Nickel speciation in the xylem sap of the hyperaccumulator Alyssum serpyllifolium ssp. lusitanicum growing on serpentine soils of northeast Portugal

Nickel speciation was studied in the xylem sap of Alyssum serpyllifolium ssp. lusitanicum, a Ni-hyperaccumulator endemic to the serpentine soils of northeast Portugal. The xylem sap was collected from plants growing in its native habitat and characterized in terms of carboxylic and amino acids content. The speciation of nickel was studied in model and real solutions of xylem sap by voltammetric titrations using Square Wave Voltammetry (SWV). The results showed that Ni transport in the xylem sap occurs mainly as a free hydrated cation (about 70%) and complexed with carboxylic acids, mainly citric acid (18%). Altogether, oxalic acid, malic acid, malonic acid and aspartic acid complexed less than 13% of total Ni. A negligible amount bounded to the amino acids, like glutamic acid and glutamine (<1%). Histidine did not play a role in Ni translocation in the xylem sap of A. serpyllifolium under field conditions. Amino acids are one of the main forms of N transport in the xylem sap, and under field conditions, N is usually a limited nutrient. We hypothesize that the translocation of Ni in the xylem sap as a free ion or chelated with carboxylic acids is ‘cheaper’ in terms of N resources.     

Effects of cadmium on the behaviour of citric acid in isolated tomato xylem cell walls

Effects of cadmium on the sorption of citric acid In isolatedxylem cell walls were Investigated. 2.5 nM to 9.5 mM [1.5–¹⁴]crticacid solutions were perfused through columns of xylem cell wallmaterial, isolated from tomato plants (Lycoperslcon esculentumMill, cv. Tiny Tim). The anion exchange potential of the column was estimated byamino acid analysis as approximately 46 meq dm whereas the apparentanion exchange capacity (AEC) was estimated as 1.65±0.1810^–4(citric acId units). This low AEC was attributed toa ‘zipper’ effect, a mutual screening of fixed R^–and A⁺ charges. Pre-loading with ¹¹⁵Cd²⁺ did not affect citric acid sorption,indicating the absence of Cd-effects on the availability offixed A⁺ charges, and the absence of the formation of effectiveR^–-Cd²⁺ and Donnan tree space (DFS) (Cd(cit)H₂]⁺ complexes. Simultaneous application of both citric acid and ¹¹⁵Cd²⁺,⁴⁵Ca²⁺or ²⁸Mg²⁺ resufted in increased sorption of citric acid, probablydue to capacity improvement rather than changes in valence-dependentanion sorption; this may be due to the presence of bulk (M(cit)H₂]⁺,held in the column as [M(cit)H₂]⁺ after protonation in the DFS.Sorption of citric acid was greatest in the presence of Ca²⁺which was discussed in the light of the differences betweenCa, Cd and Mg in their characteristics as co-ordinative M-complexes of citric acid. The overall results indicate the potentialimportance of the presence of metal ions for the xylem transportbehaviour of organic acids in plants. Key words: Cadmium, citric acid, ion exchange, ligand exchange, tomato, xylem cell walls     

Detection and quantification of ligands involved in nickel detoxification in a herbaceous Ni hyperaccumulator Stackhousia tryonii Bailey

Field-collected, young plants of Ni hyperaccumulator Stackhousia tryonii, grown in a glasshouse for 20 weeks, were exposed to low- (available Ni concentration in the native serpentine soil, i.e. 60 microg g(-1) dry soil) and high- (external application of 1000 ppm) Ni concentrations in the substrate. Nickel concentration in the freeze-dried leaf tissues increased from 3700 microg g(-1) to 13 700 microg g(-1) with soil Ni supplementation, of which >60% was extracted with dilute acid (0.025 M HCl). Nickel supplementation also elicited a 575%, 211%, and 37% increase in the final concentrations of oxalic, citric, and malic acids, respectively, in leaf tissues. Malic acid was the dominant organic acid, followed by citric and oxalic acids. The molar ratio of Ni to malic acid was 1.0, consistent with a role for malate as a ligand for Ni in hyperaccumulating plants, supporting detoxification/transport and storage of this heavy metal in S. tryonii. The total amino acid concentrations in the xylem sap did not change with Ni supplementation (21.7+/-3.7 mM and 17.9+/-5 mM, respectively, for low- and high-nickel-treated plants). Glutamine was the major amino acid in both the low- and high-Ni-treated plants. The concentration of glutamine decreased by >60%, with a corresponding increase in alanine, aspartic acid, and glutamic acid, on exposure to high Ni. A role of amino acids in Ni complexation and transport in S. tryonii is not immediately apparent.     

Analysis of major tomato xylem organic acids and PITC-derivatives of amino acids by RP-HPLC and UV detection

Major amino acids and organic acids in xylem exudates of tomato plants were separated by reversed phase high performance liquid chromatography (RP-HPLC) and quantified by UV detection. Before separation, amino acids were converted into their phenylisothiocyanate (PITC) derivatives. In a single run, Asp, Glu, Ser, Gln, His, Thr, Ala, Tyr, Val, Met, Cys, Ile, Leu, Phe, and Lys could be separated and detected down to the pmol level. Unresolved peaks were obtained for Asn and Gly and for Arg and Pro. For organic acid analysis, exudates were pre-treated by perfusion over a prepacked Adsorbex SCX cation exchange column, to eliminate exudate amino acids. Elution recoveries for organic acids were close to 100%. The exudate organic acids were separated by ion suppression RP-HPLC chromatography, and peaks could be resolved for L-malic acid, malonic acid, maleic acid, citric acid and fumaric acid, down to the pmol level. UV signals for exudate ascorbic acid, and succinic acid were below the limits of detection. Determination of oxalic acid and tartaric acid was impossible, due to the presence of the exudate salt peak in the chromatogram. The results indicate the potential of the methods applied, and show the applicability of RP-HPLC analysis for the determination of both amino acids and organic acids in xylem exudates.     

Roles of Organic Acids and Nitrate in the Long-Distance Transport of Cobalt in Xylem Saps of <Emphasis Type="Italic">Alyssum murale</Emphasis> and <Emphasis Type="Italic">Trifolium subterraneum</Emphasis>

Roles of organic acids and nitrate in the long-distance transport of cobalt (Co) in xylem saps of hyperaccumulator Alyssum murale and non-hyperaccumulator Trifolium subterraneum were studied under hydroponic conditions. Organic acids (oxalic, malic, malonic, citric, and fumaric) and nitrate in xylem sap samples were separated and determined simultaneously by reversed-phase high performance liquid chromatography after solid-phase extraction with nanosized hydroxyapatite. Results indicated that Co treatment significantly increased the concentrations of xylem oxalic and malic acids for the hyperaccumulator A. murale compared to the control but significantly decreased the concentrations of xylem nitrate and malonic acid; concentrations of citric acid in xylem sap samples did not show significant difference between the control and Co treatments. By analyzing the relationship between the concentrations of organic acids, nitrate, and concentrations of Co in xylem saps, it could be concluded that oxalic and malic acids in xylem saps seemed to participate in the long-distance Co translocation process, and citric acid did not relate to the xylem Co transport of A. murale and T. subterraneum. Our work might be very useful for understanding the mechanism of long-distance transport of heavy metals in hyperaccumulator.     

Metal speciation in xylem and phloem exudates

Summary Two computer programs based on simultaneous chemical equilibria were compared for calculation of chemical species in xylem exudates. The first program, CHELATE, was developed to calculate the chemical species in xylem exudates while GEOCHEM was developed to calculate the speciation of natural aquatic systems. The output of the two programs should be similar since they are based on similar calculations. Data input to the programs consisted of concentration data for Ca, Cu, Fe, Mg, Mn, Zn, NH₄, PO₄, pH and 28 organic ligands reported for xylem exudates from soybean (Glycine max (L.) Merr.) and tomato (Lycopersicon esculentum Mill.) plants grown in nutrient solution¹⁷. The organic ligands included amino acids and low molecular weight organic acids (e.g., citric and malic). With the exception of Fe, there were large differences between CHELATE and GEOCHEM in the calculated speciation of nearly all metals in the xylem exudates. In general, there was better agreement between the programs for the speciation of alkaline earth metals than for transition metals. Discrepancies between the two programs were attributed to differences in 1) species considered and 2) stability constants. GEOCHEM considered a greater number of possible complexes. In addition, stability constants for some complexes differed by as much as 10 fold between the two programs. When the data base for GEOCHEM and CHELATE were the same, the output from CHELATE and GEOCHEM was almost identical. Thus, computations performed by the two programs are equally valid, but it is essential that the data base used in chemical models be verified before interpreting the output. Average concentration data for Al, Au, Ca, Cu, Fe, K, La, Mg, Mn, Na, Rb, Zn, Cl, MoO₄, PO₄, SO₄, HVO₄, pH and 18 organic ligands in phloem exudates from Yucca (Yucca flaccida Haw.) were complied from available literature and analyzed by GEOCHEM. Amino acids were the predominant organic ligand analyzed. Calculations revealed that alkali metals existed almost totally as the free ionic species (≥99%) whereas alkaline earth metals were transported as complexes with organic acids (oxalic, malic, and asparagine). Aluminum and Fe were present as hydroxyl species while <1% of micronutrients were transported as the free ion. Major micronutrient species were Cu-glutamine, Mn-asparagine and Zn-alanine. Information on calculated species present in phloem exudates could be useful to guide studies for isolation of metal-ligand complexes in phloem exudates.     

Accumulation and transport of nickel in relation to organic acids in ryegrass and maize grown with different nickel levels

Difference in Ni tolerance/accumulation in plant genotypes might be used to identify or develop plants for remediation of high Ni soils. Ryegrass was shown to be more sensitive to Ni toxicity and accumulated much more Ni in shoots than maize. The objectives of this study were to examine the relationship of organic acids to Ni accumulation and xylem transport of Ni in ryegrass (Lolium perenne L.) and maize (Zea mays L.). The results showed that accumulation of Ni in shoots was 5 to 7 fold higher in ryegrass than in maize grown at 20 to 80 µM Ni, whereas Ni concentration in ryegrass roots was only 1 to 2 fold higher at 0.1 to 40 µM Ni and 1.5-fold lower at 80 µM Ni than that of maize roots. Xylem transport rates of Ni increased with increasing Ni supply for both species, and were about 2 to 7 times higher in ryegrass than in maize. Shoot concentrations of citric, malic, oxalic and cis-aconitic acids increased at Ni levels above 20 µM, and were about 2 to 6 times higher in ryegrass than in maize. Whereas, maize roots accumulated greater amount of malic, oxalic, and cis-aconitic acids than ryegrass roots, especially at Ni levels of 40-80 µM. The rate of Ni exudation by roots in the two species was significantly correlated with root Ni concentrations. It could be concluded that high Ni accumulation in shoots was closely related to high xylem transport rates of Ni and that the accumulation of organic acids, citric and malic acid in particular. A high root exudate rate of Ni and the enhanced accumulation of organic acids, malic acid in particular, in roots might be among the important factors which are associated with the tolerance of crops to toxic Ni levels.     

Calcium complexes in the xylem sap of apple shoots

Summary Concentrations of total calcium, ionic calcium, citric and malic acids have been measured in xylem sap extracted from apple shoots. Ionic calcium, as measured by an ion selective electrode, was about 50 per cent of the total calcium. The remainder of the soluble calcium was present as complexes with citric and malic acids. The implication of these findings on the mobility of calcium in the xylem is discussed.     

Nitrogen transport in the xylem sap of Quercus ilex: the role of ornithine

The storage and remobilization of nitrogen in deciduous and evergreen species is a major source of N, supporting the seasonal growth of trees. In evergreens, in addition to wood and roots, older leaves are important reservoirs of N used in the growth of new foliage. Just before bud burst, when transpiration is inactive or low, and when uptake of nitrogen by the roots may be restricted due to low temperatures, levels of organic N in the xylem are high. Amino acids usually comprise the bulk of this organic N. Changes in amino acid concentrations in early spring are thought to result mainly from hydrolysis of N reserves, and not from current N uptake. The seasonal profiles of amino acids in the xylem sap of Quercus ilex, an evergreen Mediterranean tree, were investigated. The first amino acid detected in the xylem sap before spring was ornithine, which may result from the breakdown of arginine present in storage proteins. Arginine is one of the main amino acids present in storage proteins because each arginine molecule has four nitrogen atoms. When protein degradation increases the free arginine pool, the arginase activity is enhanced and, consequently, the conversion of arginine to ornithine. It seems that ornithine has an important role in N transport early in the growth season of Q. ilex.     

Cadmium — citric acid — xylem cell wall interactions in tomato plants

Abstract. Mutual interactions between cadmium ions, citric acid and xylem cell walls were examined. Cadmium and citric acid were measured as ¹¹⁵Cd and [1,5-¹⁴C] citric acid, respectively. Xylem cell walls were obtained by bacterial degradation of tomato stem sections (Lycopersicon esculentum Mill, cv. Tiny Tim), and applied as ion-exchange columns. The xylem column material carried 2·4 dm³ H₂O kg^?1 dry weight, and was temporarily capable of buffering perfusates at pH 5·7. Sorbed cadmium and citric acid were determined from H₂O and HCl rinses after perfusion periods. In all experiments, total cadmium and/or citric acid recoveries were better than 98%, indicating both the effectiveness of the rinses applied and the possibility of full regeneration of the xylem column. The results indicate that the presence of 2·45 mol m^?3 citric acid causes an approximately 50% reduction of adsorbed cadmium levels, irrespective of the applied total cadmium concentrations (0·04–0·4 mol m^?3 Cd(NO₃)₂.4H₂O). This reduction is probably related to a corresponding reduction to approximately 2% of the control applied free Cd²⁺ concentration, the latter also independent of the total cadmium concentrations. Furthermore, without inducing positively charged citrate complexes in the applied solution, the presence of cadmium resulted in increased levels of citric acid absorbed in the xylem column. The Donnan Free Space accumulation of citric acid in the presence of Cd(NO₃)₂.4H₂O, observed in the experiments described, could be expressed by its distribution coefficient, as approximately 15 times the control accumulation. These data indicate that the xylem column may operate as a ligand exchanger, suggesting the importance of metal ions for the longitudinal and lateral movement of organic complexing compounds in the xylem.     

The role of free histidine in xylem loading of nickel in Alyssum lesbiacum and Brassica juncea

Exposure of the hyperaccumulator Alyssum lesbiacum to nickel (Ni) is known to result in a dose-dependent increase in xylem sap concentrations of Ni and the chelator free histidine (His). Addition of equimolar concentrations of exogenous L-His to an Ni-amended hydroponic rooting medium enhances Ni flux into the xylem in the nonaccumulator Alyssum montanum, and, as reported here, in Brassica juncea L. cv Vitasso. In B. juncea, reducing the entry of L-His into the root by supplying D-His instead of L-His, or L-His in the presence of a 10-fold excess of L-alanine, did not affect root Ni uptake, but reduced Ni release into the xylem. Compared with B. juncea, root His concentrations were constitutively about 4.4-fold higher in A. lesbiacum, and did not increase within 9 h of exposure to Ni. Cycloheximide did not affect root His or Ni concentrations, but strongly decreased the release of His and Ni from the root into the xylem of A. lesbiacum, whereas xylem sap concentrations of Ca and Mg remained unaffected. Near-quantitative chelation of Ni with nitrilotriacetate in the rooting medium did not enhance Ni flux into the xylem of A. lesbiacum and B. juncea, suggesting the absence of a significant apoplastic pathway for Ni entry into the xylem. The data suggest that in B. juncea roots, Ni(2+) uptake is independent of simultaneous uptake of His. In both species, enhanced release of Ni into the xylem is associated with concurrent release of His from an increased root free His pool.     

Mechanism of water stress-induced xylem embolism

We investigated the hypothesis that water stress-induced xylem embolism is caused by air aspirated into functional vessels from neighboring embolized ones (e.g. embolized by physical damage) via pores in intervessel pit membranes. The following experiments with sugar maple (Acer saccharum Marsh.) support the hypothesis. (a) Most vessels in dehydrating stem segments embolized at xylem pressures < −3 megapascals; at this point the pressure difference across intervessel pits between air-filled vessels at the segment's ends and internal water-filled vessels was >3 megapascals. This same pressure difference was found to be sufficient to force air across intervessel pits from air injection experiments of hydrated stem segments. This suggests air entry at pits is causing embolism in dehydrating stems. (b) Treatments that increased the permeability of intervessel pits to air injection also caused xylem to embolize at less negative xylem pressures. Permeability was increased either by perfusing stems with solutions of surface tension below that of water or by perfusion with a solution of oxalic acid and calcium. The mechanism of oxalic-calcium action on permeability is unknown, but may relate to the ability of oxalate to chelate calcium from the pectate fraction of the pit membrane. (c) Diameter of pores in pit membranes measured with the scanning electron microscope were within the range predicted by hypothesis (≤0.4 micrometer).     

Features of protein adsorption by silicopolymethylsiloxanes

The adsorption of tripsin and albumin on silicapolymetylsilocsan (SG-PMS) and its modified forms by cooper (II)--(SG-PMS (Cu)--from water-salt solutions were studied. It was determined difference in peculiarities of proteins sorption depending on its amino acids composition, chemistry of sorbent surface and acidity of medium. It was showed, that modified by cooper (II) sorbent have high affinity to tripsin than albumin in studied solutions. Influence of bearer modification degree on albumin immobilisation and interaction character of SG-PMS (Cu) active centres with function groups of enzyme and albumin have been showed.     

A method for measuring hydraulic conductivity and embolism in xylem

Abstract Hydraulic conductivity of the xylem is computed as the quotient of mass flow rate and pressure gradient. Measurements on excised plant stems can be difficult to interpret because of time-dependent reductions in flow rate, and because of variable degrees of embolism. Using Acer saccharum Marsh. stems, we found that certain perfusing solutions including dilute fixatives (e.g. 0.05% formaldehyde) and acids with pH below 3 (e.g. 10 mol m^?3 oxalic) prevent long-term decline in conductivity. Xylem embolism can be quantified by expressing the initial conductivity as a percentage of the maximum obtained after flow-impeding air emboli have been removed by repeated high-pressure (175 kPa) flushes. Correlation between microbial contamination and declining conductivity suggests that long-term (> 4h) declines are caused by microbial growth within the vessels. Unpredictable trends in short-term (< 4h) measurements may be caused by movements of air emboli in vessels and/or participate matter.     

Chemical forms of aluminum in xylem sap of tea plants (Camellia sinensis L.)

To identify the chemical forms of aluminum (Al) transported from roots to shoots of tea plants (C. sinensis L.), ²⁷Al-nuclear magnetic resonance and ¹⁹F NMR spectroscopy were used to analyze xylem sap.The concentration of Al in collected xylem sap was 0.29 mM, twice as high as that of F. Catechins were not detected in xylem sap. The concentration of malic acid in xylem sap was higher than that of citric acid, whereas the concentration of oxalic acid was negligible.There were two signals in the ²⁷Al NMR spectra of xylem sap, a larger signal at 11 ppm and a smaller one at −1.5 ppm. The former signal was consistent with the peak for an Al-citrate model solution, suggesting that an Al-citrate complex was present in xylem sap. Although the latter signal at −1.5 ppm was thought to indicate the presence of an Al-F complex (at 1.7 ppm) in xylem sap, there was only one signal at −122 ppm in the ¹⁹F NMR spectrum of xylem sap, indicating that the main F complex in xylem sap was F⁻.These results indicate that Al might be translocated as a complex with citrate, while Al-malate, Al-oxalate and Al-F complexes are not major Al complexes in xylem sap of tea plants.     

Diurnal and temporal changes in the chemical profile of xylem exudate from Vitis rotundifolia

Positive root pressure in Vitis rotundifolia Michx. cv. Noble was employed to quantify diurnal and temporal changes in the chemical profile of xylem exudate. Xylem fluid osmolarity (7.2 to 16.8 m M ), water flux (8.2 to 18.5 ml h⁻¹) and solute flux (0.7 to 2.2 mmol h⁻¹) from a cut spur exhibited a diurnal pattern with maxima during midday and minima at night. Total osmolarity was similar to the sum of all organic and inorganic entitites quantified, indicating that the major solutes have been identified. Total amino acid and organic acid concentration were about equal (2 to 7 m M ), and sugars accounted for a minor fraction of the total profile (<0.2 m M ). Glutamine represented ca 80% of the organic N and 70% of the total N transported in the xylem fluid. A circadian rhythm in water flux and net flux of most organic and inorganic entities was observed with maxima during midday and minima at night. The increase in xylem fluid osmolarity occurring during midday was primarily a consequence of increased organic acid (oxalic, citric, tartaric, malic and succinic acids) and ion (NH₄⁺, No₃⁻, P and Ca) concentration. A diurnal cycle in amino acid concentration was less clear. The concentration of individual organic and inorganic entities varied asynchronously with time. Xylem solute was comprised of 80% organic and 20% inorganic components when collected 5 min to 2 h after the commencement of bleeding, but the ratio of organic to inorganic components fell to about 50% after 7 days.     

Effects of Low-Molecular-Weight Organic Acids on Gadolinium Accumulation and Transportation in Tomato Plants

Effects of low-molecular-weight organic acids on the accumulation and transportation of gadolinium (Gd) in tomato plants were studied under hydroponic condition. The results indicated that changes of organic acids occurred in the processes of Gd accumulation and transportation in tomato plants which were treated with extraneous Gd solutions. Malic, citric, and succinic acids contributed to both Gd accumulation in roots and transportation in xylem vessels. When Gd was unloaded from the xylem to the leaf cells, formic, lactic, citric, and succinic acids played important roles in Gd accumulation in leaves. When tomato plants were cultured in the uptake solution of Gd-containing malic, citric, or succinic acid for 48 h, the succinic acid in roots and leaves and the malic acid in xylem saps both increased obviously. From the results above, we can conclude that succinic acid had the most important role in Gd accumulation in tomato roots and leaves, while malic acid transported Gd via xylem vessels more effectively.     

Effects of mono-, di- and tri-hydroxybenzoic acids on the nitrosation of propranolol: structure-activity relationship

Nitrosation of propranolol under standard conditions recommended by the World Health Organization (10mM propranolol hydrochloridre, 40mM sodium nitrite, pH 3.5) was performed in the absence and in the presence of benzoic acid and of twelve mono-, di- and tri-hydroxybenzoic acids, added to the nitrosation mixture in concentrations ranging from 2 to 40mM, in order to examine their effect on the nitrosation reaction. The yield of N-nitrosopropranol (NOP) was reduced by benzoic acid and, with potency decreasing in the following order, by 2,3,4-tri-hydroxybenzoic acid>/=3,4-tri-hydroxybenzoic acid>2,5-di-hydroxybenzoic acid>2,3-di-hydroxybenzoic acid>3-hydroxybenzoic acid>2-hydroxybenzoic acid>3,4,5-tri-hydroxybenzoic acid>4-hydroxybenzoic acid; their inhibiting effect was concentration-dependent. In contrast, 2,4-di-hydroxybenzoic acid, 2,6-di-hydroxybenzoic acid and 2,4,6-tri-hydroxybenzoic acid caused an increase in the yield of NOP that was inversely related to their concentration. 3,5-Di-hydroxybenzoic acid was substantially inactive. These findings indicate that, depending on the positions of carboxyl group and hydroxyl groups on the benzene ring, mono-, di- and tri-hydroxybenzoic acids may inhibit or hasten nitrosation reactions. As compared with benzenediols and benzenetriols [Mutat. Res. 398 (1998) 75], hydroxybenzoic acids inhibit the nitrosation of propranolol to a greater extent and have the advantage of being nonmutagenic and less toxic.     

红壤中镉在有机酸作用下的解吸行为

采用平衡批处理法,研究了3种有机酸及其两两混合液在序列pH值梯度下（pH 3.0～7.0）对华南山地红壤Cd解吸行为的影响.结果表明,草酸与苹果酸不利于Cd的解吸,反而促进了吸附,其中草酸只是在较高浓度(20 mmol·L^-1)且土壤溶液pH＞5.0时促进解吸.随着pH值升高,草s酸、苹果酸以及不含有机酸的对照溶液对红壤中Cd的解吸率都快速下降.柠檬酸在pH＜5.0时不利于Cd解吸;在pH＞5.0时显著促进Cd解吸,但两种浓度柠檬酸解吸特征有所不同,在低浓度(2 mmol·L^-1)下对镉的解吸率呈降低-升高-降低变化,在高浓度(20 mmol·L^-1)下呈降低-升高变化.在低pH条件下（pH 3.0、4.0）,苹果酸最有利于Cd的解吸,但3种酸对Cd解吸率差别不大,在较高pH条件下(pH 5.0～7.0),柠檬酸最有利于解吸,且解吸率大大高于草酸与苹果酸.有机酸混合没有明显的交互作用,对Cd的解吸率介于相应单独有机酸之间.     

End products of glucose and glutamine metabolism by L929 cells

Products of glucose and glutamine metabolism by L929 cells were detected and quantitated by gas chromatography and mass spectrometry of the oxime-trimethylsilyl derivatives. This method allowed detection and identification of all major carboxylic and amino acids produced in the system. Although lactic acid was expected to be the major product, alanine, citric, glutamic, aspartic, and pyruvic acids were also released into the culture medium at significant rates. Incorporation of labeled carbon from D-[U-13C]glucose showed that the alanine, lactic, and pyruvic acids were derived from glucose as was one-third of the citric acid carbon. The rate of glucose utilization for production of these end products was 29-fold greater than the rate of glucose oxidation to CO2, and calculated ATP production from alanine and pyruvate synthesis exceeded that from lactate synthesis by nearly 2-fold. Utilization of glutamine for synthesis of aspartic, glutamic, and citric acids also exceeded the rate of glutamine oxidation, thereby making end-product synthesis from glucose and glutamine the dominant cellular metabolic activity. In the absence of glucose, synthesis and intracellular levels of aspartic and glutamic acids increased, whereas synthesis and cell content of the other acids decreased markedly. This response is consistent with the metabolic pattern proposed by Moreadith and Lehninger (Moreadith, R.W., and Lehninger, A.L. (1984) J. Biol. Chem. 259, 6215-6221) in which much of the glutamine used by these cells is converted to aspartate in the absence of a pyruvate source and to aspartate or citrate in the presence of pyruvate.