Essential Dietary Amino Acid Research Articles

Application of Pyroligneous Acid as a Plant Growth Stimulant Can Improve the Nutritional Value of Soybean Seed

Farmers today are using biochemical treatments to improve their crop yields. Commercialized organic biostimulants exist in the form of pyroligneous acid generated by burning agricultural waste products. During the 2023 growing season, we demonstrated that soil treatment with a commercial pyroligneous acid product, Coriphol™, manufactured by Corigin Solutions, Inc., stimulated plant growth and significantly improved yield with an optimal treatment dose of 2 gal. acre−1. In the present work, we examined the effect of this treatment on soybean nutritional content using seed harvested from the 2023 season. Total mean seed protein content for untreated control plants was 32.26 ± 0.49% of dry mass and increased 10.8% to 35.64 ± 0.64% with treatment. This increase resulted in a net reduction in total free amino acid content, although levels of the essential dietary amino acid, lysine, were boosted 6-fold. Total lipid content was unaffected by treatment with mean levels of 21.61 ± 0.70% of dry mass noted. Treatment, however, reduced saturated fatty acid content by roughly 40%, and reduced the polyunsaturated content of linoleic acid in favor of the monounsaturated fatty acid, oleic acid. Finally, Coriphol™ treatment did not impact seed content of eight essential micronutrients including Na, Mg, K, Ca, Fe, Ni, Cu, and Mo, but did significantly boost Zn and Mn levels. Altogether, these results demonstrate that soil treatment with the growth stimulant Coriphol™ has the potential to improve the dietary nutritional value of soybean.

The consumption of animal products is associated with plasma levels of alpha-aminoadipic acid (2-AAA)

Background and aimsThe cardiometabolic disease-associated metabolite, alpha-aminoadipic acid (2-AAA) is formed from the breakdown of the essential dietary amino acid lysine. However, it was not known whether elevated plasma levels of 2-AAA are related to dietary nutrient intake. We aimed to determine whether diet is a determinant of circulating 2-AAA in healthy individuals, and whether 2-AAA is altered in response to dietary modification. Methods and resultsWe investigated the association between 2-AAA and dietary nutrient intake in a cross-sectional study of healthy individuals (N = 254). We then performed a randomized cross-over dietary intervention trial to investigate the effect of lysine supplementation (1 week) on 2-AAA in healthy individuals (N = 40). We further assessed the effect of a vegetarian diet on 2-AAA in a short-term (4-day) dietary intervention trial in healthy omnivorous women (N = 35). We found that self-reported dietary intake of animal products, including meat, poultry, and seafood, was associated with higher plasma 2-AAA cross-sectionally (P < 0.0001). Supplementary dietary lysine (5g/day) caused no significant increase in plasma 2-AAA; however, plasma 2-AAA was altered by general dietary modification. Further, plasma 2-AAA was significantly reduced by a short-term vegetarian diet (P = 0.003). ConclusionWe identified associations between plasma 2-AAA and consumption of animal products, which were validated in a vegetarian dietary intervention trial, but not in a trial designed to specifically increase the 2-AAA amino acid precursor lysine. Further studies are warranted to investigate whether implementation of a vegetarian diet improves cardiometabolic risk in individuals with elevated 2-AAA.

Gut Microbiota-Derived Tryptophan Metabolite Indole-3-aldehyde Ameliorates Aortic Dissection.

Tryptophan, an essential dietary amino acid, is metabolized into various metabolites within both gut microbiota and tissue cells. These metabolites have demonstrated potential associations with panvascular diseases. However, the specific relationship between tryptophan metabolism, particularly Indole-3-aldehyde (3-IAId), and the occurrence of aortic dissection (AD) remains unclear. 3-IAId showed an inverse association with advanced atherosclerosis, a risk factor for AD. In this study, we employed a well-established β-aminopropionitrile monofumarate (BAPN)-induced AD murine model to investigate the impact of 3-IAId treatment on the progression of AD. Our results reveal compelling evidence that the administration of 3-IAId significantly mitigated aortic dissection and rupture rates (BAPN + 3-IAId vs. BAPN, 45% vs. 90%) and led to a notable reduction in mortality rates (BAPN + 3-IAId vs. BAPN, 20% vs. 55%). Furthermore, our study elucidates that 3-IAId exerts its beneficial effects by inhibiting the phenotype transition of vascular smooth muscle cells (VSMCs) from a contractile to a synthetic state. It also mitigates extracellular matrix degradation, attenuates macrophage infiltration, and suppresses the expression of inflammatory cytokines, collectively contributing to the attenuation of AD development. Our findings underscore the potential of 3-IAId as a promising intervention strategy for the prevention of thoracic aortic dissection, thus providing valuable insights into the realm of vascular disease management.

252 Efficiency of Utilization of Methionine for Weight Gain in Weaning Pigs is not Affected by Methionine Source: A Meta-Analysis

Abstract Methionine is an essential dietary amino acid that can be supplied in different chemical forms: DL-methionine, L-methionine, and OH-methionine. It has been hypothesized that L-methionine might be used with greater efficacy for average daily gain (ADG) in weaning pigs due to their decreased enzymatic capacity to convert the other methionine forms. This study aimed to compare DL-methionine, L-methionine, and OH-methionine efficiency of utilization for ADG in weaned pigs through meta-analysis.The systematic review resulted in 2,167 papers screened for the title and abstract, with 24 papers meeting the inclusion criteria. The ADG was regressed as a function of the standardized ileal digestible (SID) methionine intake (Meti). The study was used as a random intercept, and regressions were weighted by the square root of the number of observations. Non-linear models were used to determine the Meti requirements. The average Meti requirement for pigs of 5 to 25 kg body weight (BW) was 2.09 g/d. The slopes of linear mixed-effects regression models were compared for the different methionine sources. Average initial BW was 7.99 (DL-methionine), 8.82 (L-methionine), and 7.06 kg (OH-methionine). Meti was 1.5 g/d for all sources whereas SID cysteine intake was 1.90, 2.23, and 1.93 g/d, for DL-methionine, L-methionine, and OH-methionine, respectively . Increase in Meti below the estimated requirement linearly increased ADG (ADG = 107 + 138 × Meti; P &amp;lt; 0.01). No difference between the slopes of methionine sources was observed, rejecting the hypothesis that L-methionine is used with greater efficiency in weaned pigs. Pigs receiving DL-methionine, L-methionine, and OH-methionine presented an estimated ADG of 319, 317, and 311 (SE = 19, 25 and, 26, respectively) g/d, respectively. In conclusion, methionine efficiency of utilization for ADG in post-weaned pigs is not affected by methionine sources.

Abstract 3046: A common gut commensal utilizes tryptophan to promote cancer via the aryl hydrocarbon receptor

Abstract Background: We have previously showed that gut microbiota-depleting oral antibiotics decrease tumor growth in C57BL/6J mice via the immune system (Sethi et al, Gastroenterology, 2018). The gut microbiota, however, includes thousands of species producing numerous metabolites. The search for individual bacterial species and metabolites that can promote cancer continues. Methods: We studied the effects of common microbiota modulation techniques in C57BL/6 mice procured from various commercial vendors and injected subcutaneously with cancer cells. 16S rRNA gene sequencing and metabolomics analyses were used to identify the putative cancer-promoting species and metabolites. Results: Mice procured from The Jackson Laboratory (JAX mice) form larger tumors at baseline compared to mice procured from the Charles River Laboratories (CR mice). JAX mice have tumor promoting microbiota that can be targeted by oral antibiotics unlike CR mice. This tumor-promoting microbiota gets transferred from JAX to CR mice via cohousing or fecal microbiota transplant. In a preclinical trial, oral vancomycin slowed the growth of cancer in avatar mice gavaged with stools of some pancreatic cancer patients but not of others. Statistical analyses reveal that the gut of JAX mice hosts a common human gram-positive gut commensal Ruminococcus gnavus that is associated with increased cancer growth in those mice. Monocolonization of germ-free mice with R gnavus directly increases tumor growth. Similarly, feeding R gnavus, but not a control bacterial species, brings the baseline tumor kinetics of CR mice up to that of JAX mice. Our experiments reveal that R gnavus needs sufficient dietary tryptophan (Trp) to promote tumor growth and in turn, catabolizes Trp into various metabolites including the Aryl Hydrocarbon Receptor (AHR) ligand Tryptamine, which we find, is also tumor-promoting per se. The tumor-modulating effects of oral vancomycin, tryptophan catabolites and R gnavus are abolished when murine AHR is stimulated by an exogenous ligand or when it is knocked out. Finally, we find that Ly6G+ cells are essential in effecting these bacteria-cancer interactions. Conclusions: We present initial evidence on how a common gut commensal hijacks an essential dietary amino acid to promote cancer via the AHR. We also demonstrate the essential but underappreciated role that the source of animal procurement plays in studies involving cancer models. Citation Format: Vrishketan Sethi, Junyi Tao, Saba Kurtom, Utpreksha Vaish, Farrukh Afaq, Shuan Zao, Xian Luo, Tejeshwar Jain, Prateek Sharma, Ejas Bava, Sundaram Ramakrishnan, Liang Li, Ashok Saluja, Vikas Dudeja. A common gut commensal utilizes tryptophan to promote cancer via the aryl hydrocarbon receptor [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3046.

An Emerging Cross-Species Marker for Organismal Health: Tryptophan-Kynurenine Pathway.

Tryptophan (TRP) is an essential dietary amino acid that, unless otherwise committed to protein synthesis, undergoes metabolism via the Tryptophan-Kynurenine (TRP-KYN) pathway in vertebrate organisms. TRP and its metabolites have key roles in diverse physiological processes including cell growth and maintenance, immunity, disease states and the coordination of adaptive responses to environmental and dietary cues. Changes in TRP metabolism can alter the availability of TRP for protein and serotonin biosynthesis as well as alter levels of the immune-active KYN pathway metabolites. There is now considerable evidence which has shown that the TRP-KYN pathway can be influenced by various stressors including glucocorticoids (marker of chronic stress), infection, inflammation and oxidative stress, and environmental toxicants. While there is little known regarding the role of TRP metabolism following exposure to environmental contaminants, there is evidence of linkages between chemically induced metabolic perturbations and altered TRP enzymes and KYN metabolites. Moreover, the TRP-KYN pathway is conserved across vertebrate species and can be influenced by exposure to xenobiotics, therefore, understanding how this pathway is regulated may have broader implications for environmental and wildlife toxicology. The goal of this narrative review is to (1) identify key pathways affecting Trp-Kyn metabolism in vertebrates and (2) highlight consequences of altered tryptophan metabolism in mammals, birds, amphibians, and fish. We discuss current literature available across species, highlight gaps in the current state of knowledge, and further postulate that the kynurenine to tryptophan ratio can be used as a novel biomarker for assessing organismal and, more broadly, ecosystem health.

Serum Levels and Removal by Haemodialysis and Haemodiafiltration of Tryptophan-Derived Uremic Toxins in ESKD Patients.

Tryptophan is an essential dietary amino acid that originates uremic toxins that contribute to end-stage kidney disease (ESKD) patient outcomes. We evaluated serum levels and removal during haemodialysis and haemodiafiltration of tryptophan and tryptophan-derived uremic toxins, indoxyl sulfate (IS) and indole acetic acid (IAA), in ESKD patients in different dialysis treatment settings. This prospective multicentre study in four European dialysis centres enrolled 78 patients with ESKD. Blood and spent dialysate samples obtained during dialysis were analysed with high-performance liquid chromatography to assess uremic solutes, their reduction ratio (RR) and total removed solute (TRS). Mean free serum tryptophan and IS concentrations increased, and concentration of IAA decreased over pre-dialysis levels (67%, 49%, −0.8%, respectively) during the first hour of dialysis. While mean serum total urea, IS and IAA concentrations decreased during dialysis (−72%, −39%, −43%, respectively), serum tryptophan levels increased, resulting in negative RR (−8%) towards the end of the dialysis session (p < 0.001), despite remarkable Trp losses in dialysate. RR and TRS values based on serum (total, free) and dialysate solute concentrations were lower for conventional low-flux dialysis (p < 0.001). High-efficiency haemodiafiltration resulted in 80% higher Trp losses than conventional low-flux dialysis, despite similar neutral Trp RR values. In conclusion, serum Trp concentrations and RR behave differently from uremic solutes IS, IAA and urea and Trp RR did not reflect dialysis Trp losses. Conventional low-flux dialysis may not adequately clear Trp-related uremic toxins while high efficiency haemodiafiltration increased Trp losses.

Acute Psychological Stress Modulates the Expression of Enzymes Involved in the Kynurenine Pathway throughout Corticolimbic Circuits in Adult Male Rats.

Tryptophan is an essential dietary amino acid that is necessary for protein synthesis, but also serves as the precursor for serotonin. However, in addition to these biological functions, tryptophan also serves as a precursor for the kynurenine pathway, which has neurotoxic (quinolinic acid) and neuroprotective (kynurenic acid) metabolites. Glucocorticoid hormones and inflammatory mediators, both of which are increased by stress, have been shown to bias tryptophan along the kynurenine pathway and away from serotonin synthesis; however, to date, there is no published data regarding the effects of stress on enzymes regulating the kynurenine pathway in a regional manner throughout the brain. Herein, we examined the effects of an acute psychological stress (120 min restraint) on gene expression patterns of enzymes along the kynurenine pathway over a protracted time-course (1–24 h post-stress termination) within the amygdala, hippocampus, hypothalamus, and medial prefrontal cortex. Time-dependent changes in differential enzymes along the kynurenine metabolism pathway, particularly those involved in the production of quinolinic acid, were found within the amygdala, hypothalamus, and medial prefrontal cortex, with no changes seen in the hippocampus. These regional differences acutely may provide mechanistic insight into processes that become dysregulated chronically in stress-associated disorders.

Metabolome-wide association study of phenylalanine in plasma of common marmosets.

Little systematic knowledge exists concerning the impacts of cumulative lifelong exposure, termed the exposome, on requirements for nutrients. Phenylalanine (Phe) is an essential dietary amino acid with an aromatic ring structure similar to endogenous metabolites, dietary compounds and environmental agents. Excess plasma Phe in genetic disease or nutritional deficiency of Phe has adverse health consequences. In principle, structurally similar chemicals interfering with Phe utilization could alter Phe requirement at an individual level. As a strategy to identify components of the exposome that could interfere with Phe utilization, we tested for metabolites correlating with Phe concentration in plasma of a non-human primate species, common marmosets (Callithrix jacchus). The results of tests for more than 5,000 chemical features detected by high-resolution metabolomics showed 17 positive correlations with Phe metabolites and other amino acids. Positive and negative correlations were also observed for 33 other chemicals, which included matches to endogenous metabolites and dietary, microbial and environmental chemicals in database searches. Chemical similarity analysis showed many of the matches had high structural similarity to Phe. Together, the results show that chemicals in marmoset plasma could impact Phe utilization. Such chemicals could contribute to early lifecycle developmental disorders when neurological development is vulnerable to Phe levels.

Brewers' spent grain; bioactivity of phenolic component, its role in animal nutrition and potential for incorporation in functional foods: a review

Brewers' spent grain (BSG) is a low-value co-product of the brewing industry produced in large quantities annually. This paper reviews the existing evidence regarding the phenolic component of BSG, focusing on composition, extraction and biofunctions such as antioxidant, anti-atherogenic, anti-inflammatory and anti-carcinogenic activities. Furthermore, the incorporation of BSG in foodstuffs will be discussed, including the use of BSG as an animal feed supplement and the potential of BSG to be incorporated into foods for human consumption. BSG contains hydroxycinnamic acids including ferulic acid, p-coumaric acid and caffeic acid; which have shown bioactivity in the pure form (antioxidant, anti-inflammatory, anti-atherogenic and anti-cancer). Phenolic extracts from BSG have also shown antioxidant potential, by protecting against oxidant-induced DNA damage, possibly by Fe chelation. Studies show that BSG has many benefits when used as a supplement in animal feed, such as increasing milk yield, milkfat content and in providing essential dietary amino acids. The incorporation of BSG in human foods such as cookies and ready-to-eat snacks has resulted in increased protein and fibre contents of the products, where the changes in organoleptic properties are controllable. It can be concluded that the phenolic component of BSG has potential bioactive effects, which are worth pursuing given that the inclusion of BSG into human foodstuffs is viable and beneficial.

Dietary factors and fluctuating levels of melatonin

Melatonin is secreted principally by the pineal gland and mainly at nighttime. The primary physiological function is to convey information of the daily cycle of light and darkness to the body. In addition, it may have other health-related functions. Melatonin is synthesized from tryptophan, an essential dietary amino acid. It has been demonstrated that some nutritional factors, such as intake of vegetables, caffeine, and some vitamins and minerals, could modify melatonin production but with less intensity than light, the most dominant synchronizer of melatonin production. This review will focus on the nutritional factors apart from the intake of tryptophan that affect melatonin levels in humans. Overall, foods containing melatonin or promoting the synthesis of it by impacting the availability of tryptophan, as well those containing vitamins and minerals which are needed as co-factors and activators in the synthesis of melatonin, may modulate the levels of melatonin. Even so, the influence of daytime diet on the synthesis of nocturnal melatonin is limited, however, the influence of the diet seems to be more obvious on the daytime levels.

Comparative studies on homocysteine and its metabolite–homocysteine thiolactone action in blood platelets in vitro

Homocysteine (Hcy), an intermediate formed during the catabolism of the essential dietary amino acid methionine, and its cyclic thioester, homocysteine thiolactone (TL) formed from Hcy in plasma, may be implicated in pathological haemostasis and atherosclerosis. The mechanism by which TL exerts the prothrombotic effect and influences blood platelets remains unclear. Activation of blood platelets plays an important role in prothrombotic events. The aim of our study was to establish and compare the influence of a reduced form of homocysteine (at final doses of 10–100 µM) and its cyclic thioester, homocysteine thiolactone (0.1–1 µM), on platelet activation induced by thrombin (platelet aggregation), on platelet protein modifications (determined by parameters such as level of protein carbonyl groups, 3-nitrotyrosine residues in proteins) and on superoxide anion radicals () generation using the model system in vitro. We have observed that TL, like its precursor, Hcy, stimulates the generation of in platelets and causes an augmentation of platelet aggregation induced by thrombin. Our present results in vitro also demonstrate that Hcy (10–100 µM) and TL at lower doses than Hcy (0.1–1 µM) cause modification of platelet proteins: diminished formation of carbonyl groups and distinctly decreased tyrosine nitration in platelet proteins after thrombin stimulation, but increased platelet aggregation induced by thrombin. TL like Hcy (at concentrations corresponding to concentrations in blood during hyperhomocysteinemia) modifies platelet responses to an important physiological agonist–thrombin.

Phenylalanine Biosynthesis in Arabidopsis thaliana: IDENTIFICATION AND CHARACTERIZATION OF AROGENATE DEHYDRATASES

There is much uncertainty as to whether plants use arogenate, phenylpyruvate, or both as obligatory intermediates in Phe biosynthesis, an essential dietary amino acid for humans. This is because both prephenate and arogenate have been reported to undergo decarboxylative dehydration in plants via the action of either arogenate (ADT) or prephenate (PDT) dehydratases; however, neither enzyme(s) nor encoding gene(s) have been isolated and/or functionally characterized. An in silico data mining approach was thus undertaken to attempt to identify the dehydratase(s) involved in Phe formation in Arabidopsis, based on sequence similarity of PDT-like and ACT-like domains in bacteria. This data mining approach suggested that there are six PDT-like homologues in Arabidopsis, whose phylogenetic analyses separated them into three distinct subgroups. All six genes were cloned and subsequently established to be expressed in all tissues examined. Each was then expressed as a Nus fusion recombinant protein in Escherichia coli, with their substrate specificities measured in vitro. Three of the resulting recombinant proteins, encoded by ADT1 (At1g11790), ADT2 (At3g07630), and ADT6 (At1g08250), more efficiently utilized arogenate than prephenate, whereas the remaining three, ADT3 (At2g27820), ADT4 (At3g44720), and ADT5 (At5g22630) essentially only employed arogenate. ADT1, ADT2, and ADT6 had k(cat)/Km values of 1050, 7650, and 1560 M(-1) S(-1) for arogenate versus 38, 240, and 16 M(-1) S(-1) for prephenate, respectively. By contrast, the remaining three, ADT3, ADT4, and ADT5, had k(cat)/Km values of 1140, 490, and 620 M(-1) S(-1), with prephenate not serving as a substrate unless excess recombinant protein (>150 microg/assay) was used. All six genes, and their corresponding proteins, are thus provisionally classified as arogenate dehydratases and designated ADT1-ADT6.

Cardiac l‐arginine transport: the CAT is back

Cardiac <scp>l</scp>‐arginine transport: the CAT is back

Dietary Lysine Requirement as Basis to Estimate the Essential Dietary Amino Acid Profile for Jundiá, Rhamdia quelen

Abstract The present study was designed to determine the optimal dietary lysine requirement for jundiá, Rhamdia quelen, fingerlings. Groups of 17 fish (1.4 ± 0.1 g) were stocked in 120‐L tanks and were fed semipurified diets (33% crude protein [CP] and 3500 kcal metabolizable energy) containing increasing concentrations of lysine (3.0, 4.0, 4.5, 5.0, 5.5, 6.0, and 6.5% CP). After 119 d, fish weight gain (WG), specific growth rate (SGR), feed intake and feed conversion (FC), apparent net protein utilization (ANPU), body composition (CP, fat, and ash), and vertebral collagen were determined. WG and SGR increased as dietary lysine concentration in protein increased up to 4.5%, reducing at 6.0 and 6.5% lysine. Fish that were fed the lowest lysine concentration presented the worst feed conversion (FC), which improved for fish fed with 4.5% or more lysine. Feed consumption followed the same trend as FC. The highest ANPU was observed in fish fed with 4.5% lysine. Fish fed diets containing 4.5, 5.0, and 5.5% lysine accumulated more body protein (P &lt; 0.05). Collagen vertebral concentration was significantly higher in fish fed with the 4.5% lysine diet. Dietary requirement for lysine was 4.5 or 5.1% depending on the statistical model used for estimation: broken line or polynomial regression, respectively. The requirements for the other essential amino acids were estimated on the basis of the ideal protein concept and were similar to the requirements for other fish species, except for isoleucine, leucine, treonine, and valine, which were higher for jundiá.

Inotropic interventions in the assessment of myocardial failure associated with taurine deficiency in domestic cats.

Of the amino acids that exist freely in the cytoplasm of myocardial cells, taurine is in highest concentration. While the precise physiological function of taurine in the myocardium has not be defined, taurine may have antioxidant properties8, 9, 29, modulating effects on myocardial calcium23, or a positive inotropic effect3, 32. In hearts isolated from taurine-de-pleted and control rats, Schaffer et al. 29 observed a significantly lower% recovery of mechanical performance in the depleted group than controls following ischemic-reperfusion injury. More recently, we24, 25 and others17 have reported that depletion of myocardial taurine results in cardiac dysfunction characterized by decreased left ventricular (LV) contractility, suggesting that taurine is essential to the maintenance of normal myocardial contractile function. Because taurine is an essential dietary amino acid in the domestic cat, a taurine-deficient state can be achieved in this species through restriction of dietary taurine14. In the cat dietary taurine deficiency leads to a spectrum of changes in myocardial function associated with decreased contractility24, 25. Dilated cardiomyopathy (DCM) appears to be one consequence of taurine deficiency in this species. However, not all cats maintained on taurine-deficient diets develop DCM24, 27, 30.

Amino acid imbalance, a nutritional model: Serotonin 3 mediation of aversive responses

The feeding responses to essential dietary amino acid (AA) disproportion have been useful in nutritional studies. These responses involve first: recognition of the imbalance and second: rejection of the diet, likely via development of a learned aversion. In the rat, we have studied the role of the limiting AA and protein synthesis in the recognition phase by replacement of the limiting AA into a brain area essential for the initial depressed feeding response. We have also reported a reciprocal relationship between serotonin (5HT) activity and intake of imbalanced diets. High doses of the 5HT 3 receptor antagonist, ICS 205–930 (ICS; 9 mg/kg IP), restored food intake to 85% or more of control intake. In the present experiments, similar treatment with ICS blocked the classical conditioned taste aversion to a saccharin solution paired with lithium chloride. These results suggest that the increased intake of AA imbalanced diets after ICS may be due to 5HT-mediated blockade of a learned aversion.

Requirements for the Essential Dietary Amino Acids of Larvae of the Rice Weevil 12

The requirements of larvae of the rice weevil, Sitophilus oryzae (L.), for 8 rat-essential amino acids were determined in a cornstarch-based diet using a mixture of 15 amino acids. With a total amino acid level of 5.0%, the lowest concentrations that gave growth rates comparable to those obtained on the standard 15 amino acid diet were: L-arginine, 0.15%; L-histidine, 0.12%; L-isoleucine, 0.20%; L-Ieucine, 0.40%; L-threonine, 0.15%; L-tryptophane, 0.04%; and L-valine, 0.18%. A strict requirement for phenylalanine could not be demonstrated with this diet. Compared to development on a wheat germ diet and the standard 15 amino acid diet, the growth rates were slower and the pupae were smaller on a diet in which all of the essential amino acids in a 15 amino acid mixture were at their minimal levels.

Essential Dietary Amino Acids for Growth of Larvae of the Yellow Mealworm, Tenebrio molitor L.

Larvae of the yellow mealworm, Tenebrio molitor L., have been used to evaluate nutritional quality of proteins and protein isolates. However, such investigations have been complicated by lack of knowledge of dietary requirements of the larvae. To determine essential dietary amino acids for growth of Tenebrio molitor, single amino acids were deleted from the amino acid mixture of the diet. Diets were maintained isonitrogenous with supplementary glycine and, in the case of deleted glycine, with glutamic acid. Growth, as measured by gain in weight, and survival were observed over a 4-week period at 27 plus or minus 0.25 degrees and 65 plus or minus 5% relative humidity. The results indicate that larvae of Tenebrio molitor require a dietary source of the same 10 amino acids essential for growth in rats, other vertebrates, and some protozoa. They also showed that serine, tyrosine, glutamic acid, and possibly glycine were dispensable for growth in this insect. Alanine, cystine, proline, and aspartic acid appeared semidispensable. Survival over the 4-week experimental period was unaffected by deleting amino acids from the diet. The results are discussed in relation to amino acid requirements of other insects and to suggested improvement of the diet of the present investigation.

The Isoleucine and Valine Nutrition of Young Laying Pullets as Influenced by Excessive Dietary Leucine

THE usual approach to assuring both adequate and economic amino acid nutrition for layers has been to combine energy and protein concentrates and supplemental amino acids in such a way as to meet the requirements for essential dietary amino acids on a least-cost basis. In so doing, it has been assumed that the excesses of some amino acids programmed into the diet are deaminated and used as sources of energy to a varying degree depending upon the amino acid in question. Otherwise, the excesses have been assumed to be rather innocuous from a nutritional standpoint.However, the work of Harper et al. (1955) has stimulated investigations into the role of excesses of certain amino acids upon the metabolism and dietary requirements for others. Specifically, their data indicated that excess leucine increased the requirement for isoleucine.In a recent report from this laboratory by Bray (1969) it was theorized that a…