Sixty years elapsed since Chang (Hsiang-Tung Chang, Xiang-Tong Zhang) presented his seminal report "Cortical neurons with particular reference to the apical dendrite" at the Cold Spring Harbor Symposium. Thanks to the development of elaborated techniques through the 6 decades, our understanding of the dendrite has been pushed forward greatly: the backward and forward conductions during excitation, sodium and calcium conductances, chemical excitation by uncaging glutamate at a dimension of micrometer, and the quantitative study of chemical organization of postsynaptic density (PSD), etc. Though the progression is great, there are still tough problems in dendritic research, especially the integration through dendritic spine.
Calcium Signaling ; Dendrites ; physiology ; Glutamic Acid ; metabolism

We produced α-ketoglutaric acid (α-KG) from L-glutamic acid, using enzymatic transformation approach with L-glutamate oxidase (LGOX). First, wild strain Streptomyces sp. FMME066 was mutated with NTG, a genetically stable mutant Streptomyces sp. FMME067 was obtained. Under the optimal nutrition conditions with fructose 10 g/L, peptone 7.5 g/L, KH2PO4 1 g/L and CaCl2 0.05 g/L, the maximum LGOX activity reached 0.14 U/mL. The LGOX was stable to pH and temperature, and Mn2+ had a stimulating effect. Finally, after 24 h enzymatic conversion under the optimal conditions, the maximum titer of α-KG reached 38.1 g/L from 47 g/L L-glutamic acid. Enzymatic transformation by LGOX is a potential approach for α-KG production.
Amino Acid Oxidoreductases ; metabolism ; Fermentation ; Glutamic Acid ; metabolism ; Ketoglutaric Acids ; metabolism ; Streptomyces ; genetics ; metabolism

Glutamic acid is an important amino acid with wide range of applications and huge market demand. Therefore, by performing transcriptome sequencing and re-sequencing analysis on Corynebacterium glutamicum E01 and high glutamate-producing strain C. glutamicum G01, we identified and selected genes with significant differences in transcription and gene levels in the central metabolic pathway that may have greatly influenced glutamate synthesis and further increased glutamic acid yield. The oxaloacetate node and α-ketoglutarate node play an important role in glutamate synthesis. The oxaloacetate node and α-ketoglutarate node were studied to explore effect on glutamate production. Based on the integrated strain constructed from the above experimental results, the growth rate in a 5-L fermenter was slightly lower than that of the original strain, but the glutamic acid yield after 48 h reached (136.1±5.53) g/L, higher than the original strain (93.53±4.52) g/L, an increase by 45.5%; sugar-acid conversion rate reached 58.9%, an increase of 13.7% compared to 45.2% of the original strain. The application of the above experimental strategy improved the glutamic acid yield and the sugar-acid conversion rate, and provided a theoretical basis for the metabolic engineering of Corynebacterium glutamicum.
Citric Acid Cycle ; Corynebacterium glutamicum/metabolism* ; Glutamic Acid/metabolism* ; Metabolic Engineering ; Metabolic Networks and Pathways/genetics*

To investigate the effect of thiopental sodium on the release of glutamate and gamma-aminobutyric acid (GABA) from synaptosomes in the prefrontal cortex, synaptosomes were made, the spontaneous release and the evoked release by 30 mmol/L KCl or 20 micromol/L veratridine of glutamate and GABA were performed under various concentrations of thiopental sodium (10-300 micromol/L), glutamate and GABA concentrations were determined by reversed-phase high-performance liquid chromatography. Our results showed that spontaneous release and evoked release of glutamate were significantly inhibited by 30 micromol/L, 100 micromol/L and 300 micromol/L thiopental sodium, IC50 of thiopental sodium was 25.8 +/- 2.3 micromol/L for the spontaneous release, 23.4 +/- 2.4 micromol/L for KCl-evoked release, and 24.3 +/- 1.8 micromol/L for veratridine-evoked release. But GABA spontaneous release and evoked release were unaffected. The study showed that thiopental sodium with clinically related concentrations could inhibit the release of glutamate, but had no effect on the release of GABA from rats prefrontal cortical synaptosomes.
Glutamic Acid/*metabolism ; Hypnotics and Sedatives/pharmacology ; Prefrontal Cortex/*metabolism ; Rats, Sprague-Dawley ; Synaptosomes/*metabolism ; Thiopental/*pharmacology ; gamma-Aminobutyric Acid/*metabolism

Epilepsy ; genetics ; metabolism ; Glutamic Acid ; metabolism ; Humans ; Ion Channels ; genetics ; Receptors, GABA-A ; genetics

The glyoxylate cycle was hypothesed to be indispensable for glutamate overproduction in coryneform bacteria, for it was thought to fulfill anaplerotic functions and to supply energy during the growth phase. During glutamate overproduction phase, however, it has been noted that the high level of the cycle is detrimental to the glutamate production. In order to clarify the relationship between the glutamate production and the glyoxylate cycle, a chromosomal aceA-disrupted mutant of wild-type C. glutamicum ATCC 13032 was constructed. The isocitrate lyase (ICL) activity of the parental strain was 0.011 u/mg of protein and reached 1.980 u/mg of protein after acetate induction; the mutant strain WTdeltaA, however, had no detectable ICL activity and was no longer able to grow on minimal medium with acetate as the sole carbon source. Compared with the wild-type C. glutamicum WT, the mutant strain WTdeltaA, exhibited the same growth rate with glucose as the sole carbon source, indicating glyoxylate cycle is not required for its growth on glucose. On the contrary, the glutamate production in WTdeltaA was severely impaired and more residual glucose was found in the fermentation broth at the end of fermentation with the mutant strain than with the wild-type strain. Further investigations into the relationship between the glutamate production and the glyoxylate cycle are under the way, which may help to elucidate the mechanism of glutamate overproduction.
Corynebacterium glutamicum ; genetics ; growth & development ; metabolism ; Culture Media ; Fermentation ; Glucose ; metabolism ; Glutamic Acid ; biosynthesis ; Glyoxylates ; metabolism ; Isocitrate Lyase ; metabolism

The Pogo mouse is an autosomal recessive ataxic mutant that arose spontaneously in the inbred KJR/MsKist strain derived originally from Korean wild mice. The ataxic phenotype is characterized by difficulty in maintaining posture and side to side stability, faulty coordination between limbs and trunk, and the consequent inability to walk straight. In the present study, the cerebellar concentrations of glutamate and GABA were analyzed, since glutamate is a most prevalent excitatory neurotransmitter whereas gammar-aminobutyric acid (GABA) is one of the most abundant inhibitory neurotransmitters, which may be the main neurotransmitters related with the ataxia and epilepsy. The concentration of glutamate of cerebellum decreased significantly in ataxic mutant Pogo mouse compared to those of control mouse. However, GABA concentration was not decrease. These results suggested that the decrease in glutamate concentration may contribute to ataxia in mutant Pogo mouse.
Animals ; Calcium-Binding Protein, Vitamin D-Dependent/metabolism ; Cerebellum/*metabolism/pathology ; Gait Ataxia/*metabolism/pathology ; Glutamic Acid/*metabolism ; Immunohistochemistry ; Mice ; Mice, Mutant Strains ; gamma-Aminobutyric Acid/*metabolism

To understand the neurochemical mechanisms underlying the vestibular compensation, we determined the levels of amino acids such as aspartate, glutamate, glutamine, glycine, taurine, alanine in the medial vestibular nucleus (MVN) following unilateral labyrinthectomy (UL), by using in vivo brain microdialysis and high-performance liquid chromatography technique. Rats were pretreated by infusing 2% lidocaine 1.2 mL or 10 mg arsanilic acid into the tympanic cavity to obstruct uni-periphery vestibular organ, and then the levels of amino acids were determined in MVN of normal control and ipsilateral or contralateral lesional (ipsi-/contra-lesional) rats. In the control experiment, the levels of aspartate, glutamate, glutamine, glycine, taurine, and alanine were (6.15 +/- 0.59), (18.13 +/- 1.21), (33.73 +/- 1.67), (9.26 +/- 0.65), (9.56 +/- 0.77) and (10.07 +/- 0.83) pmol/8 muL sample, respectively. The concentrations of aspartate and glutamate decreased, while the concentration of taurine increased in the ipsi-lesional MVN of rats 10 min after infusing 2% lidocaine into middle ear to obstruct uni-periphery vestibular organ. Whereas the concentration of glutamate increased, the concentrations of glycine and alanine decreased in the contra-lesional MVN, accompanied by imbalances of glutamate, glycine and alanine in the bilateral nuclei. In contrast, the levels of glutamate and alanine decreased, the level of glutamine increased in the ipsi-lesional MVN, and the level of glutamate decreased in the contra-lesional MVN of rats 2 weeks after infusing 10 mg arsanilic acid into the tympanic cavity to obstruct uni-periphery vestibular organ. Furthermore, the level of glutamine in the ipsi-lesional MVN was obviously higher than that in the contra-lesional MVN. These results demonstrate that an imbalance of different amino acids appeared in bilateral MVN after UL, and this imbalance decreased after the development of vestibular compensation. Whereas the imbalance of glutamine release in bilateral nuclei appeared after vestibular compensation.
Amino Acids ; metabolism ; Animals ; Aspartic Acid ; metabolism ; Ear, Inner ; physiology ; surgery ; Glutamic Acid ; metabolism ; Male ; Rats ; Rats, Wistar ; Taurine ; metabolism ; Vestibular Nuclei ; metabolism ; physiopathology

Animals ; Ascorbic Acid ; metabolism ; Brain Ischemia ; metabolism ; Glutamic Acid ; metabolism ; Hippocampus ; drug effects ; metabolism ; Male ; Propofol ; pharmacology ; Rats ; Rats, Wistar ; Reperfusion Injury ; metabolism

To investigate the effect of thiopental sodium on the release of glutamate and gamma-aminobutyric acid (GABA) from synaptosomes in the prefrontal cortex, synaptosomes were made, the spontaneous release and the evoked release by 30 mmol/L KCl or 20 micromol/L veratridine of glutamate and GABA were performed under various concentrations of thiopental sodium (10-300 micromol/L), glutamate and GABA concentrations were determined by reversed-phase high-performance liquid chromatography. Our results showed that spontaneous release and evoked release of glutamate were significantly inhibited by 30 micromol/L, 100 micromol/L and 300 micromol/L thiopental sodium, IC50 of thiopental sodium was 25.8 +/- 2.3 micromol/L for the spontaneous release, 23.4 +/- 2.4 micromol/L for KCl-evoked release, and 24.3 +/- 1.8 micromol/L for veratridine-evoked release. But GABA spontaneous release and evoked release were unaffected. The study showed that thiopental sodium with clinically related concentrations could inhibit the release of glutamate, but had no effect on the release of GABA from rats prefrontal cortical synaptosomes.
Animals ; Glutamic Acid ; metabolism ; Hypnotics and Sedatives ; pharmacology ; Male ; Prefrontal Cortex ; metabolism ; Rats ; Rats, Sprague-Dawley ; Synaptosomes ; metabolism ; Thiopental ; pharmacology ; gamma-Aminobutyric Acid ; metabolism