Search

Objective: This study aimed to establish a hollow fiber ligand fishing method for screening γ- Aminobutyrate transaminase (GABA-T) inhibitory component from the volatile oil of Acorus tatarinowii. Methods: Based on optimizing the enzyme assisted extraction process of volatile oil from A. tatarinowii using response surface methodology, GABA-T solution was injected into the hollow fiber lumen and used as a "bait" to fish out the potential active components in A. tatarinowii volatile oil, and its GABA-T inhibitory activity was verified. Results: The results showed that the optimum extraction conditions of volatile oil from A. tatarinowii were as follows: cellulase content 3 165 U/g, enzymolysis time 1.8 h, enzymolysis temperature 45 ℃, and the yield of volatile oil from A. tatarinowii was 2.56%. Finally, 51 compounds were identified, mainly including olefins, alcohols, ethers, ketones, phenols, acids, and other compounds. 3 mg/mL of GABA-T solution was injected into the cavity of the U-shaped hollow fiber tube, incubated for 160 min, sealed, and placed in the volatile oil of A. tatarinowii for ultrasonic (60 kHz) fishing for 20 min, and then analyzed with LCMS-IT-TOF system. Successfully filtered out α-Asarone has a concentration-dependent inhibitory effect on GABA-T activity, with an IC50 of 57.9 μg/mL. Conclusion: The established hollow fiber ligand fishing method is stable, feasible, and easy to operate.

Salt stress has a significant effect on plants, causing a whole range of changes in metabolism. Unfortunately, the mechanisms that ensure the adaptive response of cells in response to salinity have not been sufficiently studied. The study examined changes in the functioning of one of the enzymes of the anaplerotic pathway of the Krebs cycle - GABA shunt - GABA transaminase (GABA-T, EC 2.6.1.19). It has been shown that salt stress caused by incubation of corn seedlings in a 150 mM sodium chloride solution causes activation of GABA transaminase (GABA-T, EC 2.6.1.19). The established increase in GABA-T enzymatic activity in the first hours of incubation in saline solution reaches a maximum at 3 hours of incubation. At the same time, differences are observed in the expression profilees of the GTA-1 and GTA-2 genes, which encode this enzyme in the maize genome. Salinity in the first three hours induces an increase in the expression of the GTA-1 GABA-T gene, while the GTA-2 gene demonstrates an increase in transcriptional activity from 6 to 12 hours of the experiment. An increase in GABA-T enzymatic activity under salinity indicates activation of the GABA shunt to maintain the energy metabolism of the plant cell under stress conditions.

γ-Aminobutyric acid (GABA) transaminase (GABA-T) is a GABA-degrading enzyme that plays an essential role in regulating GABA levels and maintaining supplies of GABA. Although GABA in the mammalian brain was discovered 70 years ago, research on GABA and GABA-T has predominantly focused on the brain. Notwithstanding the high activity and expression of GABA-T in the liver, the exact functions of GABA-T in the liver remain unknown. This article reviews the up-to-date information on GABA-T in the liver. It presents recent findings on the role of liver GABA-T in food intake suppression and appetite regulation. Finally, the potential functions of liver GABA-T in other neurological diseases, natural GABA-T inhibitors, and future perspectives in this research area are discussed. [ABSTRACT FROM AUTHOR]

Copyright of Food & Machinery is the property of Food & Machinery Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Introduction: Beta-alanine is a non-essential amino acid that is naturally produced by the human body and used by many athletes and practitioners of physical activity to reduce muscle fatigue and to increase performance in high performance exercises. As a precursor of intramuscular carnosine, it has been shown to reduce the hydrogen ions that cause muscle fatigue during exercise in sports such as swimming and water polo. Objective: To evaluate various beta-alanine supplementation protocols in swimmers and water polo players and their effects on performance. Methodology: This study is a systematic review of various beta-alanine supplementation protocols used in exercises involving water polo and high-performance swimming, from searches on the Pubmed, SCIELO and RBNE platforms. Articles in English and Portuguese were included, which were evaluated on the basis of methods and parameters specific to swimming and water polo. Results: The review found that beta-alanine supplementation protocols varied according to the studies and their objectives. However, beta-alanine supplementation was shown to be effective in improving times, reducing blood lactate and increasing strength. Conclusion: Supplementation with beta-alanine generates a possible beneficial effect on swimmers and water polo players by fostering improvements in time, reduction of blood lactate and strength, all of which can positively influence the results of competitions and championships. The best protocols are those that administered a dose greater than or equal to 4.8g per day for, at least, four weeks. [ABSTRACT FROM AUTHOR]

We aimed to compare the effects of beta-alanine on Traditional Resistance Training (TRAD) or Blood Flow Restriction Training (BFR). Methods: 19 subjects were randomly allocated to a Placebo (n = 10) or beta-alanine (n = 9) group. Subjects from both groups were trained unilaterally (unilateral arm curl) for six weeks, and each arm was trained using a different paradigm (BFR or TRAD). One repetition maximum (1RM) test measurements were performed before and after the strength training program. Work output was accessed as the total weight lifted (repetitions × weight lifted × sets) for the entire strength training program. Results: 1RM or total weight lifted was not increased by beta-alanine supplementation. However, the TRAD-trained arm showed a significantly increased 1RM and total weight lifted compared to the BFR arm (p < 0.05). Conclusion: We conclude that in the short-term (6 weeks) and following the current experimental conditions, beta-alanine does not benefit BFR or TRAD in terms of total weight lifted (volume of training) or maximal strength (1RM). [ABSTRACT FROM AUTHOR]

Summary: Hepatic lipid accumulation is a hallmark of type II diabetes (T2D) associated with hyperinsulinemia, insulin resistance, and hyperphagia. Hepatic synthesis of GABA, catalyzed by GABA-transaminase (GABA-T), is upregulated in obese mice. To assess the role of hepatic GABA production in obesity-induced metabolic and energy dysregulation, we treated mice with two pharmacologic GABA-T inhibitors and knocked down hepatic GABA-T expression using an antisense oligonucleotide. Hepatic GABA-T inhibition and knockdown decreased basal hyperinsulinemia and hyperglycemia and improved glucose intolerance. GABA-T knockdown improved insulin sensitivity assessed by hyperinsulinemic-euglycemic clamps in obese mice. Hepatic GABA-T knockdown also decreased food intake and induced weight loss without altering energy expenditure in obese mice. Data from people with obesity support the notion that hepatic GABA production and transport are associated with serum insulin, homeostatic model assessment for insulin resistance (HOMA-IR), T2D, and BMI. These results support a key role for hepatocyte GABA production in the dysfunctional glucoregulation and feeding behavior associated with obesity.

The anti-obesity and anti-diabetic effects of γ-aminobutyric acid (GABA) are mainly expressed via glucose and insulin regulation in mice. It is unknown whether dietary GABA exerts anti-obesity effects via other pathways. Herein, we report that a high dietary GABA intake (5%) significantly suppressed food intake (−30%), body-weight gain, and fat accumulation, induced ketogenesis, improved glucose metabolism, and elevated the levels of circulating GABA and β-aminoisobutyric acid. These changes suggest that 5% GABA intake possibly induces calorie restriction. Interestingly, a combination of low-dose dietary GABA (0.5% and 2%) and vigabatrin (inhibitor of GABA transaminase (GABA-T)) markedly increased the levels of circulating GABA and strongly exerted antiobesity-like effects. Brain GABA levels increased slightly upon 5% GABA intake, but significantly upon intake of the low-dose GABA–vigabatrin combination. Therefore, the manipulation of peripheral and brain GABA metabolism by targeting GABA-T may lead to the development of novel interventions for overeating and obesity.

The GABA shunt is one of the metabolic pathways that is ubiquitous in prokaryotes and eukaryotes. ?-aminobutyric acid (GABA) in fungi is required in the stress responses, virulence and development. The number of genes encoding glutamate decarboxylase (gad), GABA transaminase (gta) and succinic semialdehyde dehydrogenase (ssadh) varies between fungal species. The genome-wide analysis in Neurospora crassa resulted in the identification of a gta and a ssadh. Disruption of either gta or ssadh decreased respiration rate and biomass accumulation, reduced growth on GABA and beta-alanine. The gta and ssadh mutants exhibited aberrant hyphal morphology and displayed differential transcription of the GABA shunt genes. In the gta mutant, protoperithecia and perithecia formation was almost completely suppressed in the presence of GABA and beta-alanine, indicating GTA requirement for the turnover of these amino acids. The strains displayed differential metabolic dysregulations in response to different nitrogen sources. The phenotypic differences between the gta and ssadh mutants could be contributed to accumulation of intermediates of the GABA shunt and/or GABA shunt-independent functions. Together, our data suggest that the GABA shunt could function as a moderate modulator of multiple biological events, including respiration, energy metabolism, carbon and nitrogen metabolism, growth, as well as sexual development in N. crassa. [ABSTRACT FROM AUTHOR]

• Administration of pyridoxine significantly increases the glutamic acid decarboxylase 67 expression in the hippocampus. • Administration of pyridoxine decreases the GABA transaminase in the hippocampal CA1 region and dentate gyrus. • Administration of pyridoxine has no effects on succinic semialdehyde dehydrogenase in the hippocampus. Pyridoxal-5′-phosphate, the active form of vitamin B 6 , is associated with activities of several enzymes and the treatment of various neurological disorders. Here, we investigated the effects of pyridoxine on the immunoreactivity and protein levels of γ-aminobutyric acid (GABA)-synthesizing and degradation enzymes such as glutamic acid decarboxylase (GAD), GABA transaminase (GABA-T), and succinic semialdehyde dehydrogenase (SSADH), in the hippocampus of mice. The mice intraperitonially received physiological saline and 350 mg/kg pyridoxine, twice a day for 21 days, and were euthanized 2 h after the final dose. In the vehicle-treated group, we observed GAD67 immunoreactivity in the stratum pyramidale of the CA1 and CA3 region, Schaffer collateral, polymorphic layer, and outer granule cell layer of the dentate gyrus. Pyridoxine administration significantly increased GAD67 immunoreactivity, while significantly decreasing GABA-T immunoreactivity in pyridoxine-treated mouse hippocampi (CA1 region and dentate gyrus). In the stratum lacunosum-moleculare of CA1 region, GABA-T immunoreactivity was significantly increased in the pyridoxine-treated group compared to that in the vehicle-treated group, although GAD67 immunoreactivity was similarly observed in these groups. Alternatively, there were no significant differences in SSADH immunoreactivity in any regions of the hippocampus between the vehicle- and pyridoxine-treated groups. Western blot analysis showed significant increases in GAD67 and GABA-T protein levels in the pyridoxine-treated group compared with those in the vehicle-treated group. Therefore, pyridoxine administration facilitates GABA turnover in mouse hippocampus by modulating the GABA-synthesizing and degradation enzymes. [ABSTRACT FROM AUTHOR]

Targeted intracerebral drug delivery is an attractive experimental approach for the treatment of drug-resistant epilepsies. In this regard, the subthalamic nucleus (STN) represents a focus-independent target involved in the remote modulation and propagation of seizure activity. Indeed, acute and chronic pharmacological inhibition of the STN with vigabatrin (VGB), an irreversible inhibitor of GABA transaminase, has been shown to produce antiseizure effects. This effect, however, is lost over time as tolerance develops with chronic, continuous intracerebral pharmacotherapy. Here we investigated the antiseizure effects of chronic intermittent intra-STN convection-enhanced delivery of VGB in an acute rat seizure model focusing on circumventing tolerance development and preventing adverse effects. Timed intravenous pentylenetetrazol (PTZ) seizure threshold testing was conducted before and after implantation of subcutaneous drug pumps and bilateral intra-STN cannulas. Drug pumps infused vehicle or VGB twice daily (0.4 µg) or once weekly (2.5 µg, 5 µg) over three weeks. Putative adverse effects were evaluated and found to be prevented by intermittent compared to previous continuous VGB delivery. Clonic seizure thresholds were more clearly raised by intra-STN VGB compared to myoclonic twitch. Both twice daily and once weekly intra-STN VGB significantly elevated clonic seizure thresholds depending on dose and time point, with responder rates of up to 100% observed at tolerable doses. However, tolerance could not be completely avoided, as tolerance rates of 40–75% were observed with chronic VGB treatment. Results indicate that the extent of tolerance development after intermittent intra-STN VGB delivery varies depending on infusion dose and regimen. • Intermittent intrasubthalamic vigabatrin produces long-lasting antiseizure effects. • Antiseizure effects associated with dose/regimen-dependent variation in tolerance. • Minimizing intermittent dose delays but does not eliminate tolerance development. • All doses tested were well tolerated with only few, mild adverse effects observed. • Improved efficacy was indicated vs. previous findings with continuous vigabatrin. [ABSTRACT FROM AUTHOR]

Agrobacterium tumefaciens has been utilized for both transient and stable transformations of plants. These transformation methods have been used in fields such as breeding GM crops, protein production in plant cells, and the functional analysis of genes. However, some plants have significantly lower transient gene transfer and stable transformation rates, creating a technical barrier that needs to be resolved. In this study, Super- Agrobacterium was updated to ver. 4 by introducing both the ACC deaminase (acdS) and GABA transaminase (gabT) genes, whose resultant enzymes degrade ACC, the ethylene precursor, and GABA, respectively. A. tumefaciens strain GV2260, which is similar to other major strains (EHA105, GV3101, LBA4404, and MP90), was used in this study. The abilities of the Super- Agrobacterium ver. 4 were evaluated in Erianthus ravennae , Solanum lycopersicum "Micro-Tom," Nicotiana benthamiana , and S. torvum. Super- Agrobacterium ver. 4 showed the highest T-DNA transfer (transient transformation) frequencies in E. ravennae and S. lycopersicum , but not in N. benthamiana and S. torvum. In tomato, Super- Agrobacterium ver. 4 increased the stable transformation rate by 3.6-fold compared to the original GV2260 strain. Super- Agrobacterium ver. 4 enables reduction of the amount of time and labor required for transformations by approximately 72%, and is therefore a more effective and powerful tool for plant genetic engineering and functional analysis, than the previously developed strains. As our system has a plasmid containing the acdS and gabT genes, it could be used in combination with other major strains such as EHA105, EHA101, LBA4404, MP90, and AGL1. Super- Agrobacterium ver. 4, could thus possibly be a breakthrough application for improving basic plant science research methods. [ABSTRACT FROM AUTHOR]

Abstract The anticonvulsant vigabatrin (VGB; SabrilR) irreversibly inhibits GABA transaminase to increase neural GABA, yet its mechanism of retinal toxicity remains unclear. VGB is suggested to alter several amino acids, including homocarnosine, β-alanine, ornithine, glycine, taurine, and 2-aminoadipic acid (AADA), the latter a homologue of glutamic acid. Here, we evaluate the effect of VGB on amino acid concentrations in mice, employing a continuous VGB infusion (subcutaneously implanted osmotic minipumps), dose-escalation paradigm (35–140 mg/kg/d, 12 days), and amino acid quantitation in eye, visual and prefrontal cortex, total brain, liver and plasma. We hypothesized that continuous VGB dosing would reveal numerous hitherto undescribed amino acid disturbances. Consistent amino acid elevations across tissues included GABA, β-alanine, carnosine, ornithine and AADA, as well as neuroactive aspartic and glutamic acids, serine and glycine. Maximal increase of AADA in eye occurred at 35 mg/kg/d (41 ± 2 nmol/g (n = 21, vehicle) to 60 ± 8.5 (n = 8)), and at 70 mg/kg/d for brain (97 ± 6 (n = 21) to 145 ± 6 (n = 6)), visual cortex (128 ± 6 to 215 ± 19) and prefrontal cortex (124 ± 11 to 200 ± 13; mean ± SEM; p < 0.05), the first demonstration of tissue AADA accumulation with VGB in mammal. VGB effects on basic amino acids, including guanidino-species, suggested the capacity of VGB to alter urea cycle function and nitrogen disposal. The known toxicity of AADA in retinal glial cells highlights new avenues for assessing VGB retinal toxicity and other off-target effects. Highlights • Continuous vigabatrin dosing induces amino acid alterations in mouse tissues. • Altered neuroactive amino acids indicate imbalanced excitation/inhibition. • 2-aminoadipate, a glial cell toxin, increases with VGB intake in surveyed tissues. • Basic amino acid changes suggest disrupted urea cycle activity/nitrogen disposal. • Ours is the first metabolomic analysis of VGB toxicity reported in the mouse. [ABSTRACT FROM AUTHOR]

Phenelzine (β-phenylethylhydrazine) is a monoamine oxidase (MAO)-inhibiting antidepressant with anxiolytic properties. It possesses a number of important pharmacological properties which may alter the effects of oxidative stress. After conducting a comprehensive literature search, the authors of this review paper aim to provide an overview and discussion of the mechanisms by which phenelzine may attenuate oxidative stress. It inhibits γ-aminobutyric acid (GABA) transaminase, resulting in elevated brain GABA levels, inhibits both MAO and primary amine oxidase and, due to its hydrazine-containing structure, reacts chemically to sequester a number of reactive aldehydes (e.g. acrolein and 4-hydroxy-2-nonenal) proposed to be implicated in oxidative stress in a number of neurodegenerative disorders. Phenelzine is unusual in that it is both an inhibitor of and a substrate for MAO, the latter action producing at least one active metabolite, β-phenylethylidenehydrazine (PEH). This metabolite inhibits GABA transaminase, is a very weak inhibitor of MAO but a strong inhibitor of primary amine oxidase, and sequesters aldehydes. Phenelzine may ameliorate the effects of oxidative stress by reducing formation of reactive metabolites (aldehydes, hydrogen peroxide, ammonia/ammonia derivatives) produced by the interaction of MAO with biogenic amines, by sequestering various other reactive aldehydes and by inhibiting primary amine oxidase. In PC12 cells treated with the neurotoxin MPP+, phenelzine has been reported to reduce several adverse effects of MPP+. It has also been reported to reduce lipid peroxidative damage induced in plasma and platelet proteins by peroxynitrite. In animal models, phenelzine has a neuroprotective effect in global ischemia and in cortical impact traumatic brain injury. Recent studies reported in the literature on the possible involvement of acrolein in spinal cord injury and multiple sclerosis indicate that phenelzine can attenuate adverse effects of acrolein in these models. Results from studies in our laboratories on effects of phenelzine and PEH on primary amine oxidase (which catalyzes formation of toxic aldehydes and is overexpressed in Alzheimer's disease), on sequestration of the toxic aldehyde acrolein, and on reduction of acrolein-induced toxicity in mouse cortical neurons are also reported. • The antidepressant phenelzine reduces several adverse effects of oxidative stress. • It acts through inhibition of MAO and PrAO and through scavenging reactive aldehydes. • These actions may be relevant to treating several neurodegenerative disorders. • Its metabolite PEH is also a strong inhibitor of PrAO and scavenges aldehydes. [ABSTRACT FROM AUTHOR]

Background: Salinity-alkalinity stress is one of the major abiotic stresses affecting plant growth and development. γ-Aminobutyrate (GABA) is a non-protein amino acid that functions in stress tolerance. However, the interactions between cellular redox signaling and chlorophyll (Chl) metabolism involved in GABA-induced salinity-alkalinity stress tolerance in plants remains largely unknown. Here, we investigated the role of GABA in perceiving and regulating chlorophyll biosynthesis and oxidative stress induced by salinity-alkalinity stress in muskmelon leaves. We also evaluated the effects of hydrogen peroxide (H2O2), glutathione (GSH), and ascorbate (AsA) on GABA-induced salinity-alkalinity stress tolerance. Results: Salinity-alkalinity stress increased malondialdehyde (MDA) content, relative electrical conductivity (REC), and the activities of superoxide dismutase (SOD), ascorbate peroxidase (APX) and dehydroascorbate reductase (DHAR). Salinity-alkalinity stress decreased shoot dry and fresh weight and leaf area, reduced glutathione and ascorbate (GSH and AsA) contents, activities of glutathione reductase (GR) and monodehydroascorbate reductase (MDAR). By contrast, pretreatment with GABA, H2O2, GSH, or AsA significantly inhibited these salinity-alkalinity stress-induced effects. The ability of GABA to relieve salinity-alkalinity stress was significantly reduced when the production of endogenous H2O2 was inhibited, but was not affected by inhibiting endogenous AsA and GSH production. Exogenous GABA induced respiratory burst oxidase homologue D (RBOHD) genes expression and H2O2 accumulation under normal conditions but reduced the H2O2 content under salinity-alkalinity stress. Salinity-alkalinity stress increased the accumulation of the chlorophyll synthesis precursors glutamate (Glu), δ-aminolevulinic acid (ALA), porphobilinogen (PBG), uroporphyrinogen III (URO III), Mg-protoporphyrin IX (Mg-proto IX), protoporphyrin IX (Proto IX), protochlorophyll (Pchl), thereby increasing the Chl content. Under salinity-alkalinity stress, exogenous GABA increased ALA content, but reduced the contents of Glu, PBG, URO III, Mg-proto IX, Proto IX, Pchl, and Chl. However, salinity-alkalinity stress or GABA treated plant genes expression involved in Chl synthesis had no consistent trends with Chl precursor contents. Conclusions: Exogenous GABA elevated H2O2 may act as a signal molecule, while AsA and GSH function as antioxidants, in GABA-induced salinity-alkalinity tolerance. These factors maintain membrane integrity which was essential for the ordered chlorophyll biosynthesis. Pretreatment with exogenous GABA mitigated salinity-alkalinity stress caused excessive accumulation of Chl and its precursors, to avoid photooxidation injury. [ABSTRACT FROM AUTHOR]

Key message: The new transient protein expression system using the pBYR2HS vector is applicable to several tomato cultivars and wild species with high level of protein expression.Abstract: Innovation and improvement of effective tools for transient protein expression in plant cells is critical for the development of plant biotechnology. We have created the new transient protein expression system using the pBYR2HS vector that led to about 4 mg/g fresh weight of protein expression in Nicotiana benthamiana. In this study, we validated the adaptability of this transient protein expression system by agroinfiltration to leaves and fruits of several tomato cultivars and wild species. Although the GFP protein was transiently expressed in the leaves and fruits of all tomato cultivars and wild species, we observed species-specific differences in protein expression. In particular, GFP protein expression was higher in the leaves and fruits of Micro-Tom, Solanum pimpinellifolium (0043) and S. pimpinellifolium (0049-w1) than in those of cultivars and wild species. Furthermore, Agrobacterium with GABA transaminase enhanced transient expression in tomato fruits of Micro-Tom. Taken together with these results, our system is applicable to several tomato cultivars and species as well as a model tomato, even though characteristics are often different among tomato cultivars or species. Thus, the system is an effective, simple, and valuable tool to achieve rapid transgene expression to examine gene function in tomato plant cells. [ABSTRACT FROM AUTHOR]

Banana fruits are firstly green due to chlorophyll, then yellow due to carotenoids and finally turn black due to polyphenols. However, bananas glow blue when observed under UV light. It has been reported that chlorophylls fade to give rise to fluorescent chlorophyll catabolites (FCCs) in senescent banana leaves and in ripening banana peels. FCCs are short lived catabolic intermediates that ultimately lead to non-fluorescent chlorophyll catabolites (NCCs). FCCs are abundant in bananas due to hypermodification; therefore, it was concluded that FCC caused yellow bananas to glow blue. Experiments were performed in order to shed new light into the autofluorescence phenomenon. Microscopy performed on living plant samples contradict the interpretation that the fluorescent blue glow is mainly caused by FCC inside the cell. Blue fluorescence in banana emerges from the cell wall, not from the symplasm. It is not primarily caused by soluble chlorophyll catabolites in the vacuoles or senescing plastids. Insoluble phenolics from the apoplast make bananas shine strongly blue under black light. Chlorophyll is a light trap that generates black holes of blue fluorescence, and therefore cells with chloroplasts glow less blue. The white pulp of banana fruits shine more strongly than the outer peel. In both tissues autofluorescence arises from insoluble phenols that are estherified to the cell wall. In monocot species (banana, maize, sugarcanne), blue fluorescense was strongest in the cell wall, whereas in dicots (e.g. arabidopsis, spearmint, hibiscus), blue fluorescence may be dominant from cytosolic, vacuolar or plastidial compartments. [ABSTRACT FROM AUTHOR]

Amino acids play vital roles in the central metabolism of seeds. They are primarily utilized for the synthesis of seed-storage proteins, but also serve as precursors for the biosynthesis of secondary metabolites and as a source of energy. Here, we aimed at describing the knowledge accumulated in recent years describing the changes occurring in the contents of free amino acids (FAAs) during seed development. Since several essential amino acids are found in low levels in seeds ( e.g. , Lys, Met, Thr, Val, Leu, Ile and His), or play unique functional roles in seed development ( e.g ., Pro and the non-proteinogenic γ-aminobutyrate [GABA]), we also briefly describe studies carried out in order to alter their levels in seeds and determine the effects of the manipulation on seed biology. The lion share of these studies highlights strong positive correlations between the biosynthetic pathways of FAAs, meaning that when the levels of a certain amino acid change in seeds, the contents of other FAAs tend to elevate as well. These observations infer a tight regulatory network operating in the biosynthesis of FAAs during seed development. [ABSTRACT FROM AUTHOR]

Abstract: The γ‐aminobutyrate type A receptor‐associated protein (GABARAP) is a ubiquitin‐like modifier implicated in membrane trafficking and fusion events involving the γ‐aminobutyrate type A receptor, autophagy and apoptosis. In this study, the gene encoding GABARAP was cloned from swimming crab Portunus trituberculatus (PtGABARAP) based on the expression sequence tag (EST). The full‐length cDNA of 664 bp includes a 5′ untranslated region (UTR) of 87 bp, a 3′ UTR of 223 bp with a poly(A) tail, and an open reading frame (ORF) of 354 bp encoding a polypeptide of 117 amino acids with a predicted molecular weight of 13.96 kDa. The deduced amino acid sequence shares high similarity (93%–100%) with GABARAPs from other species and includes a conserved Atg8 domain. In a phylogenetic analysis PtGABARAP clustered with GABARAPs from other species, and more widely with other GABARAP family proteins. The impact of elevated ocean acidification (OA) on P. trituberculatus behaviours was investigated, and real‐time RT‐PCR revealed that PtGABARAP expression was up‐regulated after OA exposure. Ocean acidification also caused crabs anxiety‐like behaviours, like the shoal average speed increase, preference for dark environment (scototaxis) and fast exploration. The results indicated that GABARAP might be involved in the interactions of GABAA receptors and elevated‐CO2 seawater. [ABSTRACT FROM AUTHOR]

The molluscicidal toxicity of abamectin against two economic snails namely, the brawn garden snail (Eobania vermiculata) and the white garden snail (Theba pisana), was established under in vivo conditions. Abamectin was used by the topical application technique. The mortality of snails was recorded after 24 and 72 hrs of exposure. The obtained results revealed that E. vermiculata was more resistant to abamectin than T. pisana. The LD50 for E. vermiculata after 24 and 72 hrs of exposure were 0.379 & 0.250 µg/ gm b.w, respectively. Whereas the LD50 for T. pisana were 0.199 and 0.125 µg/ gm b.w after 24 and 72 hrs of exposure, consecutively. On the other hand, the impact of abamectin upon GABA- Transaminase concentration was estimated in both snails. For the first time, the activity of GABA- T was estimated by HPLC. Abamectin has been assessed with 1/2, 1/5 and 1/10 of LD50 for 24 and 72 hrs of exposure. The most effective dose on GABA- T activity was 1/2 of LD50 after 24 and 72hrs of application for both snails. [ABSTRACT FROM AUTHOR]

Aminotransferases are pyridoxal 5'-phosphate--dependent enzymes that catalyze reversible transamination reactions between amino acids and α-keto acids, and are important for the cellular metabolism of nitrogen. Many bacterial and eukaryotic ω-aminotransferases that use L-ornithine (Orn), L-lysine (Lys), or γ-aminobutyrate (GABA) have been identified and characterized, but the corresponding enzymes from archaea are unknown. Here, we examined the activity and function of TK2101, a gene annotated as a GABA aminotransferase, from the hyperthermophilic archaeon Thermococcus kodakarensis. We overexpressed the TK2101 gene in T. kodakarensis and purified and characterized the recombinant protein and found that it displays only low levels of GABA aminotransferase activity. Instead, we observed a relatively high ω-aminotransferase activity with L-Orn and L-Lys as amino donors. The most preferred amino acceptor was 2-oxoglutarate. To examine the physiological role of TK2101, we created a TK2101 gene--disruption strain (ΔTK2101), which was auxotrophic for proline. Growth comparison with the parent strain KU216 and the biochemical characteristics of the protein strongly suggested that TK2101 encodes an Orn aminotransferase involved in the biosynthesis of L-Pro. Phylogenetic comparisons of the TK2101 sequence with related sequences retrieved from the databases revealed the presence of several distinct protein groups, some of which having no experimentally studied member. We conclude that TK2101 is part of a novel group of Orn aminotransferases that are widely distributed at least in the genus Thermococcus, but perhaps also throughout the Archaea. [ABSTRACT FROM AUTHOR]

Propionic acidemia is the accumulation of propionate in blood due to dysfunction of propionyl- CoA carboxylase. The condition causes lethargy and striatal degeneration with motor impairment in humans. How propionate exerts its toxic effect is unclear. Here, we show that intravenous administration of propionate causes dose-dependent propionate accumulation in the brain and transient lethargy in mice. Propionate, an inhibitor of histone deacetylase, entered GABAergic neurons, as could be seen from increased neuronal histone H4 acetylation in the striatum and neocortex. Propionate caused an increase in GABA (γ-amino butyric acid) levels in the brain, suggesting inhibition of GABA breakdown. In vitro propionate inhibited GABA transaminase with a Ki of ~1 mmol/l. In isolated nerve endings, propionate caused increased release of GABA to the extracellular fluid. In vivo, propionate reduced cerebral glucose metabolism in both striatum and neocortex. We conclude that propionate-induced inhibition of GABA transaminase causes accumulation of GABA in the brain, leading to increased extracellular GABA concentration, which inhibits neuronal activity and causes lethargy. Propionate-mediated inhibition of neuronal GABA transaminase, an enzyme of the inner mitochondrial membrane, indicates entry of propionate into neuronal mitochondria. However, previous work has shown that neurons are unable to metabolize propionate oxidatively, leading us to conclude that propionyl- CoA synthetase is probably absent from neuronal mitochondria. Propionate-induced inhibition of energy metabolism in GABAergic neurons may render the striatum, in which >90% of the neurons are GABAergic, particularly vulnerable to degeneration in propionic acidemia. [ABSTRACT FROM AUTHOR]

We discuss the origin of 4-aminobutyrate (GABA) from glutamate and polyamines, and its subsequent catabolism to succinic semialdehyde and either succinate or 4-hydroxybutyrate. Promiscuous activities of GABA transaminase, glyoxylate/succinic semialdehyde reductases, and aldehyde dehydrogenase 10As appear to be important determinants of cross-talk among metabolic pathways during stress. Imposition of abiotic stress, as well as genetic or chemical disruption of glutamate decarboxylase, GABA transaminase, and tricarboxylic acid cycle reactions, results in non-cyclic carbon flux in the tricarboxylic acid cycle, demonstrating that stress-induced GABA metabolism is strongly linked with respiration. Metabolic generation of 4-hydroxybutyrate is probably linked to the stimulation of succinic semialdehyde reductase activity by an increasing NADPH/NADP+ ratio. We discuss the potential signaling role of GABA in various processes, including pollen tube guidance, interaction with fungal, bacterial, and invertebrate pests, and stomatal functioning, and argue that further research on short-term responses to stress is required to determine whether or not GABA functions by binding to or regulating the activity of GABA receptor molecules. Finally, we describe how emerging information about the metabolic and signaling roles of GABA is being used to improve plant defenses against biotic and abiotic stresses, and benefit human health. [ABSTRACT FROM AUTHOR]

GABA is catabolized in the mitochondrial matrix through the GABA shunt, encompassing transamination to succinic semialdehyde followed by oxidation to succinate by the concerted actions of GABA transaminase (GABA-T) and succinic semialdehyde dehydrogenase (SSADH), respectively. Gamma-hydroxybutyrate (GHB) is a neurotransmitter and a psychoactive drug that could enter the citric acid cycle through transhydrogenation with α-ketoglutarate to succinic semialdehyde and d -hydroxyglutarate, a reaction catalyzed by hydroxyacid-oxoacid transhydrogenase (HOT). Here, we tested the hypothesis that the elevation in matrix succinate concentration caused by exogenous addition of GABA, succinic semialdehyde or GHB shifts the equilibrium of the reversible reaction catalyzed by succinate-CoA ligase towards ATP (or GTP) hydrolysis, effectively negating substrate-level phosphorylation (SLP). Mitochondrial SLP was addressed by interrogating the directionality of the adenine nucleotide translocase during anoxia in isolated mouse brain and liver mitochondria. GABA eliminated SLP, and this was rescued by the GABA-T inhibitors vigabatrin and aminooxyacetic acid. Succinic semialdehyde was an extremely efficient substrate energizing mitochondria during normoxia but mimicked GABA in abolishing SLP in anoxia, in a manner refractory to vigabatrin and aminooxyacetic acid. GHB could moderately energize liver but not brain mitochondria consistent with the scarcity of HOT expression in the latter. In line with these results, GHB abolished SLP in liver but not brain mitochondria during anoxia and this was unaffected by either vigabatrin or aminooxyacetic acid. It is concluded that when mitochondria catabolize GABA or succinic semialdehyde or GHB through the GABA shunt, their ability to perform SLP is impaired. [ABSTRACT FROM AUTHOR]

Corynebacterium glutamicum that expresses an exogenous l -glutamate decarboxylase (GAD) gene can synthesize γ-aminobutyric acid (GABA). GABA is decomposed to succinic semialdehyde (SSA) by GABA transaminase (GABA-T) and to succinate thereafter by SSA dehydrogenase (SSADH). However, deletion of the gabT gene encoding GABA-T could not prevent GABA from decomposing at neutral pH. In this study, an additional transaminase gene, NCgl2515, was deleted in a gabT -deleted GAD strain, and GABA fermentation in this gabT NCgl2515-deleted GAD strain was investigated. GABA concentration remained at 22.5–24.0 g/L when pH was maintained at 7.5–8.0, demonstrating that GABA decomposition was reduced. Activity assay indicated that unlike GabT, which exhibits high GABA-T activity (1.34 ± 0.06 U/mg) and utilizes only α-ketoglutarate as amino acceptor, the purified NCgl2515 protein exhibits very low GABA-T activity (approximately 0.03 U/mg) only when coupled with the SSADH, GabD, but can utilize both α-ketoglutarate and pyruvate as amino acceptor. The optimum pH for coupled NCgl2515–GabD was 8.0, similar to that of GabT (7.8). Therefore, NCgl2515 has weak GABA-T activity and is involved in GABA decomposition in C. glutamicum . Deletion of gabT and NCgl2515 could effectively reduce GABA decomposition at neutral pH. [ABSTRACT FROM AUTHOR]

Deficiency of gamma-amino-butyrate aminotransferase (ABAT) is a rare inherited disorder. A six-month-old girl presented with hyper-somnolence, hyperkinetic movements of distal extremities during wakefulness, hypotonia, bi-pyramidal signs, and impaired response to sound and visual stimuli. Brain MRI at five months showed restricted diffusion along the internal capsule and genu of corpus callosum. A follow up MRI at 18 months, showed hyperintensities in brainstem, external and internal capsule, ‘trilaminated’ appearance of posterior limb of internal capsule and dysmyelination of sub-cortical white matter. MRS showed a peak between 2.2 ppm and 2.4 ppm, corresponding to glutamine, glutamate and GABA. EEG was normal at six months but showed multifocal epileptiform discharges at 18 months. Targeted exome sequencing revealed compound heterozygous missense variations in ABAT resulting in its reduced function. We report the novel association of hypersomnolence and hyperkinetic movement disorder with ABAT variations thus expanding the clinical spectrum of this uncommon neuro-metabolic disorder and discuss the emerging role of GABA in pathways regulating sleep-wake cycle and movement disorders. [ABSTRACT FROM AUTHOR]

Vigabatrin (VGB) is an antiepileptic drug thatincreases brain γ-aminobutyric acid (GABA) levels through irreversible inhibition of GABA transaminase. The aim of this study was to evaluate neurotoxicological effects of VGB measuring motor activity and genotoxic and mutagenic effects after a single and repeated administration. Male Wistar rats received saline, VGB 50, 100, or 250 mg/kg by gavage for acute and subchronic (14 days) treatments and evaluated in the rotarod task. Genotoxicity was evaluated using the alkaline version of the comet assay in samples of blood, liver, hippocampus, and brain cortex after both treatments. Mutagenicity was evaluated using the micronucleus test in bone marrow of the same animals that received subchronic treatment. The groups treated with VGB showed similar performance in rotarod compared with the saline group. Regarding the acute treatment, it was observed that only higher VGB doses induced DNA damage in blood and hippocampus. After the subchronic treatment, VGB did not show genotoxic or mutagenic effects. In brief, VGB did not impair motor activities in rats after acute and subchronic treatments. It showed a repairable genotoxic potential in the central nervous system since genotoxicity was observed in the acute treatment group. [ABSTRACT FROM AUTHOR]

Anthurium flowers are susceptible to chilling injury, and the optimum storage temperature is 12.5–20 °C. The γ-aminobutyric acid (GABA) shunt pathway may alleviate chilling stress in horticultural commodities by providing energy (ATP), reducing molecules (NADH), and minimizing accumulation of reactive oxygen species (ROS). In this experiment, the impact of a preharvest spray treatment with 1 mM GABA and postharvest treatment of 5 mM GABA stem-end dipping on GABA shunt pathway activity of anthurium cut flowers (cv. Sirion) in response to cold storage (4 °C for 21 days) was investigated. GABA treatments resulted in lower glutamate decarboxylase (GAD) and higher GABA transaminase (GABA-T) activities in flowers during cold storage, which was associated with lower GABA content and coincided with higher ATP content. GABA treatments also enhanced accumulation of endogenous glycine betaine (GB) in flowers during cold storage, as well as higher spathe relative water content (RWC). These findings suggest that GABA treatments may alleviate chilling injury of anthurium cut flowers by enhancing GABA shunt pathway activity leading to provide sufficient ATP and promoting endogenous GB accumulation. [ABSTRACT FROM AUTHOR]

Due to the sensitivity of anthurium flowers to chilling injury (CI), its favorable temperature storage is 12.5–20 °C. There is evidence that maintaining the functional γ-aminobutyric acid (GABA) shunt pathway is crucial for tolerance to postharvest chilling stress by providing energy (ATP) and reducing molecule (NADH) and minimizing reactive oxygen species (ROS) accumulation. In this experiment, the impact of salicylic acid (SA) treatment applied by postharvest stem-end dipping (2 mM, 15 min at 20 °C) on GABA shunt pathway activity of anthurium cut flowers (cv. Sirion) storage at 4 °C for 21 days were investigated. The anthurium cut flowers in response to 2 mM SA treatment displayed significantly higher GABA transaminase (GABA-T) activity during storage at 4 °C for 21 days, which coincided with lower GABA content, leading to flowers with lower spathe browning. SA treatment enhanced GABA shunt pathway activity, by enhancing GABA-T activity, during storage at 4 °C, lead to consumption of GABA for providing sufficient ATP content associated with the lower H 2 O 2 content. Also, anthurium cut flowers in response to SA treatment displayed significantly higher unsaturated/saturated fatty acids (unSFA/SFA) ratio, which can be results not only from higher energy content but also from lower phospholipase D (PLD) and lipoxygenase (LOX) activities. These findings showed that SA treatment at 2 mM maintained functional GABA shunt pathway activity which leads to providing higher ATP, lower H 2 O 2 accumulation, higher unSFA/SFA ratio, proposed that the SA can be applied as an effective procedure for improving anthurium cut flowers tolerance to postharvest chilling stress, by enhancing membrane fluidity. [ABSTRACT FROM AUTHOR]

Pentylenetetrazole (PTZ), γ-aminobutyrate (GABA) antagonist, is a convulsant drug, known to induce anxiety and seizures in zebrafish. Changes in the mobility of zebrafish under light-dark transitions reflect anxiety level, serving as a useful behavioral readout. The effects of PTZ treatment have yet to be assayed in this manner. Zebrafish larvae (AB strain) at both 5 dpf (days post-fertilization) and 7 dpf were treated with different concentrations of PTZ. General locomotor activity and thigmotaxis were analyzed under continuous illumination (normal conditions) or alternating light-dark cycles (stressful conditions). Zebrafish larvae of 5 dpf and 7 dpf exhibited different sensitivities to PTZ. Anxiety level, measured in terms of response to illumination transitions under the influence of PTZ, demonstrated contrasting tendencies. Dark-light transitions dramatically increased the locomotor activity of zebrafish larvae receiving 8 mM PTZ which was indicative of anxiety. This study suggests that PTZ increases the susceptibility by activating the neuron, which perhaps makes light change easier to influence the anxiety level of larvae. We provide useful evidence for putative anti-anxiety drug screening. [ABSTRACT FROM AUTHOR]

The isotopomers of halogen derivatives ofl-tryptophan (l-Trp) (4′-F-, 7′-F-, 5′-Cl- and 7′-Br-l-Trp), specifically labelled with deuterium inα-position of the side chain, were obtained by enzymatic coupling of the corresponding halogenated derivatives of indole withS-methyl-l-cysteine in2H2O, catalysed by enzyme tryptophanase (EC 4.1.99.1). The positional deuterium enrichment of the resulting tryptophan derivatives was controlled using1H NMR. In accordance with the mechanism of the lyase reaction, a 100% deuterium labelling was observed in theα-position; the chemical yields were between 23 and 51%. Furthermore,β-F-l-alanine, synthesized fromβ-F-pyruvic acid by thel-alanine dehydrogenase reaction, has been tested as a coupling agent to obtain the halogenated deuterium-labelled derivatives ofl-Trp. The chemical yield (∼30%) corresponded to that as observed withS-methyl-l-cysteine but the deuterium label was only 63%, probably due to the use of a not completely deuterated incubation medium. [ABSTRACT FROM PUBLISHER]

The γ-aminobutyrate (GABA)-degradative enzyme GABA aminotransferase (GABA-AT) is regarded as an attractive target to control GABA levels in the central nervous system: this has important implications in the treatment of several neurological disorders and drug dependencies. We have investigated the ability of newly synthesized compounds to act as GABA-AT inhibitors. These compounds have a unique bicyclic structure: the carbocyclic ring bears the GABA skeleton, while the fused 3-Br-isoxazoline ring contains an electrophilic warhead susceptible of nucleophilic attack by an active site residue of the target enzyme. Out of the four compounds tested, only the one named (+)-3was found to significantly inhibit mammalian GABA-ATin vitro. Docking studies, performed on the available structures of GABA-AT, support the experimental findings: out of the four tested compounds, only (+)-3suitably orients the electrophilic 3-Br-isoxazoline warhead towards the active site nucleophilic residue Lys329, thereby explaining the irreversible inhibition of GABA-AT observed experimentally. [ABSTRACT FROM AUTHOR]

Increased sympathetic nervous system (SNS) activity is associated with cardiovascular diseases but its role has not been completely explored in pulmonary hypertension (PH). Increased SNS activity is distinguished by elevated level of norepinephrine (NE) and activity of γ-Amino butyric acid Transminase (GABA-T) which degrades GABA, an inhibitory neurotransmitter within the central and peripheral nervous system. Therefore, we hypothesized that GABA-T may contribute in pathophysiology of PH by modulating level of GABA and NE. The effect of daily oral administration of GABA-T inhibitor, Vigabatrin (GVG, 50 and 75 mg/kg/day, 35 days) was studied following a single subcutaneous administration of monocrotaline (MCT, 60 mg/kg) in male SD rats. The pressure and hypertrophy of right ventricle (RV), oxidative stress, inflammation, pulmonary vascular remodelling were assessed after 35 days in MCT treated rats. The expression of GABA-T and HIF-1α was studied in lung tissue. The levels of plasma NE (by High performance liquid chromatography coupled with electrochemical detector; HPLC-ECD) and lung GABA (by liquid chromatography-mass spectrometry) were also estimated. GVG at both doses significantly attenuated increased in pressure (35.82 ± 4.80 mm Hg, p < 0.001; 28.37 ± 3.32 mm Hg, p < 0.001 respectively) and hypertrophy of RV, pulmonary vascular remodelling, oxidative stress and inflammation in lungs of MCT exposed rats. GVG also reduced the expression of GABA-T and HIF-1α in MCT treated rats. Increased NE level and decreased GABA level was also reversed by GVG in MCT exposed rats. GABA-T plays an important role in PH by modulating SNS activity and may be considered as a therapeutic target in PH. [ABSTRACT FROM AUTHOR]

Colon cancer cells contain high levels of cystathionine-β-synthase (CBS). Its product, hydrogen sulfide (H2S), promotes the growth and proliferation of colorectal tumor cells. To improve the antitumor efficacy of the prototypical CBS inhibitor aminooxyacetic acid (AOAA), we have designed and synthesized YD0171, a methyl ester derivative of AOAA. The antiproliferative effect of YD0171 exceeded the antiproliferative potency of AOAA in HCT116 human colon cancer cells. The esterase inhibitor paraoxon prevented the cellular inhibition of CBS activity by YD0171. YD0171 suppressed mitochondrial respiration and glycolytic function and induced G0/G1 arrest, but did not induce tumor cell apoptosis or necrosis. Metabolomic analysis in HCT116 cells showed that YD0171 affects multiple pathways of cell metabolism. The efficacy of YD0171 as an inhibitor of tumor growth was also tested in nude mice bearing subcutaneous HCT116 cancer cell xenografts. Animals were treated via subcutaneous injection of vehicle or AOAA (0.1, 0.5 or 1 mg/kg/d) for 3 wks. Tumor growth was significantly reduced by 9 mg/kg/d AOAA, but not at the lower doses. YD0171 was more potent: tumor volume was significantly inhibited at 0.5 and 1 mg/kg/d. Thus, the in vivo efficacy of YD0171 is nine times higher than that of AOAA. YD0171 (1 mg/kg/d) attenuated tumor growth and metastasis formation in the intracecal HCT116 tumor model. YD0171 (3 mg/kg/d) also reduced tumor growth in patient-derived tumor xenograft bearing athymic mice. YD0171 (3 mg/kg/d) induced the regression of established HCT116 tumors in vivo. A 5-d safety study in mice demonstrated that YD0171 at 20 mg/kg/d (given in two divided doses) does not increase plasma markers of organ injury, nor does it induce histological alterations in the liver or kidney. YD0171 caused a slight elevation in plasma homocysteine levels. In conclusion, the prodrug approach improves the pharmacological profile of AOAA; YD0171 represents a prototype for CBS inhibitory anticancer prodrugs. By targeting colorectal cancer bioenergetics, an emerging important hallmark of cancer, the approach exemplified herein may offer direct translational opportunities. [ABSTRACT FROM AUTHOR]

In the present study, three Arabidopsis thaliana pop2 mutant lines with different T-DNA insertions in a gene coding γ-aminobutyric acid transaminase (GABA-TA) were screened for seed germination percentage, stress-induced oxidative damage, and GABA content and metabolism under various abiotic stresses including high temperature (42 °C), low temperature (4 °C), salinity (NaCl), and osmotic stress (mannitol). All mutant lines showed a decreased germination under all the stress treatments with a significant reduction in the pop2 -1 and pop2-3 mutant lines. Content of GABA and MDA increased significantly in all pop2 mutants and wild type (WT) seedlings in response to all the treatments. However, content of GABA and MDA was lower in all pop2 mutants comparing to the WT under the same treatments. GABA increased already after 30 min and increased significantly after 2 h at 42 °C especially in the pop2-3 and WT seedlings. In response to the cold treatment, GABA content increased up to 4-fold compared to the control in all pop2 mutants and WT seedlings. In response to the NaCl treatment, GABA accumulated slightly in the WT and all pop2 mutants. On the contrary, GABA content increased significantly in the pop2, pop2-1, and pop2-3 mutants and WT under all mannitol treatments. [ABSTRACT FROM AUTHOR]