ratios than in virgin rats. During fasting, glucose fell to sustained hypoglycemic levels in the pregnant animals whereas glucose declined but did not achieve hypoglycemia at any point in the virgins. Despite the hypoglycemia, greater levels of plasma insulin persisted in the pregnant throughout the 120 hours of fasting and insulin/glucagon ratios did not differ significantly from the euglycemic virgins. Thus, “accelerated starvation” in pregnancy cannot be ascribed to relative glucagon excess. Rather, the preservation of normal insulin/glucagon ratios despite prevailing hypoglycemia, may provide a mechanism during fasting in pregnancy for restraining maternal protein catabolism in the face of the added fuel demands of the conceptus.

Several isotopic methods for the measurement of liver protein turnover were compared in a study of plasma albumin and the mixed hepatic proteins during liver regeneration. In albumin after the administration of [14C]carbonate, the rate of decay of the radioactivity of the intact protein was similar to that of arginine isolated therefrom, whereas after the administration of [guanidino-14C]arginine, the decay rate was 30% slower than that obtained with [14C]carbonate. When [guanidino-14C]arginine is given, the extrahepatic tissues, such as muscle and the plasma globulins, are labeled more heavily than the liver proteins. It is likely that the reutilization of this extrahepatic arginine by the liver accounts for the slower disappearance of radioactivity from albumin. Similar results were obtained with the mixed, indigenous hepatic proteins. In animals that had been partially hepatectomized, the decay in radioactivity in arginine after [14C]carbonate administration showed that the rate of protein breakdown was reduced by 30 % during the first 5 days of liver regeneration. There was no decay in radioactivity in similar animals given [guanidino-14C]arginine, suggesting a massive transfer of labeled extrahepatic protein arginine into the liver during regeneration.

Regulation of protein breakdown by amino acids is abolished in relaxed strains of E. coli, but these mutants do respond to the deprivation of inorganic phosphate. Protein synthesis is directly required for the control of protein degradation. We suggest that the failure of amino acid-deprived rel - strains to regulate protein breakdown may be due to defective protein synthesis.

The suitability of radioactively labeled proline as a marker of axonally transported protein in the goldfish visual system is further investigated and compared with another amino acid, leucine, in double-label experiments. Intraocularly injected proline is incorporated into protein in the eye 5 times more efficiently than is leucine, while local labeling of brain protein from precursor which has left the eye and entered the blood, (observed in the ipsilateral optic tectum) is five- to eight-fold less from proline than from leucine. The difference is attributed to the superior transport of leucine, an essential amino acid, into the brain from the blood. Once in the brain, the apparent rates of incorporation of the two amino acids are similar. Proline- or leucine-labeled, axonally transported proteins have a longer apparent half-life in the brain than do proteins labeled from intracranial injection of the precursors. By either route, proline-labeled proteins have a longer apparent half-life than leucine-labeled proteins. It is proposed that proline, released from protein breakdown is reutilized to a greater extent than is leucine.

The hypothesis that an essential amino acid will accumulate in blood plasma only when supplied in excess of requirement was the basis of an attempt to identify essential amino acids most likely limiting lactation. In a 5 X 5 Latin-square experiment, five lactating cows were fed a corn-based basal ration containing 9.0% crude protein. Casein treated with .8% wt/wt formaldehyde to prevent protein breakdown by ruminal microorganisms was fed in five quantities to give diets containing 9.0 (basal), 11.2, 13.5, 15.7, and 18.0% crude protein (dry matter basis). Milk production and milk crude protein content for each of the five treatments were: 20.4kg and 2.98%; 22.1 and 3.04; 24.7 and 3.14; 26.8 and 3.17; and 25.7 and 3.15. This indicated that amino acid supply was inadequate at the two lowest but adequate at the two highest percents of dietary protein. Comparison of milk samples obtained at the lowest and highest protein feeding indicated that 82% of the increase in milk nitrogen content was accounted for as true protein (trichloroacetic acid-precipitable nitrogen). There was little evidence of change in the amino acid composition of milk protein with increased protein intake. Essential amino acid concentrations in jugular and mammary vein plasma for cows at all intakes of formaldehyde-treated casein indicated that methionine, valine, and lysine were the most likely limiting amino acids for milk production.

HeLa cells, prelabeled with [3H]leucine for several generations, were pulse-labeled with [14C]-leucine. The 14C/3H ratio of the leucine in the medium, in the total amino acid pool and bound to transfer RNA was determined. It was found that the 14C/3H ratio of the leucyl-tRNA was identical with that of the extracellular medium while that of the amino acid pool was much lower. These results confirm previous reports that selection of amino acids for protein synthesis takes place before the amino acids are released intracellularly. Further, it was concluded that amino acids resulting from intracellular proteolysis are not reutilized directly under the conditions of our experiments. A possible model of intracellular amino acid pathways is discussed.

Sixteen nonproteinous amino acids (those not coded for in contemporary protein biosynthesis) were incorporated during the thermal formation of polyamino acids under postulated prebiotic conditions, although not all into a single polyamino acid. The copresence of proteinous or even α-amino acids was not required. (Norleucine color equivalents and elution times on a Beckman model 120C amino acid analyzer were determined for these nonproteinous amino acids). The results suggest that prebiotically available nonproteinous amino acids would have been constituents of prebiotic protein if the latter were formed thermally. Some differences in properties of the polyamino acids could be attributed to particular nonproteinous amino acid residues; however, the tested properties did not suggest a means for evolutionary selection against nonproteinous amino acids as a group . Selection against this class of amino acids in toto was likely a later, biotic, event.

1. Total lysosomal hydrolase activities were measured in liver, gastrocnemius muscle and plasma of malnourished and normal rats between 3 and 8 weeks of age.2. Concurrently, the DNA and protein contents of the livers and muscles were determined.3. Increased amounts of acid hydrolase activities were found to be associated with subnormal protein: DNA ratios in the tissues of malnourished rats.4. It was concluded that lysosomal enzymes may be involved in protein catabolism during malnutrition.

Synchronous cultures obtained by isopycnic density gradient centrifugation are used to investigate amino acid metabolism during the cell division cycle of the food yeast Candida utilis . Isotopic labeling experiments demonstrate that the rates of uptake and catabolism of arginine, the sole source of nitrogen, double abruptly during the first half of the cycle, while the cells undergo bud expansion. This is accompanied by a doubling in rate of amino acid biosynthesis, and an accumulation of amino acids. The accumulation probably occurs within the storage pools of the vacuoles. Amino acids derived from protein degradation contribute little to this accumulation. For the remainder of the cell cycle, during cell separation and until the next bud initiation, the rates of uptake and catabolism of arginine and amino acid biosynthesis remain constant. Despite the abrupt doubling in the rate of formation of amino acid pools, their rate of utilization for macromolecular synthesis increases steadily throughout the cycle. The significance of this temporal organization of nitrogen source uptake and amino acid metabolism during the cell division cycle is discussed.

The anterior pituitary growth hormone is known to promote the retention of nitrogen in the body. This effect is best seen when observations are made in animals fed adequate protein over a day or more. Anterior pituitary extracts will lower the plasma amino nitrogen of fasted animals within a few hours, an effect presumably also the result of growth hormone action. From the conditions of these experiments, it is not possible to say whether the effects seen are due to suppression of protein catabolism or to an increase in the rate of protein anabolism. An acute effect of the growth hormone on the retention of administered nitrogen has not heretofore been demonstrated. In the present experiments, the rate of increase of urea in the blood of nephrectomized rats has been used as a measure of the rate of protein metabolism. A mixture of amino acids in the form of a casein hydrolysate was given intravenously

Amino acids in plasma of 12 cows were determined during 10 days to measure effects of a lowenergy ration and exogenous thyroxine. Cows were fed rations which provided either their energy and protein requirements on Day 0, or only 30% of the energy and 90% of die protein required. A daily dosage of 6.9mg of L-thyroxine (sodium) pentahydrate injected on Days 4 through 7 in combination with the lowenergy ration induced signs of clinical ketosis. The combination of thyroxine injections with a low-energy ration elevated valine, leucine, and isoleucine on Day 5. These were much lower on Day 7. These changes were similar to those of the pattern of glucose in blood. Glutamic acid was highest on Day 6. These changes in amino acids were apparently the result of protein catabolism in response to energy deficiency. Possible causes for the elevation of tiiese amino acids in plasma, and the possibility of these amino acids having triggered a release of insulin are discussed. In addition, some possible metabolic deficiencies are discussed considering commonly established biochemical pathways.

The daily drinking of three liters of water with meals, for a period of five days, by a man twenty-two years of age who was in a condition of nitrogen equilibrium through the ingestion of a uniform diet, was productive of the following findings : 1. An increase in body weight, aggregating two pounds in five days. 2. An increased excretion of urinary nitrogen, the excess nitrogen being mainly in the form of urea, ammonia, and creatine. 3. A decreased excretion of creatinine and the coincident appearance of creatine in the urine. The decreased creatinine output is believed to indicate that the copious water drinking has stimulated protein catabolism. The appearance of creatine is considered evidence that the water has caused a partial muscular disintegration resulting in the release of creatine, but not profound enough to yield the total nitrogen content of the muscle. The output of creatine is, therefore, out of all proportion to the increase in the excretion of total nitrogen. 4. An increased output of ammonia which is interpreted as indicating an increased output of gastric juice. 5. A decreased excretion of feces and of fecal nitrogen, the decrease in the excretion of fecal nitrogen being of sufficient magnitude to secure a lowered excretion of both the bacterial and the non-bacterial nitrogen. 6. A decrease in the quantity of bacteria excreted daily. 7. An increase in the percentage of total nitrogen appearing as bacterial nitrogen. 8. A lower creatinine coefficient. 9. A more economical utilization of the protein constituents of the diet. 10. The general conclusion to be reached as the result of this experiment is to the effect that the drinking of a large amount of water with meals was attended by many desirable and by no undesirable features.

T HE difference in composition of blood collected from an artery and from the coronary sinus is determined by the processes of intermediary metabolism in the heart muscle cell; but, because of storage of substrates and their interchange in heart muscle, the coronary arteriovenous difference reflects only a balance and permits no conclusions as to the pathways of intermediary metabolism in the heart muscle cell. ,The limitations of such biochemical observations are exemplified by studies on the nitrogen equilibrium of the body. This furnishes information on the balance between dietary protein and its relation to protein breakdown or protein synthesis; but such studies tell nothing of the rate and degree of deamination, transamination, decarboxylation, or other intermediary processes of protein metabolism. It is therefore essential to combine metabolism balance studies with investigations of cellular metabolism. Although this report is primarily concerned with in vivo studies, using intubation of the coronary sinus, frequent reference will be made to results pertaining to the intermediary metabolism of heart muscle.

Associated with the intoxication of intestinal obstruction there exists a definite impairment of the excretory function of the kidneys. The degree of functional depression corresponds roughly with the intensity of the clinical intoxication. The decrease in the urea ratio and in the capacity of the kidneys to excrete sodium chloride is more marked than is the percentage decrease of phenolsulfonephthalein elimination. The great increase in the non-protein nitrogen of the blood usually observed in acute intestinal obstruction, which has hitherto been explained as being due entirely to an increased rate of protein catabolism, is due in part to retention of the products released from the injured cell protein. It is probable that the impaired renal function is due to direct action of the toxic substances upon the renal epithelium. The actual demonstration of this renal injury is perhaps the strongest evidence so far obtained to prove the presence of an actual toxic substance in the blood during intestinal obstruction. This obscure disability of the kidneys during the height of the intoxication of acute ileus should always be considered in the clinical management of this condition. It may also serve as a guide to indicate the degree of intoxication.

Protein catabolism and carbohydrate spared or synthesized following injection of 5 mg cortisone in fasted normal mice were equal, but in fasted, altitude-exposed mice (simulated 20,000 ft. continuously for 3–5 wk.) there was less carbohydrate increase than protein decrease. In fed mice of both groups a balance between protein loss and carbohydrate increase was observed after cortisone, but the absolute quantities involved were less in altitude-exposed animals. Fasted altitude-exposed mice excreted more urinary nitrogen than controls. However, administration of bacterial endotoxin to the hypoxic group decreased the urinary nitrogen to normal levels. ACTH failed to increase urinary nitrogen under these conditions in both groups. Altitude-exposed mice were also significantly more susceptible to endotoxin than normal mice. Both glutamic-oxaloacetic and glutamic-pyruvic transaminases were lower in the livers of altitude-exposed mice than in normal animals. These enzymes were also lower 4 weeks after adrenalectomy and 17 hours after the injection of 5 mg cortisone.

Cortisol (50 or 150 mg. daily) given to mature sheep throughout a fast of 10 days increased the blood glucose level but greatly diminished the increases in blood ketone and plasma free fatty acid concentrations in comparison with those observed in fasting control sheep. Cortisol treatment did not change the plasma amino acid nitrogen level, but urinary nitrogen excretion of treated sheep continued at a higher rate throughout the fast. Phloridzin treatment reduced the elevated blood glucose of cortisol-treated sheep and increased circulating ketone, free fatty acid and amino acid nitrogen levels, as well as increasing urinary nitrogen excretion and causing glycosuria in both control and cortisol-treated sheep. Subcutaneously administered insulin, while also abolishing the hyperglycemia, decreased or prevented increases in the blood ketone, free fatty acid and amino acid nitrogen concentrations of cortisol-treated sheep. It is concluded from the relationships between the circulating concentration of glucose and the levels of ketones, free fatty acids and amino acids that the minor effect of cortisol on protein catabolism, and the antilipolytic and antiketogenic actions of cortisol in the sheep are dependent on the presence of hyperglycemia and probably reflect a compensatory hypersecretion of insulin accompanying this hyperglycemia.

1. 1. Experiments involving the simultaneous in vivo labeling of the glycine and benzoyl moieties of urinary hippuric acid of rats have been described. 2. 2. Urinary hippuric acid labeled in carbon atoms C 7 and C 8 with 14 C contributed by DL -phenylalanine-3- 14 C and glycine-2- 14 C, respectively, was isolated and the specific activity of C 7 and C 8 was determined in an effort to detect changes in the isotope concentrations of the “free” phenylalanine and glycine pools after irradiation with X-rays. 3. 3. The finding of higher specific activity in the benzoyl and glycine moieties of hippuric acid subsequent to X-irradiation is believed to constitute a direct chemical measure of the extent to which breakdown of 14 C-labeled tissue proteins is increased after exposure of rats to X-rays.

Summary Kinetin maintains the protein content of detached leaves, but the reason is not clear. This work attempted to find out whether the effect arises from maintenance of protein synthesis or retardation of protein breakdown. Protein synthesis and degradation in detached Tropaeolum majus leaves were estimated by measuring the incorporation into amino acids and protein of photo-synthetically fixed 14C, and by determining the total amounts of amino acids and protein present in ageing leaves. Protein synthesis in kinetin-treated leaves kept in darkness was higher than in the control. Rough calculation showed, however, that enhancement of protein synthesis by kinetin cannot directly account for the higher protein level found after this treatment. It seems to result from decreased degradation rather than from the maintenance of protein synthesis.

SummaryThe induction of hemorrhagic shock in the rat is accompanied by 1) no change in dipeptidase activity of extracted or surviving diaphragm; and 2) a significant increase in net protein catabolism of surviving; diaphragm. Evidence is presented indicating that isolated diaphragms from shocked animals undergo some degree of “recovery” when exposed to an oxygen atmosphere.

サイレージ調製における,詰込み時の蛋白質添加および埋蔵初期の空気導入という処理が,埋蔵過程における蛋白質の分解に及ぼす影響を調べるために,イタリアンライグラスおよびオーチャードグラスを材料として,6回にわたる実験室規模のサイレージ調製実験を行なった.すなわち,(A) 細切材料をできるだけ密に誌込む対照区,(B) 詰込みに際してグルテンを2%添加する区,(C) 対照区の半量の草を詰込み,当初4日間にわたって空気を導入する区,の3区を設け,埋蔵過程における蛋白態窒素(PN)と揮発性塩基態窒素(VBN)の変化を調べ,次の結果を得た.1. 対照区においては,初期(詰込み後4-7日まで)に急速にPNが減少し,その後の変化は僅かであった.VBNの生成は,きわめて少ない場合と,詰込み後14-21日あるいは21-70日の間に顕著に増大する場合とがあった.2. グルテン添加区においては,添加したグルテンを含めて初期に著しい蛋白分解が行なわれたが,詰込み後7日以降においてもひきつづきかなりのPNの減少があり,70日後のPNの量の対照区との差は小さくなった.VBNの生成は,対照区で顕著な場合は添加区も同様であったが,一方,対照区では少なく添加区で顕著な場合もあった.3. 空気導入区では,PNの減少が他の2区よりも著しく緩慢で,かつ,最終的にもPNの量が比較的多く,好気的条件による蛋白分解の阻害が考えられた.しかし,VBNの生成は,例外なく顕著であった.4. 以上の結果と有機酸組成とから,サイレージの品質低下は蛋白質の第1段階の分解には直接関係せず,第2段階のVBNの生成に対応するものと考えられる.

The initiation of growth of a polyaromatic auxotrophic mutant of Saccharomyces cerevisiae was inhibited by several amino acids, whereas growth of the parent prototroph was unaffected. A comparative investigation of amino acid transport in the two strains employing 14 C-labeled amino acids revealed that the transport of amino acids in S. cerevisiae was mediated by a general transport system responsible for the uptake of all neutral as well as basic amino acids. Both auxotrophic and prototrophic strains exhibited stereospecificity for l -amino acids and a K m ranging from 1.5 × 10 −5 to 5.0 × 10 −5 M. Optimal transport activity occurred at pH 5.7. Cycloheximide had no effect on amino acid uptake, indicating that protein synthesis was not a direct requirement for amino acid transport. Regulation of amino acid transport was subject to the concentration of amino acids in the free amino acid pool. Amino acid inhibition of the uptake of the aromatic amino acids by the aromatic auxotroph did not correlate directly with the effect of amino acids on the initiation of growth of the auxotroph but provides a partial explanation of this effect.

The metabolic rates of Sorex cinereus, Sorex arcticus, Microsorex hoyi, and Blarina brevicauda were calculated from oxygen consumption, carbon dioxide production, and urinary nitrogen excretion and found to be 6.1, 6.9, 67, and 9.7 Calories per animal per day respectively. The resting rate of oxygen consumption was lower for S. cinereus than values reported by previous authors and was probably close to the basal level. Respiratory quotients were higher than expected for carnivorous animals, averaging 0.83 for all species. Protein catabolism accounted for about half the daily caloric output. Metabolic rate increased with increasing population densities.The minimum numbers of larch sawfly eonymphs required to support the daily metabolic requirements, including fecal wastage, for S. cinereus, S. arcticus, M. hoyi, and B. brevicauda were 87, 123, 98, and 150 respectively. Because of digestive inefficiency and wasteful feeding habits the approximate numbers of eonymphs destroyed daily could be as high as 663, 570, 711, and 150, and if hoarding is considered, 833, 790, 891, and 410 respectively could be taken. Excepting B. brevicauda, the larch sawfly is a preferred food of the group and, when available in abundance, comprises over 70% of the diet. It was estimated that shrews have the capacity to consume numbers of cocoons in excess of naturally occurring populations, but the likelihood of complete destruction of populations is remote. Of the species studied, S. cinereus appeared to be the most likely to provide effective control of larch sawfly populations.

THE ROLE of the adrenal cortex in promoting the formation of carbohydrate from protein sources has been demonstrated in experimental animals (1). Recently it has also been shown that adrenal cortical hormone therapy had a striking effect in regulating carbohydrate utilization as well as in facilitating gluconeogenesis in patients with Addison's disease (2). The present study was undertaken to investigate the relationship between the increase in carbohydrate utilization and the decrease in gluconeogenesis which has been observed in adrenal cortical insufficiency. It appeared possible that an inability to form glucose from intermediate products of carbohydrate catabolism as well as from protein catabolism could account for many of the abnormalities. In the present report the ability of adrenalectomized animals (phlorrhizin or insulin treated) to form glucose following the administration of potentially glycogenic substances has been studied. The comparative effectiveness of treatment with several adrenal cor...

Plasma concentration, splanchnic and renal exchange, and urinary excretion of 20 amino acids were studied in obese subjects during prolonged (5-6 wk) starvation. Splanchnic amino acid uptake was also investigated in postabsorptive and briefly (36-48 hr) fasted subjects.A transient increase in plasma valine, leucine, isoleucine, methionine, and alpha-aminobutyrate was noted during the 1st wk of starvation. A delayed, progressive increase in glycine, threonine, and serine occurred after the 1st 5 days. 13 of the amino acids ultimately decreased in starvation, but the magnitude of this diminution was greatest for alanine which decreased most rapidly during the 1st week of fasting. In all subjects alanine was extracted by the splanchnic circulation to a greater extent than all other amino acids combined. Brief fasting resulted in an increased arterio-hepatic venous difference for alanine due to increased fractional extraction. After 5-6 wk of starvation, a marked falloff in splanchnic alanine uptake was attributable to the decreased arterial concentration. Prolonged fasting resulted in increased glycine utilization by the kidney and in net renal uptake of alanine. It is concluded that the marked decrease in plasma alanine is due to augmented and preferential splanchnic utilization of this amino acid in early starvation resulting in substrate depletion. Maintenance of the hypoalaninemia ultimately serves to diminish splanchnic uptake of this key glycogenic amino acid and is thus an important component of the regulatory mechanism whereby hepatic gluconeogenesis is diminished and protein catabolism is minimized in prolonged fasting. The altered renal extraction of glycine and alanine is not due to increased urinary excretion but may be secondary to the increased rate of renal gluconeogenesis observed in prolonged starvation.

The effects of thiols, ATP and CoA on the breakdown of 14 C-labelled rat serum albumin by mitochondrial and lysosomal fractions from rat liver have been studied. The breakdown of serum albumin at neutral pH was negligible in comparison with the digestion at pH 5. At acid pH the hydrolysis was strongly activated by thiols like dithiothreitol, cysteine and glutathione and also to some extent by CoASH, but not by ATP. The digestion was enhaced by those treatments which rupture the lysosomal membrane. In contrast with reports in the literature, our results do not point to the presence in subcellular fractions of a proteolytic system that could be responsible for the energy dependence of intracellular protein turnover.

Various hormones have been shown to enhance the incorporation of labeled amino acids into protein of their target organs. The precise mechanism or the exact site at which these hormones act to stimulate protein synthesis is not known for any of them. The hormone which has been most carefully studied in this respect is insulin. Thus, it has been shown that this hormone stimulates the incorporation of labeled amino acids into protein of isolated rat diaphragm (1,2,3,4). When it was found that insulin also stimulates the accumulation of normal amino acids and of the non-utilizable amino acid α-aminoisobutyric acid (AIB) by cells of the isolated, “intact” diaphragm, the possibility was considered that the increased protein synthesis might be caused by increased amino acid concentration (5,6,7). However, other observations have failed to support this possibility and have led instead to the conclusion that insulin primarily stimulates the rate of intracellular protein syntheis and that the increased uptake of amino acids is secondarily induced by the effect of insulin in stimulating the rate of protein synthesis (8). It has recently been reported that follicle stimulating hormone (FSH) under certain experimental conditions enhances the incorporation of labeled amino acids into the protein of isolated rat ovaries (9,10), and, further, that under similar conditions this hormone also stimulates the accumulation of utilizable and non-utilizable amino acids (10,11). In relation to the above mentioned theories concerning the mechanism of action of insulin in stimulating protein synthesis, it seems important to discover whether FSH acts primarily on the rate of protein synthesis in the ovarian cells or on the transport of amino acids. In the experiments which will be presented in this paper it was found that FSH can stimulate the accumulation of utilizable and non-utilizable amino acids by the isolated rat ovary even when protein synthesis has been inhibited by puromycin.

1. 1. Enzymatic degradation of calf-thymus deoxyribonucleoproteins by the proteases present in the nuclei of calf thymus has been investigated. 2. 2. Autolytic breakdown of the purified deoxyribonucleoprotein substrate was observed during incubation at 37°, showing a peak at pH 7.8. The endogenous proteolytic activity was completely suppressed by heating the deoxyribonucleoprotein substrate for 20 min at 85°. 3. 3. It has been shown that the calf-thymus nuclei contain 2 histone-splitting proteases which have peaks of activity at pH 4.4 and 7.8. The results suggest that the neutral protease is located exclusively in the nuclei, whereas the presence of the acid protease might be ascribed to contamination of the nuclear preparation by whole cells. 4. 4. Influence of ionic strength on the rate of deoxyribonucleoprotein breakdown has been studied. An optimum in the digestion rate was found in the range of minimum solubility of nucleoprotein. Another rise in the digestion rate was demonstrated at high salt concentrations. 5. 5. The neutral protease hydrolyzes all 3 main histone fractions of thymus deoxyribonucleoprotein; the lysine-rich histone is considerably more susceptible than the other two histone fractions.

(1) A brief method for the characterization of carboxyl-terminal amino acids in peptides and proteins was investigated. (2) Several new amino acid hydrazides were synthesized. (3) Soveral di- and tri-peptides were hydrazinolyzed and identified their carboxylterminal amino acid. (4) The method was applied to beef insulin and tyrocidin for the demonstration of its applicability.