Low Concentrations Of Glycine Research Articles

High dosage of exogenous glycine in cross-feeding breaks the equilibrium of anammox system

Strategies to break the cross-feeding equilibrium by dosing essential metabolites and thus enriching and isolating anammox bacteria (AnAOB) have been proposed, but amino acids have not been investigated as important cross-feeding pathways in anammox consortia. In this study, long-term experiments were designed to verify the effect of exgenous glycine on anammox consortia and changes in the bacterial community and metabolic activity after the addition of glycine in a highly active anammox system were investigated. The results showed that the impact of glycine on the activity of anammox highly depended on glycine concentrations, which was manifested as a promotive effect at low concentrations (0–150 mg/L) and an inhibitory effect at high concentrations (300–600 mg/L). The addition of low concentrations of glycine not only enhanced the diversity and richness of bacterial communities but also promoted the enrichment of Candidatus Kuenenia. The qPCR results showed that the content of functional genes Hzs, NirS and anammox 16S rRNA increased while the expression of amoA and NrfA genes was suppressed when glycine acted positively on AnAOB; Hzs and amoA were suppressed when glycine acted negatively on AnAOB, while the expression of NirS and NrfA genes increased dramatically. Specific anammox activity (SAA) experimental results show that 50–150 mg/L glycine was the optimal amount for promoting the activity of AnAOB. Analysis of community metabolic functions indicated that the addition of exogenous glycine resulted in a imbalance of glycine cross-feeding and promoted AnAOB enrichment mainly by affecting pathways such as other glycan degradation and Lysosome. Overall, this study provided new insights into understanding the glycine cross-feeding, which is essential for improving anammox-based technologies.

Hyperglucagonaemia and amino acid alterations in individuals with type 2 diabetes and non-alcoholic fatty liver disease.

Hyperglucagonaemia contributes to the pathophysiology in type 2 diabetes (T2D), but the mechanisms behind the inappropriate glucagon secretion are not fully understood. Glucagon and amino acids are regulated in a feedback loop referred to as the liver-α cell axis. Individuals with non-alcoholic fatty liver disease (NAFLD) appear to be glucagon resistant, disrupting the liver-α cell axis resulting in hyperglucagonaemia and hyperaminoacidaemia. We investigated the associations between circulating glucagon, amino acids, and liver fat content in a cohort of individuals with T2D. We included 110 individuals with T2D in this cross-sectional study. Liver fat content was quantified using 1H magnetic resonance spectroscopy (MRS). Associations between liver fat content and plasma glucagon and amino acids, respectively, were estimated in multivariate linear regression analyses. Individuals with NAFLD (n = 52) had higher plasma glucagon concentrations than individuals without NAFLD (n = 58). The positive association between plasma glucagon concentrations and liver fat content was confirmed in the multivariable regression analyses. Plasma concentrations of isoleucine and glutamate were increased, and glycine and serine concentrations were decreased in individuals with NAFLD. Concentrations of other amino acids were similar between individuals with and without NAFLD, and no clear association was seen between liver fat content and amino acids in the regression analyses. MRS-diagnosed NAFLD in T2D is associated with hyperglucagonaemia and elevated plasma concentrations of isoleucine and glutamate and low plasma concentrations of glycine and serine. Whether NAFLD and glucagon resistance per se induce these changes remains to be elucidated.

GO/Ag2S/ZnO nanorods coatings for non-enzymatic photoelectrochemical glycine determination at trace levels

Photoelectrochemical (PEC) detection as the accurate sensor detection technology was applied to monitor the low concentration of glycine based on GO/Ag2S/ZnO nanorods coatings, which were fabricated on stainless steel. The maximum photocurrent of 116.8 μA cm−2 was obtained for the samples with the deposition time of 120 s, which was indicating that GO/Ag2S/ZnO samples with the deposition time of 120 s had excellent photochemical properties compared to other samples, including Ag2S/ZnO and ZnO samples. The PEC sensing of GO/Ag2S/ZnO nanorods coatings electrodes against glycine were tested by i-t. The results showed that the GO/Ag2S/ZnO nanorods coatings electrodes have high sensitivity of 5.44 μA−1 nM−1 cm−2, big linear range of 5 nM–99.775 μM and low detection limit of 3 nM. Hence the obtained results confirmed the possibility of the GO/Ag2S/ZnO nanorods coatings electrodes used as PEC sensors for low concentration glycine measurements. If the sensor can be applied to clinical detection, it can not only monitor the content of glycine in patients in real time, but also greatly reduce the risk of kidney stones caused by excessive glycine (Gly) in humans.

Illumination of a progressive allosteric mechanism mediating the glycine receptor activation

Pentameric ligand-gated ion channel mediate signal transduction at chemical synapses by transiting between resting and open states upon neurotransmitter binding. Here, we investigate the gating mechanism of the glycine receptor fluorescently labeled at the extracellular-transmembrane interface by voltage-clamp fluorometry (VCF). Fluorescence reports a glycine-elicited conformational change that precedes pore opening. Low concentrations of glycine, partial agonists or specific mixtures of glycine and strychnine trigger the full fluorescence signal while weakly activating the channel. Molecular dynamic simulations of a partial agonist bound-closed Cryo-EM structure show a highly dynamic nature: a marked structural flexibility at both the extracellular-transmembrane interface and the orthosteric site, generating docking properties that recapitulate VCF data. This work illuminates a progressive propagating transition towards channel opening, highlighting structural plasticity within the mechanism of action of allosteric effectors.

Mild phenotypes of phosphoglycerate dehydrogenase deficiency by a novel mutation of PHGDH gene: Case report and literature review.

Phosphoglycerate dehydrogenase (PHGDH) deficiency is a rare autosomal recessive genetic disease of serine biosynthesis. Its typical features are congenital microcephaly, epileptic seizures, and psychomotor developmental delay. Here, we reported the first Chinese familial cases with genetically confirmed PHGDH deficiency and reviewed several previous reports. Two siblings in this family presented with microcephaly, psychomotor retardation, and epilepsy in early juvenile. Brain magnetic resonance imaging (MRI) showed only a slight change of enlarged ventricle. Biochemical investigations revealed low serum serine and glycine concentrations. The whole-exome sequencing (WES) results identified a missense variant in the PHGDH gene (NM_006623.4: exon11: c.1211T>A, p. Val404Asp). Although two patients in this Chinese family carried the same pathogenic mutation in the PHGDH, their symptoms and responses to treatment were not exactly the same. We found a novel variant in the PHGDH gene and expanded the genotypic and phenotypic spectrum of serine biosynthesis disorders.

Mild Cognitive Impairment Is Associated With Markers of Muscle Weakness and Reduced Bone Density, and Specific Metabolic Alterations Despite Preserved Physical Activity

ObjectivesBone loss and frailty commonly occur in people with dementia residing in nursing homes and lead to increased risk of disabilities and poor health outcomes. Whether these systemic manifestations and related metabolic disturbances are present in older adults with Mild Cognitive impairment (MCI), who are still physically active, remains unclear. MethodsCommunity dwelling older adults without confounding comorbidities were divided, using the Montreal Cognitive Assessment (MoCA) score cut-off of 26, into two groups: non-MCI (n = 18; age: 67.3 [63.3, 71.2 y]) and MCI (n = 20; age: 71.3 [66.9, 75.7 y]). Body composition (by DXA), respiratory strength (by mouth pressure), and extremity strength (by dynamometer) were assessed. Stable isotope techniques were used to measure production and plasma concentrations of amino acids involved in muscle, bone, and brain health (tau-methylhistidine, hydroxyproline, glycine, tryptophan). Plasma enrichments were analyzed by LC-MS/MS. Statistics performed by ANCOVA with age, gender, and BMI as covariates. Significance set at P < 0.05. Results expressed as means [95% CI]. ResultsMCI participants (MoCA score: 22.5 [21.3, 23.6]) had lower respiratory muscle strength (p = 0.007) than the non-MCI group (MoCA score: 28.2 [27.5, 28.8]) but muscle mass and daily physical activity were not different. Bone density of the spine (p = 0.02) and hip (p = 0.07) were lowest in those with the lowest MoCA scores. The MCI group had lower concentrations of glycine (p = 0.0045), tryptophan corrected for large neutral amino acids (p = 0.0017), and productions of glycine (p = 0.0085), tau-methylhistidine (p = 0.05), and tryptophan (p = 0.06). MoCA score was negatively associated with plasma triglyceride (p = 0.02) and liver enzyme (AST) level (p = 0.01), but not with glucose or CRP levels. ConclusionsOlder adults with MCI are prone to low bone density and respiratory muscle weakness despite preserved physical activity. Whether these systemic manifestations are causally related to the observed metabolic alterations in MCI deserves further investigation. Funding SourcesNone

Prospects of foliar treatments with glycine solution to increase the productivity of dill

Relevance. Dill is a popular food and medicinal crop (Anethum graveolens L.) of the Celery family (Apiaceae). Seeds of dill are included in the 14th edition of the State Pharmacopoeia of the Russian Federation. However, this crop is characterized by a relatively low yield, which reduces the efficiency of its production. The use of environmentally friendly growth-regulating compounds can significantly increase the yield and improve its quality. As a growth-regulating, foliar treatment with a solution of the amino acid glycine was tested. The amino acid glycine is environmentally friendly and does not pose a danger to humans and animals. The aim of the work was to increase the productivity of garden dill using foliar treatments with glycine amino acid.Materials and methods. Dill varieties Gribovsky and Symphony were chosen as objects to study the effect of the foliar treatments with glycine. Sowing of seeds was carried out at an early date, which for the conditions of the Lipetsk region corresponds to the first decade of April, with a SZT-3.6 seeder with 15 cm row spacing. The seeding rate was 15 kg/ha, the seeding depth was 1-2 cm. were Treatment with glycine solution was achieved in plants rosette phase. The concentration of glycine was 25, 50 and 100 mg / l. The control plants were sprayed with distilled water. The crop was cut during the period of brown seeds on the central umbrella. The content of essential oil was determined by the 14th edition of the State Pharmacopoeia of the Russian Federation (method 1). The content of the main components was determined by gas chromatography.Results. As a result of the research, a positive effect of foliar treatments with glycine on both yield and the content of essential oil in the raw material of dill varieties Gribovsky and Symphony was revealed. As a result of treatments, regardless of concentration, the seeds yield and the yield of essential oil per unit area increased. The increase in the mass of 1000 pieces of fruits was not unambiguous. Based on the results obtained, the effective concentration of amino acid glycine is determined not only by the characteristics of the variety, but also by weather conditions, when, depending on the conditions during the processing period and prior to harvesting, different aspects of the drug's action appear. According to the results of observations for 2 years and an assessment by the sum of the indicators, the optimal concentration of glycine in most cases was 100 mg / l, at the same time, for the Symphony variety for two years, two-foliar treatment with low concentrations of glycine (10 mg / l rosette + 10 mg / l budding).

Correlation of glycine with cardiometabolic variables and carotid atherosclerosis

Background and Aims: Cardiometabolic disorders are associated with low glycine concentrations and glycine genetic loci are associated with lower coronary heart disease risk. We study the correlation of glycine concentrations with carotid atherosclerosis in a multiethnic type 2 diabetes cohort in Singapore.

Tuning the nucleophilic attack and the reductive action of glycine on graphene oxide under basic medium

Amino acids are important compounds for GO functionalization because they can improve GO properties for many applications ranging from biomedicine to depollution. However, amino acids can act as nucleophiles or as reducing agents for GO functionalization or reduction, respectively. Hence, we systematically studied the GO functionalization/reduction using glycine as a model amino acid under basic conditions at room temperature. Attenuated total reflectance–Fourier transform infrared (ATR-FTIR), X-ray photoelectron spectroscopy, and Raman spectroscopy were used to characterize the modified GO with glycine. We found that low glycine concentrations produced an epoxide ring opening reaction, whereas an increase in glycine concentration led to GO reduction. The basic medium allowed to conserve the carboxylic acid groups, whereas the GO reduction mechanism was governed by the partial hydrolysis of epoxide groups and the subsequent reduction of carboxylic acids to carbonyls. This article opens up the opportunity to study and control the conditions in which different amino acids could be used for either GO functionalization or GO reduction.

Detecting Low Concentrations of Nitrogen-Based Adulterants in Whey Protein Powder Using Benchtop and Handheld NIR Spectrometers and the Feasibility of Scanning through Plastic Bag.

Nitrogen-rich adulterants in protein powders present sensitivity challenges to conventional combustion methods of protein determination which can be overcome by near Infrared spectroscopy (NIRS). NIRS is a rapid analytical method with high sensitivity and non-invasive advantages. This study developed robust models using benchtop and handheld spectrometers to predict low concentrations of urea, glycine, taurine, and melamine in whey protein powder (WPP). Effectiveness of scanning samples through optical glass and polyethylene bags was also tested for the handheld NIRS. WPP was adulterated up to six concentration levels from 0.5% to 3% w/w. The two spectrometers were used to obtain three datasets of 819 diffuse reflectance spectra each that were pretreated before linear discriminant analysis (LDA) and regression (PLSR). Pretreatment was effective and revealed important absorption bands that could be correlated with the chemical properties of the mixtures. Benchtop NIR spectrometer showed the best results in LDA and PLSR but handheld NIR spectrometers showed comparatively good results. There were high prediction accuracies and low errors attesting to the robustness of the developed PLSR models using independent test set validation. Both the plastic bag and optical glass gave good results with accuracies depending on the adulterant of interest and can be used for field applications.

Glycine exerts dose-dependent biphasic effects on vascular development of zebrafish embryos

Glycine, a non-essential amino acid, is involved in both angiogenesis and anti-angiogenesis. We hypothesized that glycine would exert dose-dependent different effects on angiogenesis. In this study, we investigated the effects of a broad range of concentrations of glycine on vascular development using transgenic zebrafish Tg(fli1a:Myr-mCherry)ncv1 embryos. Effects of glycine transporter (GlyT) inhibitors (sarcosine and bitopertin) and a glycine receptor (GlyR) inhibitor (strychnine) were also examined in embryos in the absence or presence of glycine. After exposure to glycine and inhibitors, intersegmental vessels (ISVs) were observed by fluorescent microscopy. Low concentrations of glycine promoted the development of ISVs, whereas high concentrations reduced it. These effects of glycine could generally be reversed by treatment with GlyT and GlyR inhibitors. Furthermore, expressions of vascular endothelial growth factor (VEGF) (an angiogenic factor) and nitric oxide synthase (NOS) (an enzyme for nitric oxide synthesis) were associated with the dose-dependent effects of glycine. Our results suggest that glycine exerts dose-dependent biphasic effects on vascular development, which rely on GlyTs and GlyRs, and correlate with the expression of VEGF and NOS genes. At low concentrations, glycine acted as an angiogenic factor. In contrast, at high concentrations, glycine induced anti-angiogenesis. This evidence provides a novel insight into glycine as a unique target in angiogenic and anti-angiogenic therapy.

Glycine contributes to the control of hepatic response to insulin by promoting mitochondrial-endoplasmic reticulum interactions

AbstractIntroductionDeterminants of health and diseases in humans involve complex interactions between diet, gut microbiota and host metabolism. The liver is a major organ that coordinates host adaptations to environmental factors. Mitochondria and endoplasmic reticulum tightly regulate liver nutrient sensing and metabolic adaptations, shaping its metabolic flexibility. Both organelles interact through contact points (named MAMs) in order to exchange calcium and lipids, and MAMs’ integrity settles metabolic flexibility of the liver. Disrupted MAMs’ integrity in obesity is linked to liver steatosis and insulin resistance. This occurs in association with alterations circulating amino acid profiles, among which glycine. Meta-analyses showed that the low plasma glycine concentration observed in obesity is a predictive factor for developing type 2 diabetes. We thus aimed at exploring whether glycine could participate to the regulation of the hepatic response to insulin and whether mechanisms may involve regulation of mitochondrial-ER (MAMs) interactions.Materials and MethodsThe study was carried out in 12 week-old male C57B16J mice fed a standard chow (n = 12/group, 36 total) in accordance with the French guidelines for the care and use of animals. Glycine (1.2g/kg) was provided for 3 days in drinking water vs. water vs. isonitrogenous placebo amino acids. Liver was collected after an overnight fast, 15 min after ip injection of saline (n = 6/group) or insulin (0.75U/kg, n = 6/group). Liver samples were fixed in glutaraldehyde/cacodylate for quantifying MAMs by transmission electronic microscopy. Fractions enriched in MAMs were isolated by differential ultracentrifugation on fresh tissue for Western Blot explorations. Insulin response was assessed through Akt phosphorylation at Ser473.ResultsGlycine supplementation increased the percentage of interaction between ER and mitochondria (compare to mitochondrial surface) for all spacing from 10 to 50 nm. Thus, glycine supplementation induced a 45% increase in mitochondrial-ER (MAMs) interactions compared to other groups (p &lt; 0.001). In agreement to the improved MAMs’ integrity, insulin response was enhanced by 50% after glycine supplementation compared to other groups (p &lt; 0.05). Finally, protein analysis of the MAMs' fraction corroborates the importance of PP2A as a key enzyme regulating MAMs’ integrity.ConclusionGlycine is therefore an interesting nutritional actor that can play a crucial role in regulating the integrity of MAMs in the liver, thus contributing to the control of the insulin response.

Effects of root exudates on the activation and remediation of cadmium ion in contaminated soils.

To screen out plants with hyperaccumulation of heavy metals and explore the effects of root exudates on the phytoremediation in contaminated soils. The germination rates of five plants including Lolium perenne L. (L. perenne), Sorghum sudanense (Piper) Stapf. (S. sudanense), Pennisetum alopecuroides (L.) Spreng. (P. alopecuroides), Medicago sativa L. (M. sativa), and Trifolium repens L. (T. repens) in different concentrations of cadmium ion solution (0-100mg/kg) were determined. The growth adaptability of these five plants under conditions of contaminated soils with the above cadmium ion concentrations was also evaluated. S. sudanense and P. alopecuroides had higher germination rates and better growth than the three other plants and were selected as the latter experimental varieties. The activation amounts of cadmium ion in soils were measured using AAS in the presence of three types of root secretions (citric acid, glycine, and maltose) with different concentrations (10-500mmol/L). The activation amounts decrease in the following order: citric acid > glycine > maltose. The effect of these three root exudates on the removal of cadmium-contaminated soils in combination with S. sudanense and P. alopecuroides was also tested. For S. sudanense and P. alopecuroides, the maximum biomass and removal rate reaches the maximum at 100mmol/L of citric acid. Conversely, low concentrations (approximately 10-50mmol/L) of glycine and maltose are more effective for plant growth and phytoremediation. The addition of citric acid at 100mmol/L and approximately 10-50mmol/L of glycine and maltose can effectively promote the transfer of cadmium ion from roots to leaves and the accumulation of cadmium ion in leaves.

Molecularly imprinted polypyrrole counter electrode for gel-state dye-sensitized solar cells

The chemical complexity of traditional Dye Sensitized Solar Cells (DSSCs) electrolyte requires the development of high selectivity and catalytic counter-electrode (CE) materials for the triiodide target molecule. In this work is reported for the first time that molecularly imprinted polypyrrole (MIP-PPy) can help to overcome these challenges. Different template molecules such as 2-aminoacetic acid (Glycine) and L-2-aminopropionic acid (l-Alanine) are considered during the electropolymerization process in order to verify the application of MIP-PPy as CE. The use of low concentration of Glycine leads to a MIP-PPy film exhibiting higher catalytic activity and electrochemical properties on triiodide reduction than the non-imprinted polypyrrole (NIP-PPy) one. Gel-state DSSCs based on MIP materials were prepared and tested and the optimized MIP-PPy CE with Glycine as template showed an increase of around 20% of the power conversion efficiency and a reduction of 50% of the charge transfer resistance in comparison with the cells based on NIP-PPy. These results demonstrate the possibility to enhance the catalytic properties of PPy CE without adding any other materials or considerable modifications of the production process but simply increasing the electrode selectivity.

Effects of foliar application of glycine and glutamine amino acids on growth and quality of sweet basil

Amino acids have diverse roles in plant metabolism, and recently amino acid based fertilizers have been used largely in crop production systems. Despite most of these new fertilizers are formulated for foliar application; however, morphophysiological responses of crops to amino acids application have not yet been well documented. In the present study, foliar application of glycine or glutamine in different concentrations of 0 (distilled water), 250, 500, 1000 mg·L-1, as well as a treatment of 250 mg·L-1 glycine + 250 mg·L-1 glutamine were evaluated on growth of sweet basil (Ocimum basilicum L.) plants. The results showed that foliar application of glycine or glutamine at 1000 mg·L-1 showed no improvement in comparison with control for all traits except for leaf L-ascorbic acid concentration that showed the highest value under these amino acids treatments. However, foliar application of these amino acids at 250 and particularly 500 mg·L-1 showed promising effect on sweet basil growth. Plant shoot fresh and dry weight, leaf area, leaf SPAD value, and leaf chlorophyll content were improved by foliar application of 500 mg·L-1 glycine or glutamine in comparison with control plants. Foliar application of amino acids increased leaf nitrogen (glutamine 250 and 500 mg·L-1), potassium (glycine 250 mg·L-1), magnesium (glutamine 250 or 500 mg·L-1, glycine 250 mg·L-1, glycine + glutamine; 250 + 250 mg·L-1), iron (glycine and glutamine at 500 mg·L-1 and glutamine at 250 mg·L-1), and zinc (glycine and glutamine at 250 or 500 mg·L-1), whereas the increase in leaf nutrients caused by other treatments was not significantly different from control plants. Leaf calcium concentration was not changed by amino acid treatments. The results indicate that foliar application of moderate to low concentrations of glutamine or glycine can improve sweet basil growth.

A Glycine Riboswitch in Streptococcus pyogenes Controls Expression of a Sodium:Alanine Symporter Family Protein Gene.

Regulatory RNAs play important roles in the control of bacterial gene expression. In this study, we investigated gene expression regulation by a putative glycine riboswitch located in the 5′-untranslated region of a sodium:alanine symporter family (SAF) protein gene in the group A Streptococcus pyogenes serotype M49 strain 591. Glycine-dependent gene expression mediated by riboswitch activity was studied using a luciferase reporter gene system. Maximal reporter gene expression was observed in the absence of glycine and in the presence of low glycine concentrations. Differences in glycine-dependent gene expression were not based on differential promoter activity. Expression of the SAF protein gene and the downstream putative cation efflux protein gene was investigated in wild-type bacteria by RT-qPCR transcript analyses. During growth in the presence of glycine (≥1 mM), expression of the genes were downregulated. Northern blot analyses revealed premature transcription termination in the presence of high glycine concentrations. Growth in the presence of 0.1 mM glycine led to the production of a full-length transcript. Furthermore, stability of the SAF protein gene transcript was drastically reduced in the presence of glycine. We conclude that the putative glycine riboswitch in S. pyogenes serotype M49 strain 591 represses expression of the SAF protein gene and the downstream putative cation efflux protein gene in the presence of high glycine concentrations. Sequence and secondary structure comparisons indicated that the streptococcal riboswitch belongs to the class of tandem aptamer glycine riboswitches.

Uticaj sastava goriva i odnos goriva/oksidatora na sintezu rastvora sagorevanja nanodelića katalizatora MgFe2O4

Solution combustion synthesis (SCS) has been widely applied to produce oxide catalysts due to the possibility of producing highly pure and homogeneous nanostructured powders at low cost. The smaller the particles are and the higher the surface area is, the more efficient the powder catalyst will be. For iron-based catalysts such as ferrites, the degree of spinel inversion is another factor that affects the catalyst activity. In SCS, the particle size, surface area, and degree of spinel inversion are fundamentally related to process variables such as the fuel composition and the fuel/oxidizer ratio. Therefore, we studied the application of glycine and polyethylene glycol - 200 molecular weight (PEG 200) as fuels and the influence of the fuel/oxidizer ratio in the SCS of MgFe2O4 catalyst nanoparticles. The products' morphology and composition were systematically characterized by X-ray diffraction, microscopy analyses, and specific surface area. The results indicate the production of high-purity nanoparticles with increased surface area, which was obtained with low concentrations of glycine and a wide range of particle sizes that depend on the fuel composition and concentration.

Vitamin B6 is essential for serine de novo biosynthesis

Pyridoxal 5′-phosphate (PLP), the metabolically active form of vitamin B6, plays an essential role in brain metabolism as a cofactor in numerous enzyme reactions. PLP deficiency in brain, either genetic or acquired, results in severe drug-resistant seizures that respond to vitamin B6 supplementation. The pathogenesis of vitamin B6 deficiency is largely unknown. To shed more light on the metabolic consequences of vitamin B6 deficiency in brain, we performed untargeted metabolomics in vitamin B6-deprived Neuro-2a cells. Significant alterations were observed in a range of metabolites. The most surprising observation was a decrease of serine and glycine, two amino acids that are known to be elevated in the plasma of vitamin B6 deficient patients. To investigate the cause of the low concentrations of serine and glycine, a metabolic flux analysis on serine biosynthesis was performed. The metabolic flux results showed that the de novo synthesis of serine was significantly reduced in vitamin B6-deprived cells. In addition, formation of glycine and 5-methyltetrahydrofolate was decreased. Thus, vitamin B6 is essential for serine de novo biosynthesis in neuronal cells, and serine de novo synthesis is critical to maintain intracellular serine and glycine. These findings suggest that serine and glycine concentrations in brain may be deficient in patients with vitamin B6 responsive epilepsy. The low intracellular 5-mTHF concentrations observed in vitro may explain the favourable but so far unexplained response of some patients with pyridoxine-dependent epilepsy to folinic acid supplementation.

Low concentrations of glycine inhibit photorespiration and enhance the net rate of photosynthesis in Caragana korshinskii

The inhibition of photorespiration can be used to improve plant carbon fixation. In order to compare the effects of three photorespiration inhibitors [glycine, NaHSO3, and isonicotinyl hydrazide (INH)], photosynthetic parameters of leaves sprayed respectively with these chemicals were examined and their inhibiting efficiency was evaluated in Caragana korshinskii. Our results showed that 5 mM glycine could reduce the photorespiratory rate (PR) effectively, while the net photosynthetic rate (PN), stomatal conductance (gs), and intercellular CO2 concentration (Ci) significantly increased. The ratio of electron flow for ribulose-1,5-bisphosphate (RuBP) carboxylation to RuBP oxygenation was elevated markedly. NaHSO3 and INH could also suppress the PR in some cases, whereas PN was not improved. The glyoxylate content increased considerably after application of low concentrations of glycine. These results suggested that low concentrations of glycine could suppress photorespiration by feed-back inhibition of glyoxylate and enhance photosynthesis by regulating gs, Ci, and the distribution of electron flow in C. korshinskii.

Neurometabolic abnormalities in schizophrenia and depression observed with magnetic resonance spectroscopy at 7 T.

BackgroundExamining neurometabolic abnormalities in critical brain areas in schizophrenia and major depressive disorder (MDD) may help guide future pharmacological interventions including glutamate-modulating treatments.AimsTo measure metabolite concentrations within the anterior cingulate cortex (ACC) and thalamus of people with schizophrenia and people with MDD.MethodsSpectra were acquired from 16 volunteers with schizophrenia, 17 with MDD and 18 healthy controls using magnetic resonance spectroscopy on a 7 Tesla scanner.ResultsIn the thalamus, there were lower glycine concentrations in the schizophrenia group relative to control (P=0.017) and MDD groups (P=0.012), and higher glutamine concentrations relative to healthy controls (P=0.009). In the thalamus and the ACC, the MDD group had lower myo-inositol concentrations than the control (P=0.014, P=0.009, respectively) and schizophrenia (P=0.004, P=0.002, respectively) groups.ConclusionThese results support the glutamatergic theory of schizophrenia and indicate a potential glycine deficiency in the thalamus. In addition, reduced myo-inositol concentrations in MDD suggest its involvement in the disorder.Declaration of interestNone.Copyright and usage© The Royal College of Psychiatrists 2017. This is an open access article distributed under the terms of the Creative Commons Non-Commercial, No Derivatives (CC BY-NC-ND) license.