The Influence of water salinity on the free amino acid concentration in muscle and hepatopancreas of adult shrimps, Penaeus japonicus

Variations of the total free amino acid (FAA) pool and the content of specific amino acids have been measured in the muscle and hepatopancreas of adult shrimps, Penaeus japonicus, acclimatized at five water salinities: 38, 32, 26, 20 and 14%‰ The FAA content is always higher in muscle than in hepatopancreas at all tested salinites. On the other hand, the hepatopancreas exhibits the highest concentrations of essential amino acids. Two steps in the evolution of FAA content can be observed, the first one regarding decrease in salinity from 38 to 20%‰ and the second one, when salinity goes below 20%_°. The first step can be characterized by a 16% decrease of total FAA content in the muscle and a 36% increase in the hepatopancreas. In muscle, the variations are mainly due to changes in non-essential FAA content, whereas in the hepatopancreas, they are linked to variations in essential FAA content. The other step is characterized by a drastic increase in moisture and decrease in FAA content in both studied organs when water salinity is 14%‰ The total FAA content is about 40% lower in shrimps at 14%_° compared to 38%‰ seawater salinity. During adaptation, the FAA pool (mainly NEFAAs) of muscle seems to be directly related to osmoregulation, whereas in the hepatopancreas, its evolution seems to be linked with energy expenditure and protein synthesis. The results are evaluated in order to elucidate the role of FAA in intracellular osmoregulation and in relation to animal ecology.     

不同施肥水平对不同品种小麦籽粒蛋白质和地上器官游离氨基酸含量的影响

研究了小麦不同品种开花后各地上器官游离氨基酸含量的变化动态及其与籽粒蛋白质含量的关系,以及氮素营养的调节作用。结果表明,小麦叶片和颖壳十穗轴游离氨基酸含量均在开花后持续增加,至花后14d达到最大值,之后开始下降。茎和叶鞘游离氨基酸含量则在开花后上升较缓慢,至花后21d达最大值。籽粒游离氨基酸含量一般在开花后就持续降低。各地上器官游离氨基酸含量与成熟期籽粒蛋白质含量均呈显著或极显著正相关,说明源器宫中游离氨基酸供应充足,有利于籽粒蛋白质积累。增施氮肥能够提高各地上器官中的游离氨基酸含量,进而促进籽粒蛋白质的合成,提高籽粒蛋白质含量。品种之间籽粒蛋白质含量的差异,是由各地上营养器官向籽粒运输氨基酸的综合作用所造成的。     

基因型和地域分布对小麦籽粒氨基酸含量影响的研究

根据河南省7个试验基点的10个小麦基因型籽粒中17种氨基酸含量的测定结果,对不同基因型氨基酸含量差异及其地域分布进行了研究,结果表明,小麦籽粒氨基酸含量不仅存在基因型的差异,而且在很大程度上受生态环境条件的影响,环境间氨基酸含量的变异明显大于基因型,约为基因型间变异的1．5倍。不同试点所对应的气候分布、土壤类型与氨基酸含量变异有较大的吻合程度,表现出随湿润条件增加,氨基酸含量和必需氨基酸、非必需氨基酸总量逐渐下降,而非必需氨基酸占氨基酸总量的比例呈逐渐上升趋势,与人体代谢关系密切的赖氨酸化学记分较 低,且变异较小。     

灌浆期高温对冬小麦籽粒氨基酸含量和组成的影响

以强筋小麦品种郑麦366和中筋小麦品种洛旱2号为材料,采用盆栽和人工气候室模拟的方法,研究了花后不同时段(灌浆前期即花后5 d,灌浆中期即花后15 d)和持续时间(处理2 d和4 d)的高温胁迫对籽粒氨基酸含量和积累量(以单粒中氨基酸含量表示)的影响。结果显示:(1)高温胁迫显著增加了小麦籽粒中必需氨基酸(EAA)、非必需氨基酸(NAA)和总氨基酸(TAA)含量,但降低了其积累量和EAA/TAA,2品种表现一致;(2)灌浆前期高温胁迫对2品种籽粒氨基酸含量的影响大于灌浆中期,而对氨基酸积累量的影响则相反;(3)高温持续时间对籽粒氨基酸含量的影响在2品种间存在差异,洛旱2号籽粒赖氨酸、EAA、NAA和TAA含量均随高温持续时间的延长显著增加,而郑麦366籽粒中上述指标仅在高温胁迫4 d下较对照增加显著;(4)从受高温胁迫的影响看,籽粒EAA/TAA对高温时段更敏感,而氨基酸含量表现为更易受高温持续时间的影响;(5)高温时段与持续时间的互作效应体现在:灌浆前期籽粒氨基酸积累量2品种均以高温胁迫4 d的影响最大,而灌浆中期则均以高温2 d的降幅最大。上述结果表明,小麦籽粒氨基酸及其组分对高温胁迫的响应不仅在品种间存在差异,且受高温时段和持续时间的影响。     

Protein and free amino acids in wheat grain as affected by soil types and salinity levels in irrigation water

Summary The effects of four lysimeter soil series under three salinity levels were evaluated for grain yield, wt/1000 seeds, protein, and amino acids in Mexican dwarf wheat (Triticum aestivum L. var. Cajeme 71). The soil series consisted of: Holtville clay loam, Greenfield sandy loam, San Emigdio sandy loam, and Altamont clay loam. The irrigation water salinity levels were designated: low –2.2 mmho, medium –4.2 mmho, and high –7.1 mmho.No significant differences were found in the amount of grain harvested or wt/1000 seeds in the 1976 crop produced on the differential soil series. The yield of the 1977 crop was significantly affected by the soil types.Effects of soil type on the protein amino acids in the grain in both years were similar. Significantly higher protein amino acid levels of histidine, arginine, aspartic acid, threonine, serine, glutamic acid, glycine, alanine, cystine, valine, methionine, isoleucine, leucine, tyrosine, and phenylalanine were found in the grain grown on Altamont clay loam soil than the other types.The free amino acids in grain from the 1976 and 1977 crops were similarly affected by the soil types, except that the quantitative values of the free amino acids were substantially lower in 1977 than in 1976. The free amino acids significantly influenced by soil types were tryptophane, lysine, arginine, aspartic acid, threonine, serine, glycine, alanine, valine, isoleucine, tyrosine, and phenylalanine. In both years' crops, the sum of the free amino acid fractions was significantly higher in the grain produced on the Altamont soil than on the other soils.Salinity level in the irrigation water did not affect the 1976 crop yield or wt/1000 seeds. Although yields of the 1977 crop were significantly reduced by salinity, the wt/1000 seeds was not. The sum of protein amino acids was significantly higher in the 1976 and 1977 grain crops irrigated with high salinity water than in low salinity irrigated crops.An increased salinity irrigation water significantly reduced the sum of free amino acid fractions in the 1976 grain crop. Since some of the free amino acids in the 1977 grain crop increased while the others decreased due to the salinity level in the irrigation water, the sum of the free amino acid fractions was not significantly influenced.Significant interactions were found between soil types and salinity levels on free arginine, threonine, serine, glutamic acid, and alanine, and also on the sum of the free amino acids in the 1976 wheat grain. In the 1977 wheat grain, there were significant interactions between soil types and salinity levels on the free glutamic acid, valine, leucine, tyrosine, and phenylalanine, and on protein serine, glutamic acid, glycine, alanine, and the sum of the protein amino acids.The amounts of essential amino acids expressed as mg of amino acid/g of protein were not affected by the soil types or salinity levels. With the exception of lysine, and possibly threonine and methionine plus cystine, the essential amino acids were present in the grain at concentrations equal to or greater than recommended by WHO and FAO.     

Interaction of salinity and enhanced ammonium and potassium nutrition in wheat

Wheat (Triticum aestivum L.) was grown to maturity in a pot experiment in a calcareous silty sand soil. N was applied at two levels as granulated N-P fertilizers, amended or not with nitrification inhibitors (1% and 5% DCD, 1% N-serve). Potassium as KCl was given at three levels of application. P was applied at a uniform rate. Two levels of salinity were obtained by using the soil as such (EC= 0.3 mmho/cm) and by adding NaCl to the same soil (EC=2.4 mmho/cm). 1% DCD and 1% N-serve treatments gave significantly higher wheat grain yields and N-uptake than the other ones. Nitrate content of leachates indicated a prevalent nitrate nutrition in the treatment without nitrification inhibitors. The 5% DCD treatment showed a yield depression. In the lower N level treatments, a significant yield increase, generated by 1% DCD and N-serve was found in the salinized soil as compared to the non-saline soil. Soil salinity reduced N-uptake when nitrification inhibitors were not present. In treatments having the inhibitors, N-uptake was equal or greater in the salinized than in the non saline soil. An enhanced ammonium nutrition increased the P uptake.     

The effect of caffeine on some mouse brain free amino acid levels

Changes in free amino acids were examined in the central nervous system of mice treated with caffeine for three weeks. Caffeine was administered in the drinking water, and at the end of three weeks the level of caffeine in the cerebral cortex was 113±19 g/g. When amino acid levels in cerebral hemispheres, midbrain, pons and medulla, and cerebellum were measured a significant increase in glutamine levels was found in all four regions. Glycine, alanine, serine, threonine, and GABA were significantly reduced in some regions. Caffeine appears to alter some of the metabolic or transport processes regulating amino acid pools in the brain. The decrease of GABA found in pons and medulla may contribute to the observed increase in reflex excitability after caffeine.Special issue dedicated to Dr. Elling Kvamme     

Genetic analysis of amino acid content in wheat grain

Complete diallel crosses with five parents of common wheat (Triticum aestivum L.) were conducted to analyse inheritance of 17 amino acid contents by using the genetic model including seed, cytoplasmic, maternal and environment interaction effects on quantitative traits of seeds in cereal crops. The results showed that inheritance of 17 amino acid contents, except tyrosine, was controlled by several genetic systems including seed, cytoplasmic, and maternal effects, and by significant gene × environment interaction effects. Seed-direct additive and maternal effects constituted a major part of genetic effects for lysine, tyrosine, arginine, methionine, and glutamic acid content. Seed-direct additive effect formed main part in inheritance of isoleucine and serine contents. Threonine content was mainly governed by maternal additive effect. The other nine amino acid contents were almost entirely controlled by dominance effects. High general heritability of tyrosine (36.3%), arginine (45.8%), lysine (24.7%) and threonine (21.4%) contents, revealed that it could be effective to improve them by direct selection in progenies from appropriate crosses. Interaction heritability for phenylalanine, proline, and histidine content, which was 36.1%, 39.5% and 25.7%, respectively, was higher than for the other amino acids.     

花后盐与渍水逆境对小麦植株钾钠吸收和籽粒淀粉积累的影响

以扬麦12和淮麦17为材料,研究花后渍水、盐胁迫及盐渍逆境条件对离子平衡、小麦籽粒淀粉及营养器官碳氮代谢的影响。结果表明,盐胁迫和盐渍处理下,小麦叶片和茎鞘Na+含量快速上升,K+含量相对下降,K+/Na+比快速下降,导致离子平衡失调和Na+离子毒害;花后渍水、盐胁迫及盐渍处理降低了籽粒总糖、蔗糖、游离氨基酸含量及花前营养器官可溶性总糖转运量和转运率,从而抑制籽粒灌浆,导致籽粒干物质积累下降,淀粉含量降低,尤以盐胁迫和盐渍处理更为严重;盐胁迫和盐渍处理对淮麦17的抑制作用大于扬麦12,其中盐胁迫和盐渍处理导致成熟期淮麦17籽粒重分别下降60.3%和61.1%,而扬麦12下降46.6%和43.7%;此外,盐胁迫对扬麦12影响大于盐渍处理,而盐渍处理对淮麦17影响大于盐胁迫处理。     

Protein content and amino acid composition of cassava leaf

On the basis of leaf dry wt, the protein content of six varieties of cassava varied from 29.3 to 38.6% and the estimated leaf protein production ranged from 242 to 953 kg per ha. On the basis of fr. wt of leaf, the total amino acids ranged from 8.42 to 9.4% while the essential amino acids averaged 4.21% and the sulphur-containing amino acids only 0.25%. The amino acid composition profiles for the six varieties was similar.     

Influence of some exogenous amino acids on the production of maize embryogenic callus and on endogenous amino acid content

The effects of four exogenous amino acids (proline, glycine, asparagine and serine) on the production of maize embryogenic callus and on its endogenous amino acid content have been investigated. For this purpose, an established embryogenic line of Type 1 callus from the inbred W64Ao2 has been used. From the results it may be concluded that a concentration of proline exceeding 6 mM is negative for the production of embryogenic callus. When proline is eliminated from the medium, other amino acids tested in certain concentrations yield a percentage of embryogenic callus production that exceeds or equals that of proline. The endogenous free proline content in embryogenic callus is significantly higher than that in non-embryogenic callus regardless of proline presence in the medium. The only exception are the glycine-containing media, in which endogenous free alanine of embryogenic callus increases at the expense of endogenous free proline. This study suggest a positive role of endogenous free proline or alanine accumulation in the embryogenic callus production which might be related to an adaptation to the metabolic changes produced by in vitro culture and embryogenesis induction. Furthermore, these results indicate that treatments with amino acids that are different from proline can be used to improve the efficiency of embryogenic callus production from well established maize callus cultures.Abbreviations Ala alanine - Asn asparagine - 2,4-d 2,4-dichlorophenoxyacetic acid - EC embryogenic callus - nEC non-embryogenic callus - Gaba gamma-aminobutyric acid - Glu glutamic acid - Gly glycine - Pro proline - Ser serine     

The effects of sensory stimulation on the free amino acid pool of the developing brain

Developing chicks were subjected to three different paradigmata of sensory stimulation, and the effects on the free amino acid concentrations in the blood and in various brain regions were monitored. The free amino acid pool of individual brain regions was found to be affected in a treatment-and age-specific manner. The increased neuronal activity resulting from sensory stimulation seems to affect intrinsic factors involved in the regulation of the free amino acid pool, most likely via modulations of the rate of metabolization of individual amino acids and/or of the rate of synthesis and degradation of individual proteins in certain brain regions.Special Issue dedicated to Prof. Holger Hydén.     

Impact of potato psyllid (Hemiptera: Triozidae) feeding on free amino acid composition in potato

Abstract The impacts of potato psyllid (Bactericera cockerelli) feeding on potato foliage on the free amino acids (FAAs) composition in potato leaf and tubers were determined under greenhouse conditions. The free amino acids in plant extracts were separated by high‐performance liquid chromatography, and in both leaf and tuber samples, at least 17 FAAs were detected. Psyllid feeding significantly changed the levels of several FAAs in both leaf and tuber samples. The concentration of leucine increased 1.5‐fold, whereas that of serine and proline increased 2‐ and 3‐fold, respectively. In contrast, the concentrations of glutamic acid, aspartic acid and lyscine were significantly reduced by 42.0%, 52.1% and 27.5%, respectively. There were also significant changes in the levels of FAAs in the Zebra chip (ZC) infected tubers compared with the healthy tubers, and the levels of six of the FAAs increased, and the levels of nine of the FAAs decreased. The results from this study indicate that potato psyllid causes major changes in free amino acid composition of plant tissues, and this change in plant metabolism may contribute to the plant stress as indicated by increased levels of proline in the leaves and hence promoting the development of plant diseases such as ZC disease.     

The effects of starvation on the sodium, potassium, water and free amino acid content of parietal muscle from Agonus cataphractus.

1. The levels of the individual free amino acids, K, Na and water present in parietal muscle were measured in fish starved for periods of 3-115 days. 2. The Na and water content progressively increased relative to dry weight of tissue during the starvation period whereas an initial increase in the K content up to 67 days was followed by a decrease to near the normal fed level by 115 days. The ammonia content remained essentially stable over the same period. 3. The essential free amino acid content tended to follow the muscle sodium pattern while the non-essential amino acids and taurine gave results somewhat similar to those of potassium. 4. The net result of these changes is that the Na, K and total free amino acid concentration is maintained within fairly narrow limits relative to the tissue water content during 11-67 days of the starvation period under the experimental conditions used.     

Influence of the nitrogen source and concentration on N fractions and free amino acid levels of grape vine explants

The influence of the source of inorganic nitrogen (KNO₃, (NH₄)₂SO₄ and NH₄NO₃) and its concentration (5, 10, 20 and 30 mM N) on total N incorporation, as well as on N distribution into different fractions (amminiacal, amino, amide and protein) and on free amino acid levels has been determined in grape vine explants cultured in vitro.Increasing concentrations of the nitrogen source resulted in increased total N content in tissues. This effect was small for KNO₃, higher for (NH₄)₂SO₄ and maximal for NH₄NO₃. In addition, nitrate promoted an increase in amino-N only, whereas ammonium increased both the ammoniacal-N and the amino-N fractions. Incorporation of N into amide-N and protein-N were not affected significantly by the N sources tested.The application of increasing quantities of N enhanced the accumulation of most free amino acids, especially arginine, alanine and proline, but to different extents, depending on both the N source and its concentration. The combination of ammonium and nitrate resulted in a higher accumulation of amino acids than that observed with either one of the two forms alone.     

Feeding pigs amino acids as protein-bound or in free form influences postprandial concentrations of amino acids,metabolites, and insulin

Dietary proteins need to be digested first while free amino acids (AAs) and small peptides are readily available for absorption and rapidly appear in the blood. The rapid postprandial appearance of dietary AA in the systemic circulation may result in inefficient AA utilisation for protein synthesis of peripheral tissues if other nutrients implicated in AA and protein metabolism are not available at the same time. The objective of this experiment was to compare the postprandial concentrations of plasma AA and other metabolites after the ingestion of a diet that provided AA either as proteins or as free AA and small peptides. Twenty-four male growing pigs (38.8 ± 2.67 kg) fitted with a jugular catheter were assigned to one of three diets that provided AA either in protein form (INT), free AA and small peptides (HYD), or as free AA (FAA). After an overnight fast and initial blood sampling, a small meal was given to each pig followed by serial blood collection for 360 min. Postprandial concentrations of plasma AA, glucose, insulin, and urea were then measured from the collected blood. Non-linear regression was used to summarise the postprandial plasma AA kinetics. Fasting concentrations of urea and some AA were higher (P < 0.05) while postprandial plasma insulin and glucose were lower (P < 0.01) for INT than for HYD and FAA. The area under the curve of plasma concentration after meal distribution was lower for INT for most AAs (P < 0.05), resulting in a flatter curve compared to HYD and FAA. This was the result of the slower appearance of dietary AA in the plasma when proteins are fed instead of free AA and small peptides. The flatter curve may also result from more AAs being metabolised by the intestine and liver when INT was fed. The metabolism of AA of the intestine and liver was higher for HYD than FAA. Providing AA as proteins or as free AA and small peptides affected the postprandial plasma kinetics of AA, urea, insulin, and glucose. Whether the flat kinetics when feeding proteins has a positive or negative effect on AA metabolism still needs to be explored.     

Selenium distribution in wheat grain, and the effect of postharvest processing on wheat selenium content

Selenium (Se) is an essential micronutrient for animals and humans, and wheat is a major dietary source of this element. It is improtant that postharvest processing losses of grain Se are minimized. This study, using grain dissection, milling with a Quadrumat mill, and baking and toasting studies, investigated the distribution of Se and other mineral nutrients in wheat grain and the effect of postharvest processing on their retention. The dissection study, although showing Se concentration to be highest in the embryo, confirmed (along with the milling study) previous findings that Se (which occurs mostly as selenomethionine in wheat grain) and S are more evenly distributed throughout the grain when compared to other mineral nutrients, and hence, lower proportions are removed in the milling residue. Postmilling processing did not affect Se concentration or content of wheat products in this study. No genotypic variability was observed for grain distribution of Se in the dissection and milling studies, in contrast to Cu, Fe., Mn, and Zn. This variability could be exploited in breeding for higher proportions of these nutrients in the endosperm to make white flour more nutritious. Further research could include grain dissection and milling studies using larger numbers of cultivars that have been grown together and a flour, extraction rate of around 70%     

Effects of branched chain amino acids,pyruvate, or ketone bodies on the free amino acid pool and release from brain cortex slices of normal and streptozotocindiabetic rats

Brain cortex slices from diabetic rats incubated in Krebs-Ringer-bicarbonate (KRB)-glucose medium show, compared to the normals, a 75% higher glutamine content. Branched chain amino acids (BCAA) added, at 0.5mM each, to this medium increase (53%) the glutamine content in the normal slices but have no effect on the glutamine content in the slices from diabetic rats. When the incubation medium is KRB-pyruvate, glutamine and glutamate contents are lower than in the KRB-glucose medium. The addition of BCAA in the KRB-pyruvate medium partially restores the contents of glutamine in the normal and of glutamine plus glutamate in the diabetic. Keto acids or BCAA added to the incubation medium of normal slices decrease the pool of most of the neutral and acidic amino acids but they do not affect this pool in slices from the diabetic rats. In addition keto acids increase the ratio glutamate in the tissue: glutamate in the medium.Abbreviations used BCAA branched chain amino acids - 3-OHB d,l-3-hydroxybutyrate - AcAc acetoacetate - KRB Krebs-Ringer-bicarbonate     

Regulation of the plasma amino acid profile by leucine via the system L amino acid transporter

Plasma concentrations of amino acids reflect the intracellular amino acid pool in mammals. However, the regulatory mechanism requires clarification. In this study, we examined the effect of leucine administration on plasma amino acid profiles in mice with and without the treatment of 2-aminobicyclo-(2,2,1)-heptane-2-carboxylic acid (BCH) or rapamycin as an inhibitor of system L or mammalian target of rapamycin complex 1, respectively. The elevation of plasma leucine concentration after leucine administration was associated with a significant decrease in the plasma concentrations of isoleucine, valine, methionine, phenylalanine, and tyrosine; BCH treatment almost completely blocked the leucine-induced decrease in plasma amino acid concentrations. Rapamycin treatment had much less effects on the actions of leucine than BCH treatment. These results suggest that leucine regulates the plasma concentrations of branched-chain amino acids, methionine, phenylalanine, and tyrosine, and that system L amino acid transporters are involved in the leucine action.