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1.
A method was developed for the purification of main intermediates and storage products of leaves and tubers of potato for
analysis of their 13C content. The method was tested for recovery of metabolites and carbon isotope discrimination during the purification process.
Leaf metabolite δ13C values showed an enrichment of starch relative to sucrose and citrate. This result is in agreement with previous findings
in other higher plants and indicates the existence of isotope discrimination steps during transport and metabolism of triose-phosphates
in potato leaf mesophyll cells. Active anaplerotic replenishment of the tricarboxylic acid cycle in the leaves of the plants
investigated was also deduced from the significant 13C enrichment of malate relative to citrate and asparagine/aspartate relative to glutamine/glutamate. Analysis of tuber metabolite
δ13C values showed no difference between starch and sucrose. However, tuber sucrose appeared significantly enriched compared
with leaf sucrose and also relative to tuber citrate and malate. This finding suggests the existence of sites of isotopic
discrimination during sucrose processing in developing tubers. It also confirms that metabolic cycles of sucrose synthesis
and breakdown and of hexose-phosphate/triose-phosphate interconversion, which have been described in excised tuber tissue,
also occur in intact organs. The δ13C values were also used to estimate the metabolic rate of carbon oxidation in developing tubers on the assumption that pyruvate
dehydrogenase is the main site of isotopic discrimination in the tuber cells. The result obtained was in agreement with the
available literature, suggesting that analyses of natural isotopic distribution in plant products may be a useful tool for
the study of metabolic processes and sink-source relationships in intact plants.
Received: 21 May 1998 / Accepted: 10 July 1998 相似文献
2.
Masahiro Sugimoto Akiyoshi Hirayama Takamasa Ishikawa Martin Robert Richard Baran Keizo Uehara Katsuya Kawai Tomoyoshi Soga Masaru Tomita 《Metabolomics : Official journal of the Metabolomic Society》2010,6(1):27-41
In metabolomics, the rapid identification of quantitative differences between multiple biological samples remains a major
challenge. While capillary electrophoresis–mass spectrometry (CE–MS) is a powerful tool to simultaneously quantify charged
metabolites, reliable and easy-to-use software that is well suited to analyze CE–MS metabolic profiles is still lacking. Optimized
software tools for CE–MS are needed because of the sometimes large variation in migration time between runs and the wider
variety of peak shapes in CE–MS data compared with LC–MS or GC–MS. Therefore, we implemented a stand-alone application named
JDAMP (Java application for Differential Analysis of Metabolite Profiles), which allows users to identify the metabolites that
vary between two groups. The main features include fast calculation modules and a file converter using an original compact
file format, baseline subtraction, dataset normalization and alignment, visualization on 2D plots (m/z and time axis) with matching metabolite standards, and the detection of significant differences between metabolite profiles.
Moreover, it features an easy-to-use graphical user interface that requires only a few mouse-actions to complete the analysis.
The interface also enables the analyst to evaluate the semiautomatic processes and interactively tune options and parameters
depending on the input datasets. The confirmation of findings is available as a list of overlaid electropherograms, which
is ranked using a novel difference-evaluation function that accounts for peak size and distortion as well as statistical criteria
for accurate difference-detection. Overall, the JDAMP software complements other metabolomics data processing tools and permits easy and rapid detection of significant differences
between multiple complex CE–MS profiles. 相似文献
3.
Water stress stimulates sucrose synthesis and inhibits starch and cell-wall synthesis in tissue slices of growing potato
(Solanum tuberosum L. cv. Desirée) tubers. Based on the analysis of fluxes and metabolites, Geigenberger et al. (1997, Planta 201: 502–518)
proposed that water deficits up to −0.72 MPa stimulate sucrose synthesis, leading to decreased starch synthesis as a result
of the resulting decline of phosphorylated metabolite levels, whereas more-severe water deficits directly inhibit the use
of ADP-glucose. Potato plants with decreased expression of adenosine 5′-diphosphoglucose pyrophosphorylase (AGPase) have been
used to test the prediction that the contribution of AGPase to the control of starch synthesis should decrease in severely
water-stressed tuber material. Freshly cut slices from wild-type and antisense tubers were incubated at a range of mannitol
concentrations (20, 300 and 500 mM) and the metabolism of [14C]glucose was analysed. A 86–97% reduction of AGPase activity led to a major but non-stoichiometric inhibition of starch accumulation
in intact growing tubers attached to the plant (40–85%), and an inhibition of starch synthesis in non-stressed tuber slices
incubated in 20 mM mannitol (60–80%). The inhibition of starch synthesis was accompanied by a 2- to 8-fold increase in the
levels of sugars in intact tubers and a 2- to 3-fold stimulation of sucrose synthesis in tuber slices, whereas respiration
and cell-wall synthesis were not significantly affected. The strong impact of AGPase on carbon partitioning in non-stressed
tubers and tuber slices was retained in slices subjected to moderate water deficit (300 mM mannitol, corresponding to −0.72 MPa).
In discs incubated in 500 mM mannitol (corresponding to −1.2 MPa) this response was modified. A 80–97% reduction of AGPase
resulted in only a 0–40% inhibition of starch synthesis. Further, the water stress-induced stimulation of sucrose synthesis
was abolished in the transformants. The results provide direct evidence that the contribution of AGPase to the control of
starch synthesis can be modified by environmental factors, leading to a lower degree of control during severe water deficits.
There was also a dramatic decrease in the labelling of cell-wall components in wild-type tuber slices incubated with 300 or
500 mM mannitol. The water stress-induced inhibition of cell-wall synthesis occurred independently of AGPase expression and
the accompanying changes in starch and sucrose metabolism, indicating a direct inhibition of cell-wall synthesis in response
to water stress.
Received: 24 February 1999 / Accepted: 28 May 1999 相似文献
4.
Strawberry (Fragaria × ananassa Duch), a fruit of economic and nutritional importance, is also a model species for fleshy fruits and genomics in Rosaceae. Strawberry fruit quality at different harvest stages is a function of the fruit's metabolite content, which results from physiological changes during fruit growth and ripening. In order to investigate strawberry fruit development, untargeted (GC-MS) and targeted (HPLC) metabolic profiling analyses were conducted. Principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA) were employed to explore the non-polar and polar metabolite profiles from fruit samples at seven developmental stages. Different cluster patterns and a broad range of metabolites that exerted influence on cluster formation of metabolite profiles were observed. Significant changes in metabolite levels were found in both fruits turning red and fruits over-ripening in comparison with red-ripening fruits. The levels of free amino acids decreased gradually before the red-ripening stage, but increased significantly in the over-ripening stage. Metabolite correlation and network analysis revealed the interdependencies of individual metabolites and metabolic pathways. Activities of several metabolic pathways, including ester biosynthesis, the tricarboxylic acid cycle, the shikimate pathway, and amino acid metabolism, shifted during fruit growth and ripening. These results not only confirmed published metabolic data but also revealed new insights into strawberry fruit composition and metabolite changes, thus demonstrating the value of metabolomics as a functional genomics tool in characterizing the mechanism of fruit quality formation, a key developmental stage in most economically important fruit crops. 相似文献
5.
《Animal : an international journal of animal bioscience》2023,17(4):100727
The aim of this study is built in two phases: to quantify the ability of novel milk metabolites to measure between-animal variability in response and recovery profiles to a short-term nutritional challenge, then to derive a resilience index from the relationship between these individual variations. At two different stages of lactation, sixteen lactating dairy goats were exposed to a 2-d underfeeding challenge. The first challenge was in late lactation, and the second was carried out on the same goats early in the following lactation. During the entire experiment period, samples were taken at each milking for milk metabolite measures. For each metabolite, the response profile of each goat was characterised using a piecewise model for describing the dynamic pattern of response and recovery profiles after the challenge relative to the start of the nutritional challenge. Cluster Analysis identified three types of response/recovery profiles per metabolite. Using cluster membership, multiple correspondence analyses (MCAs) were performed to further characterise response profile types across animals and metabolites. This MCA analysis identified three groups of animals. Further, discriminant path analysis was able to separate these groups of multivariate response/recovery profile type based on threshold levels of three milk metabolites: β-hydroxybutyrate, free glucose and uric acid. Further analyses were done to explore the possibility of developing an index of resilience from milk metabolite measures. Different types of performance response to short-term nutritional challenge can be distinguished using multivariate analyses of a panel of milk metabolites. 相似文献
6.
Wei-Li Yang Mark A. Bernards 《Metabolomics : Official journal of the Metabolomic Society》2007,3(2):147-159
Suberin is a specific cell wall-associated biopolymer characterized by the deposition of both a poly(phenolic) domain (SPPD)
associated with the cell wall, and a poly(aliphatic) domain (SPAD) thought to be deposited between the cell wall and plasma
membrane. In planta, suberin functions to prevent plants from desiccation and pathogen attack. Although the chemical identity of the monomeric
components of the SPPD and SPAD are well known, their concerted biosynthesis and assembly into the suberin macromolecule is
poorly understood. To expand our knowledge of suberin biosynthesis, a GC/MS-based metabolite profiling study was conducted,
using wound healing potato (Solanum tuberosum L.) tubers as a model system. A time series of both non-polar and polar metabolite profiles were created, yielding a broad-based,
dynamic picture of wound-induced metabolism, including suberization. Principal component analysis revealed a separation of
metabolite profiles according to different suberization stages, with clear temporal differences emerging in the non-polar
and polar profiles. In the non-polar profiles, suberin-associated aliphatics contributed the most to cluster formation, while
a broader range of metabolites (including organic acids, sugars, amino acids and phenylpropanoids) influenced cluster formation
amongst polar profiles. Pair-wise correlation analysis revealed strong correlations between known suberin-associated compounds,
as well as between suberin-associated compounds and several un-identified metabolites in the profiles. These data may help
to identify additional, as yet unknown metabolites associated with suberization process. 相似文献
7.
8.
The sucrose transporter StSUT1 localizes to sieve elements in potato tuber phloem and influences tuber physiology and development 总被引:17,自引:0,他引:17
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Kühn C Hajirezaei MR Fernie AR Roessner-Tunali U Czechowski T Hirner B Frommer WB 《Plant physiology》2003,131(1):102-113
The sucrose (Suc) H(+)-cotransporter StSUT1 from potato (Solanum tuberosum), which is essential for long-distance transport of Suc and assumed to play a role in phloem loading in mature leaves, was found to be expressed in sink tubers. To answer the question of whether SUT1 serves a function in phloem unloading in tubers, the promoter was fused to gusA and expression was analyzed in transgenic potato. SUT1 expression was unexpectedly detected not in tuber parenchyma but in the phloem of sink tubers. Immunolocalization demonstrated that StSUT1 protein was present only in sieve elements of sink tubers, cells normally involved in export of Suc from the phloem to supply developing tubers, raising the question of the role of SUT1 in tubers. SUT1 expression was inhibited by antisense in transgenic potato plants using a class I patatin promoter B33, which is primarily expressed in the phloem of developing tubers. Reduced SUT1 expression in tubers did not affect aboveground organs but led to reduced fresh weight accumulation during early stages of tuber development, indicating that in this phase SUT1 plays an important role for sugar transport. Changes in Suc- and starch-modifying enzyme activities and metabolite profiles are consistent with the developmental switch in unloading mechanisms. Altogether, the findings may suggest a role of SUT1 in retrieval of Suc from the apoplasm, thereby regulating the osmotic potential in the extracellular space, or a direct role in phloem unloading acting as a phloem exporter transferring Suc from the sieve elements into the apoplasm. 相似文献
9.
Biogenesis and Degradation of Starch: I. The Fate of the Amyloplast Membranes during Maturation and Storage of Potato Tubers
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Storage of mature or developing potato tubers (Solanum tuberosum “Up-to-Date” variety) at 4 C causes a reduction in the starch content and the elevation in the level of free sugars. This phenomenon is not observed when the tubers are stored at 25 C. Changes in the morphology of cells from developing or mature tubers after storage at 4 or 25 C have been followed by electron microscopy. During all stages of the tuber development the starch granules are surrounded by a membrane derived from the plastid envelope. Storage in the cold induces disintegration of this membrane. A membrane fraction isolated from starch granules of tubers stored at 4 C has a lower buoyant density, and the electrophoretic pattern of its proteins is different from that of a similar membrane fraction obtained from tubers stored at 25 C. It is suggested that the cold-induced changes in the starch and sugar content during storage of potato tubers might be correlated with damage to the membranes surrounding the starch granules and changes in their permeability to degradative enzymes and substrates. 相似文献
10.
As part of a research program on nucleotide metabolism in potato tubers (Solanum tuberosum L.), profiles of pyridine (nicotinamide) metabolism were examined based on the in situ metabolic fate of radio-labelled precursors
and the in vitro activities of enzymes. In potato tubers, [3H]quinolinic acid, which is an intermediate of de novo pyridine nucleotide synthesis, and [14C]nicotinamide, a catabolite of NAD, were utilised for pyridine nucleotide synthesis. The in situ tracer experiments and in
vitro enzyme assays suggest the operation of multiple pyridine nucleotide cycles. In addition to the previously proposed cycle
consisting of seven metabolites, we found a new cycle that includes newly discovered nicotinamide riboside deaminase which
is also functional in potato tubers. This cycle bypasses nicotinamide and nicotinic acid; it is NAD → nicotinamide mononucleotide → nicotinamide
riboside → nicotinic acid riboside → nicotinic acid mononucleotide → nicotinic acid adenine dinucleotide → NAD. Degradation
of the pyridine ring was extremely low in potato tubers. Nicotinic acid glucoside is formed from nicotinic acid in potato
tubers. Comparative studies of [carboxyl-14C]nicotinic acid metabolism indicate that nicotinic acid is converted to nicotinic acid glucoside in all organs of potato
plants. Trigonelline synthesis from [carboxyl-14C]nicotinic acid was also found. Conversion was greater in green parts of plants, such as leaves and stem, than in underground
parts of potato plants. Nicotinic acid utilised for the biosynthesis of these conjugates seems to be derived not only from
the pyridine nucleotide cycle, but also from the de novo synthesis of nicotinic acid mononucleotide. 相似文献
11.
Changes in the sugarcane metabolome with stem development. Are they related to sucrose accumulation?
Sucrose content increases with internode development down the stem of sugarcane. In an attempt to determine which other changes in metabolites may be linked to sucrose accumulation gas chromatography-mass spectrometry was used to obtain metabolic profiles from methanol/water extracts of four samples of different age down the stem of cultivar Q117. Extracts were derivatized with either N-methyl-N-(trimethylsilyl) trifluoracetamide (TMS) or N-methyl N-(tert-butyldimethylsilyl) trifluoroacetamide (TBS) separately in order to increase the number of metabolites that could be detected. This resulted in the measurement of 121 and 71 metabolites from the TMS and TBS derivatization, respectively. Fifty-five metabolites were identified using commercial and publicly available libraries. Statistical analysis of the metabolite profiles resulted in clustering of tissue types. Particular metabolites were correlated with the level of sucrose accumulation, which as expected increased down the stem. Metabolites, such as tricarboxylic acid cycle intermediates and amino acids, were more abundant in the M2 sample (meristem to internode 2) that was actively growing and decreased in an apparently coordinated developmentally programmed manner in more mature internodes down the stem. However, other metabolites such as trehalose and raffinose showed positive correlations with sucrose concentration. Here we discuss the technique used to measure metabolites in sugarcane and the changes in metabolite abundance down the sugarcane stem. 相似文献
12.
Warwick B. Dunn David I. Broadhurst Sasalu M. Deepak Mamta H. Buch Garry McDowell Irena Spasic David I. Ellis Nicholas Brooks Douglas B. Kell Ludwig Neyses 《Metabolomics : Official journal of the Metabolomic Society》2007,3(4):413-426
There is intense interest in the identification of novel biomarkers which improve the diagnosis of heart failure. Serum samples
from 52 patients with systolic heart failure (EF < 40% plus signs and symptoms of failure) and 57 controls were analyzed by
gas chromatography – time of flight – mass spectrometry and the raw data reduced to 272 statistically robust metabolite peaks.
38 peaks showed a significant difference between case and control (p < 5 × 10−5). Two such metabolites were pseudouridine, a modified nucleotide present in t- and rRNA and a marker of cell turnover, as
well as the tricarboxylic acid cycle intermediate 2-oxoglutarate. Furthermore, 3 further new compounds were also excellent
discriminators between patients and controls: 2-hydroxy, 2-methylpropanoic acid, erythritol and 2,4,6-trihydroxypyrimidine.
Although renal disease may be associated with heart failure, and metabolites associated with renal disease and other markers
were also elevated (e.g. urea, creatinine and uric acid), there was no correlation within the patient group between these
metabolites and our heart failure biomarkers, indicating that these were indeed biomarkers of heart failure and not renal
disease per se. These findings demonstrate the power of data-driven metabolomics approaches to identify such markers of disease.
Warwick B. Dunn, David I. Broadhurst and Sasalu M. Deepak contributed equally to this work. 相似文献
13.
Michaud MR Denlinger DL 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2007,177(7):753-763
Flesh flies can enhance their cold hardiness by entering a photoperiod-induced pupal diapause or by a temperature-induced
rapid cold-hardening process. To determine whether the same or different metabolites are involved in these two responses,
derivatized polar extracts from flesh flies subjected to these treatments were examined using gas chromatography–mass spectrophotometry
(GC–MS). This metabolomic approach demonstrated that levels of metabolites involved in glycolysis (glycerol, glucose, alanine,
pyruvate) were elevated by both treatments. Metabolites elevated uniquely in response to rapid cold-hardening include glutamine,
cystathionine, sorbitol, and urea while levels of β-alanine, ornithine, trehalose, and mannose levels were reduced. Rapid
cold-hardening also uniquely perturbed the urea cycle. In addition to the elevated metabolites shared with rapid cold-hardening,
leucine concentrations were uniquely elevated during diapause while levels of a number of other amino acids were reduced.
Pools of two aerobic metabolic intermediates, fumarate and citrate, were reduced during diapause, indicating a reduction of
Krebs cycle activity. Principal component analysis demonstrated that rapid cold-hardening and diapause are metabolically distinct
from their untreated, non-diapausing counterparts. We discuss the possible contribution of each altered metabolite in enhancing
the overall cold hardiness of the organism, as well as the efficacy of GC–MS metabolomics for investigating insect physiological
systems. 相似文献
14.
Microviscosity of the highly purified plasma membranes isolated from the maturing goat caput, corpus and cauda epididymal
sperm, was measured using l,6-diphenyl-l,3,5-hexatriene as the lipophilic probe at varying temperatures (12–42°C). As shown
by the Arrhenius plot of the data each of the maturing sperm membranes had two distinct lipid phase transitions in the temperature
zones 19–25°C and 34–37°C. The low-temperature transitions for the immature caput- and mature cauda-sperm membranes were noted
at 19–20°C, and 24–25°C, respectively, whereas both these membranes showed high temperature transition at 36–37°C. The maturing
corpus-sperm membrane had phase transitions at 21–22°C and 35–36°C that were significantly different from those of the immature/mature
sperm membranes. The data implicate significant alteration of the sperm membrane structure during epididymal maturation. The
phase transition of the mature male gametes at 36–37°C may have a great impact on the subsequent events of the sperm life
cycle since the mature spermatozoa that are stored in the epididymis a few degrees below the body temperature, experience
higher temperature when ejaculated into the female reproductive tract. 相似文献
15.
Regulation of sucrose and starch metabolism in potato tubers in response to short-term water deficit 总被引:24,自引:0,他引:24
Peter Geigenberger Ralph Reimholz Michael Geiger Lucia Merlo Vittoria Canale Mark Stitt 《Planta》1997,201(4):502-518
To investigate the effect of water stress on carbon metabolism in growing potato tubers (Solanum tuberosum L.), freshly cut and washed discs were incubated in a range of mannitol concentrations corresponding to external water potential
between 0 and −1.2 MPa. (i) Incorporation of [14C]glucose into starch was inhibited in water-stressed discs, and labeling of sucrose was increased. High glucose overrode
the changes at low water stress (up to −0.5 MPa) but not at high water stress. (ii) Although [14C]sucrose uptake increased in water-stressed discs, less of the absorbed [14C]sucrose was metabolised. (iii) Analysis of the sucrose content of the discs confirmed that increasing water deficit leads
to a switch, from net sucrose degradation to net sucrose synthesis. (iv) In parallel incubations containing identical concentrations
of sugars but differing in which sugar was labeled, degradation of [14C]sucrose and labeling of sucrose from [14C]glucose and fructose was found at each mannitol concentration. This shows that there is a cycle of sucrose degradation and
resynthesis in these tuber discs. Increasing the extent of water stress changed the relation between sucrose breakdown and
sucrose synthesis, in favour of synthesis. (v) Analysis of metabolites showed a biphasic response to increasing water deficit.
Moderate water stress (0–200 mM mannitol) led to a decrease of the phosphorylated intermediates, especially 3-phosphoglycerate
(3PGA). The decrease of metabolites at moderate water stress was not seen when high concentrations of glucose were supplied
to the discs. More extreme water stress (300–500 mM mannitol) was accompanied by an accumulation of metabolites at low and
high glucose. (vi) Moderate water stress led to an activation of sucrose phosphate synthase (SPS) in discs, and in intact
tubers. The stimulation involved a change in the kinetic properties of SPS, and was blocked␣by protein phosphatase inhibitors.
(vii) The amount of ADP-glucose (ADPGlc) decreased when discs were incubated on 100 or 200 mM mannitol. There was a strong
correlation between the in vivo levels of ADPGlc and 3PGA when discs were subjected to moderate water stress, and when the
sugar supply was varied. (viii) The level of ADPGlc increased and starch synthesis was further inhibited when discs were incubated
in 300–500 mM mannitol. (ix) It is proposed that moderate water stress leads to an activation of SPS and stimulates sucrose
synthesis. The resulting decline of 3PGA leads to a partial inhibition of ADP-glucose pyrophosphorylase and starch synthesis.
More-extreme water stress leads to a further alteration of partitioning, because it inhibits the activities of one or more
of the enzymes involved in the terminal reactions of starch synthesis.
Received: 26 August 1996 / Accepted: 5 November 1996 相似文献
16.
Sofia Moco Jenny Forshed Ric C. H. De Vos Raoul J. Bino Jacques Vervoort 《Metabolomics : Official journal of the Metabolomic Society》2008,4(3):202-215
Nuclear magnetic resonance (NMR) and liquid chromatography-mass spectrometry (LCMS) are frequently used as technological platforms
for metabolomics applications. In this study, the metabolic profiles of ripe fruits from 50 different tomato cultivars, including
beef, cherry and round types, were recorded by both 1H NMR and accurate mass LC-quadrupole time-of-flight (QTOF) MS. Different analytical selectivities were found for these both
profiling techniques. In fact, NMR and LCMS provided complementary data, as the metabolites detected belong to essentially
different metabolic pathways. Yet, upon unsupervised multivariate analysis, both NMR and LCMS datasets revealed a clear segregation
of, on the one hand, the cherry tomatoes and, on the other hand, the beef and round tomatoes. Intra-method (NMR–NMR, LCMS–LCMS)
and inter-method (NMR–LCMS) correlation analyses were performed enabling the annotation of metabolites from highly correlating
metabolite signals. Signals belonging to the same metabolite or to chemically related metabolites are among the highest correlations
found. Inter-method correlation analysis produced highly informative and complementary information for the identification
of metabolites, even in de case of low abundant NMR signals. The applied approach appears to be a promising strategy in extending
the analytical capacities of these metabolomics techniques with regard to the discovery and identification of biomarkers and
yet unknown metabolites.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
17.
Yuri C Martins Guilherme L Werneck Leonardo J Carvalho Beatriz PT Silva Bruno G Andrade Tadeu M Souza Diogo O Souza Cláudio T Daniel-Ribeiro 《Malaria journal》2010,9(1):1-13
Background
Metabolic changes in the host in response to Plasmodium infection play a crucial role in the pathogenesis of malaria. Alterations in metabolism of male and female mice infected with Plasmodium berghei ANKA are reported here.Methods
1H NMR spectra of urine, sera and brain extracts of these mice were analysed over disease progression using Principle Component Analysis and Orthogonal Partial Least Square Discriminant Analysis.Results
Analyses of overall changes in urinary profiles during disease progression demonstrate that females show a significant early post-infection shift in metabolism as compared to males. In contrast, serum profiles of female mice remain unaltered in the early infection stages; whereas that of the male mice changed. Brain metabolite profiles do not show global changes in the early stages of infection in either sex. By the late stages urine, serum and brain profiles of both sexes are severely affected. Analyses of individual metabolites show significant increase in lactate, alanine and lysine, kynurenic acid and quinolinic acid in sera of both males and females at this stage. Early changes in female urine are marked by an increase of ureidopropionate, lowering of carnitine and transient enhancement of asparagine and dimethylglycine. Several metabolites when analysed individually in sera and brain reveal significant changes in their levels in the early phase of infection mainly in female mice. Asparagine and dimethylglycine levels decrease and quinolinic acid increases early in sera of infected females. In brain extracts of females, an early rise in levels is also observed for lactate, alanine and glycerol, kynurenic acid, ureidopropionate and 2-hydroxy-2-methylbutyrate.Conclusions
These results suggest that P. berghei infection leads to impairment of glycolysis, lipid metabolism, metabolism of tryptophan and degradation of uracil. Characterization of early changes along these pathways may be crucial for prognosis and better disease management. Additionally, the distinct sexual dimorphism exhibited in these responses has a bearing on the understanding of the pathophysiology of malaria. 相似文献18.
N. Rispail B. Hauck B. Bartholomew A. A. Watson R. J. Nash K. J. Webb 《Symbiosis (Philadelphia, Pa.)》2010,50(3):119-128
Plant secondary metabolites, particularly flavonoids, are key components in the early stages of nitrogen-fixing symbiosis.
Despite their importance, the endogenous secondary metabolites involved in symbiosis have not yet been identified in the model
legume Lotus japonicus. We therefore determined changes in the secondary metabolic profile of Lotus japonicus roots in response to its symbiont. Analysis of the root secondary metabolite profiles 1 week after inoculation with Mesorhizobium loti revealed quantitative changes in the level of 14 phenolic peaks when compared with non-inoculated control plants. These changes
affected compounds from most phenolic classes, possibly resulting from interconversion between classes since the total phenolic
level remained constant. In addition, the use of 2 M. loti strains differing only in their capacity to synthesise Nod factor revealed that, although Nod factor signalling induced accumulation
of a specific subset of 4 phenolic peaks, most changes were induced in response to both rhizobial strains. 相似文献
19.
The short-term changes in metabolism that occurred after adding glucose or sucrose to freshly cut discs from growing potato
(Solanum tuberosum L.) tubers were investigated. (i) When glucose was supplied, there was a marked increase in glycolytic metabolites, and respiration
was stimulated. When sucrose was supplied, amounts of glycolytic metabolites including hexose phosphates and 3-phosphoglycerate
(3PGA) were similar to or lower than in control discs incubated without sugars, and respiration did not rise initially above
that in control discs. This different response to sucrose and glucose was found across the concentration range 5–200 mM. A
larger proportion of the metabolised 14C was converted to starch when [14C] sucrose was supplied than when [14C] glucose was supplied. The different effect on metabolite levels, respiration and starch synthesis was largest after 20–30 min,
and decreased in longer incubations. (ii) When 5 or 25 mM sucrose was added in the presence of [14C] glucose, it led to a decrease in hexose phosphates and 3PGA, and a small increase in the rate of starch synthesis compared
to discs incubated with glucose in the absence of sucrose. These differences were seen in a 30-min pulse and a 2-h pulse.
Whereas ADP-glucose levels after adding sucrose resembled those in control discs, glucose led to a decrease in ADP-glucose.
This decrease did not occur when 5 or 25 mM sucrose was added with the glucose. (iii) To check the relevance of these experiments
for intact tubers, water or 100 mM mannitol, sucrose or glucose were supplied through the stolon to intact tubers for 24 h.
A 0.2 mM solution of [14C] glucose was then introduced into the tubers, and its metabolism investigated during the next 30 min. Labelling of starch
was increased after preincubation with sucrose, and significantly inhibited after preincubation with glucose. (iv) It is concluded
that glucose and sucrose have different effects on tuber metabolism. Whereas glucose leads to a preferential stimulation of
respiration, sucrose preferentially stimulates starch synthesis via a novel mechanism that allows stimulation of ADP-glucose
pyrophosphorylase even though the levels of hexose phosphates and the allosteric activator 3PGA decrease.
Received: 9 October 1997 / Accepted: 3 February 1998 相似文献
20.
Miyako Kusano Atsushi Fukushima Henning Redestig Makoto Kobayashi Hitomi Otsuki Hitoshi Onouchi Satoshi Naito Masami Yokota Hirai Kazuki Saito 《Amino acids》2010,39(4):1013-1021
Methionine (Met) is an essential amino acid for all organisms. In plants, Met also functions as a precursor of plant hormones,
polyamines, and defense metabolites. The regulatory mechanism of Met biosynthesis is highly complex and, despite its great
importance, remains unclear. To investigate how accumulation of Met influences metabolism as a whole in Arabidopsis, three methionine over-accumulation (mto) mutants were examined using a gas chromatography–mass spectrometry-based metabolomics approach. Multivariate statistical
analyses of the three mto mutants (mto1, mto2, and mto3) revealed distinct metabolomic phenotypes. Orthogonal projection to latent structures–discriminant analysis highlighted discriminative
metabolites contributing to the separation of each mutant and the corresponding control samples. Though Met accumulation in
mto1 had no dramatic effect on other metabolic pathways except for the aspartate family, metabolite profiles of mto2 and mto3 indicated that several extensive pathways were affected in addition to over-accumulation of Met. The pronounced changes
in metabolic pathways in both mto2 and mto3 were associated with polyamines. The findings suggest that our metabolomics approach not only can reveal the impact of Met
over-accumulation on metabolism, but also may provide clues to identify crucial pathways for regulation of metabolism in plants. 相似文献