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Photosynthesis is critically dependent on both adequate light and nitrogen availability. In controlled agricultural environments with limited natural light, cucumber faces substantial challenges, including reduced photosynthetic efficiency and biomass accumulation. Nitrogen (N) is a vital component for the synthesis of various macromolecules, metabolites, and signaling molecules in plants. This study assessed the impact of different nitrate levels (LL-N, LL-1/2N, and LL-2N) on the physiological, biochemical, and metabolic responses of cucumber under low light conditions (80-100 µmol m-2 s-1 photosynthetic photon flux density) in comparison to standard light (400-500 µmol m-2 s-1 photosynthetic photon flux density) and unchanged nitrate. We observed that increasing nitrate levels to twice the standard concentration (LL-2N) significantly enhanced shoot morphology, including weight and size, and improved photosynthetic performance, stomatal conductance, and transpiration rates. In contrast, lower nitrate levels (LL-1/2N) exacerbated stress, leading to diminished photosynthesis and biomass. Biochemical analyses indicated that elevated nitrate concentrations activated key enzymes involved in the metabolism of carbon and nitrogen, including glutamine synthetase, sucrose phosphate synthase, nitrate reductase, and glutamate synthase. This led to improvement in the amounts of sucrose, fructose, soluble sugars, free amino acids, and soluble proteins. Additionally, the activities of antioxidant enzymes including superoxide dismutase, peroxidase, catalase, and ascorbate peroxidase were considerably greater under conditions of increased nitrate, which reduced the levels of malondialdehyde and H2O2 as oxidative stress markers. Furthermore, enhanced nitrate levels upregulated critical photosynthetic genes (rbcL, rbcS, FBPase, and SBPase mRNA), supporting the RuBisCO contents and overall photosynthetic capacity. These findings underscore the effectiveness of strategic nitrate enrichment in mitigating low light stress, providing essential insights for optimizing cucumber cultivation in controlled environments and improving productivity. [ABSTRACT FROM AUTHOR]

Boundary cap cells are a population of multipotent stem cells that have great potential for the use in the treatment of damaged nervous system. We studied the patterns of distribution of the gap junction protein connexin-43 (Cx43) in boundary cap cells of the ventral root of the spinal cord of rat embryos (E12-E20; n=40). It was found that Cx43 is expressed in ventral boundary cap cells at all stages of its existence during embryogenesis. At the early stages of prenatal development, the cytoplasmic distribution of Cx43 in the boundary cap cells predominates; at the later stages, Cx43-immunopositive punctate structures are identified. These puncta represent gap junction plaques between the cells. It can be assumed that during the early embryogenesis, Cx43 regulates the main histogenetic processes in boundary cap cells and only in the later stages of prenatal development, Cx43-mediated communications are formed between boundary cap cells. [ABSTRACT FROM AUTHOR]

The trade-offs exist between microbial growth and bioproduct synthesis including intracellular polyester polyhydroxybutyrate (PHB). Under nitrogen limitation, more carbon flux is directed to PHB synthesis while growth is inhibited with diminishing overall carbon utilization, similar to the suboptimal carbon utilization during glycolysis-derived pyruvate decarboxylation. This study reconfigured the central carbon network of Halomonas blu e phagenesis to improve PHB yield theoretically and practically. It was found that the downregulation of glutamine synthetase (GS) activity led to a synchronous improvement on PHB accumulation and cell growth under nitrogen non-limitation condition, increasing the PHB yield from glucose (g/g) to 85% of theoretical yield, PHB titer from 7.6 g/L to 12.9 g/L, and from 51 g/L to 65 g/L when grown in shake flasks containing a rich N-source, and grown in a fed-batch cultivation conducted in a 7-L bioreactor also containing a rich N-source, respectively. Results offer better metabolic balance between glucose conversion efficiency and microbial growth for economic PHB production. • PHB synthesis was improved by regulating C- and N-metabolic flux in H. bluephagenesis. • Glutamine synthetase was found as a regulator balancing growth and PHB synthesis. • 85% theoretical PHB yield was achieved when grown in N-rich media. [ABSTRACT FROM AUTHOR]

Hydrogen sulfide (H2S) functions as a signaling molecule affecting plant growth, development, and stress adaptation. Tall fescue (Festuca arundinacea Schreb.), a bioenergy crop, encounters significant challenges in agricultural production owing to low light by shading. However, the influence of H2S on tall fescue under low light stress (LLS) remains unclear. To examine the role of H2S in acclimation of tall fescue to low light, we conducted combined analyses of physiological traits, metabolomics, and transcriptomics. These results showed that H2S mitigated LLS‐induced inhibition of photosynthesis and maintained normal chloroplast ultrastructure by boosting the expression of photosynthesis‐related genes, including PsbQ, PsbR, PsaD, PsaK, and PetH, thereby enhancing the synthesis of carbohydrates (sucrose, starch). H2S upregulated the expression of key genes (PFK, PK, IDH, G6PD) connected to glycolysis, the tricarboxylic acid cycle, and the pentose phosphate pathway to promote carbon metabolism and ensure the supply of carbon skeletons and energy required for nitrogen metabolism. H2S application reverted the LLS‐induced accumulation of nitrate nitrogen and the changes in the key nitrogen metabolism enzymes glutamate synthase (GOGAT, EC 1.4.1.13), nitrate reductase (NR, EC 1.6.6.1), glutamine synthetase (GS, EC 6.3.1.2), and glutamate dehydrogenase (GDH, EC 1.4.1.2), thus promoting amino acid decomposition to produce proteins involved in nitrogen assimilation and nitrogen use efficiency as well as specialized metabolism. Ultimately, H2S upregulated the C/N ratio of tall fescue, balanced its carbon and nitrogen metabolism, enhanced shade tolerance, and increased biomass. These results provided new insights into enhancing plant resilience under LLS. [ABSTRACT FROM AUTHOR]

The spermatogenic capacity of adult individuals depends on, among other factors, the number of Sertoli cells (SCs) that result from the proliferative waves during development. FSH upregulates SC proliferation at least partly, through the activation of the PI3K/Akt/mTORC1 pathway, among other mechanisms. It is widely known that mTORC1 is a sensor of amino acids. Among amino acids, glutamine acquires relevance since it might contribute to cell cycle progression through the modulation of mTORC1 activity. It has not been studied yet whether glutamine intervenes in FSH-mediated regulation of SC proliferation and cell cycle progression, or if FSH has any effect on glutamine metabolism. Eight-day-old rat SCs were incubated in culture media without glutamine or with glutamine in the absence or presence of a glutamine transporter inhibitor or a glutaminase activity inhibitor under basal conditions or stimulated with FSH. The results obtained show that FSH does not promote SC proliferation and mTORC1 activation in the absence of glutamine. Also, FSH modulates glutamine metabolism increasing glutaminase isoform 2 and reducing glutamine synthetase expression. FSH did not promote SC proliferation and mTORC1 activation when glutaminase activity was inhibited. The results suggest that glutamine or its metabolites might cooperate with FSH in the upregulation of SC proliferation through mTORC1. In addition, as FSH modulates glutamine metabolism through the induction of glutaminase isoform 2, the hormonal control of glutamine metabolism might be part of the intricate signaling network triggered by FSH, which is crucial to establish the population of mature SCs that supports the reproductive function. [ABSTRACT FROM AUTHOR]

Acute liver dysfunction commonly leads to rapid increases in ammonia concentrations in both the serum and the cerebrospinal fluid. These elevations primarily affect brain astrocytes, causing modifications in their structure and function. However, its impact on neurons is not yet fully understood. In this study, we investigated the impact of elevated ammonium chloride levels (NH4Cl, 5 mM) on synaptic transmission onto CA1 pyramidal neurons in mouse organotypic entorhino-hippocampal tissue cultures. We found that acute exposure to NH4Cl reversibly reduced excitatory synaptic transmission and affected CA3-CA1 synapses. Notably, NH4Cl modified astrocytic, but not CA1 pyramidal neuron, passive intrinsic properties. To further explore the role of astrocytes in NH4 Clinduced attenuation of synaptic transmission, we used methionine sulfoximine to target glutamine synthetase, a key astrocytic enzyme for ammonia clearance in the central nervous system. Inhibition of glutamine synthetase effectively prevented the downregulation of excitatory synaptic activity, underscoring the significant role of astrocytes in adjusting excitatory synapses during acute ammonia elevation. [ABSTRACT FROM AUTHOR]

Rapid and efficient cell line development (CLD) process is essential to expedite therapeutic protein development. However, the performance of widely used glutamine‐based selection systems is limited by low selection efficiency, stringency, and the inability to select multiple genes. Therefore, an AND‐gate synthetic selection system is rationally designed using split intein‐mediated protein ligation of glutamine synthetase (GS) (SiMPl‐GS). Split sites of the GS are selected using a computational approach and validated with GS‐knockout Chinese hamster ovary cells for their potential to enable cell survival in a glutamine‐free medium. In CLD, SiMPl‐GS outperforms the wild‐type GS by selectively enriching high producers. Unlike wild‐type GS, SiMPl‐GS results in cell pools in which most cells produce high levels of therapeutic proteins. Harnessing orthogonal split intein pairs further enables the selection of four plasmids with a single selection, streamlining multispecific antibody‐producing CLD. Taken together, SiMPl‐GS is a simple yet effective means to expedite CLD for therapeutic protein production. [ABSTRACT FROM AUTHOR]

Waxy corn is a special type of maize primarily consumed as a fresh vegetable by humans. Nitrogen (N) plays an essential role in regulating the growth progression, maturation, yield, and quality of waxy maize. A reasonable N application rate is vital for boosting the accumulation of both N and carbon (C) in the grains, thereby synergistically enhancing the grain quality. However, the impact of varying N levels on the dynamic changes in N metabolism, carbohydrate formation, and anthocyanin synthesis in purple waxy corn kernels, as well as the regulatory relationships among these processes, remains unclear. To explore the effects of varying N application rates on the N metabolism, carbohydrate formation, and anthocyanin synthesis in kernels during grain filling, a two-year field experiment was carried out using the purple waxy maize variety Jinnuo20 (JN20). This study examined the different N levels, specifically 0 (N0), 120 (N1), 240 (N2), and 360 (N3) kg N ha−1. The results of the analysis revealed that, for nearly all traits measured, the N application rate of N2 was the most suitable. Compared to the N0 treatment, the accumulation and content of anthocyanins, total nitrogen, soluble sugars, amylopectin, and C/N ratio in grains increased by an average of 35.62%, 11.49%, 12.84%, 23.74%, 13.00%, and 1.87% under N2 treatment over five filling stages within two years, respectively, while the harmful compound nitrite content only increased by an average of 30.2%. Correspondingly, the activities of related enzymes also significantly increased and were maintained under N2 treatment compared to N0 treatment. Regression and correlation analysis results revealed that the amount of anthocyanin accumulation was highly positively correlated with the activities of phenylalanine ammonia-lyase (PAL) and flavanone 3-hydroxylase (F3H), but negatively correlated with anthocyanidin synthase (ANS) and UDP-glycose: flavonoid-3-O-glycosyltransferase (UFGT) activity, nitrate reductase (NR), and glutamine synthetase (GS) showed significant positive correlations with the total nitrogen content and lysine content, and a significant negative correlation with nitrite, while soluble sugars were negatively with ADP-glucose pyrophosphorylase (AGPase) activity, and amylopectin content was positively correlated with the activities of soluble starch synthase (SSS), starch branching enzyme (SBE), and starch debranching enzyme (SDBE), respectively. Furthermore, there were positive or negative correlations among the detected traits. Hence, a reasonable N application rate improves purple waxy corn kernel nutritional quality by regulating N metabolism, as well as carbohydrate and anthocyanin biosynthesis. [ABSTRACT FROM AUTHOR]

Improving vegetable yield and optimizing its quality through nutrient management have long been central to plant nutrition and horticultural science. Copper (Cu) is recognized as an essential trace element that promotes plant growth and development. However, the mechanisms by which Cu influences nitrogen (N) metabolism remain largely unknown, with limited studies exploring the interaction between Cu and varying nitrate-to-ammonium (nitrate/ammonium) ratios. In this study, Chinese cabbage was exposed to two Cu concentrations (0 and 0.02 mg L-1) in combination with three nitrate/ammonium ratios (10/90, 50/50, and 90/10) under hydroponic conditions. The results showed that Cu application increased plant biomass, nitrate reductase (NR) and glutamine synthetase (GS) enzyme activities, the expression of NR (NIA) and GS2 (Gln2) genes, and N content in both shoots and roots. Additionally, Cu treatment decreased nitrate and free amino acid contents, as well as the expression of nitrate transporters NRT1.1 and NRT2.1 in roots while increasing these four parameters in shoots. Additionally, these effects were significantly modulated by the nitrate/ammonium ratios. In conclusion, Cu may facilitate nitrate transportation, enhance nitrate reduction, promote ammonium assimilation, and influence the transformation of organic N compounds, highlighting its potential role in improving N metabolism in Chinese cabbage. [ABSTRACT FROM AUTHOR]

This article discusses the disruption of the retinal endothelial cell barrier by direct contact with retinal Müller glial cells (RMGCs) in vitro. The inner blood-retinal barrier plays a crucial role in protecting the neural retina by restricting the passage of solutes and microbes. The study aimed to develop a model for investigating the interactions between human retinal endothelial cells (RECs) and RMGCs to understand the breakdown of the blood-retinal barrier. The results showed that direct contact between RMGCs and RECs led to an activated and leaky retinal endothelium. This model could be useful for studying diseases like diabetic retinopathy and posterior uveitis and evaluating targeted treatments. [Extracted from the article]

This study selected two sweet potato varieties as research subjects and conducted a field experiment using a two-factor design with two potassium (K) levels (K0 and K1) and five nitrogen (N) levels (N0–N4). The physiological changes in sweet potato leaves under different N and K treatments were measured, and nutrients such as the soluble sugar, protein, and starch content of sweet potato roots were analyzed. The results indicate that the activity of glutamine synthetase (GS) and the soluble protein content in sweet potato leaves increase first and then decrease with increasing N application, while K application can significantly increase the activity of GS and the soluble protein content. The N metabolic capacity of leaves is strongest when the fertilizer ratio is K1N2. The SPAD value of sweet potato leaves increases with increasing N application. The net photosynthetic rate, stomatal conductance, and intercellular CO2 concentration first increase and then decrease with increasing N application. K fertilizer has a significant effect on these parameters. As the N application rate increases, the starch and protein content in the tubers increase, while the soluble sugar content decreases. However, the number of tubers per plant, fresh weight of the tubers, and dry weight of the tubers increase initially and then decrease, while the vine length continuously increases. The application of K fertilizer can significantly increase the number of tubers per plant and stem thickness of sweet potato. In conclusion, the appropriate N–K combined application can promote N metabolism, enhance the photosynthetic capacity of sweet potato, increase yield, and improve quality. [ABSTRACT FROM AUTHOR]

The concentration of nitrogen fertilizer is matched with the nutrient requirements in different growth stages of plants, which coordinates their vegetative and reproductive growth. In this study, the influences of nitrogen concentration before and after initiation of flower bud differentiation (first and second stage, respectively) on pepper seedling quality were studied. The chlorophyll a content, sucrose synthase activity, and sucrose phosphate synthase activity of pepper seedlings grown under moderate nitrogen (15 mmol L−1) in the first stage combined with high nitrogen (25.61 mmol L−1) in the second stage were 15.7%, 39.3%, and 34.6% higher than those of the same nitrogen concentration (15 mmol L−1) in the first and second stages treatment, respectively. The regression model also showed that the values of flower bud diameter, shoot fresh weight, root fresh weight, and glutamine synthetase activity of pepper were high under the condition of moderate nitrogen in the first stage and higher nitrogen in the second stage. In addition, the results of comprehensive evaluation showed that moderate nitrogen (15 mmol L−1) in the first stage and high nitrogen (25.61 mmol L−1) in the second stage treatment ranked first, which improved carbon and nitrogen metabolism, increased biomass accumulation, and promoted the flower bud differentiation and flowering of pepper seedlings. [ABSTRACT FROM AUTHOR]

Volicitin [N-(17-hydroxylinolenoyl)-L-glutamine] and N-linolenoyl-L-glutamine were originally identified in the regurgitant of Spodoptera exigua larvae. These fatty acid amino acid conjugates (FACs) are known to be elicitors that induce plants to release volatile compounds which in turn attract natural enemies of the larvae such as parasitic wasps. FAC concentrations are regulated by enzymatic biosynthesis and hydrolysis in the intestine of Lepidoptera larvae. It has been proposed that FAC metabolism activates glutamine synthetase and plays an important role in nitrogen metabolism in larvae. In this study, we identified candidate genes encoding a FACs hydrolase in Spodoptera litura using genomic information of various related lepidopteran species in which FACs hydrolases have been reported. We analyzed the importance of FAC hydrolysis on caterpillar performance with CRISPR/Cas9 knock outs. Larvae of strains with an inactive FACs hydrolase excreted FACs in their feces. They absorbed 30% less nitrogen from the diet compared to WT caterpillars resulting in a reduction of their body weight of up to 40% compared to wild type caterpillars. These results suggest that the hydrolysis of FACs is an important metabolism for insects and that FACs are important for larval growth. [ABSTRACT FROM AUTHOR]

Background: Polyaspartic Acid-Calcium (PASP-Ca) is a versatile and eco-friendly amino acid complex, primarily recognized for bolstering nitrogen use efficiency and crop productivity. However, the core significance of this complex remains enigmatic in potato crop. We hypothesized that simultaneous application of PASP-Ca with potato genotypes characterized by substantial root systems and high genetic potentials for nitrogen-use efficiency (NUE) would best address this knowledge gap. Methods: The synergistic effect of various PASP-Ca treatments on morph physiological, N-related, and enzymatic parameters coupled with their transcript levels (shoot and root) in four potato genotypes having contrasting NUEs under low and high N supplies in aeroponics. Results: PASP-Ca markedly boosted plant growth, yield components, and photosynthetic efficiency, with pronounced effects observed in nitrogen-efficient genotypes, especially Qingshu-9, emphasizing the importance of genotype selection in optimizing nitrogen utilization. Moreover, PASP-Ca treatments, particularly LN-P100 significantly enhances root system architecture (RSA), contributing to expanded root dimensions and improved nutrient acquisition capacity, especially under nitrogen-deficient conditions. Carbohydrate metabolism in potato tubers benefits from PASP-Ca treatment, leading to increased starch content, thereby impacting tuber quality. Among the N-assimilating enzymes, a large genotypic variation was observed for glutamine synthetase (GS), which may be considered a potential trait for improving NUE. Molecular analysis further elucidated the underlying mechanisms, demonstrating the upregulation of essential genes involved in nitrogen metabolism. Conclusions: The potential efficacy of PASP-Ca synergist as a novel accelerant for enhancing potato crop growth, biomass production, and nitrogen utilization efficiency, all coalescing seamlessly with the ethos of sustainable agricultural practices. [ABSTRACT FROM AUTHOR]

High temperature during early grain‐filling stage is one of the serious abiotic stresses limiting maize yield in the North China Plain. Nitrogen (N) fertiliser has an important role in promoting crop growth, especially under abiotic stresses. However, its contribution to alleviating heat stress (HS) inhibition on maize photosynthesis during early grain‐filling stage is still unclear. Experiments with three N rates (LN, low nitrogen; MN, medium nitrogen; HN, high nitrogen) and two temperature (HS, heat stress; CK, ambient temperature as control) regimes were conducted to examine the effects of increasing N supply on photosynthesis, N assimilation, antioxidant system, and hormones homeostasis of maize during early grain‐filling stage using two maize hybrids Xianyu335 (XY335, heat‐sensitive) and Zhengdan (ZD958, heat‐tolerant). HS negatively affected photosynthesis of both two hybrids, exhibited lower net photosynthetic rate, chlorophyll content and activities of Rubisco and phosphoenolpyruvate carboxylase (PEPC) compared with CK, and then decreased dry matter accumulation of maize, with a lesser extent for ZD958 than XY335. However, increasing N supply alleviated the adverse effects of HS on maize photosynthesis due to improved N assimilation capacity. Under HS condition, greater N content and higher activities of glutamine synthetase and glutamate synthase in maize ear leaf were found in treatment of HN compared with LN and MN. HN with higher N assimilation capacity directly increased the net photosynthetic rate due to improved chlorophyll content, activities of Rubisco and PEPC and antioxidant capacity. HS‐induced abscisic acid (ABA) accumulation was also repressed by HN, and then enhanced the stomatal conductance and transpiration rate to maintain higher photosynthetic capacity compared with LN and MN. Moreover, the positive effects of increasing N supply on maize photosynthesis under HS condition exhibited a larger extent for XY335 than ZD958. As a result of improved photosynthesis and N assimilation capacity by adequate N supply, maize accumulated more biomass under HS, especially for heat‐sensitive hybrid. [ABSTRACT FROM AUTHOR]

The unscientific application of nitrogen (N) fertilizer not only increases the economic input of pear growers but also leads to environmental pollution. Improving plant N use efficiency (NUE) is the most effective economical method to solve the above problems. The absorption and utilization of N by plants is a complicated process. Glutamine synthetase (GS) and glutamate synthase (GOGAT) are crucial for synthesizing glutamate from ammonium in plants. However, their gene family in pears has not been documented. This study identified 29 genes belonging to the GS and GOGAT family in the genomes of Pyrus betulaefolia (P.be, 10 genes), Pyrus pyrifolia (P.py, 9 genes), and Pyrus bretschneideri (P.br, 10 genes). These genes were classified into two GS subgroups (GS1 and GS2) and two GOGAT subgroups (Fd–GOGAT and NADH–GOGAT). The similar exon–intron structures and conserved motifs within each cluster suggest the evolutionary conservation of these genes. Meanwhile, segmental duplication has driven the expansion and evolution of the GS and GOGAT gene families in pear. The tissue–specific expression dynamics of PbeGS and PbeGOGAT genes suggest significant roles in pear growth and development. Cis–acting elements of the GS and GOGAT gene promoters are crucial for plant development, hormonal responses, and stress reactions. Furthermore, qRT–PCR analysis indicated that PbeGSs and PbeGOGATs showed differential expression under exogenous hormones (GA3, IAA, SA, ABA) and abiotic stress (NO3− and salt stress). In which, the expression of PbeGS2.2 was up–regulated under hormone treatment and down–regulated under salt stress. Furthermore, physiological experiments demonstrated that GA3 and IAA promoted GS, Fd–GOGAT, and NADH–GOGAT enzyme activities, as well as the N content. Correlation analysis revealed a significant positive relationship between PbeGS1.1, PbeGS2.2, PbeNADH–GOGATs, and the N content. Therefore, PbeGS1.1, PbeGS2.2, and PbeNADH–GOGATs could be key candidate genes for improving NUE under plant hormone and abiotic stress response. To the best of our knowledge, our study provides valuable biological information about the GS and GOGAT family in the pear for the first time and establishes a foundation for molecular breeding aimed at developing high NUE pear rootstocks. [ABSTRACT FROM AUTHOR]

Nitrogen (N) is a macronutrient essential for plant growth and development; insufficient N availability has an extensive impact on the overall plant metabolism and productivity. Polyamines, short aliphatic amino-containing compounds naturally produced by living cells, have been widely reported to be beneficial for plant performance under several unfavorable conditions. In this work, the role of polyamine spermine (Spm) as a priming agent for wheat growing under N deficit was investigated. Wheat seeds were primed with 0.1 mM Spm for 3 h, germinated for 48 h, and then grown in N-sufficient or N-deficient media for 8 d. Spm treatment anticipated seed germination and, though priming with Spm did not result in any stimulatory effect on plants developed under an N-sufficient medium, under N limitation many of the studied traits improved compared with control plants. Under N deficit, wheat seedlings originated from Spm-primed seeds showed increased root length, developed the third leaf earlier, and maintained higher total N and protein contents and higher nitrate reductase (NR) and glutamine synthetase (GS) activities in their leaves, compared to control plants. Likewise, total amino acids increased in the roots of primed seedlings, and carbohydrates enhanced both in roots and leaves. Our findings indicate that seed priming with Spm promotes wheat germination and early seedling growth under N limitation, mainly by promoting root elongation and N allocation to the aerial part. [ABSTRACT FROM AUTHOR]

This study was conducted to investigate the effects and mechanisms of glutamine (Gln) on the repair of acid-induced injury in dairy cow ruminal epithelial cells (RECs) in vitro. Dairy cow RECs were cultured in a medium with pH of 5.5 for 3 h and subsequently treated with various concentrations of Gln (4, 8, 12, 32 mmol/l) for 12 h. The messenger ribonucleic acid (mRNA) expression levels of occludin (OCLN), claudin 1 (CLDN1), toll-like receptor 2 (TLR2), toll-like receptor 4 (TLR4) and genes for inflammatory factors were measured using reverse transcription-quantitative real-time PCR (RT-qPCR). The results showed that cellular activity and OCLN expression were significantly highest at 8 mmol/l Gln (P < 0.05). CLDN1 expression was significantly higher at 4 mmol/l Gln compared to the other groups (P < 0.05). The relative expression levels of tumour necrosis factor (TNF), interleukin 1B (IL1B), C-X-C motif chemokine ligand 8 (CXCL8), TLR2 and TLR4 in the acid treatment group were significantly higher than those in the control group (P < 0.05), but they were lower in the Gln-treated groups than in the acid treatment group (P < 0.05). These findings demonstrate that Gln promotes the proliferation of RECs, enhances the expression of epithelial cell junction proteins, and inhibits the expression of inflammatory factors and surface receptors. In conclusion, Gln shows a potential for repairing acid-induced injury in RECs. [ABSTRACT FROM AUTHOR]

Severe malarial anemia (SMA, Hb < 6.0 g/dL) is a leading cause of childhood morbidity and mortality in holoendemic Plasmodium falciparum transmission zones. This study explored the entire expressed human transcriptome in whole blood from 66 Kenyan children with non-SMA (Hb ≥ 6.0 g/dL, n = 41) and SMA (n = 25), focusing on host immune response networks. RNA-seq analysis revealed 6862 differentially expressed genes, with equally distributed up-and down-regulated genes, indicating a complex host immune response. Deconvolution analyses uncovered leukocytic immune profiles indicative of a diminished antigenic response, reduced immune priming, and polarization toward cellular repair in SMA. Weighted gene co-expression network analysis revealed that immune-regulated processes are central molecular distinctions between non-SMA and SMA. A top dysregulated immune response signaling network in SMA was the HSP60-HSP70-TLR2/4 signaling pathway, indicating altered pathogen recognition, innate immune activation, stress responses, and antigen recognition. Validation with high-throughput gene expression from a separate cohort of Kenyan children (n = 50) with varying severities of malarial anemia (n = 38 non-SMA and n = 12 SMA) confirmed the RNA-seq findings. Proteomic analyses in 35 children with matched transcript and protein abundance (n = 19 non-SMA and n = 16 SMA) confirmed dysregulation in the HSP60-HSP70-TLR2/4 signaling pathway. Additionally, glutamine transporter and glutamine synthetase genes were differentially expressed, indicating altered glutamine metabolism in SMA. This comprehensive analysis underscores complex immune dysregulation and novel pathogenic features in SMA. [ABSTRACT FROM AUTHOR]

Sorghum is a plant that mainly requires chemical nitrogen fertilization. There are organic fertilizers that can provide nutrients to plants with great benefits to the soil, such as chicken manure. To determine the influence of organic fertilization on nitrate reductase (NR), glutamine synthetase (GS), and the amount of chlorophyll, sorghum plants were grown using the following four treatments: soil (T1), soil + chicken manure 100 kg ha−1 of nitrogen (N) (T2), soil + chicken manure 200 kg ha−1 N (T3), and soil + ammonium sulfate 100 kg ha−1 N (T4). Leaves were sampled in the vegetative stage (VS), the reproductive stage (RS), and the maturation stage (MS). The highest NR activity occurred in plants with T2 and T3 in the VS. The highest GS activity was in T3 and T4 in the RS. The amount of chlorophyll a was the same in all phenological stages. However, the amount of chlorophyll b was influenced by the type of fertilization at different phenological stages. Organic fertilizers (OF) produced the highest NR activity. On the other hand, GS activity was higher with chemical fertilization (T4), which was equal to the second dose of organic fertilization (T3). Finally, chlorophyll a and b were influenced by both types of fertilization, and was different from T1.

In prion diseases (PrDs), aggregates of misfolded prion protein (PrPSc) accumulate not only in the brain but also in extraneural organs. This raises the question whether prion-specific pathologies arise also extraneurally. Here we sequenced mRNA transcripts in skeletal muscle, spleen and blood of prion-inoculated mice at eight timepoints during disease progression. We detected gene-expression changes in all three organs, with skeletal muscle showing the most consistent alterations. The glutamate-ammonia ligase (GLUL) gene exhibited uniform upregulation in skeletal muscles of mice infected with three distinct scrapie prion strains (RML, ME7, and 22L) and in victims of human sporadic Creutzfeldt-Jakob disease. GLUL dysregulation was accompanied by changes in glutamate/glutamine metabolism, leading to reduced glutamate levels in skeletal muscle. None of these changes were observed in skeletal muscle of humans with amyotrophic lateral sclerosis, Alzheimer's disease, or dementia with Lewy bodies, suggesting that they are specific to prion diseases. These findings reveal an unexpected metabolic dimension of prion infections and point to a potential role for GLUL dysregulation in the glutamate/glutamine metabolism in prion-affected skeletal muscle. Author summary: This study examined how prion diseases, typically affecting the brain, also impact other body tissues. We analyzed gene activity in skeletal muscle, spleen, and blood of prion-infected mice across different disease stages. We found significant gene expression changes, particularly in skeletal muscle. The GLUL gene was consistently upregulated in the muscles of prion infected mice and in humans with Creutzfeldt-Jakob disease. This led to disruptions in glutamate and glutamine metabolism, reducing glutamate levels in muscle tissue. These changes were unique to prion diseases and not seen in other neurodegenerative conditions like ALS or Alzheimer's. The findings suggest that prion infections cause specific metabolic disruptions in skeletal muscle, linked to the GLUL gene. [ABSTRACT FROM AUTHOR]

Introduction: Salinity negatively affects maize productivity. However, calcium lignosulfonate (CLS) could improve soil properties and maize productivity. Methods: In this study, we evaluated the effects of CLS application on soil chemical properties, plant physiology and grain quality of maize under salinity stress. Thus, this experiment was conducted using three CLS application rates, CLS0, CLS5, and CLS10, corresponding to 0%, 5%, and 10% of soil mass, for three irrigation water salinity (WS) levels WS0.5, WS2.5, and WS5.5 corresponding to 0.5 and 2.5 and 5.5 dS/m, respectively. Results and discussion: Results show that the WS0.5 × CLS10 combination increased potassium (K 0.167 g/kg), and calcium (Ca, 0.39 g/kg) values while reducing the sodium (Na, 0.23 g/kg) content in soil. However, the treatment WS5.5 × CLS0 decreased K (0.120 g/kg), and Ca (0.15 g/kg) values while increasing Na (0.75 g/kg) content in soil. The root activity was larger in WS0.5 × CLS10 than in WS5.5 × CLS0, as the former combination enlarged K and Ca contents in the root while the latter decreased their values. The leaf glutamine synthetase (953.9 µmol/(g.h)) and nitrate reductase (40.39 µg/(g.h)) were higher in WS0.5 × CLS10 than in WS5.5 × CLS0 at 573.4 µmol/(g.h) and 20.76 µg/(g.h), leading to the improvement in cell progression cycle, as revealed by lower malonaldehyde level (6.57 µmol/g). The K and Ca contents in the leaf (881, 278 mg/plant), stem (1314, 731 mg/plant), and grains (1330, 1117 mg/plant) were greater in WS0.5 × CLS10 than in WS5.5 × CLS0 at (146, 21 mg/plant), (201, 159 mg/plant) and (206, 157 mg/plant), respectively. Therefore, the maize was more resistance to salt stress under the CLS10 level, as a 7.34% decline in yield was noticed when salinity surpassed the threshold value (5.96 dS/m). The protein (13.6 %) and starch (89.2 %) contents were greater in WS0.5 × CLS10 than in WS5.5 × CLS0 (6.1 %) and (67.0 %), respectively. This study reveals that CLS addition can alleviate the adverse impacts of salinity on soil quality and maize productivity. Thus, CLS application could be used as an effective soil amendment when irrigating with saline water for sustainable maize production. [ABSTRACT FROM AUTHOR]

Metabolic dysfunction‐associated steatotic liver disease (MASLD) affects over 30% of the global population, with a significant risk of advancing to liver cirrhosis and hepatocellular carcinoma. The roles of ammonia and glutamine in MASLD's pathogenesis are increasingly recognized, prompting this systematic review. This systematic review was conducted through a meticulous search of literature on December 21, 2023, across five major databases, focusing on studies that addressed the relationship between ammonia or glutamine and MASLD. The quality of the included studies was evaluated using CASP checklists. This study is officially registered in the PROSPERO database (CRD42023495619) and was conducted without external funding or sponsorship. Following PRISMA guidelines, 13 studies were included in this review. The studies were conducted globally, with varying sample sizes and study designs. The appraisal indicated a mainly low bias, confirming the reliability of the evidence. Glutamine's involvement in MASLD emerged as multifaceted, with its metabolic role being critical for liver function and disease progression. Variable expressions of glutamine synthetase and glutaminase enzymes highlight metabolic complexity whereas ammonia's impact through urea cycle dysfunction suggests avenues for therapeutic intervention. However, human clinical trials are lacking. This review emphasizes the necessity of glutamine and ammonia in understanding MASLD and identifies potential therapeutic targets. The current evidence, while robust, points to the need for human studies to corroborate preclinical findings. A personalized approach to treatment, informed by metabolic differences in MASLD patients, is advocated, alongside future large‐scale clinical trials for a deeper exploration into these metabolic pathways. [ABSTRACT FROM AUTHOR]

Ammonium nitrogen (NH4+-N) is one of the main forms of nitrogen absorbed and utilized by plants, and mastering the regulatory mechanism of plant ammonium assimilation is a key way to improve the efficiency of plant nitrogen utilization. Glutamine synthetase (GS) and glutamate synthase (GOGAT), two key enzymes for ammonium assimilation, have rarely been studied in pecan. In this study, GS and GOGAT family members of pecan were identified and analyzed using bioinformatics methods. The results indicated that 6 GS and 4 GOGAT genes were identified. The cis-acting elements can be broadly categorized into light-responsive, hormone-responsive, and stress-responsive elements. The findings from the analysis of homologous evolution revealed that neither of the two gene families experienced tandem duplication events. Additionally, different ratios of ammonium to nitrate nitrogen were set to analyze the activities of GS and GOGAT enzymes and expression levels in pecan. The results demonstrate differences in the activities of GS and GOGAT enzymes and the gene expression levels in various tissues of pecan under different nitrogen form ratios. This study established a foundation for further mastering the molecular regulatory mechanism of nitrogen assimilation in pecan, and provided a theoretical basis for enhancing the ability of pecan to absorb and utilize nitrogen. [ABSTRACT FROM AUTHOR]

This study investigated the effects of exogenous nitric oxide (NO) on growth, antioxidant enzymes, and key nitrogen metabolism enzymes in pepper seedlings under high-temperature stress. In addition, targeted metabolomics was used to study the differential accumulation of amino acid metabolites, thereby providing theoretical support for the use of exogenous substances to mitigate high-temperature stress damage in plants. The results showed that high-temperature stress increased soluble sugar, soluble protein, amino acids, proline, malondialdehyde (MDA), and hydrogen peroxide (H2O2) content, electrolyte leakage, and superoxide anion (O2·-) production rate while altering the activities of antioxidant enzymes [superoxide dismutase (SOD), catalase (CAT), peroxidase (POD) and ascorbate peroxidase (APX)] and key nitrogen metabolism enzymes [nitrate reductase (NR), glutamine synthetase (GS), glutamate dehydrogenase (GDH), and nitric oxide synthase (NOS)]. c-PTIO (2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide, an NO scavenger) exacerbates oxidative stress and further reduces NO content and enzyme activities. However, exogenous SNP (sodium nitroprusside, an NO donor) effectively alleviated these adverse effects by enhancing antioxidant defense mechanisms, increasing NO content, and normalizing amino acid metabolite levels (kynurenine, N-acetyl-L-tyrosine, L-methionine, urea, and creatine), thereby maintaining normal plant growth. These findings suggest that SNP can enhance stress tolerance in pepper seedlings by improving osmotic regulation, antioxidant capacity, and nitrogen metabolism, effectively mitigating the damage caused by high-temperature stress. [ABSTRACT FROM AUTHOR]

Sorghum is a plant that mainly requires chemical nitrogen fertilization. There are organic fertilizers that can provide nutrients to plants with great benefits to the soil, such as chicken manure. To determine the influence of organic fertilization on nitrate reductase (NR), glutamine synthetase (GS), and the amount of chlorophyll, sorghum plants were grown using the following four treatments: soil (T1), soil + chicken manure 100 kg ha−1 of nitrogen (N) (T2), soil + chicken manure 200 kg ha−1 N (T3), and soil + ammonium sulfate 100 kg ha−1 N (T4). Leaves were sampled in the vegetative stage (VS), the reproductive stage (RS), and the maturation stage (MS). The highest NR activity occurred in plants with T2 and T3 in the VS. The highest GS activity was in T3 and T4 in the RS. The amount of chlorophyll a was the same in all phenological stages. However, the amount of chlorophyll b was influenced by the type of fertilization at different phenological stages. Organic fertilizers (OF) produced the highest NR activity. On the other hand, GS activity was higher with chemical fertilization (T4), which was equal to the second dose of organic fertilization (T3). Finally, chlorophyll a and b were influenced by both types of fertilization, and was different from T1. [ABSTRACT FROM AUTHOR]

Introduction. The use of valproic acid (VPA) in the treatment of some psychiatric and neurological disorders such as bipolar disorder, migraines, and epilepsy is associated with hyperammonemia. However, the mechanism of this negative effect of VPA is unclear. In this study, we investigate gene glutamate-ammonia ligase (GLUL) polymorphisms for the glutamine synthetase (GS) enzyme, a key enzyme that catalyzes the removal of ammonia by incorporating it with glutamate to form glutamine, and we investigate whether it has a relationship with the emergence of hyperammonemia during VPA-based therapy. Patients and methods. We enrolled 180 Egyptian epilepsy patients in this study. Patient history, general and neurological examination and blood samples from arm veins were taken. Real time TaqMan PCR polymorphism for three polymorphism SNPs (rs2296521, rs10911021 and rs12136955) of GLUL was done. We assessed the relationship between the patient features, including three GLUL polymorphisms, and the development of hyperammonemia during VPA-based therapy. Results. We found that the ammonia levels showed a positive correlation with VPA treatment duration (p = 0.015) and a negative correlation with carbamazepine total dose per day (p = 0.027) and with WBCs count (p = 0.026). Also, female patients having rs2296521 SNPs with the A allele and patients having rs10911021 SNPs with the C allele were at high risk for elevated plasma ammonia levels. Moreover, patients having rs12136955 SNPs with the A allele or associated hypertension as a co-morbidity were at high risk for elevated plasma ammonia levels. Conclusions. Female patients who have rs2296521 with the A allele, rs10911021 with the C allele, or rs12136955 with the A allele, are independent risk factors for elevated plasma ammonia levels during VPA-based therapy. Moreover, carbamazepine combined therapy may protect against the development of hyperammonemia in VPA-treated patients. [ABSTRACT FROM AUTHOR]

Leaves experience near-constant light fluctuations daily. Past studies have identified many limiting factors of slow photosynthetic induction when leaves transition from low light to high light. However, the contribution of photorespiration in influencing photosynthesis during transient light conditions is largely unknown. This study employs dynamic measurements of gas exchange and metabolic responses to examine the contribution of photorespiration in constraining net rates of carbon assimilation during light induction. This work indicates that photorespiratory glycine accumulation during the early light induction contributes 5–7% to the additional carbon fixed relative to the low light conditions. Mutants with large glycine pools under photorespiratory conditions (5-formyl THF cycloligase and hydroxypyruvate reductase 1) showed a transient spike in net CO2 assimilation during light induction, with glycine buildup accounting for 22–36% of the extra carbon assimilated. Interestingly, levels of many C3 cycle intermediates remained relatively constant in both mutants and wild-type throughout the light induction period where glycine accumulated, indicating that recycling of carbon into the C3 cycle via photorespiration is not needed to maintain C3 cycle activity under transient conditions. Furthermore, our data show that oxygen transient experiments can be used as a proxy to identify the photorespiratory component of light-induced photosynthetic changes. [ABSTRACT FROM AUTHOR]

The retina is light-sensitive neuronal tissue in the back of the eye. The phospholipid composition of the retina is unique and highly enriched in polyunsaturated fatty acids, including docosahexaenoic fatty acid (DHA). While it is generally accepted that a high DHA content is important for vision, surprisingly little is known about the mechanisms of DHA enrichment in the retina. Furthermore, the biological processes controlled by DHA in the eye remain poorly defined as well. Here, we combined genetic manipulations with lipidomic analysis in mice to demonstrate that acyl-CoA synthetase 6 (Acsl6) serves as a regulator of the unique composition of retinal membranes. Inactivation of Acsl6 reduced the levels of DHA-containing phospholipids, led to progressive loss of light-sensitive rod photoreceptor neurons, attenuated the light responses of these cells, and evoked distinct transcriptional response in the retina involving the Srebf1/2 (sterol regulatory element binding transcription factors 1/2) pathway. This study identifies one of the major enzymes responsible for DHA enrichment in the retinal membranes and introduces a model allowing an evaluation of rod functioning and pathology caused by impaired DHA incorporation/retention in the retina. Acyl-CoA synthetase 6 (Acsl6)-facilitated enrichment of docosahexaenoic acid (DHA) in the retina is essential for rod photoreceptor function, viability and control of basal activity of the Srebf1/2 pathway. [ABSTRACT FROM AUTHOR]

Photorespiration, caused by oxygenation of the enzyme Rubisco, is considered a wasteful process, because it reduces photosynthetic carbon gain, but it also supplies amino acids and is involved in amelioration of stress. Here, we show that a sudden increase in photorespiratory activity not only reduced carbon acquisition and production of sugars and starch, but also affected diurnal dynamics of amino acids not obviously involved in the process. Flux calculations based on diurnal metabolite profiles suggest that export of proline from leaves increases, while aspartate family members accumulate. An immense increase is observed for turnover in the cyclic reaction of glutamine synthetase/glutamine-oxoglutarate aminotransferase (GS/GOGAT), probably because of increased production of ammonium in photorespiration. The hpr1-1 mutant, defective in peroxisomal hydroxypyruvate reductase, shows substantial alterations in flux, leading to a shift from the oxoglutarate to the aspartate family of amino acids. This is coupled to a massive export of asparagine, which may serve in exchange for serine between shoot and root. [ABSTRACT FROM AUTHOR]

[Objective] Glutamine synthetase (GS) is a key enzyme in the GS-GOGAT cycle of nitrogen metabolism. This work is aimed to investigate the family members of GS in soybean and the response to external stress. [Method] Based on bioinformatics methods, we comprehensively identified GS genes in soybean (Glycine max), clarified the location and structure of soybean GmGSs genes, the physicochemical properties of proteins, and the tissue expression patterns, and also studied the responses to abiotic stresses. [Result] The total of eight GS genes were identified from the soybean, located on eight chromosomes, corresponding to coding amino acid sequences with lengths ranging from 356 to 432 aa. Among the ten conserved motifs, all eight GmGS contained nine conserved motifs, and GmGS7 and GmGS8 had one more motif 10 conserved motif than other members. Analysis of promoter's cis-acting elements showed that the promoters of GmGSs contained abundant light-responsive elements, hormone-responsive elements, and adversity stress-responsive elements. Transcriptome data analysis showed that GmGSs genes were expressed in all tissues, with GmGS3 and GmGS4 having higher expression in all tissues. Fluorescence quantitative qPCR results revealed that GmGS4, GmGS5, and GmGS7 of soybean GS family responded most significantly to the late stage of low concentration ammonium treatment after different concentrations of ammonium chloride. And after high salt stress treatment, the expression of GmGS5 decreased in the root, stem and leaf tissues; while the expression of GmGS7 increased in root and stem tissues. [Conclusion] There are eight GS members in soybean, of which GmGS7 is involved in response to both ammonium chloride treatment and salt stress. [ABSTRACT FROM AUTHOR]

The amide proteogenic amino acids, asparagine and glutamine, are two of the twenty amino acids used in translation by all known life. The aminoacyl‐tRNA synthetases for asparagine and glutamine, asparaginyl‐tRNA synthetase and glutaminyl tRNA synthetase, evolved after the split in the last universal common ancestor of modern organisms. Before that split, life used two‐step indirect pathways to synthesize asparagine and glutamine on their cognate tRNAs to form the aminoacyl‐tRNA used in translation. These two‐step pathways were retained throughout much of the bacterial and archaeal domains of life and eukaryotic organelles. The indirect routes use non‐discriminating aminoacyl‐tRNA synthetases (non‐discriminating aspartyl‐tRNA synthetase and non‐discriminating glutamyl‐tRNA synthetase) to misaminoacylate the tRNA. The misaminoacylated tRNA formed is then transamidated into the amide aminoacyl‐tRNA used in protein synthesis by tRNA‐dependent amidotransferases (GatCAB and GatDE). The enzymes and tRNAs involved assemble into complexes known as transamidosomes to help maintain translational fidelity. These pathways have evolved to meet the varied cellular needs across a diverse set of organisms, leading to significant variation. In certain bacteria, the indirect pathways may provide a means to adapt to cellular stress by reducing the fidelity of protein synthesis. The retention of these indirect pathways versus acquisition of asparaginyl‐tRNA synthetase and glutaminyl tRNA synthetase in lineages likely involves a complex interplay of the competing uses of glutamine and asparagine beyond translation, energetic costs, co‐evolution between enzymes and tRNA, and involvement in stress response that await further investigation. [ABSTRACT FROM AUTHOR]

Achieving the green development of agriculture requires the reduction of chemical nitrogen (N) fertilizer input. Previous studies have confirmed that returning green manure to the field is an effective measure to improve crop yields while substituting partial chemical N fertilizer. However, it remains unclear how to further intensify the substituting function of green manure and elucidate its underlying agronomic mechanism. In a split-plot field experiment in spring wheat, different green manures returned to the field under reduced chemical N supply was established in an oasis area since 2018, in order to investigate the effect of green manure and reduced N on grain yield, N uptake, N use efficiency (NUE), N nutrition index, soil organic matter, and soil N of wheat in 2020-2022. Our results showed that mixed sown common vetch and hairy vetch can substitute 40% of chemical N fertilizer without reducing grain yield or N accumulation. Noteworthily, mixed sown common vetch and hairy vetch under reduced N by 20% showed the highest N agronomy efficiency and recovery efficiency, which were 92.0% and 46.0% higher than fallow after wheat harvest and conventional N application rate, respectively. The increase in NUE of wheat was mainly attributed to mixed sown common vetch and hairy vetch, which increased N transportation quantity and transportation rate at pre-anthesis, enhanced N harvest index, optimized N nutrition index, and increased activities of nitrate reductase and glutamine synthetase of leaf, respectively. Meanwhile, mixed sown common vetch and hairy vetch under reduced N by 20% improved soil organic matter and N contents. Therefore, mixed sown common vetch and hairy vetch can substitute 40% of chemical N fertilizer while maintaining grain yield and N accumulation, and it combined with reduced chemical N by 20% or 40% improved NUE of wheat via enhancing N supply and uptake. [ABSTRACT FROM AUTHOR]

Androgens have long been recognized as oncogenic agents. They can induce both benign and malignant hepatocellular neoplasms, including hepatocellular adenoma (HCA) and hepatocellular carcinoma, though the underlying mechanisms remain unclear. Androgen-induced liver tumors are most often solitary and clinically silent. Herein, we reported an androgen-induced HCA complicated by spontaneous rupture. The patient was a 24-year-old male presenting with fatigue, diminished libido, radiology-diagnosed hepatocellular adenomatosis for 3 years, and sudden-onset, severe, sharp, constant abdominal pain for one day. He used Aveed (testosterone undecanoate injection) from age 17 and completely stopped one year before his presentation. A physical exam showed touch pain and voluntary guarding in the right upper quadrant of the abdomen. An abdominal CT angiogram demonstrated multiple probable HCAs, with active hemorrhage of the largest one (6.6 × 6.2 × 5.1 cm) accompanied by large-volume hemoperitoneum. After being stabilized by a massive transfusion protocol and interventional embolization, he underwent a percutaneous liver core biopsy. The biopsy specimen displayed atypical hepatocytes forming dense cords and pseudoglands. The lesional cells diffusely stained β-catenin in nuclei and glutamine synthetase in cytoplasm. Compared to normal hepatocytes from control tissue, the tumor cells were positive for nuclear AR (androgen receptor) expression but had no increased EZH2 (Enhancer of Zeste 2 Polycomb Repressive Complex 2 Subunit) protein expression. The case indicated that androgen-induced hepatocellular neoplasms should be included in the differential diagnosis of acute abdomen. [ABSTRACT FROM AUTHOR]

The function of proteins depends on their correct structure and proper dynamics. Understanding the dynamics of target proteins facilitates drug design and development. However, dynamic information is often hidden in the spatial structure of proteins. It is important but difficult to identify the specific residues that play a decisive role in protein dynamics. Here, we report that a critical glycine residue (Gly463) dominates the motion of threonyl-tRNA synthetase (ThrRS) and the sensitivity of the enzyme to antibiotics. Obafluorin (OB), a natural antibiotic, is a novel covalent inhibitor of ThrRS. The binding of OB induces a large conformational change in ThrRS. Through five crystal structures, biochemical and biophysical analyses, and computational simulations, we found that Gly463 plays an important role in the dynamics of ThrRS. Mutating this flexible residue into more rigid residues did not damage the enzyme's three-dimensional structure but significantly improved the thermal stability of the enzyme and suppressed its ability to change conformation. These mutations cause resistance of ThrRS to antibiotics that are conformationally selective, such as OB and borrelidin. This work not only elucidates the molecular mechanism of the self-resistance of OB-producing Pseudomonas fluorescens but also emphasizes the importance of backbone kinetics for aminoacyl-tRNA synthetase-targeting drug development. Crystal structures and molecular dynamics simulations reveal that a critical glycine residue dominates the motion of threonyl-tRNA synthetase and the sensitivity of the enzyme to conformation selective inhibitors. [ABSTRACT FROM AUTHOR]

The AMP-forming acetyl-CoA synthetase is regulated by lysine acetylation both in bacteria and eukaryotes. However, the underlying mechanism is poorly understood. The Bacillus subtilis acetyltransferase AcuA and the AMP-forming acetyl-CoA synthetase AcsA form an AcuA•AcsA complex, dissociating upon lysine acetylation of AcsA by AcuA. Crystal structures of AcsA from Chloroflexota bacterium in the apo form and in complex with acetyl-adenosine-5′-monophosphate (acetyl-AMP) support the flexible C-terminal domain adopting different conformations. AlphaFold2 predictions suggest binding of AcuA stabilizes AcsA in an undescribed conformation. We show the AcuA•AcsA complex dissociates upon acetyl-coenzyme A (acetyl-CoA) dependent acetylation of AcsA by AcuA. We discover an intrinsic phosphotransacetylase activity enabling AcuA•AcsA generating acetyl-CoA from acetyl-phosphate (AcP) and coenzyme A (CoA) used by AcuA to acetylate and inactivate AcsA. Here, we provide mechanistic insights into the regulation of AMP-forming acetyl-CoA synthetases by lysine acetylation and discover an intrinsic phosphotransacetylase allowing modulation of its activity based on AcP and CoA levels. AMP-forming acetyl-CoA synthetase (AcsA) is an essential enzyme in all domains of life. Here, the authors provide mechanistic insights into regulation of AcsA by lysine acetylation, uncovering a regulatory phosphotransacetylase activity. [ABSTRACT FROM AUTHOR]

The interplay between humans and their microbiome is crucial for various physiological processes, including nutrient absorption, immune defense, and maintaining homeostasis. Microbiome alterations can directly contribute to diseases or heighten their likelihood. This relationship extends beyond humans; microbiota play vital roles in other organisms, including eukaryotic pathogens causing severe diseases. Notably, Wolbachia, a bacterial microbiota, is essential for parasitic worms responsible for lymphatic filariasis and onchocerciasis, devastating human illnesses. Given the lack of rapid cures for these infections and the limitations of current treatments, new drugs are imperative. Here, we disrupt Wolbachia's symbiosis with pathogens using boron-based compounds targeting an unprecedented Wolbachia enzyme, leucyl-tRNA synthetase (LeuRS), effectively inhibiting its growth. Through a compound demonstrating anti-Wolbachia efficacy in infected cells, we use biophysical experiments and x-ray crystallography to elucidate the mechanism behind Wolbachia LeuRS inhibition. We reveal that these compounds form adenosine-based adducts inhibiting protein synthesis. Overall, our study underscores the potential of disrupting key microbiota to control infections. [ABSTRACT FROM AUTHOR]

Cholangiocarcinoma (CCA) is often diagnosed late, leading to incomplete tumor removal, drug resistance and reduced chemotherapy efficacy. Curcumin has the potential for anti-cancer activity through various therapeutic properties and can improve the efficacy of chemotherapy. We aimed to investigate the synergistic effect of a combination of curcumin and gemcitabine against CCA, targeting the LAT2/glutamine pathway. This combination synergistically suppressed proliferation in gemcitabine-resistant CCA cells (KKU-213BGemR). It also resulted in a remarkable degree of CCA cell apoptosis and cell cycle arrest, characterized by a high proportion of cells in the S and G2/M phases. Knockdown of SLC7A8 decreased the expressions of glutaminase and glutamine synthetase, resulting in inhibited cell proliferation and sensitized CCA cells to gemcitabine treatment. Moreover, in vivo experiments showed that a combination curcumin and gemcitabine significantly reduced tumor size, tumor growth rate and LAT2 expression in a gemcitabine-resistant CCA xenograft mouse model. Suppression of tumor progression in an orthotopic CCA hamster model provided strong support for clinical application. In conclusion, curcumin synergistically enhances gemcitabine efficacy against gemcitabine-resistant CCA by induction of apoptosis, partly via inhibiting LAT2/glutamine pathway. This approach may be an alternative strategy for the treatment of gemcitabine-resistant in CCA patients. [ABSTRACT FROM AUTHOR]

The glutamine synthetase/glutamic acid synthetase (GS/GOGAT) cycle plays important roles in N metabolism, growth, development, and stress resistance in plants. Excess ammonium (NH4+) restricts growth, but GS can help to alleviate its toxicity. In this study, the 84K model clone of hybrid poplar (Populus alba × P. tremula var. glandulosa), which has reduced biomass accumulation and leaf chlorosis under high-NH4+ stress, showed less severe symptoms in transgenic lines overexpressing GLUTAMINE SYNTHETASE 1;2 (GS1;2 -OE), and more severe symptoms in RNAi lines (GS1;2 -RNAi). Compared with the wild type, the GS1;2 -OE lines had increased GS and GOGAT activities and higher contents of free amino acids, soluble proteins, total N, and chlorophyll under high-NH4+ stress, whilst the antioxidant and NH4+ assimilation capacities of the GS1;2 -RNAi lines were decreased. The total C content and C/N ratio in roots and leaves of the overexpression lines were higher under stress, and there were increased contents of various amino acids and sugar alcohols, and reduced contents of carbohydrates in the roots. Under high-NH4+ stress, genes related to amino acid biosynthesis, sucrose and starch degradation, galactose metabolism, and the antioxidant system were significantly up-regulated in the roots of the overexpression lines. Thus, overexpression of GS1;2 affected the carbon and amino acid metabolism pathways under high-NH4+ stress to help maintain the balance between C and N metabolism and alleviate the symptoms of toxicity. Modification of the GS/GOGAT cycle by genetic engineering is therefore a potential strategy for improving the NH4+ tolerance of cultivated trees. [ABSTRACT FROM AUTHOR]

Cancer cells undergo metabolic adaptation to promote their survival and growth under energy stress conditions, yet the underlying mechanisms remain largely unclear. Here, we report that tripartite motif‐containing protein 2 (TRIM2) is upregulated in response to glutamine deprivation by the transcription factor cyclic AMP‐dependent transcription factor (ATF4). TRIM2 is shown to specifically interact with carnitine O‐palmitoyltransferase 1 (CPT1A), a rate‐limiting enzyme of fatty acid oxidation. Via this interaction, TRIM2 enhances the enzymatic activity of CPT1A, thereby regulating intracellular lipid levels and protecting cells from glutamine deprivation‐induced apoptosis. Furthermore, TRIM2 is able to promote both in vitro cell proliferation and in vivo xenograft tumor growth via CPT1A. Together, these findings establish TRIM2 as an important regulator of the metabolic adaptation of cancer cells to glutamine deprivation and implicate TRIM2 as a potential therapeutic target for cancer. [ABSTRACT FROM AUTHOR]

Glutamine‐addicted cancer metabolism is recently recognized as novel cancer target especially for KRAS and KEAP1 co‐occurring mutations. To identify more drug‐like GLS inhibitors, we report the amides in the wing macrocycles for GLS inhibition with unique SAR analysis. Although the amidotriazoles (amides in the wing) are in general less potent than those of acylaminothiadiazole analogs (reverse amides in the wing), macrocycle 4, 5, and 7 are selected as a potent macrocyclic GLS inhibitor in both biochemical and cell viability assays. Selected molecules result in partial reduction in intracellular glutamate levels in LR (LDK378‐resistant) cells which is consistent to their cells viability result. Finally, selected compounds reduce the growth of A549 and H460 cells which have co‐occurring mutations including KRAS and KEAP1. The putative binding mode of macrocycle 4 is also suggested using a molecular docking model. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Oil Crop Sciences is the property of Oil Crops Research Institute of Chinese Academy of Agricultural Sciences 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.)

Copyright of Journal of Henan Agricultural Sciences is the property of Editorial Board of Journal of Henan Agricultural Sciences 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.)

Glutamine, the most abundant amino acid in the body, plays a critical role in preserving immune function, nitrogen balance, intestinal integrity, and resistance to infection. However, its limited solubility and instability present challenges for its use a functional nutrient. Consequently, there is a preference for utilizing glutamine‐derived peptides as an alternative to achieve enhanced functionality. This article aims to review the applications of glutamine monomers in clinical, sports, and enteral nutrition. It compares the functional effectiveness of monomers and glutamine‐derived peptides and provides a comprehensive assessment of glutamine‐derived peptides in terms of their classification, preparation, mechanism of absorption, and biological activity. Furthermore, this study explores the potential integration of artificial intelligence (AI)‐based peptidomics and synthetic biology in the de novo design and large‐scale production of these peptides. The findings reveal that glutamine‐derived peptides possess significant structure‐related bioactivities, with the smaller molecular weight fraction serving as the primary active ingredient. These peptides possess the ability to promote intestinal homeostasis, exert hypotensive and hypoglycemic effects, and display antioxidant properties. However, our understanding of the structure–function relationships of glutamine‐derived peptides remains largely exploratory at current stage. The combination of AI based peptidomics and synthetic biology presents an opportunity to explore the untapped resources of glutamine‐derived peptides as functional food ingredients. Additionally, the utilization and bioavailability of these peptides can be enhanced through the use of delivery systems in vivo. This review serves as a valuable reference for future investigations of and developments in the discovery, functional validation, and biomanufacturing of glutamine‐derived peptides in food science. [ABSTRACT FROM AUTHOR]

Cold is one of the abiotic environmental factors that severely affect plant metabolism. It causes changes in the fluidity of biological membranes, induces oxidative and osmotic stress, photoinhibition, reduces photosynthetic rates and slows down numerous metabolic enzyme activities. Some effects of cold overlap with drought response processes. Drought itself has a dualistic effect on plants. Severe drought stress is detrimental, while a mild preceding drought may prepare the otherwise sensitive maize to cope with cold. This study focused on the effects of mild drought on photosynthesis, sugar and amino acid metabolism at low temperature. Maize (Zea mays L.) plants were drought-hardened (15±5% relative soil moisture) between stages V4 and V6 at 25°C for 10 days and then subjected to cold treatmet at 10°C for 2 weeks at two light levels (PPFD=450 and 150 µmol m-2 s-1). The control population was watered daily (35±5% soil moisture), and in completely dried pots, 5±3% soil moisture was measured. The present results confirmed that photosynthetic performance and glutamine biosynthesis were positively affected by drought under both light intensities. Plants exposed to combined cold and moderate drought stress had a higher dry weight than those exposed to cold stress alone. The metabolism of several sugars, organic acids and amino acids was maintained by mild drought acclimation. The cold protective DHN2-like dehydrin gene was induced by moderate drought treatment, which may have contributed to the drought-induced higher tolerance to low temperature. However, cold stress markers were lower in low light than in normal growth light under drought acclimation, suggesting that drought-induced stress defense may require a certain level of light.

Background and AimSalidroside (SA) is the main active component of Rhodiola rosea L., with potential in treating cardiovascular and cerebrovascular diseases and cerebral ischemia. However, its efficacy and mechanism in cerebral ischemia remain unclear, particularly regarding its effect on glutamate (Glu) metabolism. In this paper, we aimed to investigate the efficacy of SA in treating cerebral ischemia and its pharmacological mechanism.Experimental procedureWe studied the effects of SA on SD rats with cerebral ischemia, evaluating neurobehavior, cerebral water content, infarct size, and brain microstructure. We also assessed its impact on glial fibrillary acidic protein (GFAP), glutamine synthetase (GS), and glutamate transporter 1 (GLT-1) proteins using immunohistochemistry and Western blot. Additionally, we used SVGp12 cells to simulate cerebral ischemia and measured Glu levels and used Western blot to observe the level of GS and GLT-1.ResultsSA improved neural function, reduced infarct size, and regulated GSH and Glu levels in rats. In cell experiments, SA increased cell viability and decreased Glu concentration after ischemia induction. It also regulated the expression of GFAP, GS, and GLT-1.ConclusionSA alleviates cerebral ischemia-induced injury by acting on astrocytes, possibly through regulating the glutamate metabolic pathway.

Acute liver dysfunction commonly leads to rapid increases in ammonia concentrations in both the serum and the cerebrospinal fluid. These elevations primarily affect brain astrocytes, causing modifications in their structure and function. However, its impact on neurons is not yet fully understood. In this study, we investigated the impact of elevated ammonium chloride levels (NH4Cl, 5 mM) on synaptic transmission onto CA1 pyramidal neurons in mouse organotypic entorhino-hippocampal tissue cultures. We found that acute exposure to NH4Cl reversibly reduced excitatory synaptic transmission and affected CA3-CA1 synapses. Notably, NH4Cl modified astrocytic, but not CA1 pyramidal neuron, passive intrinsic properties. To further explore the role of astrocytes in NH4Cl-induced attenuation of synaptic transmission, we used methionine sulfoximine to target glutamine synthetase, a key astrocytic enzyme for ammonia clearance in the central nervous system. Inhibition of glutamine synthetase effectively prevented the downregulation of excitatory synaptic activity, underscoring the significant role of astrocytes in adjusting excitatory synapses during acute ammonia elevation.

Abstract The enzyme glutamine synthetase (GLN) is mainly responsible for the assimilation and reassimilation of nitrogen (N) in higher plants. Although the GLN gene has been identified in various plants, there is little information about the GLN family in cotton (Gossypium spp.). To elucidate the roles of GLN genes in cotton, we systematically investigated and characterized the GLN gene family across four cotton species (G. raimondii, G. arboreum, G. hirsutum, and G. barbadense). Our analysis encompassed analysis of members, gene structure, cis-element, intragenomic duplication, and exploration of collinear relationships. Gene duplication analysis indicated that segmental duplication was the primary driving force for the expansion of the GhGLN gene family. Transcriptomic and quantitative real-time reverse-transcription PCR (qRT-PCR) analyses indicated that the GhGLN1.1a gene is responsive to N induction treatment and several abiotic stresses. The results of virus-induced gene silencing revealed that the accumulation and N use efficiency (NUE) of cotton were affected by the inactivation of GhGLN1.1a. This study comprehensively analyzed the GhGLN genes in Gossypium spp., and provides a new perspective on the functional roles of GhGLN1.1a in regulating NUE in cotton.