Composition Of Amino Acid Pool Research Articles

Vegetation affects pool size and composition of amino acids in Tibetan alpine meadow soils

Soil amino acids are of great importance for nitrogen cycling and plant nutrition, especially in the nitrogen-limited ecosystems. However, the factors that influence amino acid pools in alpine meadow soils remain unclear. The aims of this study were to answer the following questions: (1) Do soil amino acid pools under different vegetation cover show appreciable differences in their concentration and composition during the growing season? (2) Is the pool size of soil amino acids in the alpine meadow smaller or larger than those in other ecosystems? Soils were sampled from three sites dominated by three typical types of plants (Kobresia graminifolia, Polygonum viviparum and Elymus nutans) in a Tibetan alpine meadow, respectively, during the growing season. Soils were extracted with water and 2M KCl solution, respectively, and amino acids were quantitatively determined by high performance liquid chromatography. The results show that the pool size of soil exchangeable amino acids extracted by 2M KCl in this alpine meadow is comparable to those in other N-limited ecosystems. The pool size of soil amino acids across the three sites displayed temporal dynamics during the growing season, with the pool size increased from May to July and decreased in August. The P. viviparum soil had the largest amino acid pool among the three sites in May, whereas the largest pool in July and August was found in the K. graminifolia soil. The composition of the soil amino acid pools across the sites changed over the season, with acidic amino acids being abundant (63.6–84.3%) in spring, and neutral amino acids dominating (53.7–66.0%) in summer. The three sites shared five dominant amino acids (lysine, glutamic acid, leucine, alanine, and serine) through June to August; however, the other dominant amino acids (glycine, valine and threonine) varied among the sites and the months. These results suggest that the concentration and composition of amino acid pools in the Tibetan alpine meadow soils could be significantly influenced by the vegetation cover. Additionally, soil sampling time and extraction methods could also exert pronounced effect on the results. The information obtained in this study may help in understanding the influence of plant-soil feedback on soil amino acid pools, and the mechanisms of organic nitrogen uptake by alpine plants.

Jellyfish biochemical composition: importance of standardised sample processing

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 510:275-288 (2014) - DOI: https://doi.org/10.3354/meps10959 Jellyfish biochemical composition: importance of standardised sample processing T. Kogovšek1,2,*, T. Tinta1, K. Klun1, A. Malej1 1National Institute of Biology, Marine Biology Station, Fornač 41, 6330 Piran, Slovenia 2Present address: Graduate School of Biosphere Science, Hiroshima University, 4-4 Kagamiyama 1 Chome, Higashi-Hiroshima 739-8528, Japan *Corresponding author: tjasa.kogovsek@mbss.org ABSTRACT: Jellyfish play a key role in many pelagic ecosystems, especially in areas of extensive bloom events. In order to understand their role in pelagic food webs and in biogeochemical cycling, the energy stored and the trophic level occupied by jellyfish need to be quantified. To date, the common protocols applied for quantifying jellyfish biomass and analyzing its biochemical composition have been the same as for crustacean zooplankton, despite the difference in the body composition of the 2 groups. With the goal of establishing a uniform and reliable protocol for assessing jellyfish biomass, elemental, stable isotope and amino acid pool composition, we compared several methods commonly used in zooplankton ecology. Our results show that jellyfish dry mass varied with ambient salinity changes, thus giving a poor representation of jellyfish biomass. Moreover, the content of organic matter determined as ash free dry mass was overestimated; it was on average 2.2 times higher when compared to the mass of the retained material after dialysis. Furthermore, we demonstrated that during oven-drying at 60°C the protein-rich jellyfish tissue underwent significant changes: samples were (1) depleted in elemental C and N and total amino acid pool and (2) enriched in 15N, when compared to freeze-dried samples. We therefore suggest that freeze-drying should be selected over oven-drying before isotope and total amino acid analysis is applied. Overall, the results of this study suggest that the methods used to assess jellyfish biochemical composition should be carefully chosen. KEY WORDS: Scyphomedusae · Biochemical composition · Stable isotopes · Membrane dialysis · Salinity · Amino acid pool composition Full text in pdf format PreviousCite this article as: Kogovšek T, Tinta T, Klun K, Malej A (2014) Jellyfish biochemical composition: importance of standardised sample processing. Mar Ecol Prog Ser 510:275-288. https://doi.org/10.3354/meps10959 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 510. Online publication date: September 09, 2014 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2014 Inter-Research.

Amino acid fingerprint of a grassland soil reflects changes in plant species richness

A positive plant diversity to plant aboveground productivity relation has been shown to alter carbon and nitrogen fluxes in soils. Thus, most investigations focussed on the C- and N-input via litter fall, widely neglecting the importance of root exudation. As microbes, which are known to be important drivers of matter fluxes in soil, feed on these root exudates, increased knowledge on the availability of these compounds in soil might help to understand biodiversity effects on soil. We therefore investigated the effect of plant diversity on size and composition of the free soil amino acid pool in a grassland experiment, as amino acids are an important C- as well as N-source for microbes. Despite a positive diversity effect on plant productivity, we only found an insignificant increase of the size of the free amino acid pool in soil. This was most likely caused by an increase of the microbial population and thus an increased amino acid mineralization. At the same time the composition of the amino acid pool changed significantly between plant diversity levels. This most likely reflects differences in plant input as well as differences in microbial mineralization and enabled us to separate diversity levels by means of discriminant analysis.

Involvement of exopeptidases in dehydration tolerance of spring wheat seedlings

The observed inability of 6-d-old seedlings of spring wheat (Triticum aestivum L.) to tolerate the same water deficit as compared to the 4-d-old seedlings seems to be associated with the higher carboxypeptidase and lower aminopeptidase activities. Free amino acid pools differentiated also the 4-d-old seedlings from the older ones. Dehydration decreased the amino acid content in 4-d-old seedlings, increased it in 6-d-old seedlings and changed composition of amino acid pool. In tolerant phase of wheat seedling growth carboxypeptidase activity increased in response to water deficit and aminopeptidase activity increased in dehydrated seedlings, independently of their age.

The Influence of Nitrogen Sources on Growth and Protein Metabolism of Nectria haematococca Berk. & Br.

Summary Isolate II (IMI No. 267377) of Nectria haematococca (Fusarium solani) was highly virulent for cvs. “Marglobe” and “Pusa Ruby” causing higher per cent of pre- and post-emergence killing of tomato seedlings. On the other hand isolate I (IMI No: 267376) had high virulence for cvs. “Punjab Chuhara”, “Best of All”, and “Early Dwarf”. In both isolates increase in mat accumulation was rapid and linear between 10–15 days of growth. Nitrogen source of the medium and age of the culture determined the variation in growth response, protein build up, protease activity and size and composition of amino acid pool. Protein accumulation, protease activity and amino acid composition which varied with age of culture could be indirect determinants of virulence of the isolates of N. haematococca . High protein content and high protease activity with profuse liberation of amino acids at an early growth stage enables the pathogen to cause pre-emergence death of tomato seedlings. Similarly, late stage accumulation of protein by the pathogen enhances virulence and results in prominent post-emergence damping off of the seedlings.

Dissolved free amino acid pool composition and size in a hypertrophic, warm lake

Dissolved free amino acid pool composition and size in a hypertrophic, warm lake

Effect of nitrate-N incorporation on the composition of the intracellular amino acid pool of N-deprivedTetraselmis marina

The major free amino acids in N-replete cells of Tetraselmis marina were arginine, taurine, glutamate, glutamine, aspartate, asparagine, serine and alanine. During N-deprivation in light, levels of all of these decreased; free α-amino-N decreased by 85% after 72 h N-deprivation. In contrast, cells deprived of N in darkness accumulated free amino acids in their pool, presumably reflecting the need for products of photosynthesis for processes of amination and protein synthesis. When cells N-deprived in light were supplied with a pulse of NO- 3, there was a slow increase in levels of each amino acid, but levels similar to those in N-replete cells were not attained within 48 h of pulsing. The only major amino acids showing a significant response within 24 h of pulsing were arginine, ornithine, and glutamine. The slow return to levels found in N-replete cells is suggested to be a consequence of the complex interaction between the pathways leading to the synthesis of individual amino acids coupled with the removal of amino acids for protein synthesis. Despite this, the qualitative composition of the amino acid pool (by rank) was remarkably conservative, only differing significantly in cells subjected to prolonged N-deprivation in light.

The establishment of essential and metabolically derived amino acid profiles in developing chick embryo organs.

The accumulation of certain essential and metabolically derived amino acids in the free amino acid pools of three excitable tissues has been studied in the chick embryo. Valine together with leucine are at the onset present in the yolk at higher concentrations than any of the other essential amino acids. By 15 days all the amino acids studied have accumulated in the embryonic pools at a higher rate than valine, although certain amino acids, such as phenylalanine or methionine, always remain at lower relative concentrations than valine. This reflects their low supply in the yolk, rather than a more rapid rate of disappearance (utilization). During early embryogenesis (E2-E4), tissues preferentially concentrate glutamic acid, besides taurine and phosphoethanolamine (6). The next distinct stage of development (E4-E7) is marked in the brain by a gradual rise in glutamic acid, glutamine and aspartic acid; the same three amino acids do not demonstrate a further increase in the pool of the heart, while in the whole eye the amino acid profile begins to resemble the blood. Leucine in all three tissues declines rapidly, to reach isoleucine levels by day 7 of development; tyrosine increases slowly in apparent reciprocity to an equally gradual phenylalanine decrease. Into the second week of embryo growth (E7-E15), GABA appears in the mesencephalon (E7) and the eye (E9-E10). In the mesencephalon, the free amino acid pool composition exhibits a rather sudden increase of most metabolically derived amino acids.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of cold-temperature exposure and acclimation on amino acid pool changes and enzyme activities of rat brown adipose tissue

The amino acid pool composition and its concentration ratios with respect to blood and plasma, as well as the activities of alanine, aspartate and branched chain amino acid transaminases, glutamina synthetase, adenylate deaminase and glutamate dehydrogenase have been studied in the interscapular brown adipose tissue of control, 12-h cold-exposed and 15-day cold-acclimated rats. Cold temperature affected the amino acid metabolism and pool composition more intensely after 15 days than after 12-h cold-exposure, even though the patterns of change were very similar in both groups. Cold temperatures induced a decrease in glutamine and an increase in glutamate concentration in the tissue. This probably increased the metabolism of branched chain amino acids and caused a decrease in adenylate deaminase activity. It also seemed to increase alanine utilization. We concluded that amino acid metabolism in brown adipose tissue is enhanced by cold temperature acclimation.

Protein synthesis and amino acid pool during yeast-mycelial transition induced by N-acetyl-D-glucosamine in Candida albicans.

Protein synthesis at different stages of yeast-mycelial transition induced by N-acetyl-D-glucosamine in Candida albicans was evaluated by following incorporation of radioactive amino acids into the acid-insoluble cellular material. In passing from the early germ-tube formation (60-90 min) to the mature hyphal cell (240-270 min) there was a marked decrease in the capacity for protein synthesis. Apparently, this decrease was not due to a decreased amino acid uptake into the soluble cellular pool or to exhaustion of carbon/energy source in the inducing medium with consequent arrest of growth. Protein synthesis, however, did not decay when amino acids at high concentration were added to the medium fostering the yeast-mycelial transition and this effect was potentiated by glucose. Analysis of the intracellular amino acid pool showed that both germ-tubes and hyphal cells were relatively depleted of several amino acids as compared to the yeast-form cells, whereas in the hyphae there was a higher concentration of glutamic acid/glutamine, the latter being the predominant component. These modulations in amino acid pool composition were not seen when yeasts were converted to hyphae in an amino acid-rich induction medium. This study emphasizes that yeast-form cells of C. albicans may efficiently convert to the mycelial form even under a progressively lowered rate of protein synthesis, and suggests that initiation of hyphal morphogenesis in the presence of N-acetyl-D-glucosamine is somehow separated from cellular growth.

The free amino acid pool composition during growth of the culture of Xanthomonas citri (hasse) dowson

Fourteen amino acids were found to constitute the intracellular amino compound pool of the developing culture of Xanthomonas citri (Hasse) Dowson. These were serine, dl-alanine, beta-alanine, leucine/isoleucine, threonine, aspartic acid, glutamic acid, asparagine, glutamine, cystine, histidine, tyrosine, tryptophan, and proline. Of these, beta-alanine, threonine, aspartic acid, glutamic acid, asparagine, and tyrosine could be traced as excretory amino acids in the bacterial culture filtrate, being exuded at the cost of and parallel to the depletion of their amounts in bacterial cell extract. Thus, the composition and pool size of intra- and extracellular amino acids varies considerably during the growth of this pathogen. The wall constituents of X. citri, especially alanine, glutamic acid, and aspartic acid, were prominent among the amino compounds detected.

Amino-acid pool composition of Saccharomyces cerevisiae as a function of growth rate and amino-acid nitrogen source.

The composition of the amino-acid pool of Saccharomyces cerevisiae is markedly influenced by the amino-acid nitrogen source. The yeast tends to accumulate the amino acid supplied and those closely related to it metabolically. A relatively high concentration of glutamic acid is maintained in the pools of all cultures irrespective of the nitrogen source, reflecting the central role of glutamic acid in nitrogen metabolism. The total amino-acid pool concentration increases as a function of growth rate, although differences exist in the behaviour of individual amino acids.

Studies on the Induction and Repression of Enzymes in Rat Liver: V. Regulation of the Rate of Synthesis and Degradation of Serine Dehydratase by Dietary Amino Acids and Glucose

Abstract The enzyme, serine dehydratase (l-serine hydro-lyase, EC 4.2.1.13), has been purified by a previously unpublished method involving heat denaturation, ammonium sulfate treatment, Sephadex gel filtration, and hydroxylapatite chromatography. Antibodies to the pure enzyme have been prepared in rabbits and have been shown to be antigenically homogeneous. Utilizing the technique of pulse labeling of the enzyme in vivo with 14C-valine, it has been shown that administration of mixtures of amino acids dramatically increases the rate of synthesis of this enzyme in vivo without appreciably enhancing the synthesis of total soluble proteins. The amino acid, l-tryptophan, as well as the hormone, glucagon, also effects an increased rate of synthesis of the enzyme. Administration of glucose results in a complete cessation of enzyme synthesis whether administered from zero time or at a time interval thereafter at which the synthesis of the enzyme is completely resistant to the antibiotic, actinomycin D. Amino acid induction and glucose repression as well as hormonal induction by both glucagon and hydrocortisone occur in adrenalectomized animals. The effects of glucose administration on protein synthesis are not general since serum protein synthesis was not affected by this treatment. By prelabeling the enzyme and administering glucose with and without amino acids, it has been shown that glucose appears to effect primarily a cessation of enzyme synthesis and an increase of degradation of the enzyme. Studies of the composition of amino acid pools in the intact animal have shown that the different rates of synthesis seen in rats fed amino acids with respect to those fed glucose are not the result of differential labeling of the labeled precursor pool. The studies reported here show that the synthesis of rat liver serine dehydratase may be regulated by amino acids and glucose as well as by the hormones, hydrocortisone and glucagon, the latter being the most efficient inducer of the enzyme of those compounds studied. The repression of serine dehydratase synthesis in vivo by glucose appears in a number of ways to be analogous to catabolite repression seen in microorganisms.