Chemotaxis toward amino acids in Escherichia coli

Escherichia coli cells are shown to be attracted to the l-amino acids alanine, asparagine, aspartate, cysteine, glutamate, glycine, methionine, serine, and threonine, but not to arginine, cystine, glutamine, histidine, isoleucine, leucine, lysine, phenylalanine, tryptophan, tyrosine, or valine. Bacteria grown in a proline-containing medium were, in addition, attracted to proline. Chemotaxis toward amino acids is shown to be mediated by at least two detection systems, the aspartate and serine chemoreceptors. The aspartate chemoreceptor was nonfunctional in the aspartate taxis mutant, which showed virtually no chemotaxis toward aspartate, glutamate, or methionine, and reduced taxis toward alanine, asparagine, cysteine, glycine, and serine. The serine chemoreceptor was nonfunctional in the serine taxis mutant, which was defective in taxis toward alanine, asparagine, cysteine, glycine, and serine, and which showed no chemotaxis toward threonine. Additional data concerning the specificities of the amino acid chemoreceptors with regard to amino acid analogues are also presented. Finally, two essentially nonoxidizable amino acid analogues, alpha-aminoisobutyrate and alpha-methylaspartate, are shown to be attractants for E. coli, demonstrating that extensive metabolism of attractants is not required for amino acid taxis.     

Release of Endogenous Amino Acids from the Striatum from Developing and Adult Mice in Ischemia

In most other studies the release of amino acid neurotransmitters and modulators in vitro has been studied mostly using labeled preloaded compounds. For several reasons the estimated release may not reliably reflect the release of endogenous compounds. The magnitudes of the release cannot thus be quite correctly estimated using radioactive labels. The basal and K⁺-evoked release of the neuroactive endogenous amino acids γ-aminobutyrate (GABA), glycine, taurine, glutamate and aspartate was now studied in slices from the striatum from 7-day-old to 3-month-old mice under control (normoxic) and ischemic conditions. The release of alanine, threonine and serine was assessed as control. GABA and glutamate release was much greater in 3-month-old than in 7-day-old mice, whereas with taurine the situation was the opposite. Ischemia markedly enhanced the release of all these three amino acids. The release of aspartate and glycine was markedly enhanced as well whereas no effects were discernible in the release of glutamine, alanine, serine and threonine. K⁺ stimulation (50 mM) enhanced the release of GABA, glutamate, taurine, aspartate and glycine in most cases, except with taurine in 3-month-old mice under the ischemic conditions and with aspartate in 7-day-old mice under the control conditions. K⁺ stimulation did not affect the release of glutamine, alanine, serine or threonine. The results on endogenous amino acids are qualitatively similar to those obtained in our earlier experiments with labeled preloaded amino acids. In conclusion, in developing mice only inhibitory taurine is released in such amounts that may counteract the harmful effects of excitatory amino acids in ischemia.     

Interstitial Concentrations of Amino Acids in the Rat Striatum During Global Forebrain Ischemia and Potassium-Evoked Spreading Depression

The early detection and appropriate treatment of brain ischemia is of paramount importance. The interstitial concentrations of neurotransmitter amino acids are often used as an index of neuronal injury. However, monitoring of non-neurotransmitter amino acids may be equally important. We have studied the behavior of 10 amino acids during K⁺-induced spreading depression (application of 70 mM KCl during 40 min) and global forebrain ischemia (two-vessel occlusion with hypotension during 20 min). The concentrations of glutamate, aspartate, taurine, GABA, glycine, and alanine, measured in the rat striatum by microdialysis, increased during both ischemia and spreading depression, whereas glutamine concentrations decreased in both cases. Only ischemia, but not spreading depression, led to enhanced release of serine, threonine, and asparagine. We thus conclude that an elevation in the interstitial concentrations of non-neurotransmitter amino acids is specific to deep ischemic injury to nervous tissue. We propose the monitoring of serine, asparagine, and threonine, together with excitatory amino acids, as an index of the degree of ischemic brain injury.     

THE INFLUENCE OF SODIUM, POTASSIUM AND LANTHANUM ON AMINO ACID RELEASE FROM SPINAL–MEDULLARY SYNAPTOSOMES

Abstract— The effects of electrical pulses and raised potassium on glycolysis and the release of the putative transmitter amino acids glutamate, aspartate, glycine and GABA from spinal medullary synaptosomes is studied and compared with effects on glutamine, alanine and serine. The actions of ouabain, p -hydroxymercuribenzoate ( p -HMB), lanthanum chloride and lowered sodium levels on the release of all the amino acids is examined. All agents caused a change in the pattern of release of the amino acids, mostly, producing an increase, but only lanthanum, p -HMB and lowered sodium prevented the stimulus-induced release.     

Nitrogen metabolism in tumor bearing mice

In experiments with whole animals infested with a highly malignant strain of Ehrlich ascites tumor cells, serial concentrations of amino acids were determined for host plasma, ascitic fluid, and tumor cells, throughout tumor development. Concentration gradients of glutamine, asparagine, valine, leucine, isoleucine, phenylalanine, tyrosine, histidine, tryptophan, arginine, serine, methionine, and taurine from the host plasma toward the ascitic liquid were established; while on the other hand, concentration gradients from the ascitic liquid toward the plasma were established for glutamate, aspartate, glycine, alanine, proline, and threonine. With the exception of aspartate the concentrations of these amino acids were highest inside the cells. Arginine was the only amino acid not detected in tumor cells. In vitro incubations of tumor cells in the presence of glutamine and/or glucose, as the energy and nitrogen sources, confirmed the amino acid fluxes previously deduced from the observed relative concentrations of amino acids in plasma, ascitic liquid, and tumor cells, suggesting that glutamate, alanine, aspartate, glycine, and serine can be produced by tumors. These findings support that changes in amino acid patterns occurring in the host system are related to tumor development.     

Effect of Impact Trauma on Neurotransmitter and Nonneurotransmitter Amino Acids in Rat Spinal Cord

N-Methyl-D-aspartate (NMDA) administration exacerbates neurological dysfunction after traumatic spinal cord injury in rats, whereas NMDA antagonists improve outcome in this model. These observations suggest that release of excitatory amino acids contributes to secondary tissue damage after traumatic spinal cord injury. To further examine this hypothesis, concentrations of free amino acids were measured in spinal cord samples from anesthetized rats subjected to various degrees of impact trauma to the T9 spinal segment. Levels of excitatory and inhibitory neurotransmitter amino acids [gamma-aminobutyric acid (GABA), glutamate, aspartate, glycine, taurine] and levels of nonneurotransmitter amino acids (asparagine, glutamine, alanine, threonine, serine) were determined at 5 min, 4 h, and 24 h posttrauma. Uninjured surgical (laminectomy) control animals showed modest but significant declines in aspartate and glutamate levels, but not in other amino acids, at all time points. In injured animals, the excitatory amino acids glutamate and aspartate were significantly decreased by 5 min posttrauma, and remained depressed at 4 h and 24 h as compared with corresponding laminectomy controls. In contrast, the inhibitory amino acids, glycine, GABA, and taurine, were decreased at 5 min postinjury, had partially recovered at 4 h, and were almost fully recovered at 24 h. The nonneurotransmitter amino acids were unchanged at 5 min posttrauma and significantly increased at 4 h, with partial recovery at 24 h. At 4 h postinjury, severe trauma caused significantly greater decreases in aspartate and glutamate than did either mild or moderate injury. These findings are consistent with the postulated role of excitatory amino acids in CNS trauma.     

Effect of natural amino acids on ethanol oxidation in isolated rat hepatocytes]

The effects of the various naturally occurring amino acids on ethanol oxidation in hepatocytes from starved rats was systematically studied. In order to minimize the non ADH pathways, the ethanol concentration used was 4 mmol/litre, the amino acids being added at the same concentration. In hepatocytes from fasted rats, alanine, arginine, asparagine, aspartate, citrulline, cysteine, glutamate, glutamine, glycine, histidine, hydroxyproline, ornithine and serine increase significantly ethanol consumption. The stimulatory effect of glutamine being much less pronounced than the asparagine one and proline being devoid of action, the influence of ammonium chloride addition on ethanol consumption in the presence of these amino acids was studied. Ammonium chloride determines an enhancement of ethanol oxidation in these conditions, the results showing no apparent correlation between intracellular glutamate concentration and ethanol oxidation rate, contrarily to previous data. In hepatocytes from fed rats, only alanine, asparagine, cysteine, glycine, hydroxyproline, ornithine and serine increase ethanol oxidation, although to a lesser extent than in cells from starved rats.     

The influence of peptides on the uptake of amino acids inFusobacterium; predicted interactions withPorphyromonas gingivalis

A study of the uptake of amino acids and its influence by a peptide source was carried out withFusobacterium varium as a convenient representative of the genus. Reference strains and a clinical isolate had similar amino acid uptake profiles, but most amino acids were incorporated at lower concentrations by the latter. In general, high levels of serine, asparagine, glutamate, cysteine, and arginine were incorporated by all species. Histidine, lysine, threonine, and aspartate were taken up at lower levels, whereas the nonpolar neutral amino acids such as alanine, valine, leucine, isoleucine, glycine, proline, phenylalanine, and methionine were poorly metabolized. Yeast extract, as a source of peptides, stimulated the uptake of several amino acids such as histidine and glutamate, whereas others such as methionine, threonine, and asparagine were repressed. The incorporation of some amino acids such as aspartate, ornithine, lysine, and arginine was unaffected by the presence of peptides. Equimolar nitrogen concentrations of amino acids or ammonia could not replace the peptide requirement, emphasizing the importance of peptides as an energy source. The limited capacity ofFusobacterium spp. to hydrolyze proteins increased approximately 30% in the presence of the proteolytic species,Porphyromonas gingivalis, and may represent one bacterial interaction in which peptides may become available toFusobacterium species in vivo.     

Changes in plasma amino acid concentrations with increasing age in patients with propionic acidemia

The objective of the study is to analyze plasma amino acid concentrations in propionic acidemia (PA) for the purpose of elucidating possible correlations between propionyl-CoA carboxylase deficiency and distinct amino acid behavior. Plasma concentrations of 19 amino acids were measured in 240 random samples from 11 patients (6 families) with enzymatically and/or genetically proven propionic acidemia (sampling period, January 2001–December 2007). They were compared with reference values from the literature and correlated with age using the Pearson correlation coefficient test. Decreased plasma concentrations were observed for glutamine, histidine, threonine, valine, isoleucine, leucine, phenylalanine and arginine. Levels of glycine, alanine and aspartate were elevated, while values of serine, asparagine, ornithine and glutamate were normal. For lysine, proline and methionine a clear association was not possible. Significant correlations with age were observed for 13 amino acids (positive correlation: asparagine, glutamine, proline, alanine, histidine, threonine, methionine, arginine; negative correlation: leucine, phenylalanine, ornithine, glutamate and aspartate). This study gives new insight over long-term changes in plasma amino acid concentrations and may provide options for future therapies (e.g., substitution of anaplerotic substances) in PA patients.     

凤眼莲根分泌物氨基酸组分对根际肠杆菌属F2细菌的趋化作用

凤眼莲(Eichhornia crassipes)的根分泌物中含有Met等多种氨基酸,其中Met、GABA、Gly、Ala、Asp、Ser、Val和Leu(10^-7～10^-2mol·L^-1)均对凤眼莲的根际肠杆菌属F₂(Enterobacter sp.F₂)细菌有强烈的正趋化作用;Glu、Thr和His(10^-7～10^-3mol·L^-1)也对该菌有一定的正趋化作用;而Lys、Cys、Arg、Tyr、Pro、Asn、Gln、Ile、Phe和Typ则对该菌表现出一定的负趋化作用.对细菌的正趋化作用存在一个趋化物的最适浓度范围.具有正趋化作用的氨基酸在凤眼莲根际的浓度都较高,而具有负趋化作用的浓度则较低,这正是凤眼莲与该根际细菌结合为根际微生态系统的原因之一.     

Effect of acetyl-l-carnitine on extracellular amino acid levels in vivo in rat brain regions

Acetyl-l-carnitine (ALCAR) was found to have beneficial effects in senile patients. In recent years many of its effects on the nervous system have been examined, but its mechanism(s) of action remains to be elucidated. We previously reported that it causes release of dopamine in the striatum. In the present paper we report that ALCAR, when administered at intracerebral sites via microdialysis, stimulates the release of amino acids in a concentration-dependent and regionally heterogeneous manner. The effect was strong in the striatum and cerebellum, less so in the frontal cortex, and weak in the thalamus. Seven amino acids were measured: the increase in the level of aspartate, glutamate, and taurine was substantial, and the increase in the level of glycine, serine, threonine, alanine, and glutamine in the microdialysate was minor. The stimulatory effect of ALCAR on the release of amino acids in the striatum was inhibited by the muscarinic antagonist atropine, but was not inhibited by the nicotinic antagonist mecamylamine. The effect of ALCAR on the levels of most of the amino acids tested was independent of the presence of Ca²⁺ in the perfused. These results indicate that ALCAR, when administered intracerebrally at fairly high concentrations, can affect the level and the release not only of such neurotransmitters as acetylcholine and dopamine, but also of amino acids. The mechanism of action of ALCAR on the release of cerebral amino acids may involve the participation of muscarinic receptors or may be mediated through the release of dopamine, but the lack of Ca²⁺ dependence indicates a release from the cytoplasmic amino acid pool, possibly through the effect of ALCAR on cell membrane permeability.     

Amino Acid Metabolism of Lemna minor L. : III. Responses to Aminooxyacetate

Aminooxyacetate, a known inhibitor of transaminase reactions and glycine decarboxylase, promotes rapid depletion of the free pools of serine and aspartate in nitrate grown Lemna minor L. This compound markedly inhibits the methionine sulfoximine-induced accumulation of free ammonium ions and greatly restricts the methionine sulfoximine-induced depletion of amino acids such as glutamate, alanine, and asparagine. These results suggest that glutamate, alanine, and asparagine are normally catabolized to ammonia by transaminase-dependent pathways rather than via dehydrogenase or amidohydrolase reactions. Aminooxyacetate does not inhibit the methionine sulfoximine-induced irreversible deactivation of glutamine synthetase in vivo, indicating that these effects cannot be simply ascribed to inhibition of methionine sulfoximine uptake by amino-oxyacetate. This transaminase inhibitor promotes extensive accumulation of several amino acids including valine, leucine, isoleucine, alanine, glycine, threonine, proline, phenylalanine, lysine, and tyrosine. Since the aminooxyacetate induced accumulations of valine, leucine, and isoleucine are not inhibited by the branched-chain amino acid biosynthesis inhibitor, chlorsulfuron, these amino acid accumulations most probably involve protein turnover. Depletions of soluble protein bound amino acids are shown to be approximately stoichiometric with the free amino acid pool accumulations induced by aminooxyacetate. Aminooxyacetate is demonstrated to inhibit the chlorsulfuron-induced accumulation of α-amino-n-butyrate in L. minor, supporting the notion that this amino acid is derived from transamination of 2-oxobutyrate.     

Biosynthesis of amino acids in Clostridium pasteurianum

1. Clostridium pasteurianum was grown on a synthetic medium with the following carbon sources: (a) (14)C-labelled glucose, alone or with unlabelled aspartate or glutamate, or (b) unlabelled glucose plus (14)C-labelled aspartate, glutamate, threonine, serine or glycine. The incorporation of (14)C into the amino acids of the cell protein was examined. 2. In both series of experiments carbon from exogenous glutamate was incorporated into proline and arginine; carbon from aspartate was incorporated into glutamate, proline, arginine, lysine, methionine, threonine, isoleucine, glycine and serine. Incorporations from the other exogenous amino acids indicated the metabolic sequence: aspartate --> threonine --> glycine right harpoon over left harpoon serine. 3. The following activities were demonstrated in cell-free extracts of the organism: (a) the formation of aspartate by carboxylation of phosphoenolpyruvate or pyruvate, followed by transamination; (b) the individual reactions of the tricarboxylic acid route to 2-oxoglutarate from oxaloacetate; glutamate dehydrogenase was not detected; (c) the conversion of aspartate into threonine via homoserine; (d) the conversion of threonine into glycine by a constitutive threonine aldolase; (e) serine transaminase, phosphoserine transaminase, glycerate dehydrogenase and phosphoglycerate dehydrogenase. This last activity was abnormally high. 4. The combined evidence indicates that in C. pasteurianum the biosynthetic role of aspartate and glutamate is generally similar to that in aerobic and facultatively aerobic organisms, but that glycine is synthesized from glucose via aspartate and threonine.     

Contribution of the Pericarp to the Amino Acids of the Seeds of Datura stramonium L.

Pericarps of Datura stramomum L. photosynthesizing in ¹⁴CO₂,have been shown to contribute amino acids (especially aspartate,threonine, serine, glutamate, glycine, alanine, phenylalanine,lysine, and histidine) to the protein-bound amino acids of theseed. This contribution is, however, a relatively minor onein comparison with the contribution made by photosyntheaizingleaves in the close proximity of the fruit.     

Amino Acid transport and metabolism in relation to the nitrogen economy of a legume leaf

Net balances of amino acids were constructed for stages of development of a leaf of white lupin (Lupinus albus L.) using data on the N economy of the leaf, its exchanges of amino acids through xylem and phloem, and net changes in its soluble and protein-bound amino acids. Asparagine, aspartate, and γ-aminobutyrate were delivered to the leaf in excess of amounts consumed in growth and/or phloem export. Glutamine was supplied in excess until full leaf expansion (20 days) but was later synthesized in large amounts in association with mobilization of N from the leaf. Net requirements for glutamate, threonine, serine, proline, glycine, alanine, valine, isoleucine, leucine, tyrosine, phenylalanine, histidine, lysine, and arginine were met mainly or entirely by synthesis within the leaf. Amides furnished the bulk of the N for amino acid synthesis, asparagine providing from 24 to 68%. In vitro activity of asparaginase (EC 3.5.1.1) exceeded that of asparagine:pyruvate aminotransferase (EC 2.6.1.14) during early leaf expansion, when in vivo estimates of asparagine metabolism were highest. Thereafter, aminotransferase activity greatly exceeded that of asparaginase. Rates of activity of one or both asparagine-utilizing enzymes exceeded estimated rates of asparagine catabolism throughout leaf development. In vitro activities of glutamine synthetase (EC 6.3.1.2) and glutamate synthase (EC 1.4.7.1) were consistently much higher than that of glutamate dehydrogenase (EC 1.4.1.3), and activities of the former two enzymes more than accounted for estimated rates of ammonia release in photorespiration and deamidation of asparagine.     

Conversion of [U-14C]threonine into 14C-labelled amino acids in the brain of thiamin-deficient rats.

In confirmation of the findings of Gaitonde et al. (1974), a decrease in the brain concentration of threonine and serine, and an increase in glycine, were observed in rats maintained on a thiamin-deficient diet. Similar changes were found in the blood, and the concentration of several other amino acids in the blood decreased significantly. There was a correlation between the concentrations of threonine, serine, aspartate and asparagine in the brain and blood. In experiments in which [U-14C]threonine was injected into rats most of the radioactivity in the brain and blood of control rats was, as expected, in threonine in the acid soluble metabolites. In contrast, a considerable proportion of radioactivity was also found in other amino acids, namely glutamate, glutamine, aspartate, gamma-aminobutyrate and alanine, in the brain of thiamin-deficient rats. [U-14C]Threonine was also converted into 14C-labelled lactate and glucose, but the extent of this conversion was severalfold higher in thiamin-deficient than in control rats. This finding gave evidence of the stimulation in thiamin-deficient rats of the catabolism of [U-14C]threonine to [14C]lactate by the aminoacetone pathway catalysed by threonine dehydrogenase, and into succinate via propionate by the alpha-oxobutyrate pathway catalysed by threonine dehydratase (deaminase). The measurement of specific radioactivities of glutamate, aspartate and glutamine after injection of [U-14C]threonine, indicated a stimulation of the activities of threonine dehydrogenase and threonine dehydratase (deaminase) in the brain of thiamin-deficient rats. The specific radioactivities of glutamate, asparatate and glutamine int he brain were consistent with an alteration in the metabolism of threonine, mainly in the 'large' compartment of the brain of thiamin-deficient rats. The measurement of relative specific radioactivity of proteins after injection of [U-14C]threonine indicated a marked decrease in the synthesis of proteins, mainly in the liver of thiamin-deficient rats.     

The effects of electrical stimulation and ionic alterations on the metabolism of amino acids and proteins in excised superior cervical ganglia of the rat

Abstract— The effects of supramaximal electrical stimulation on the metabolism of amino acids and proteins in incubated superior cervical ganglia of the rat were studied by the use of a gas-liquid chromatographic (GLC) assay procedure. Stimulation at 5 Hz for 2 h caused an apparent increase in tissue levels of free amino acids, with alanine, serine, glycine, valine, threonine, isoleucine and aspartate (+ asparagine) most noticeably affected. The amino acid composition (partial) of the TCA-insoluble proteins of resting and stimulated ganglia was approximately the same after 60 min of incubation, but there was less TCA-insoluble protein in the stimulated ganglia. The addition of amino acids (at plasma concentrations) to the standard media had no apparent affect on the amino acid composition of this protein fraction. Stimulation for 0 , 5 h initially increased the efflux of alanine, valine, proline and ornithine into the incubation media but prolonged stimulation (for 4–0 h) decreased the efflux of alanine, serine, glycine and isoleucine and increased the efflux of lysine into the incubation media. The leakage of amino acids from the ganglia appeared to be a sodium-dependent process. The incorporation of ¹⁴C from [U-¹⁴C]glucose into glutamate (+ glutamine) and aspartate (+ asparagine) was greater in stimulated than in resting ganglia. However, the conversion of glutamate carbons from [U-¹⁴C]l -glutamate into aspartate was not affected by stimulation. Incorporation of ¹⁴C from [U-¹⁴C]glucose into glycine and serine was apparently not affected by stimulation during the 60 min of incubation. However, serine was the only amino acid which exhibited a higher specific radioactivity in stimulated ganglia than in resting ganglia incubated for 4 h in standard media. Lithium ions had the apparent specific effect of increasing the labelling with ¹⁴C from [U-¹⁴C]glucose into ornithine, and increasing the efflux and overall metabolism of serine in the ganglia. Incorporation of ¹⁴C from [U-¹⁴C]glucose into proteins was lower in the stimulated than in the resting ganglia if compensation was made for the higher radioactivity available in the total free amino acid pool of the stimulated ganglia. The rate of ¹⁴C incorporation from [U-¹⁴C]glutamate into the TCA-insoluble proteins of resting ganglia was greater when no other amino acids at concentrations approximating plasma levels were added to the bathing media; this rate was lower in stimulated than in resting ganglia.     

Effects of Cyclohexanonic Long-Chain Fatty Alcohol, tCFA15 on Amino Acids in Diabetic Rat Brain: A Preliminary Study

The aim of this study was to evaluate the effects of streptozotocin-induced type 1diabetes and a subchronic treatment with cyclohexanonic long-chain fatty alcohol, 3-(15-hydroxypentadecyl)-2,4,4-trimethyl-2-cyclohexen 1-one (tCFA15) on contents of amino acids including aspartate, glutamate, glutamine, GABA, glycine, taurine, alanine, serine, threonine, and arginine in the prefrontal cortex, hippocampus and striatum. Levels of glutamate, threonine, taurine, alanine, arginine, and the ratio of glutamate/glutamine were altered region-differently in the brain of diabetic rats. However, tCFA15 region-specifically antagonized the changes in taurine and arginine levels and the ratio of glutamate/glutamine. The alteration in glutamate/glutamine ratio may indicate that experimental models of type 1 diabetes have abnormalities of neuron-gria interaction in brain.     

Amino acid concentrations in fluids from the bovine oviduct and uterus and in KSOM-based culture media.

Amino acids in bovine oviductal and uterine fluids were measured and compared with those in modified simplex optimized medium (KSOM) supplemented with either fetal calf serum or Minimum Essential Medium amino acids in addition to bovine serum albumin, fetal calf serum or polyvinyl alcohol. Concentrations of cysteine, threonine, tryptophan, alanine, aspartate, glycine, glutamate, proline, beta-alanine, and citrulline were higher in oviductal fluids than in KSOM-based culture media. Nonessential and essential amino acids were present in ratios of 5:1 and 2:1 in oviductal and uterine fluids, respectively. Concentrations of alanine (3.7 mM), glycine (14.1 mM) and glutamate (5.5 mM) were high in oviductal fluids, comprising 73% of the free amino acid pool. Of the amino acids measured in uterine fluids, alanine (3.1 mM), glycine (12.0 mM), glutamate (4.2 mM), and serine (2.7 mM) were highest in concentration, and the first three comprised 43% of the free amino acid pool. In conclusion, amino acid concentrations in the bovine reproductive tract were substantially higher than those in embryo culture media. Certain amino acids, particularly alanine, glutamate, glycine and taurine, are present in strikingly high concentrations in both oviductal and uterine fluids, suggesting that they might play important roles in early embryo development. The particular pattern of amino acid concentrations may be an important factor to be considered for the improvement of embryo culture media.     

Effect of the composition of branched chain amino acids, taurine, and tryptophan on the amino acid metabolism in experimental models of alcoholism

Ethanol withdrawal after forced alcoholization of rats according to Majchrowicz led to the development of amino acid imbalance in the pool of free amino acids in the liver (increasing levels of alanine, aspartate, glutamate, glutamine and histidine, decreasing levels of glycine, lysine, threonine and taurine) and blood plasma (increasing levels of tyrosine and alanine, decreasing levels of most glycogen aminoacids, branched-chain aminoacids and Lys). Less profound changes were observed after prolonged alcohol intoxication (decreasing levels of alanine, ornitine, citrulline and increasing level of Glu in liver, increasing levels of sulfur-containing compounds, Asp and Lys in blood plasma). Amino acid mixture which contained branched-chain amino acids, taurine and tryptophan administered intragastrically was found to correct levels of sulfur-containing amino acids, threonine, lysine and isoleucine after ethanol withdrawal and to eliminate disorders in urea cycle, exchange of threonine, glycine and phenylalanine after prolonged alcohol intoxication.