A comparison of three methods for the determination of available lysine in barley

The protein quality of barley was determined by the measurement of the protein efficiency ratio (PER). Available lysine in the same samples was determined chemically and by microbiological assay, and relationships were obtained between PER and either total or available lysine content.In the PER test, groundnut meal was found to be a suitable protein supplement to barley for the purpose of detecting differences in the protein quality of barley. The method was sufficiently sensitive to detect a reduction in protein quality of one variety as a result of micronization. Available lysine values obtained by the modified Tetrahymena method were significantly correlated (r = 0.99) with PER values; there was no significant correlation between total lysine content and the PER value.The available lysine values measured by the two chemical methods were higher than the Tetrahymena values. The Silcock method gave results better correlated (r = 0.93) with the Tetrahymena values than did the Carpenter method (r = 0.82). The results of chemical methods were not significantly related with PER values, but the methods ranked the barleys in an order similar to that obtained with the PER and Tetrahymena tests.     

Antibiotic amendment for suppression of indigenous microflora in feed sources for an Escherichia coli auxotroph lysine assay

Growth responses of lysine auxotrophic mutants of Escherichia coli have been used as a measurement of bioavailable lysine in protein sources and animal feeds. Sterilizing feed samples by autoclaving to eliminate non-specific background growth of indigenous feed micro-organisms prior to conducting the bacterial assay may introduce chemical and physical alterations to the feeds, influencing the estimation of available feed lysine. In this study, an antibiotic- and antifungal-supplemented medium was constructed to support growth of an E. coli lysine auxotroph assay organism, and was tested for its ability to repress indigenous bacterial and fungal growth in feed samples. To determine which antibiotics to include, an ampicillin-sensitive E. coli lysine mutant strain (ATCC no. 23812) was screened for antibiotic resistance and transformed with a plasmid carrying an ampicillin resistance gene. Maximum optical density quantitative response of the E. coli auxotroph to lysine was not altered by the antibiotic medium amendments (ampicillin, novobiocin and cycloheximide). Indigenous microfloral growth in a variety of typical animal feeds was suppressed in the presence of the antistatic agents. The estimated lysine recovery was 91.6% and 98.1% when the medium was used in an assay of available lysine in a lysine-supplemented feed. This indicates that the antibiotic-amended basal medium can be used for the E. coli-determined lysine availability of a variety of animal feeds without prior sterilization of the feed sources.     

Amino acids and growth substances in barley root excretions (Hordeum distichon L.) and their biological effect

The biological effect of barley root excretions was studied during a 4 to 10 days cultivation period. The effect of root excretions changes according to the cultivation period of barley. It was ascertained by means of a bioassay that growth was either conclusively stimulated or the root excretions did not affect growth of the roots and of the upper part ofNasturtium. No significant inhibitory effect was observed. The effect of the single amino acids and of their mixtures found in the root excretions of barley was quite different. The following amino acids were determined by paper chromatography in root excretions: alanine, asparagine, phenylalanine, glycine, leucine, lysine, serine, tyrosine, glutamic acid and valine plus methionine. During cultivation their total quantity increased from 5·48. 10^?5 up to 1·13. 10^?3 mg per plant. Most of the 20 amino acids observed, displayed in theNasturtium test at a concentration from 0·1 to 1,000 mg/l an inhibitory effect onNasturtium growth. The effect of amino acid mixtures, corresponding qualitatively and quantitatively to the free amino acids in barley root excretions was dependent on their concentration. Growth regulators of the auxin type were found in culture solutions by chromatographic separation and with bioassay. As it may be seen from the results obtained, there are besides amino acids and indole derivatives other non-identified compounds involved in the effect of barley root excretions.     

Feedback-insensitive aspartate kinase isoenzymes in barley mutants resistant to lysine plus threonine

The regulatory properties of aspartate kinase (EC 2.7.2.4) and homoserine dehydrogenase (EC 1.1.1.3) in two barley (Hordeum vulgare L.) mutants resistant to growth inhibition by lysine plus threonine, Rothamsted (R) 3004 and R3202, were compared with those in the normal, sensitive parent line cv. Bomi. Three forms of aspartate kinase (AKI, AKII, AKIII) were chromatographically separated and were considered to represent at least three independently regulated isoenzymes. Aspartate kinase I was inhibited by threonine; AKII and AKIII by lysine or lysine plus S-adenosylmethionine. The characteristics of AKI were unchanged in the mutants. Aspartate kinase II and AKIII from Bomi were both inhibited by lysine and by lysine plus S-adenosylmethionine. Aspartate kinase II from mutant R3202 was altered in its properties such that it was insensitive to lysine or lysine plus S-adenosylmethionine; AKII from mutant R3004 did not differ in its properties from AKII of Bomi. The concentration of lysine required to give half maximal inhibition of AKIII from R3004 was ten times that required for AKIII of Bomi; AKIII from R3202 did not differ from that of Bomi in this regard. There was no change in the properties of homoserine dehydrogenase of the mutants as compared with that of Bomi. We conclude that the lt1 and lt2 loci code for structural genes for lysine- and lysine plus S-adenosylmethionine-sensitive aspartate kinase isoenzymes. The mutant genes Lt1b and Lt2 in R3202 and R3004 respectively code for feedback-desensitized isoenzymes. The presence of one of these is sufficient to allow the synthesis of methionine to overcome the growth inhibition by lysine plus threonine.     

In situ and in vitro ruminal starch degradation of grains from different rye,triticale and barley genotypes

In recent years, advances in plant breeding were achieved, which potentially led to modified nutritional values of cereal grains. The present study was conducted in order to obtain a broad overview of ruminal digestion kinetics of rye, triticale and barley grains, and to highlight differences between the grain species. In total, 20 genotypes of each grain species were investigated using in situ and in vitro methods. Samples were ground (2 mm), weighed into polyester bags, and incubated in situ 1 to 48 h in three ruminally cannulated lactating dairy cows. The in vitro gas production of ground samples (1 mm) was measured according to the ‘Hohenheim Gas Test’, and cumulative gas production was recorded over different time spans for up to 72 h. There were significant differences (P<0.05) between the species for most parameters used to describe the in situ degradation of starch (ST) and dry matter (DM). The in situ degradation rate (c) and effective degradability (assuming a passage rate of 8%/h; ED8) of ST differed significantly between all grains and was highest for rye (rye: 116.5%/h and 96.2%; triticale: 85.1%/h and 95.0%; barley: 36.2%/h and 90.0% for c and ED₈, respectively). With respect to DM degradation, the ranking of the species was similar, and predicted c values exhibited the highest variation within species. The in vitro gas production rate was significantly higher (P<0.05) for rye than for triticale and barley (rye: 12.5%/h; triticale: 11.5%/h; barley: 11.1%/h). A positive relationship between the potential gas production in vitro and the maximal degradable DM fraction in situ was found using all samples (r=0.84; P<0.001) as well as rye (P=0.002) and barley (P<0.001) alone, but not for triticale. Variation in ruminal in situ degradation parameters within the grain species resulted from the high c values, but was not reflected in the ED estimates. Therefore, the usage of mean values for the ED of DM and ST for each species appears reasonable. Estimated metabolisable energy concentrations (ME, MJ/kg DM) and the estimated digestibility of organic matter (dOM, %) were significantly lower (P<0.05) for barley than for rye and triticale. Rye and triticale dOM and ME values were not significantly different (P=0.386 and 0.485).     

Screening of Saccharomyces cerevisiae strains with respect to anaerobic growth in non-detoxified lignocellulose hydrolysate

A microplate screening method was used to assess anaerobic growth of 12 Saccharomyces cerevisiae strains in barley straw, spruce and wheat straw hydrolysate. The assay demonstrated significant differences in inhibitor tolerance among the strains. In addition, growth inhibition by the three hydrolysates differed so that wheat hydrolysate supported growth up to 70%, while barley hydrolysate only supported growth up to 50%, with dilute-acid spruce hydrolysate taking an intermediate position.     

The impact of Fusarium culmorum infection on the protein fractions of raw barley and malted grains

Contaminating fungi, such as Fusarium species, produce metabolites that may interfere with normal barley grain proteolysis pattern and consequently, affect malt and beer quality. Protein compositional changes of an initial mixture of 20 % Fusarium culmorum infected and 80 % noninfected mature barley grains and respective malt are reported here. Proteolytic activity of infected barley grains (IBG) and respective malt, with controls (uninfected grains), were characterized using protease inhibitors from each class of this enzyme, including metallo-, cysteine, serine, and aspartic proteases, as well as uninhibited protease fractions. The proteins were extracted according to the Osborne fractionation and separated by size exclusion chromatography. Additionally, two-dimensional (2D) gel electrophoresis (GE) was used to analyze hydrophobic storage proteins isolated from the control and IBG. Analyses revealed that F. culmorum IBG had a twofold increase of proteolytic activity compared to the control sample, which showed an increase in all protease classes with aspartic proteases dominating. Infected and control malt grains were comparable with cysteine proteases representing almost 50 % of all proteolytic enzymes detected. Protein extractability was 31 % higher in IBG compared to the control barley. The albumin fraction showed that several metabolic proteins decreased and increased at different rates during infection and malting, thus showing a complex F. culmorum infection interdependence. Prolamin storage proteins were more hydrophobic during barley fungal infection. F. culmorum interfered with the grain hydrolytic protein profile, thereby altering the grain's protein content and quality.     

Recombinant barley-produced antibody for detection and immunoprecipitation of the major bovine milk allergen, β-lactoglobulin

Recombinant allergens and antibodies are needed for diagnostic, therapeutic, food processing and quality verification purposes. The aim of this work was to develop a barley-based production system for β-lactoglobulin (BLG) specific immunoglobulin E antibody (D1 scFv). The expression level in the best barley cell clone was 0.8–1.2 mg/kg fresh weight, and was constant over an expression period of 21 days. In the case of barley grains, the highest stable productivity (followed up to T2 grains) was obtained when the D1 scFv cDNA was expressed under a seed-specific Glutelin promoter rather than under the constitutive Ubiquitin promoter. Translational fusion of ER retention signal significantly improved the accumulation of recombinant antibody. Furthermore, lines without ER retention signal lost D1 scFv accumulation in T2 grains. Pilot scale purification was performed for a T2 grain pool (51 g) containing 55.0 mg D1 scFv/kg grains. The crude extract was purified by a two-step purification protocol including IMAC and size exclusion chromatography. The purification resulted in a yield of 0.47 mg of D1 scFv (31 kD) with high purity. Enzyme-linked immunosorbent assay revealed that 29 % of the purified protein was fully functional. In immunoprecipitation assay the purified D1 scFv recognized the native 18 kD BLG in the milk sample. No binding was observed with the heat-treated milk sample, as expected. The developed barley-based expression system clearly demonstrated its potential for application in the processing of dairy milk products as well as in detecting allergens from foods possibly contaminated by bovine milk.     

Effect of plant growth promoting Bacillus spp. on nutritional properties of Amaranthus hypochondriacus grains

Amaranth (Amaranthus hypochondriacus Linn.) is an important pseudocereal crop having important nutrients along with the indispensable amino-acids. The present study was aimed to study the effect of plant growth promoting bacilli on proximate constituents of amaranth grains, including three of the essential amino acids (methionine, lysine and, tryptophan). The combination of Bacillus pumilus and Bacillus subtilis showed a significant increase in different proximate constituents, including crude protein (22.13%), dry matter (32.25%), fat (30.77%), and carbohydrate (49.08%) in amaranth grains. Similarly, a significant increase in essential amino-acids (methionine 47.68%, lysine 59.41% and, tryptophan 38.05%) was recorded. This study suggests that the combination of Bacillus pumilus BS-27 and Bacillus subtilis BS-58 provides the natural, persistent and durable potential to enhance the nutritive value of the crop. Therefore, present study was designed to explore the enhancement of most desirable amino acid synthesis in amaranth due to application of plant growth promoting Bacillus spp.     

Changes in Properties of Barley Leaf Mitochondria Isolated from NaCl-Treated Plants

Treatment of barley (Hordeum vulgare) seedlings with 400 millimolar NaCl for 3 days resulted in a reduction in plant growth and an increase in the leaf content in ions (K⁺ + Na⁺) and proline. Purified mitochondria were successfully isolated from barley leaves. Good oxidative and phosphorylative properties were observed with malate as substrate. Malate-dependent electron transport was found to be only partly inhibited by cyanide, the remaining oxygen uptake being SHAM sensitive. The properties of mitochondria from NaCl-treated barley were modified. The efficiency of phosphorylation was diminished with only a slight decrease in the oxidation rates. In both isolated mitochondria and whole leaf tissue of treated plants, the lower respiration rate was due to a lower cytochrome pathway activity. In mitochondria, the activity of the alternative pathway was not modified by salt treatment, whereas this activity was increased in whole leaf tissue. The possible participation of the alternative pathway in response to salt stress will be discussed.     

Uptake,distribution, and turnover rates of selenium in barley

The present communication elucidates initially the topographic distribution of selenium in barley grains. Then by the fluorimetric method the uptake of selenium (selenite) in 8–16 d old germinating barley was estimated. Finally by means of⁷⁵Se the anabolic and catabolic rates (turnover) of⁷⁵Se (selenite) was compared. The distribution of selenium in barley was evaluated after microdissection of barley grains. In dried grains the highest concentration was found in husk and pericarp with about 0.6 ppm Se. Then followed Scutellum with 0.4 and 0.3 ppm in embryon. The aleurone layer, embryonic leaves, and initial root did only have 0.2 ppm Se. In order to know more about the uptake and distribution of selenium in 8-d-old barley, the plants were cultivated for a further 8 d in the culture medium with variation in selenite concentration. In roots and leaves, the uptake did not arrive at saturation during the period studied since the dose-response curve increased up to 0.34 mM selenite in the medium, whereas the selenium levels were about 200 ppm in roots and 30 ppm in leaves. However, the uptake was linear, with concentration during 8 d of cultivation up to 0.84 μM selenite for grain and stem. At higher concentrations the dose-response curve diminished its slope. At 0.34 mM selenite the concentration in grain increased to 6.87 ppm and in the stem to 8.13 ppm. The uptake, distribution, and catabolic rate of selenium components in germinating barley were further evaluated by exposing the plants to 0.0492 μCi⁷⁵Se (12.6 μM selenite) for up to 4 d. Then the plants were moved to a selenium deficient medium for further 4 d. Then finally the medium was supplemented with high doses of cold selenite (0.126 mM selenite) for further 4 d. The first third period made it possible to estimate the rate of uptake. It was highest in roots (313 fmol/h/mg dw), i.e., about 10 times those of grains, stems, and leaves. The intermediate period where the barley was transferred to a selenium deficient medium made it possible to estimate the kinetics and eventual sparing mechanisms. The selenium losses were highest for leaves (39%), then followed by roots and stems (22 and 25%, respectively). The losses were lowest in grain with 9% Se losses. The losses were three times more pronounced during the first day than in the following 3 d. These data may argue that the selenium is distributed into different pools and that sparing mechanisms may be in function. The last period, i.e., the chase experiment, revealed the rate of elimination of selenium under conditions with surplus selenium. The catabolic rate was about 10 times faster in roots (169 fmol/h/mg dw) than in grains and about 8 times faster than in leaves.     

Barley HvPAPhy_a as transgene provides high and stable phytase activities in mature barley straw and in grains

The phytase purple acid phosphatase (HvPAPhy_a) expressed during barley seed development was evaluated as transgene for overexpression in barley. The phytase was expressed constitutively driven by the cauliflower mosaic virus 35S‐promoter, and the phytase activity was measured in the mature grains, the green leaves and in the dry mature vegetative plant parts left after harvest of the grains. The T₂‐generation of HvPAPhy_a transformed barley showed phytase activity increases up to 19‐fold (29 000 phytase units (FTU) per kg in mature grains). Moreover, also in green leaves and mature dry straw, phytase activities were increased significantly by 110‐fold (52 000 FTU/kg) and 57‐fold (51 000 FTU/kg), respectively. The HvPAPhy_a‐transformed barley plants with high phytase activities possess triple potential utilities for the improvement of phosphate bioavailability. First of all, the utilization of the mature grains as feed to increase the release of bio‐available phosphate and minerals bound to the phytate of the grains; secondly, the utilization of the powdered straw either directly or phytase extracted hereof as a supplement to high phytate feed or food; and finally, the use of the stubble to be ploughed into the soil for mobilizing phytate‐bound phosphate for plant growth.     

Genetic modification of the waxy character in barley under the action of exogenous DNA of the wild variety

Genetic transformation was studied on spring barley mutants carrying the recessive mutant allele of waxy locus.Analysis of the pollen grains of 38 control plants that were not subjected to any treatment showed that in the whole sample there was no mutant grain that stained black with iodine. It is also indicative of the genotypical purity of the original waxy plants.After mechanical damage (puncture in the top and in the side of a grain) there were 5 pollen grains fo wild type among 124000 mutant grains. Injection of grains with 2 μl distilled water led to the emergence of pollen grains that stained black at a frequency similar to that after puncture. The overall frequency of wild barley pollen grains for all control variants was 2.2·10⁻⁵.The frequencies of wild-type pollen grains were practically the same after injections of DNA from E. coli, extensively deproteinized highly polymeric DNA from barley leaves or slightly deproteinized low polymeric DNA from barley endospermal material.There was no marked increase of the wild pollen frequency after the injection of slightly deproteinized low polymeric DNA from the endospernal material (2.2·10⁻⁵ in the control versus 3.7·10⁻⁵ in the experiment).The analysis of the material for the amount of altered pollen grains in invidual plants also unequivocally demonstrated significant differences between the control and the experiment. In the first four variants there was no plant having over these altered pollen grains among the 2500 mutant grains examined. In the variants with injections of barley DNA differing in the extent of deproteinization and in polymerisation only in one case (of low polymeric slightly deproteinized DNA) there were no plants with many altered pollen grains. In all the other variants there were plants having much pollen of wild type.The largest number of plants with a great many affected pollen grains occurred in the variant with highly polymeric DNA from the endospermal material not subjected to deproteinization with chloroform and isoamyl alcohol.     

Methylobacterium Species Promoting Rice and Barley Growth and Interaction Specificity Revealed with Whole-Cell Matrix-Assisted Laser Desorption / Ionization-Time-of-Flight Mass Spectrometry (MALDI-TOF/MS) Analysis

Methylobacterium species frequently inhabit plant surfaces and are able to utilize the methanol emitted from plants as carbon and energy sources. As some of the Methylobacterium species are known to promote plant growth, significant attention has been paid to the mechanism of growth promotion and the specificity of plant–microbe interactions. By screening our Methylobacterium isolate collection for the high growth promotion effect in vitro, we selected some candidates for field and pot growth tests for rice and barley, respectively. We found that inoculation resulted in better ripening of rice seeds, and increased the size of barley grains but not the total yield. In addition, using whole-cell matrix-assister laser desorption/ionization- time-of-flight mass spectrometry (MALDI-TOF/MS) analysis, we identified and classified Methylobacterium isolates from Methylobacterium-inoculated rice plants. The inoculated species could not be recovered from the rice plants, and in some cases, the Methylobacterium community structure was affected by the inoculation, but not with predomination of the inoculated species. The isolates from non-inoculated barley of various cultivars grown in the same field fell into just two species. These results suggest that there is a strong selection pressure at the species level of Methylobacterium residing on a given plant species, and that selection of appropriate species that can persist on the plant is important to achieve growth promotion.     

In situ ruminal degradation of amino acids and in vitro protein digestibility of undegraded CP of dried distillers’ grains with solubles from European ethanol plants

The objectives of this study were to compare the in situ ruminal degradation of CP and amino acids (AAs) of dried distillers’ grains with solubles (DDGS), and to estimate intestinal digestibility (ID) of undegradable crude protein (UDP) with the in vitro pepsin–pancreatin solubility of CP (PPS), using either DDGS samples (DDGS-s) or DDGS residues (DDGS-r) obtained after 16 h ruminal incubation. Thirteen samples originating from wheat, corn, barley and blends were studied. Lysine and methionine content of DDGS-s varied from 1.4 to 4.0 and 1.3 to 2.0 g/16 g N, respectively. The milk protein score (MPS) of DDGS-s was low and ranged from 0.36 to 0.51, and lysine and isoleucine were estimated to be the most limiting AAs in DDGS-s and DDGS-r. DDGS-r contained slightly more essential AAs (EAAs) than did the DDGS-s. Rumen degradation after 16 h varied from 44% to 94% for CP, from 39% to 90% for lysine and from 35% to 92% for methionine. Linear regressions showed that the ruminal degradation of individual AAs can be predicted from CP degradation. The PPS of DDGS-s was higher than that of DDGS-r and it varied from 70% to 89% and from 47% to 81%, respectively. There was no significant correlation between the PPS of DDGS-s and PPS of DDGS-r (R²=0.31). The estimated intestinally absorbable dietary protein (IADP) averaged 21%. Moderate correlation was found between the crude fibre (CF) content and PPS of DDGS-r (R²=0.43). This study suggests an overestimation of the contribution of UDP of DDGS to digestible protein supply in the duodenum in some currently used protein evaluation systems. More research is required and recommended to assess the intestinal digestibility of AAs from DDGS.     

Biological Value of Proteins Allowed to React with Phenolic Compounds in Presence of o-Diphenol Oxidase

Studies were made on the influence of phenolic compounds on the nutritive value of casein by the nitrogen-balance technique with rats and by the chemical measurement of available lysine.

It was found that caseins allowed to react with caffeic, isochlorogenic acids and phenolic compounds of red clover leaves in the presence of o-diphenol oxidase were inferior to control casein in biological value, digestibility and available lysine content. In the absence of o-diphenol oxidase, caffeic acid showed none of these effects. p-Coumaric acid lowered the biological value of casein in the presence of o-diphenol oxidase but did not lowered its digestibility.     

Quantitative detection of crystalline lysine supplementation in poultry feeds using a rapid bacterial bioluminescence assay

Lysine is an essential amino acid for both humans and animals; and it is usually the first or second limiting amino acid in most formulated diets. In order to estimate the lysine content in feeds and feed sources, rapid amino acid bioassays have been developed. The objective of this work is to assess a rapid assay for lysine supplementation in chicken feeds, using a luminescent Escherichia coli lysine-auxotrophic strain, to avoid prior thermal sterilization. An E. coli lysine auxotroph carrying a plasmid with lux genes was used as the test organism. The lysine assay was conducted using depleted auxotrophic cells in lysine samples. Luminescence was measured with a Dynex MLX luminometer after addition of the aldehyde substrate. Growth response (monitored as optical density at 600 nm) and light emission response of the assay E. coli strain were monitored to generate standard curves. Bioluminescent analysis of feed samples indicated that the method works well in the presence of a complex feed matrix. Comparison of both optical density and luminescent-based methods indicated that, when the assay takes place under optimal conditions, both methodologies correlated well ( r(2)=0.99). Except for the 0.64% lysine-supplemented feed, estimates for lysine based on the bacterial assay were over 80% (82-97%) of the theoretical values. Animal data showed that the bacterial bioluminescent method correlated well with the chick bioassay when diets with different levels of lysine supplementation were assayed for lysine bioavailability ( r(2)=0.97). Luminescent methodology coupled with a bacterial growth assay is a promising technique to assess lysine availability in supplemented animal feeds.     

Genomics-based high-resolution mapping of the BaMMV/BaYMV resistance gene rym11 in barley (Hordeum vulgare L.)

Soil-borne barley yellow mosaic virus disease, caused by different strains of Barley yellow mosaic virus (BaYMV) and Barley mild mosaic virus (BaMMV), is one of the most important diseases of winter barley (Hordeum vulgare L.) in Europe and East Asia. The recessive resistance gene rym11 located in the centromeric region of chromosome 4HL is effective against all so far known strains of BaMMV and BaYMV in Germany. In order to isolate this gene, a high-resolution mapping population (10,204 meiotic events) has been constructed. F₂ plants were screened with co-dominant flanking markers and segmental recombinant inbred lines (RILs) were tested for resistance to BaMMV under growth chamber and field conditions. Tightly linked markers were developed by exploiting (1) publicly available barley EST sequences, (2) employing barley synteny to rice, Brachypodium distachyon and sorghum and (3) using next-generation sequencing data of barley. Using this approach, the genetic interval was efficiently narrowed down from the initial 10.72 % recombination to 0.074 % recombination. A marker co-segregating with rym11 was developed providing the basis for gene isolation and efficient marker-assisted selection.     

Lysine transport in two barley mutants with altered uptake of basic amino acids in the root

Amino acid uptake was examined in two barley (Hordeum vulgare L.) mutants R906 and R4402 which had been selected as resistant to the lysine analog S-(2-aminoethyl)-cysteine. The mutants were found to be allelic by crossing and examination of F₁ and F₂ progeny. The mutant genes were designated aec1a and aec1b, respectively. The uptake of the basic amino acids lysine, arginine, and ornithine from 50 micromolar solutions was strongly decreased in roots of the mutants, whereas uptake of neutral and acidic amino acids was unaffected. The pattern of uptake of lysine over the range 10⁻⁷ to 10⁻² molar was consistent with there being, principally, two uptake systems operating for basic amino acids in roots and that a low-concentration, high-affinity system is reduced or lacking in the mutants. The residual transport activity in the mutants had a different relative affinity for lysine and arginine to the wild-type system. Uptake of lysine by leaf slices was unimpaired in the mutants suggesting that the leaf uptake system is unaffected by the aec1 gene.     

Determination of useful barley selections in an improvement program for increased lysine content by larvae of Tenebrio molitor L.

Larvae of the yellow mealworm, Tenebrio molitor L., Gembloux strain, race F, were reared for 4 weeks at 27 +/- 0.25 degrees C and 65 +/- 5% relative humidity. They were fed on each of 22 cultivars of barley, at the protein level occurring in harvested seed and at a protein level of 10% of dietary protein. Growth and body composition of the larvae were correlated positively and significantly with the concentrations of basic amino acids in the barleys and negatively and significantly with the concentrations of leucine. The percentage of crude protein in larval tissues can be used as a measure of available lysine in barley cultivars, and gains in fresh weight of larvae as indices of arginine concentrations. Differences were evident between the biological and chemical estimations of these amino acids. Several of the Saskatoon barley selections, derived from crosses with Hiproly, were equal to Hiproly or Ris? varieties in the amounts of lysine available to the larvae.