Nutritional evaluation of wheat and barley cultivars by growth rate and body composition of larvae of Tenebrio molitor.

Larvae of the yellow mealworm, Tenebrio molitor L., Gembloux strain, race F, were reared on diets of 17 cultivars of wheat and 29 cultivars of barley, prepared for determination of digestible energy with mice, for 4 weeks at 27 +/- 0.25 degrees C and 65 +/- 5% relative humidity. Values for percentage crude protein of tissues of larvae fed wheat cultivars were significantly and positively correlated with values for digestible energy as determined with mice. These values were not correlated for larvae fed barley cultivars; however, values for per cent dry matter content of larvae were significantly and positively correlated with values for digestible energy determined with mice. This apparent discrepancy is explained on the basis of the chemical constitution of barley and the availability of amino acids of barley to the larvae. Use of larvae of Tenebrio molitor to indicate the digestible energy of cereal grains is feasible, provided that the proper parameter is chosen. Nevertheless, use of this biological method seems more suitable for evaluation of protein quality and of amino acid availability than for a measure of digestible energy of feeds.     

Lysine-rich proteins in high-lysine Hordeum vulgare grain

The salt-soluble proteins in barley grain selected for high-lysine content (Hiproly, CI 7115 and the mutants 29 and 86) and of a control (Carlsberg II) with normal lysine content, contain identical major proteins as determined by MW and electrophoretic mobility. The concentration of a protein group with a high lysine content varies significantly among the barleys examined. One protein, present in large amounts in Hiproly, is assumed to be partially responsible for the high-lysine character of Hiproly, CI 7115 and the mutants 29 and 86.     

Protein turnover and amino acid transport kinetics in end-stage renal disease

Protein and amino acid metabolism is abnormal in end-stage renal disease (ESRD). Protein turnover is influenced by transmembrane amino acid transport. The effect of ESRD and hemodialysis (HD) on intracellular amino acid transport kinetics is unknown. We studied intracellular amino acid transport kinetics and protein turnover by use of stable isotopes of phenylalanine, leucine, lysine, alanine, and glutamine before and during HD in six ESRD patients. Data obtained from amino acid concentrations and enrichment in the artery, vein, and muscle compartments were used to calculate intracellular amino acid transport and muscle protein synthesis and catabolism. Fractional muscle protein synthesis (FSR) was estimated by the precursor product approach. Despite a significant decrease in the plasma concentrations of amino acids in the artery and vein during HD, the intracellular concentrations remained stable. Outward transport of the amino acids was significantly higher than the inward transport during HD. FSR increased during HD (0.0521 +/- 0.0043 vs. 0.0772 +/- 0.0055%/h, P < 0.01). Results derived from compartmental modeling indicated that both protein synthesis (118.3 +/- 20.6 vs. 146.5 +/- 20.6 nmol.min-1.100 ml leg-1, P < 0.01) and catabolism (119.8 +/- 18.0 vs. 174.0 +/- 14.2 nmol.min-1.100 ml leg-1, P < 0.01) increased during HD. However, the intradialytic increase in catabolism exceeded that of synthesis (57.8 +/- 13.8 vs. 28.0 +/- 8.5%, P < 0.05). Thus HD alters amino acid transport kinetics and increases protein turnover, with net increase in protein catabolism.     

Evaluation of optimum lysine and threonine supplements to a wheat and barley-based diet in rats

Experiments were conducted on growing male SPF-rats to study the optimum supplementation with essential amino acids of diets containing wheat and barley (1.4:1) as the only source of nitrogen. In growth and balance experiments comprising 30 and 17 combinations of L-lysine and L-threonine, respectively, the concentrations of the two amino acids corresponding to maximum body weight gain, feed conversion efficiency, biological value of protein and net protein utilization were calculated using multiple regression analysis. Addition of lysine and threonine to the basal diet markedly improved the nutritional value of cereal proteins. The optimum concentrations found were 0.69–0.70% total dietary lysine and 0.52–0.55% total dietary threonine. Statistical analysis showed that the number of observations used for the estimation of regression functions in the growth experiment could be reduced to ca. 100 without substantially affecting precision.     

Leucine transport in membrane vesicles from Chironomus riparius larvae displays a mélange of crown-group features

Leucine uptake into membrane vesicles from larvae of the midge Chironomus riparius was studied. The membrane preparation was highly enriched in typical brush border membrane enzymes and depleted of other membrane contaminants. In the absence of cations, there was a stereospecific uptake of l-leucine, which exhibited saturation kinetics. Parameters were determined both at neutral (Km 33 +/- 5 microM and Vmax 22.6 +/- 6.8 pmol/7s/mg protein) and alkaline (Km 46 +/- 5 microM and Vmax 15.5 +/- 2.5 pmol/7s/mg protein) pH values. At alkaline pH, external sodium increased the affinity for leucine (Km 17 +/- 1 microM) and the maximal uptake rate (Vmax 74.0 +/- 12.5 pmol/7s/mg protein). Stimulation of leucine uptake by external alkaline pH agreed with lumen pH measurements in vivo. Competition experiments indicated that at alkaline pH, the transport system readily accepts most L-amino acids, including branched, unbranched, and alpha-methylated amino acids, histidine and lysine, but has a low affinity for phenylalanine, beta-amino acids, and N-methylated amino acids. At neutral pH, the transport has a decreased affinity for lysine, glycine, and alpha-methylleucine. Taken together, these data are consistent with the presence in midges of two distinct leucine transport systems, which combine characters of the lepidopteran amino acid transport system and of the sodium-dependent system from lower neopterans.     

Identification of Flavones in Thirteen Liliaceae Species

Changes in the levels of free and protein amino acids in the callus of Hiproly barley were studied during differentiation. Adventitious roots were formed in the callus after 90 days of cultivation on modified White’s medium containing 1 μm indoleacetic acid (IAA) and 200 μm adenine sulfate, and callus placed on Murashige–Skoog’s medium without plant hormones formed adventitious roots after 30 days of cultivation. During differentiation, protein amino acids in the callus decreased, then increased, without an appreciable compositional change in the protein amino acids. The amount of free amino acids in the callus increased with root formation. The major free amino acids during differentiation were glutamine, asparagine, alanine, and proline. Glutamine increased until roots were found in the callus after cultivation. Asparagine gradually increased during differentiation.     

A plant serpin gene. Structure, organization and expression of the gene encoding barley protein Z4

A 3133-bp nucleotide sequence of the gene Paz1 on chromosome 4 of barley, encoding endosperm protein Z4, has been determined. The sequence includes 1079 bp 5' upstream and 523 bp 3' downstream of the coding region. The 1079-bp 5' upstream region of the gene shows little similarity to 5' regions of other sequences genes expressed in the developing cereal endosperm. The coding sequence is interrupted by one 334-bp-long intron (bases 1497-1830). The deduced amino acid sequence, which was corroborated by peptide sequences, consists of 399 amino acids and has a molecular mass of 43,128 Da. This sequence confirms protein Z4 to be a member of the serpin superfamily of proteins. The similarity with other members of the family expressed as amino acids in identical positions is in the order of 25-30% and pronounced in the carboxy-terminal half of the molecule. Sequence residues assumed to form clusters stabilizing the tertiary structure are highly conserved. Protein Z4 is synthesized in the developing endosperm without a signal peptide and protein Z4 mRNA was evenly distributed among the free and membrane-bound polyribosomes of the endosperm cell. An internal hydrophobic region of 21 amino acids (residues 36-56) may serve as a signal for targeting the polypeptide into the lumen of the endoplasmic reticulum. The gene for protein Z4 could not be detected in the barley variety Maskin and some of its descendants. The 'high-lysine' allees, lys1 (Hiproly barley) and lys3a (Bomi mutant 1508) on chromosome 7, enhance and repress, respectively, the expression of the protein Z4 gene. Also, 1554 bp of another 8-kbp fragment of the barley genome Paz psi, similar to the protein-Z4-coding region, have been determined. Small insertions and deletions and the presence of an internal stop codon identify this fragment as part of a pseudogene related to the protein Z4 gene.     

Efficient regeneration of fertile barley plants from callus cultures of several Nordic cultivars

The regeneration potential of three major Estonian barley cultivars was tested and compared to that of the Finnish cultivar Kymppi. Two different regeneration systems were used. The first was characterized by the high maltose concentration (60 g l(-1)) and by the use of 2,4D together with two different combinations of amino acids in the callus induction medium followed by the regeneration medium containing BAP (2 mg l(-1)) and 2,4D (0.2 mg l(-1)). The second exploited callus induction medium that contained Dicamba, lower concentrations of maltose (30 g l(-1)) and higher concentrations of myo-inositol and thiamine and different set of amino acids and regeneration medium that contained higher concentrations of Cu2+ and inorganic nitrogen accompanied by lower concentrations of NH4+ and BAP, when compared to the first regeneration system. The second regeneration system used produced significantly higher rates of callus induction, callus growth and regeneration of plantlets. However, it yielded also many albino plants (up to 51%), whereas the first regeneration system used did not produce practically any albino plants. No major genotype-dependent differences were observed in comparison between two regeneration systems - in both systems higher regeneration potential of Anni, Elo and Kymppi contradicted to the low regeneration potential of Teele. It is concluded that the continuous somatic embryogenesis on the regeneration medium allows the regeneration of many plants from the same callus over long periods of time and makes available highly efficient regeneration protocols for Estonian and Finnish barley cultivars.     

Comparative composition of free,peptide and protein amino acids in symbiotic and aposymbiotic Sitophilus oryzae (coleoptera,curculionidae)

Free, peptide-bound and total amino acids were determined in symbiotic and aposymbiotic Sitophilus oryzae. The concentrations of free and peptide amino acids were higher, that of protein amino acids lower in aposymbiotic larvae (+30, +66 and −35%, respectively). In the free fraction, tyrosine concentration was the only one to be lower in aposymbiotic larvae (−41%) and could be a limiting factor for protein synthesis.In nymphs and adults, the compositions in symbiotic and aposymbiotic insects were very similar. A deficiency of tyrosine occurred however in aposymbiotic nymphs and of aspartate, glutamate, arginine, lysine and tyrosine in aposymbiotic adults. On the other hand, the composition in ovaries was unchanged.It is suggested that symbiotes could favour the synthesis of proteins in the larvae by increasing the efficiency of the conversion of phenylalanine in tyrosine.     

Substrate-dependent regulation of intracellular amino acid concentrations in cultured bovine aortic endothelial cells

Amino acid deprivation induces adaptive changes in amino acid transport and the intracellular amino acid pool in cultured cells. In this study intracellular amino acid levels were determined in cultured bovine aortic endothelial cells (EC) deprived of L-arginine or total amino acids for 1, 3, 6 and 24 h. Amino acid concentrations were analyzed by reverse phase HPLC after precolumn derivatisation. Under normal culture conditions levels of L-arginine L-citrulline, total essential and non-essential amino acids were 840 +/- 90 microM, 150 +/- 40 microM, 11.4 +/- 0.9 mM and 53.3 +/- 3.4 mM (n = 9), respectively. In EC deprived of L-arginine or all amino acids for 24 h L-arginine and L-citrulline levels were 200 microM and 50 microM, and 670 microM and 100 microM Deprivation of L-arginine or total amino acids induced rapid (1 h) decreases (30 - 50%) in the levels of other cationic (lysine, ornithine) and essential branched-chain (valine, isoleucine, leucine) and aromatic (phenylalanine, tryptophan) amino acids. L-glutamine was reduced markedly in EC deprived of total amino acids for 1 h - 6 h but actually increased 3-fold in EC deprived of L-arginine for 6 h or 24 h. Arginine deprivation resulted in a rapid decrease in the total intracellular amino acid pool, however concentrations were restored after 24 h. Increased amino acid transport and/or reduced protein synthesis may account for the restoration of amino acid levels in EC deprived of L-arginine. The sustained reduction in the free amino acid pool of EC deprived of all amino acids may reflect utilization of intracellular amino acids for protein synthesis.     

异育银鲫幼鱼对饲料中赖氨酸的利用及需要量研究

以添加晶体氨基酸的半精制饲料饲喂异育银鲫幼鱼,通过69d的生长实验来确定其赖氨酸需要量。饲料以白鱼粉为主要蛋白源,饲料中的总赖氨酸含量分别为1.82%、2.32%、2.82%、3.32%3、.82%、4.32%和4.82%7个水平。实验在室内循环水养殖系统中进行,每种饲料随机3个重复。实验结果表明,异育银鲫能够利用饲料中的晶体赖氨酸、蛋氨酸。在投喂后3h,其血浆中的游离赖氨酸、蛋氨酸含量最高。当饲料中赖氨酸含量为3.32%时,异育银鲫的终末尾均重、特定生长率和鱼空壳占体重的百分比最高,肝体指数最低。当饲料中赖氨酸含量为3.82%时,异育银鲫的干物质表观消化率显著高于其他组(PPP>0.05)。血红蛋白含量以赖氨酸含量为2.82%的饲料组最高,4.82%组最低;随着饲料中赖氨酸含量的升高,异育银鲫红细胞数下降,血清脲氮含量升高,且血清脲氮含量具有组间显著性差异(P<0.05)。根据折线法,由异育银鲫的特定生长率同饲料中赖氨酸水平的相关性得出其赖氨酸需要量为3.27%,占饲料蛋白的8.52%。       

Properties and Regulation of Aspartate Kinase from Barley Seedlings (Hordeum vulgare L.)

Aspartate kinase (EC 2.7.2.4) has been purified 8-fold and characterized from germinating barley (Hordeum vulgare) seedlings. The enzyme is inhibited 50% by 0.7 mm l-lysine and almost completely at 5 mm. l-Methionine does not affect the enzyme on its own, but at low concentrations (0.1-1 mm) increases the inhibition in the presence of lysine, indicating that the two amino acids act as cooperative feedback regulators.     

Dietary protein reduction in sheep and goats: different effects on <Emphasis Type="SmallCaps">l</Emphasis>-alanine and <Emphasis Type="SmallCaps">l</Emphasis>-leucine transport across the brush-border membrane of jejunal enterocytes

It was the aim of this study to examine the potential regulatory effects of a long-term low dietary protein supply on the transport capacity of the jejunal brush-border membrane for amino acids. For this purpose, we used the neutral amino acids L-alanine (representative for nonessential amino acids) and L-leucine (representative for essential amino acids) as model substances. Ten sheep lambs, 8 weeks of age and 19-27 kg body weight, were allotted to two dietary regimes with either adequate or reduced protein supply which was achieved by 17.9% and 9.7% of crude protein in the concentrated feed, respectively. The feeding periods were 4-6 weeks in length. Similarly, eight goat kids of 5-7 weeks of age and 8-14 kg body weight were allotted to either adequate (crude protein 20.1%, feeding period 9-12 weeks) or reduced protein supply (10.1%, feeding period 17-18 weeks). Dietary protein reduction in lambs caused a significant body weight loss of 0.6 +/- 0.7 kg, whereas the body weight in control animals increased by 1.9 +/- 0.7 kg (P<0.05). Plasma urea concentrations decreased significantly by 60% (low protein 2.3 +/- 0.1 versus control 5.7 +/- 0.2 mmol l(-1), P<0.001). In kids, reduction of dietary protein intake led to significant decreases of the daily weight gain by 48% from 181 +/- 8 g to 94 +/- 3 g (P<0.001) and daily dry matter intake by 27% from 568 +/- 13 g to 417 +/- 6 g (P<0.01). Respective urea concentrations in plasma were reduced by 77% from 5.2 +/- 0.4 to 1.2 +/- 0.2 mmol l(-1) (P<0.01). Kinetic analyses of the initial rates of alanine uptake into isolated jejunal brush-border membrane vesicles from sheep and goats as affected by low dietary protein supply yielded that the apparent Km was neither significantly different between the species nor significantly affected by the feeding regime thus ranging between 0.12 and 0.16 mmol.l(-1). Reduction of dietary protein, however, resulted in significantly decreased Vmax values of the transport system by 25-30%, irrespective of the species. Kinetic analyses of the initial rates of leucine uptake into jejunal brush-border membrane vesicles from sheep and goats yielded that leucine uptake was mediated by Na+-dependent as well as Na+-independent processes. Similar to alanine, apparent Km values of leucine uptake were neither different between the species nor affected due to low dietary protein and ranged between 0.08 and 0.15 mmol l(-1). In contrast to the alanine transport mechanism, dietary protein reduction resulted in increased Vmax values of Na+-dependent leucine transport by 53% in sheep and 230% in goats. Similarly, Na+-independent leucine uptake was stimulated by 85% and 200% in sheep and in goats, respectively. This study shows adaptation of amino acid absorption at the brush-border membrane level of jejunal enterocytes of small ruminants due to dietary protein reduction. Whereas the transport capacity for the nonessential amino acid alanine was reduced due to low dietary protein, the transport capacity for the essential amino acid leucine was markedly stimulated. From this, the involvement of rather different feedback mechanisms in adaptation of intestinal amino acid transport mechanisms has to be discussed.     

Nutrient, fatty acid, amino acid and mineral analysis of natural prey of the Hawaiian monk seal, Monachus schauinslandi.

Proximate nutrients, gross energy content, mineral, amino acid and fatty acid composition were determined for teleost, cephalopod and crustacean prey of the Hawaiian monk seal. Crude protein was highest in the octopus, Octopus cyanea (80.0%), crude fat was highest in the Muraenid teleost, Gymnothorax eurostus (14.1%), whereas crude ash was highest in the lobster, Panulirus marginatus (11.6%). Gross energies ranged from 4.0 +/- 0.01 kcal g-1 in the Labrid teleost Bodianus bilulunatus to 6.0 +/- 0.12 kcal g-1 in the moray eel, Gymnothorax undulatus. Essential amino acids occurred in lower concentrations as a percentage of the total amino acids (35.8 +/- 2.6%) than non-essential amino acids (64.2 +/- 2.6%), but the ratio of individual amino acids to total amino acid concentrations were similar to those required by some monogastric terrestrial species and fingerling salmon. The fatty acid concentrations varied widely among species (range = 1.2-16.5 mg 100 mg-1); however, the teleosts had higher total fatty acids than the non-teleosts. This study indicates that, from a nutritional standpoint, some prey may be more beneficial to the Hawaiian monk seal; however, these prey are not necessarily the most abundant or available to some populations of the monk seal.     

Changes in accumulation of seed nitrogen compounds in maize under conditions of sulphur deficiency

Maize ( Zea mays L., hybrid INRA 260) was grown in the greenhouse with mineral nutrition of different sulphate concentrations. Mature seeds from these plants were compared for their free amino acid and protein N forms. For the most S-deficient sample, the Asx (asparagine + aspartic acid) content increased by 30% as compared with control, while methionine and cysteine decreased (by 25 and 30%, respectively), as well as glycine, lysine, histidine, arginine and tryptophan. In seeds lowest in S the non-protein N to total N ratio was 77% higher than in the control. Free asparagine dominated in starved seeds (50 mol % of total free amino acids) and was ten-fold more concentrated than in the control, where proline was the predominant free amino acid. Thus the Asx of non-protein N reached 28% of the total mol Asx of the whole starved seed. Altered S nutrition had virtually no effect on the amino acid composition of the main protein fractions, but it significantly changed their ratios. Zeins, which are poor in S-containing amino acids, showed 25% higher level than in seeds supplied with normal S. As a counterbalance, two glutelin subfractions rich in S-containing amino acids, decreased by 36–71% under limiting S nutrition.
It is concluded that the plant reacts against S deficiency by modifying its N metabolism. Significant accumulation occurred of free asparagine, which is the main form of N transportation. The biosynthesis of seed storage protein occurred through the accumulation of the highest possible protein quantity allowed by the available S-containing amino acids, i.e. proteins low in S-containing amino acids were preferentially synthesized.     

72份青稞氨基酸组成与营养价值评价

为了解青稞氨基酸的组成及营养品质,本研究测定了72份青稞材料籽粒的17种氨基酸(色氨酸除外)含量,通过对供试青稞材料氨基酸含量进行聚类分析,并比较育成品种与地方品种的氨基酸组成差异,对青稞的氨基酸进行了营养价值评价。结果表明,青稞氨基酸总含量平均为87.454 mg/g DW,变幅为47.8~178.7 mg/g DW,其中必需氨基酸含量占37.15%,谷氨酸的含量最高且变异大,蛋氨酸含量最低,赖氨酸含量变异小,91.67%的青稞材料的第一限制性氨基酸为赖氨酸。青稞氨基酸的贴近度为0.903,与世界粮农组织(FAO)、世界卫生组织(WHO)、联合国大学(UNU)提出的模式蛋白质的必需氨基酸组成较接近,氨基酸比值系数分SRC(73.14)较高。非必需氨基酸占青稞总氨基酸含量的62.85%,其中鲜味和甜味氨基酸含量分别为26.58 mg/g DW和21.85 mg/g DW,分别占总氨基酸含量的30.04%和24.43%。不同青稞材料的氨基酸含量和营养价值有很大的差异,地方品种各氨基酸含量均高于育成品种。供试材料中有4份青稞的氨基酸营养价值及风味氨基酸含量均较高。研究结果可为优质氨基酸组成的青稞选育及青稞加工提供指导。     

The effect of prolonged exposure of pregnant rats to high ambient temperature on several constituents of the genital tract's fluids

1. Various constituents of the genital tract's (GT) fluids were measured in heat-exposed rats (kept for at least 30 days at 35 +/- 1 degree C) and control rats (maintained at 22 +/- 2 degrees C). 2. There were no differences between the groups in the GT fluid volume, protein, free amino acids and glucose contents. 3. Arterial and venous blood glucose levels, pO2 and pH values were similar in both groups. 4. GT fluid protein hydrolysate from heat-exposed rats showed significantly reduced contents of glycine and alanine and elevated contents of valine and lysine as compared with controls. 5. The GT fluid's free amino acid components showed reduced glycine and elevated valine and isoleucine in the heat-exposed group as compared with controls. 6. Progesterone levels in GT fluid of heat-exposed rats was 60% higher than that of controls. 7. It is suggested that the higher progesterone concentration and the altered relative contents of several free amino acids with a possible change in the proteins of the GT fluid may affect the development of the embryo in heat-exposed rats.     

Amino acid repletion does not decrease muscle protein catabolism during hemodialysis

Intradialytic protein catabolism is attributed to loss of amino acids in the dialysate. We investigated the effect of amino acid infusion during hemodialysis (HD) on muscle protein turnover and amino acid transport kinetics by using stable isotopes of phenylalanine, leucine, and lysine in eight patients with end-stage renal disease (ESRD). Subjects were studied at baseline (pre-HD), 2 h of HD without amino acid infusion (HD-O), and 2 h of HD with amino acid infusion (HD+AA). Amino acid depletion during HD-O augmented the outward transport of amino acids from muscle into the vein. Increased delivery of amino acids to the leg during HD+AA facilitated the transport of amino acids from the artery into the intracellular compartment. Increase in muscle protein breakdown was more than the increase in synthesis during HD-O (46.7 vs. 22.3%, P < 0.001). Net balance (nmol.min(-1).100 ml (-1)) was more negative during HD-O compared with pre-HD (-33.7 +/- 1.5 vs. -6.0 +/- 2.3, P < 0.001). Despite an abundant supply of amino acids, the net balance (-16.9 +/- 1.8) did not switch from net release to net uptake. HD+AA induced a proportional increase in muscle protein synthesis and catabolism. Branched chain amino acid catabolism increased significantly from baseline during HD-O and did not decrease during HD+AA. Protein synthesis efficiency, the fraction of amino acid in the intracellular pool that is utilized for muscle protein synthesis decreased from 42.1% pre-HD to 33.7 and 32.6% during HD-O and HD+AA, respectively (P < 0.01). Thus amino acid repletion during HD increased muscle protein synthesis but did not decrease muscle protein breakdown.     

Arginine and lysine product inhibition of bovine adrenomedullary carboxypeptidase H, a prohormone processing enzyme

Carboxypeptidase H (CPH) is one of the later enzymes in the cascade of proteolytic steps required for the posttranslational processing of peptide hormone precursors, including processing of proenkephalin. In this study, CPH activity in the soluble and membrane fractions of enkephalin-containing bovine chromaffin granules was competitively inhibited by its products arginine and lysine. Ki values for arginine and lysine were 4.6 +/- 1.3 and 7.6 +/- 1.9 mM, respectively, indicating that arginine was a more effective inhibitor than lysine. Other amino acids (at 10 mM) had no effect. The in vivo intragranular concentrations of lysine and arginine are similar to the measured Ki values, indicating that product inhibition of CPH by basic amino acids may occur in vivo.     

Effects of amino-acid mixtures on food utilization and growth in Tenebrio molitor L

Ten holidic diets, varying in amino-acid concentration or composition, were fed to larvae of Tenebrio molitor for four weeks at 27 +/- 0.25 degrees C and 65 +/- 5% r.h. Effects of diet on growth, food utilization and energy utilization were recorded for individual larvae. Differences in gains in fresh weight or in dry matter among larvae fed diets containing 0% to 5% of the amino-acid mixture were not demonstrated. However, larvae fed 10% or 20% of this mixture gained more than the former, but less than larvae fed a diet of ground whole wheat and brewer's yeast (9:1, w/w). When the amino-acid mixture was supplemented with alanine, aspartic acid, and serine, or with these three and asparagine, and was fed to larvae at the 10% level, growth was slower than with the unsupplemented mixture. Supplementation of the amino-acid mixture with the first three amino acids did not reduce larval growth when fed at the 20% level. Amounts of food and of energy utilized were positively correlated with larval fresh-weight and dry-matter gains. Energy utilization was negatively correlated with dietary amino-acid level. Food and energy utilization and larval growth were influenced by dietary amino acids, either metabolically or through phagostimulation.