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Nitric oxide (NO) promotes angiogenesis via various mechanisms; however, the effective transmission of NO in ischemic diseases is unclear. Herein, we tested whether NO-releasing nanofibers modulate therapeutic angiogenesis in an animal hindlimb ischemia model. Male wild-type C57BL/6 mice with surgically-induced hindlimb ischemia were treated with NO-releasing 3-methylaminopropyltrimethoxysilane (MAP3)–derived or control (i.e., non-NO-releasing) nanofibers, by applying them to the wound for 20 min, three times every two days. The amount of NO from the nanofiber into tissues was assessed by NO fluorometric assay. The activity of cGMP-dependent protein kinase (PKG) was determined by western blot analysis. Perfusion ratios were measured 2, 4, and 14 days after inducing ischemia using laser doppler imaging. On day 4, Immunohistochemistry (IHC) with F4/80 and gelatin zymography were performed. IHC with CD31 was performed on day 14. To determine the angiogenic potential of NO-releasing nanofibers, aorta-ring explants were treated with MAP3 or control fiber for 20 min, and the sprout lengths were examined after 6 days. As per either LDPI (Laser doppler perfusion image) ratio or CD31 capillary density measurement, angiogenesis in the ischemic hindlimb was improved in the MAP3 nanofiber group; further, the total nitrate/nitrite concentration in the adduct muscle increased. The number of macrophage infiltrations and matrix metalloproteinase-9 (MMP-9) activity decreased. Vasodilator-stimulated phosphoprotein (VASP), one of the major substrates for PKG, increased phosphorylation in the MAP3 group. MAP3 nanofiber or NO donor SNAP (s-nitroso-n-acetyl penicillamine)-treated aortic explants showed enhanced sprouting in an ex vivo aortic ring assay, which was partially abrogated by KT5823, a potent inhibitor of PKG. These findings suggest that the novel NO-releasing nanofiber, MAP3 activates PKG and promotes therapeutic angiogenesis in response to hindlimb ischemia. [ABSTRACT FROM AUTHOR]

Nitrite has been widely used in meat products for its abilities including color formation, antimicrobial properties, flavor formation and preventing lipid oxidation. However, the possible generation of N-nitrosamines through reaction of nitrite with secondary amines arises many concerns in the usage of nitrite. For a long time, nitrite substitution is unsettled issue in the meat industry. Many attempts have been tried, however, the alternative solutions are often ephemeral and palliative. In recent years, bacterial nitric oxide synthase (bNOS) has received attention for its critical roles, especially in reddening meat products. This comprehensive background study summarizes the application of bNOS in colorizing meat products, its functions in bacteria, and methods of regulating the bNOS pathway. Based on this information, some strategies for promoting the nitric oxide yield for effectively substituting nitrite are presented, such as changing the environmental conditions for bacterial survival and adding substrate. Thus, bNOS is a promising nitrite substitute for color formation, and further research on its other roles in meat needs to be carried out to obtain the complete picture. [ABSTRACT FROM AUTHOR]

Two bacterial strains, designated FR2A1T and MT2-5-38, were isolated from the surface sediments of an oyster farm on a tidal flat in Quanzhou Bay, China. Both strains were Gram-stain-negative, rod-shaped, aerobic, catalase-positive, and oxidase-positive. The 16S rRNA gene sequences of the two strains were 100% identical and had the highest similarity (97.1%) with Phaeovulum vinaykumarii JA123T. The average nucleotide identity (ANI) value and digital DNA-DNA hybridization (DDH) value indicated that the two strains belonged to a single species. Gene annotation revealed that the two strains contained a gene cluster for nitrate reduction and a gene cluster for sulfur oxidation, indicating a possible role in N and S cycling in the tidal flat sediment. The phylogeny inferred from the 16S rRNA gene and 120 conserved proteins indicated that the two strains formed a distinct monophyletic clade within the family Paracoccaceae. The respiratory quinone was Q-10. The major fatty acids consisted of summed feature 8 (C18:1 ω7c and/or C18:1 ω6c) and C18:0. The polar lipids consisted of phosphatidylethanolamine, phosphatidylglycerol, and several unidentified phospholipids. Based on the above characteristics, strains FR2A1T and MT2-5-38 represent a novel genus and a novel species, for which we propose the name Ostreiculturibacter nitratireducens gen. nov., sp. nov. The type strain is FR2A1T (=MCCC 1K08809T = KCTC 8317T). Phylogenomic analysis of 1,606 high-quality genomes of the family Paracoccaceae, including type strains, non-type strains, and uncultivated bacteria, was performed using the Genome Taxonomic Database Toolkit (GTDB-Tk), and the average amino acid identity (AAI) value of the phylogenetic clade was estimated. We found that 35 species of the family Paracoccaceae needed re-classification, and an AAI value of 70% was chosen as the genus boundary within the family Paracoccaceae. [ABSTRACT FROM AUTHOR]

Coding transcript-derived siRNAs (ct-siRNAs) produced from specific endogenous loci can suppress the translation of their source genes to balance plant growth and stress response. In this study, we generated Arabidopsis mutants with deficiencies in RNA decay and/or post-transcriptional gene silencing (PTGS) pathways and performed comparative sRNA-seq analysis, revealing that multiple RNA decay and PTGS factors impede the ct-siRNA selective production. Genes that produce ct-siRNAs often show increased or unchanged expression and typically have higher GC content in sequence composition. The growth and development of plants can perturb the dynamic accumulation of ct-siRNAs from different gene loci. Two nitrate reductase genes, NIA1 and NIA2, produce massive amounts of 22-nt ct-siRNAs and are highly expressed in a subtype of mesophyll cells where DCL2 exhibits higher expression relative to DCL4, suggesting a potential role of cell-specific expression of ct-siRNAs. Overall, our findings unveil the multifaceted factors and features involved in the selective production and regulation of ct-siRNAs and enrich our understanding of gene silencing process in plants. Research on Arabidopsis indicates that RNA decay, PTGS pathway, GC content, and spatial-temporal gene expression impact ct-siRNA production, vital for gene silencing during plant growth and stress responses. [ABSTRACT FROM AUTHOR]

Salinity is a global challenge to sustainable agriculture, impacting plant growth at cellular and functional levels. Nevertheless, silicon (Si), a multifunctional micro-element, plays a vital role in restoring and maintaining growth and development during unfavourable abiotic conditions such as high salinity exposure. Therefore, in the current research, two salinity levels [S1; 1 M (1000 mM) NaCl and S2; 2 M (2000 mM) NaCl] were used to assess the effects of exogenous Si (Si-1; 150 mg/L and Si-2; 250 mg/L) on key biological characteristics and especially the metabolite profiles of Panicum turgidum plants. Our findings revealed that the salt stress negatively affected the plants through high salt content (Na+ and Cl−) that further antagonized the essential nutrient balance in tissues; increased NH 4 +, but lowered NO 3 − and K+ in both roots and leaves. The excessive production of NH 4 + led to over-accumulation of methylglyoxal (MG), resulting in the hyper-accumulation of sugars and altering the concentrations of amino acids, thereby inducing diabetes-like symptoms in P. turgidum plants. Interestingly, Si application restored the growth of P. turgidum plants by reducing oxidative damage thereby modifying the nutritional status, metabolic and biochemical characteristics of the plants. Specifically, the application of Si-2 showed improvement of key biological indictors in leaves and roots under both salinity levels. The current study also demonstrated that Si substantially reduced the NH 4 +-mediated MG-induced stress by lowering the concentration of MG, up-regulating the antioxidant capacity of various enzymes glyoxalase I (Gly-I), glyoxalase II (Gly-II), glutathione (GSH), glutamine: 2-oxoglutarate aminotransferase (GOGAT), nitrate reductase (NR), glutamine synthetase (GS), glutamate dehydrogenase (GDH); with concomitant changes in the levels of sugar/carbohydrates in roots and leaves of P. turgidum. [Display omitted] • The over-accumulation of salt ions negatively affected the essential nutrients uptake and altered the metabolic profile of Panicum turgidum. • The imbalanced NH 4 + and NO 3 − ratio resulted in the hyper-accumulation of methylglyoxal (MG) and carbohydrates; concomitant lowering of the amino acids content leading to diabetes-like symptoms in Panicum turgidum. • Silicon effectively reduced the negative impacts of salinity by reducing the MG and NH 4 + content, thereby restoring the nutritional, biochemical, and metabolic profile of Panicum turgidum plants undergoing unfavorable conditions. [ABSTRACT FROM AUTHOR]

Climate change, which causes periods with relatively high temperatures in winter in Poland, can lead to a shortening or interruption of the cold hardening of crops. Previous research indicates that cold acclimation is of key importance in the process of acquiring cereal tolerance to stress factors. The objective of this work was to verify the hypothesis that both natural temperature fluctuations and the plant genotype influence the content of metabolites as well as proteins, including antioxidant enzymes and photosystem proteins. The research material involved four winter triticale genotypes, differing in their tolerance to stress under controlled conditions. The values of chlorophyll a fluorescence parameters and antioxidant activity were measured in their seedlings. Subsequently, the contribution of selected proteins was verified using specific antibodies. In parallel, the profiling of the contents of chlorophylls, carotenoids, phenolic compounds, and proteins was carried out by Raman spectroscopy. The obtained results indicate that a better PSII performance along with a higher photosystem II proteins content and thioredoxin reductase abundance were accompanied by a higher antioxidant activity in the field-grown triticale seedlings. The Raman studies showed that the cold hardening led to a variation in photosynthetic dyes and an increase in the phenolic to carotenoids ratio in all DH lines. [ABSTRACT FROM AUTHOR]

The present study examined the regulatory mechanism of hydrogen sulfide (H2S) and nitric oxide (NO) in nickel (Ni) stressed cyanobacteria viz., Nostoc muscorum and Anabaena sp. by analyzing growth, photosynthetic pigments, biochemical components (protein and carbohydrate), exopolysaccharides (EPS), inorganic nitrogen content, and activity of enzymes comprised in nitrogen metabolism and Ni accumulation. The 1 µM Ni substantially diminished growth by 18% and 22% in N. muscorum and Anabaena sp. respectively, along with declining the pigment contents (Chl a/Car ratio and phycobiliproteins), and biochemical components. It also exerted negative impacts on inorganic uptake of nitrate and nitrite contents; nitrate reductase and nitrite reductase; and ammonium assimilating enzymes (glutamine synthetase, glutamate synthase, and glutamate dehydrogenase exhibited a reverse trend) activities. Nonetheless, the adverse impact of Ni can be mitigated through the exogenous supplementation of NaHS [sodium hydrosulfide (8 µM); H2S donor] and SNP [sodium nitroprusside (10 µM); NO donor] which showed substantial improvement on growth, pigments, nitrogen metabolism, and EPS layer and noticeably occurred as a consequence of a substantial reduction in Ni accumulation content which minimized the toxicity effects. The accumulation of Ni on both the cyanobacterial cell surface (EPS layer) are confirmed by the SEM–EDX analysis. Further, the addition of NO scavenger (PTIO; 20 µM) and inhibitor of NO (L-NAME; 100 µM); and H2S scavenger (HT; 20 µM) and H2S inhibitor (PAG; 50 µM) reversed the positive responses of H2S and NO and damages were more prominent under Ni stress thereby, suggesting the downstream signaling of H2S on NO-mediated alleviation. Thus, this study concludes the crosstalk mechanism of H2S and NO in the mitigation of Ni-induced toxicity in rice field cyanobacteria. [ABSTRACT FROM AUTHOR]

This article provides information on Acute Hepatopancreatic Necrosis Disease (AHPND), a bacterial disease that has had a significant impact on the shrimp farming industry. The main causative agent of AHPND is Vibrio parahaemolyticus, but other Vibrio strains with similar toxin genes have also been reported. The article focuses on the identification and evaluation of a novel Vibrio strain isolated from a shrimp farm in South Korea. The strain, known as HJ-2023, was found to be highly virulent and resistant to certain antibiotics. The research emphasizes the importance of biosecurity measures to prevent the spread of AHPND in aquaculture. [Extracted from the article]

Sphingolipids are produced by nearly all eukaryotes where they play significant roles in cellular processes such as cell growth, division, programmed cell death, angiogenesis, and inflammation. While it was previously believed that sphingolipids were quite rare among bacteria, bioinformatic analysis of the recently identified bacterial sphingolipid synthesis genes suggests that these lipids are likely to be produced by a wide range of microbial species. The sphingolipid synthesis pathway consists of three critical enzymes. Serine palmitoyltransferase catalyzes the condensation of serine with palmitoyl-CoA (or palmitoyl-acyl carrier protein), ceramide synthase adds the second acyl chain, and a reductase reduces the ketone present on the long-chain base. While there is general agreement regarding the identity of these bacterial enzymes, the precise mechanism and order of chemical reactions for microbial sphingolipid synthesis is more ambiguous. Two mechanisms have been proposed. First, the synthesis pathway may follow the well characterized eukaryotic pathway in which the longchain base is reduced prior to the addition of the second acyl chain. Alternatively, our previous work suggests that addition of the second acyl chain precedes the reduction of the longchain base. To distinguish between these two models, we investigated the subcellular localization of these three key enzymes. We found that serine palmitoyltransferase and ceramide synthase are localized to the cytoplasm, whereas the ceramide reductase is in the periplasmic space. This is consistent with our previously proposed model wherein the second acyl chain is added in the cytoplasm prior to export to the periplasm where the lipid molecule is reduced. [ABSTRACT FROM AUTHOR]

Bacillus sp. possessing a periplasmic nitrate reductase was used as a recognition element to develop a nitrate biosensor. The bacteria was embedded within a polyaniline (PANI) electro-conductive matrix via electro-polymerization on miniaturized carbon screen-printed electrodes (SPE) at 100 mV/s and scan rate from −0.35 V to + 1.7 V. Surface medication of SPE was verified via Fourier Transform Infrared spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). The optimal bacterial density was OD600 1.2. To enhance the biosensors performance, Bacillus sp. was (1) grown in riboflavin (RF) inducing media as an endogenous redox mediator and (2) exposed to different gamma radiation doses as a physical method to increase electron transfer. Results show a link between exposing cells to gamma irradiation stress, this was evident by electron spin resonance (ESR) and changes in FTIR spectrum, in addition to the increase in catalase enzyme. The nitrate limit of detection (LOD) was 0.5–25 mg/L for non-irradiated RF induced immobilized cells and LOD was 0.5–75 mg/L nitrate for 2 kGy gamma irradiated cells. The prepared biosensor showed acceptable reproducibility and multiple usages after storage at 4°C over 3 months. Low cost and simple preparation allow the biosensor to be mass-produced as a disposable device. Bacillus sp. and its endogenous redox mediator immobilized within polyaniline are good candidates for the improvement of amperometric biosensors for the quantification of nitrate in aqueous solutions. [ABSTRACT FROM AUTHOR]

Knowledge of tree biomass allocation is fundamental for estimating forest acclimation and carbon stock for global changes in the future. Optimal partitioning theory (OPT) and allometric partitioning theory (APT) are two major patterns of biomass allocation, and occurrences have been tested on taxonomical, ontogenetic, geographic and environmental scales, showing conflicting results and unclear ecophysiological mechanisms. Here, we examine the biomass allocation patterns of two young poplar (Populus) clones varying greatly in drought resistance under different soil water and nitrogen availabilities and the major physiological processes involved in biomass partitioning. We found that Biyu, a drought-sensitive hybrid poplar clone, had significant relations among biomass of leaf, stem and root, showing allometric partitioning. Xiaoye, a drought-tolerant poplar clone native to semi-arid areas, on the contrary, showed tightly regulated biomass allocation following optimal partitioning theory. Biyu had higher nitrate reductase activity in the fine roots, while Xiaoye had higher nitrate reductase activity in the leaves. Biochemical analyses and measurements of fluorescence and gas exchange showed that Xiaoye maintained more stable chloroplast membranes and photosystem electron flow, showing higher water use efficiency and a higher resistance to drought. A nitrogen addition could improve leaf photosynthesis and growth both in Biyu and Xiaoye seedlings under drought conditions. We concluded that the two poplar clones showed different biomass allocation patterns and suggest that the site of nitrate assimilation may play a role in biomass partitioning under varying water and nitrogen availabilities. [ABSTRACT FROM AUTHOR]

Main Conclusion: The combined photoinhibitory and PSII-reaction centre quenching against light stress is an important mechanism that allows the green macroalga Ulva rigida to proliferate and form green tides in coastal ecosystems. Eutrophication of coastal ecosystems often stimulates massive and uncontrolled growth of green macroalgae, causing serious ecological problems. These green tides are frequently exposed to light intensities that can reduce their growth via the production of reactive oxygen species (ROS). To understand the physiological and biochemical mechanisms leading to the formation and maintenance of green tides, the interaction between inorganic nitrogen (Ni) and light was studied. In a bi-factorial physiological experiment simulating eutrophication under different light levels, the bloom-forming green macroalga Ulva rigida was exposed to a combination of ecologically relevant nitrate concentrations (3.8–44.7 µM) and light intensities (50–1100 µmol photons m−2 s−1) over three days. Although artificial eutrophication (≥ 21.7 µM) stimulated nitrate reductase activity, which regulated both nitrate uptake and vacuolar storage by a feedback mechanism, nitrogen assimilation remained constant. Growth was solely controlled by the light intensity because U. rigida was Ni-replete under oligotrophic conditions (3.8 µM), which requires an effective photoprotective mechanism. Fast declining Fv/Fm and non-photochemical quenching (NPQ) under excess light indicate that the combined photoinhibitory and PSII-reaction centre quenching avoided ROS production effectively. Thus, these mechanisms seem to be key to maintaining high photosynthetic activities and growth rates without producing ROS. Nevertheless, these photoprotective mechanisms allowed U. rigida to thrive under the contrasting experimental conditions with high daily growth rates (12–20%). This study helps understand the physiological mechanisms facilitating the formation and persistence of ecologically problematic green tides in coastal areas. [ABSTRACT FROM AUTHOR]

Hypertension reduces the bioavailability of vascular nitric oxide (NO) and contributes to the onset of vascular dementia (VaD). A loss of NO bioavailability increases inflammation and oxidative stress. 2-(4-Methylthiazol-5-yl) ethyl nitrate hydrochloride (W1302) is a novel nitric oxide donor (NOD) which is undergoing phase I clinical trials in China for the treatment of VaD. In this study, we investigated the protective effects of W1302 in VaD rats induced by the permanent occlusion of a bilateral common carotid arteries model related to spontaneous hypertension (SHR-2VO), and we further explored the underlying mechanisms. Nimodipine was used as a positive control. Our results showed that W1302 treatment for 4 weeks (10 mg/Kg/day) exhibited stronger improvement in the spatial learning and memory deficits in SHR-2VO rats compared with nimodipine with slightly lower systolic blood pressure (SBP). Meanwhile, W1302 treatment significantly increased NO and cGMP production, restored mitochondrial membrane potential and attenuated oxidative stress as evidenced by increasing ATP production and reducing malondialdehyde (MDA) levels in the brain. Furthermore, W1302 treatment markedly inhibited the iNOS activity and decreased TNF-α expression via inhibiting the nuclear factor kappa B (NF-κB) signaling pathway. Nimodipine treatment also restored these aberrant changes, but its ATP production was weaker than that of W1302, and there was no significant effect on NO release. Taken together, W1302 exhibited beneficial effects on complications in VaD with hypertension, which is involved in suppressing oxidative damage, and the inflammatory reaction might be mediated by an increase in NO release. Therefore, W1302 has therapeutic potential for the treatment of VaD caused by chronic cerebral hypoperfusion-associated spontaneous hypertension. [ABSTRACT FROM AUTHOR]

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Experiments were conducted to evaluate the role of exogenously applied jasmonic acid (JA; 0.1 and 0.5 µM) in alleviating the toxic effects of arsenic (As; 5 and 10 µM) stress in rice. Plants treated with As showed considerable decline in growth attributes like height, fresh and dry weight of plant. Arsenic stress reduced the content of δ-amino livulenic acid (δ-ALA), glutamate 1-semialdehyde (GSA), total chlorophylls and carotenoids, with more reduction evident at higher (10 µM) As concentrations, however exogenously supplied JA alleviated the decline to considerable extent. Arsenic stress mediated decline in photosynthetic gas exchange parameters, Fv/Fm (PSII activity) and Rubisco activity was alleviated by the exogenous treatment of JA. Arsenic stress caused oxidative damage which was evident as increased lipid peroxidation, lipoxygenase activity and hydrogen peroxide concentrations however, JA treatment declined these parameters. Treatment of JA improved the activity of nitrate reductase and glutamate synthase under unstressed conditions and also alleviated the decline triggered by As stress. Activity of antioxidant enzymes assayed increased due to As stress, and the supplementation of JA caused further increase in their activities. Moreover, the content of proline, free amino acids and total phenols increased significantly due to JA application under stressed and unstressed conditions. Treatment of JA increased the content of nitrogen and potassium while as reduced As accumulation significantly. [ABSTRACT FROM AUTHOR]

The industrially important transition metal tungsten (W) shares certain chemical properties with the essential plant micronutrient molybdenum and inhibits the activity of molybdoenzymes such as nitrate reductase, impacting plant growth. Furthermore, tungsten appears to interfere with metabolic processes on a much wider scale and to trigger common heavy metal stress response mechanisms. We have previously found evidence that the tungsten stress response of soybeans (Glycine max) grown with symbiotically associated N2-fixing rhizobia (Bradyrhizobium japonicum) differs from that observed in nitrogen-fertilized soy plants. This study aimed to investigate how association with symbiotic rhizobia affects the primary and secondary metabolite profiles of tungstenstressed soybean and whether changes in metabolite composition enhance the plant's resilience to tungsten. This comprehensive metabolomic and proteomic study presents further evidence that the tungsten-stress response of soybean plants is shaped by associated rhizobia. Symbiotically grown plants (N fix) were able to significantly increase the synthesis of an array of protective compounds such as phenols, polyamines, gluconic acid, and amino acids such as proline. This resulted in a higher antioxidant capacity, reduced root-to-shoot translocation of tungsten, and, potentially, also enhanced resilience of N fix plants compared to non-symbiotic counterparts (N fed). Taken together, our study revealed a symbiosis-specific metabolic readjustment in tungsten-stressed soybean plants and contributed to a deeper understanding of the mechanisms involved in the rhizobium-induced systemic resistance in response to heavy metals. [ABSTRACT FROM AUTHOR]

Rice is a major cereal crop which ensure food security to more than half of the global population. Several biotic factors impact rice grain quality and its final production. White stripe disease, caused by pathogen Stenotrophomonas maltophilia is considered among the major limiting factor for reducing rice yields and quality. Present study was performed to understand the white stripe disease, which has been frequently misdiagnosed as bacterial leaf blight (BLB) due to similar symptoms. A survey was carried out based on accessibility and farmer participation to monitor incidence and sample collection. The survey was conducted in districts Faisalabad, Gujranwala, Sialkot, Sheikhupura, and Hafizabad, these districts were selected for their importance for rice cultivation in Pakistan. The total sample size was around 500 leaves distributed evenly throughout each study area. The results of study indicated presence of new pathogen of rice. These isolates were biochemically identified and confirmed by gram staining negative, 3% KOH positive, 5% salt tolerance positive, oxidase test negative, catalase test positive, starch hydrolysis test negative, nitrate reductase test positive, indole test negative, lactose test positive, maltose test positive, methyl red test negative, Vogesprokauer test negative and urea hydrolysis test negative. The pathogenicity test was confirmed that pathogen and the Sialkot isolate were the most aggressive isolate among the five isolates collected form the studied areas. The molecular characterization was accomplished by PCR and sequencing. The results of the phylogenetic study indicate that this pathogen belongs to a distinct group, as it is distantly related to Xanthomonas oryzae pv. oryzae (Xoo). This study provides important findings into a novel clade of pathogen causing white stripe disease in rice. [ABSTRACT FROM AUTHOR]

The present study investigated the integration of halophytes in IMTA as extractive species on the water quality, growth, digestive, and antioxidant activity of Penaeus monodon and Chanos chanos in earthen ponds for 120 days. The experimental setup consisted of three treatments: control (C) and two different halophyte-based IMTA treatments, T1 and T2, randomly assigned to nine earthen ponds (200 m−2) in three replicates. All treatments were uniformly stocked with P. monodon (Post larve 12) and C. chanos (13.4–14 g); in addition to these, T1 had Avicennia officinalis and Meretrix casta and T2 had Bruguiera gymnorhiza and Meretrix casta as extractive species. The average final body weights of P. monodon (32.01 ± 0.27 g) and C. chanos (94.18 ± 1 g) were found in the A. officinalis based IMTA treatment (T1). T1 also had shown a significant (p < 0.05) reductions in total ammonia nitrogen (97.5%), nitrite-N (NO2-N) (56.1%), and nitrate (NO3-N) (41.1%). Biological oxygen demand (BOD) (3.17 ± 0.15 ppm), chemical oxygen demand (COD) (25 ± 0.58 mg L−1), and total suspended solids (TSS) (20 ± 1.15 mg L−1) were significantly (P < 0.05) lower in T1. Digestive enzyme activity in shrimp and fish was higher in T1 and T2. A decrease in catalase and SOD enzyme activities was observed in T1 and T2. Halophyte-and M. casta-based IMTA treatments (T1 and T2) showed a decrease in the total Vibrio and heterotrophic bacterial counts. The present research findings elucidated that halophytes as extractive species can be beneficial in brackishwater IMTA systems to maintain water quality, improve the health status of cultivated organisms, and increase aquaculture productivity. [ABSTRACT FROM AUTHOR]

Nano-biochar (NBC) amendment could be an effective solution for sustainable agricultural production in salt affected areas. Nano-biochar application have shown positive effects on plant germination. But the under veiling mechanism of germinating seeds under NBC application still needs to explore. In this regard, two wheat varieties were used to assess the effects of NBC application on growth, germination indices, hydrolyzing and nitrogen metabolic enzymes as well as on plant metabolites at early germination stage under salt stress. Petri-plate experiments were performed at The University of Lahore, and 4 levels of NBC supplementation (0 %, 1 %, 3 %, and 5 %) were used both under salt stress (80 mM) and non-stress (0 mM). The results clearly showed that salt stress reduced the growth parameters such as radicle length, plumule length, seedling weight and germination indices such as final germination percentage (FGP), germination index (GI), and germination rate index (GRI) but increased the germination mean time (GMT). NBC in all concentrations specifically 5 % NBC elevated growth and germination indices of wheat seeds as well as reduced the mean germination time of seed sprouting both under stress and non-stress conditions. Further, temporal variations were observed in hydrolyzing and nitrogen metabolic enzymes and results showed that salt stress exerted negative effect on activities of α-amylase, Protease and Nitrate reductase even though activities of these enzymes increased in a timely manner. But 5 % NBC application significantly improved the enzyme activities both under stress and non-stress conditions. To investigate the effect of NBC on plant metabolites, Total free amino acids, total protein contents and total soluble sugars were estimated using spectrophotometry and results clearly showed that salt stress decreased the total free amino acids and total soluble sugars content but an incline was observed in total proteins which were reduced in a timely manner. However, 5 % application of NBC increased the free amino acids and soluble sugar contents but decreased the values of total proteins under stress or non-stress conditions. These results suggests an active involvement of NBC to improve early growth and germination indices of seeds and enhance hydrolyzing enzymes and plant metabolites under stress conditions. A schematic diagram summarizing the stimulatory effects of nano-biochar supplementation on wheat seeds germination. [Display omitted] [ABSTRACT FROM AUTHOR]

Despite the well-known individual roles of potassium (K+) and jasmonic acid (JA) in plant responses to various stresses, their combined effects on improving tolerance to metalloid arsenate (AsV) toxicity and their influence on physiological and biochemical mechanisms remain largely unexplored. Therefore, the present study was conducted to explore the concomitant role of K+ and JA in nitrogen (N) and sulfur (S) metabolisms and regulation of antioxidant system in tomato seedlings under AsV toxicity conditions. The obtained data reveal that K+ and/or JA boosted the tolerance of tomato (Solanum lycopersicum L.) seedlings to AsV toxicity. However, the effect of a combined dose of K+ and JA was found to be more efficient as compared to the alone application. Seedlings subjected to AsV exhibited suppressed morphological attributes (shoot and root length, shoot and root fresh weight, and shoot and root dry weight), and physio-biochemical characteristics. Also, AsV-treated tomato seedlings showed enhanced reactive oxygen species (ROS) and increased the activity of ROS-producing enzymes (O 2 •— -generating NADPH oxidase activity and H 2 O 2 -generating glycolate oxidase] and also a chlorophyll (Chl) degrading enzyme [chlorophyllase (Chlase) activity]. However, the exogenous supply of K+ and JA synergistically inhibited Chl degradation and overproduction of ROS by suppressing their responsible enzymes activity. Moreover, it induced gas exchange parameters and activity of enzymes responsible for the photosynthesis process (carbonic anhydrase and Rubisco), Chl biosynthesis (δ -aminolevulinic acid dehydratase), and suppressed Chlase activity, and overproduction of ROS and their producing enzymes activity. Most interestingly, the combined application of K+ and JA substantially increased N and S content and their assimilation by upregulating the activity of enzymes involved in these key pathways (nitrate reductase, nitrite reductase, glutamine synthetase, glutamate synthase, ATP sulfurylase, adenosine 5-phosphosulfate reductase, O -acetylserine (thiol) lyase and sulfide reductase). The obtained results strongly reveal that the combined application of K+ and JA improved tolerance of tomato seedlings to AsV toxicity by enhancing N and S assimilation pathways and antioxidant system. [Display omitted] • AsV toxicity impaired n and s assimilation pathways in tomato seedlings. • AsV stress inhibited chl and Cys-biosynthesis and enhances overproduction of ROS. • K + plus JA enhanced n and s assimilation pathways under AsV toxicity conditions. • K + plus JA improved chl and Cys-biosynthesis in AsV stressed-tomato seedlings. • K + plus JA suppressed ROS overproduction and increased antioxidant system. [ABSTRACT FROM AUTHOR]

The release rates of different nitrogen (N) fertilizers and their matching with plant demand determine crop yields. A field experiment was conducted to investigate the effect of using no fertilizer (N0), regular urea applied at rates of 180 kg ha−1 (N180) and 240 kg ha−1 (N240), controlled-release urea applied at a rate of 180 kg ha−1 (H180), and polyaspartic acid urea (PASP) on maize seed yield, soil microbial community diversity, and leaf N-converting enzymes. XianYu 688 was selected as the test maize variety. All cobs in the sample plots were collected per unit area to estimate maize yield. The enzyme-linked immunosorbent assay (ELISA) was used to determine leaf N-converting enzyme activities. Soil DNA was extracted using the Power Max Soil DNA Isolation Kit and subsequently sequenced using the Illumina HiSeq platform (PE 2500) to determine the microbial diversity and communities. The results showed that the highest seed yields were obtained under N240 and PASP180 treatments. The N-partial factor productivity of the PASP180 fertilizer was significantly higher than that of the other treatments. PASP treatment significantly increased maize seed yield due to the potential of storing more N in the ear leaves. Additionally, partial N productivity showed a significant positive correlation with the soil microbial Shannon, Chao1, and ACE indices, indicating that increased soil microbial diversity promoted N efficiency in maize. Further analysis revealed that PASP treatment increased seed yield by promoting leaf N-converting enzyme activity and soil microbial diversity. The results revealed that nitrate reductase (NR), glutamate synthase (GOGAT), and glutaminase (GLNS) enzyme activities in maize leaves were higher under the PASP treatment than under other fertilizer treatments. The PASP treatment significantly enhanced soil microbial diversity at different maize stages. Our study revealed the effects of using different N fertilizers on seed yield by examining their impact on soil microbial diversity and leaf N-converting enzyme activity. This study provides essential insights into maize production and soil fertility maintenance in the North China Plain. [ABSTRACT FROM AUTHOR]

Molecular biological techniques and bioinformatic analysis were used to investigate the phylogenetic and functional diversity of the prokaryotic complex of soil microcosms. The dominant organisms of the hydrolytic community were different in the samples from different climatic zones. In the soils subject to anthropogenic or abiogenic load, apart from decreased diversity and abundance of prokaryotes, the number of the genes marking the ability to degrade xenobiotics, as well as those encoding nitrogen conversion and metabolism of vitamins and cofactors, was found to increase. Under heavy oil contamination, the bacterial community was capable of nitrification; its role increased in the lower horizons of the soil profile. The patterns revealed in the work indicate high metabolic potential of the prokaryotic component of the studied soils. [ABSTRACT FROM AUTHOR]

Sulphate‐reducing bacteria (SRB) are the main culprits of microbiologically influenced corrosion in water‐flooding petroleum reservoirs, but some sulphur‐oxidising bacteria (SOB) are stimulated when nitrate and oxygen are injected, which control the growth of SRB. This study aimed to determine the distributions of SRB and SOB communities in injection–production systems and to analyse the responses of these bacteria to different treatments involving nitrate and oxygen. Desulfovibrio, Desulfobacca, Desulfobulbus, Sulfuricurvum and Dechloromonas were commonly detected via 16S rRNA gene sequencing. Still, no significant differences were observed for either the SRB or SOB communities between injection and production wells. Three groups of water samples collected from different sampling sites were incubated. Statistical analysis of functional gene (dsrB and soxB) clone libraries and quantitative polymerase chain reaction showed that the SOB community structures were more strongly affected by the nitrate and oxygen levels than SRB clustered according to the sampling site; moreover, both the SRB and SOB community abundances significantly changed. Additionally, the highest SRB inhibitory effect and the lowest dsrB/soxB ratio were obtained under high concentrations of nitrate and oxygen in the three groups, suggesting that the synergistic effect of nitrate and oxygen level was strong on the inhibition of SRB by potential SOB. [ABSTRACT FROM AUTHOR]

Enhancing Nitrogen Use Efficiency (NUE) is extremely important towards mitigating climate change, especially in wheat where the NUE is less than 50%. Hence, optimizing grain yield under reduced application of nitrogenous fertilizer is a significant challenge. To address this challenge, a comprehensive study was conducted to investigate various agronomic traits and morphological, biochemical and molecular parameters related to NUE. This study explored their interrelationships and effects on grain yield, providing novel insights that were not previously reported. A set of 278 diverse wheat genotypes were assessed, encompassing eight NUE‐related field traits. All traits' values were reduced under stressed N (ranging from 7.5% to 77.5%) except Nitrogen Utilization Efficiency (NUtE) and NUE. Data analysis showed a significant positive correlation between grain yield and all other NUE‐related traits (r2 value ranged from.23 to 1.00), highlighting their relevance in comprehending the biological NUE of wheat plants. Principal component analysis (PCA) also revealed that N at head and N at harvest were more connected with gain yield, NUE and biomass under the optimum N condition, but less connected with gain yield and NUE under the stressed N condition. To complement the field data, representative genotypes were further subjected to a hydroponics experiment under absolute N control to study the different morphological parameters, photosynthetic pigments and the performance of essential N‐ and C‐metabolizing enzymes at the seedling stage. N stress had a detrimental impact on the majority of the parameters (−0.84% to −79.8%). Nitrite reductase (NiR), glutamate dehydrogenase (GDH) and isocitrate dehydrogenase (ICDH) enzymes as well as root length (RL), root fresh weight (RFW) and CS transcript, were positively affected by 5.9%–35.6%. The correlation analysis highlighted the substantial influence of four key N‐metabolizing enzymes, namely nitrate reductase (NR), glutamine synthetase (GS), glutamate oxo‐glutarate aminotransferase (GOGAT), and GDH on grain yield. Additionally, this study highlighted the direct and indirect associations between seedling parameters and field traits, where shoot and root length were found to be most significant for N acquisition, especially under N stress. In conclusion, these findings offer valuable insights into the intricate network of traits and parameters influencing wheat grain yield under varying N regimes. [ABSTRACT FROM AUTHOR]

Water resources pose a considerable limitation in arid and semi-arid regions like Iran, primarily due to the scarcity of rainfall and heightened evaporation rates. Within open hydroponic systems, a significant concern arises from the depletion of nutrient solutions utilized for crop fertigation. This predicament subsequently gives rise to environmental issues of note and a discernible surge in production expenses. Application of humic acid (HA), as a plant biostimulant, enhances plant tolerance to reduced water supply and counterbalances the effects of diluted nutrient solutions. A greenhouse experiment was conducted to investigate the impact of applying HA (600 ppm) in conjunction with three nutrient solution concentrations (complete nutrient solution (NSc), 75% NSc (NS1), and 50% NSc (NS2)), as well as two irrigation levels (100 and 50% of plant water requirement, IL100 and IL50, respectively). The treatment under IL50 was referred to as ½ NSc, ½ NS1, and ½ NS2. The findings showed that almost all of the traits studied were significantly affected by the applied treatments. The highest yield (409.4 g m−2), leaf area (34.67 cm−2 plant), biomass (1.092 g−1 plant), membrane stability index (90.47%), chlorophyll a (0.99 mg g−1 FW), chlorophyll b (0.413 mg g−1 FW), total chlorophyll (1.54 mg g−1 FW), carotenoid (0.437 mg g−1 FW), vitamin C (730.7 mg ascorbic acid kg−1 FW), amino acid (236.8 µg g−1 FW) and nitrate reductase activity (102.8 µg NO2- mg Protein−1 h−1) were observed in NSc + HA. In addition, the highest carbohydrate (46.99 mg g−1 FW), phenol (1129 mg GAE Kg−1 FW), and flavonoid content (1133 mg Catechin Kg−1 FW) and antioxidant activity (74.75%) were observed in ½ NS1 + HA. In addition, the highest relative water content (86.62%) and nitrate content (1106 mg kg−1 FW) were recorded in NS2 + HA and NSc, respectively. The application of HA combined with different concentrations of the nutrient solution under both irrigation levels caused an increase in most of the parameters studied in rocket plants compared to respective treatments without HA application. In addition, the results obtained confirmed that HA could compensate for the stress caused by a shortage of nutrients and water in the nutrient solution in this crop. [ABSTRACT FROM AUTHOR]

The generation of nitrite by the oral microbiota is believed to contribute to healthy cardiovascular function, with oral nitrate reduction to nitrite associated with systemic blood pressure regulation. There is the potential to manipulate the composition or activities of the oral microbiota to a higher nitrate-reducing state through nitrate supplementation. The current study examined microbial community composition and enzymatic responses to nitrate supplementation in sessile oral microbiota grown in continuous culture. Nitrate reductase (NaR) activity and nitrite concentrations were not significantly different to tongue-derived inocula in model biofilms. These were generally dominated by Streptococcus spp., initially, and a single nitrate supplementation resulted in the increased relative abundance of the nitrate-reducing genera Veillonella, Neisseria, and Proteus spp. Nitrite concentrations increased concomitantly and continued to increase throughout oral microbiota development. Continuous nitrate supplementation, over a 7-day period, was similarly associated with an elevated abundance of nitratereducing taxa and increased nitrite concentration in the perfusate. In experiments in which the models were established in continuous low or high nitrate environments, there was an initial elevation in nitrate reductase, and nitrite concentrations reached a relatively constant concentration over time similar to the acute nitrate challenge with a similar expansion of Veillonella and Neisseria. In summary, we have investigated nitrate metabolism in continuous culture oral biofilms, showing that nitrate addition increases nitrate reductase activity and nitrite concentrations in oral microbiota with the expansion of putatively NaR-producing taxa. IMPORTANCE Clinical evidence suggests that blood pressure regulation can be promoted by nitrite generated through the reduction of supplemental dietary nitrate by the oral microbiota. We have utilized oral microbiota models to investigate the mechanisms responsible, demonstrating that nitrate addition increases nitrate reductase activity and nitrite concentrations in oral microbiota with the expansion of nitrate-reducing taxa. [ABSTRACT FROM AUTHOR]

To study the impact of different PGR and PGR+ nutrient combinations on growth, physiological and yield attributes of sugarcane, three bud setts of variety, CoLk 94184 were primed with plant growth regulator (PGR), ethrel (@ 100 ppm) and nutrient, KCl (@0.2%) overnight and planted along with untreated control under field conditions in three replications at ICAR-IISR farm, Lucknow in spring season (2017-18). Planted sett buds were investigated for changes in reducing sugars content and SAI activity. Foliar application of ethrel and ethrel + nutrient mixture was performed in Set-I untreated control (no sett soaking) with T1-T7 treatments; T1 - No spray (Control), T2 - ethrel spray @100 ppm (Spray 1), T3 - ethrel (100 ppm) + ZnSO4 (0.5%) (Spray 2) at 60DAP, T4 - Spray 1 + GA3 spray @50 ppm (Spray 3), T5 - Spray 2 + GA3 (50 ppm) + CaCl2 (1%) (Spray 4) at 110 DAP, T6 - Spray 1 + Spray 3 + Kinetin @100ppm (spray 5), T7 - Spray 2 + Spray 4 + Kinetin (100 ppm) + MnCl2 (0.1%) (Spray 6) at 175 DAP. In Set-II ethrel treated (Pre-soaked setts) with T8-T14 treatments and Set-III KCl treated (Pre-soaked setts) with T15-T21) treatments, same types of treatments were given as in Set I. After 25 days of foliar application, total shoot population, fresh and dry weight of different plant parts, chlorophyll contents, and nitrate reductase (NR) activity were determined. Juice quality attributes were recorded in cane juice in each month starting from November 2017 to February 2018 and cane yield after harvesting. Findings obtained indicated higher SAI activity and reducing sugar content in treated buds. Further foliar application of ethrel and ethrel + nutrient and at elongation stage, foliar application of GA3 and GA3 + nutrient showed increased shoot population, chlorophyll a, b and total contents, fresh and dry weight of different plant parts and NR activity in treated sets. At harvesting, number of milliable cane (NMC/plot) in most of the treatments were higher; highest was in T11, T5 was at par followed by T13, T14 and then T8. Cane yield observed maximum in T5 (111.6 t/ha), T14 was at par (111.1 t/ha) followed by T8 (107.0 t/ha), T12 (106.4 t/ha), T11 (105.0 t/ha) and minimum in T1 (83.2 t/ha). Similarly, highest cane height and girth were observed in T11 (275.3 cm) and T8 (2.14 cm) treatments, respectively. Highest increase in sucrose % juice, CCS% and °Brix were observed in T11 treatment, while lowest reducing sugars was obtained in T17 followed by T15 treatment. Results suggested beneficial impact of PGR and PGR+ nutrient combination application on growth, yield and juice quality attributes of sugarcane when applied sequentially in whole crop duration. [ABSTRACT FROM AUTHOR]

Introduction: An appropriate supply of ammonium (NH4+) in addition to nitrate (NO3-) can greatly improve plant growth and promote maize productivity. However, knowledge gaps exist regarding the mechanisms by which different nitrogen (N) fertilizer sources affect the enzymatic activity of nitrogen metabolism and non-structural carbohydrates during the post-anthesis period. Methods: A field experiment across 3-year was carried out to explore the effects of four nitrateammonium ratio (NO3-/NH4+ = 1:0 (N1), 1:1 (N2), 1:3 (N3), and 3:1 (N4)) on postanthesis dry matter (DM) and N accumulation, partitioning, transportation, and grain yield in maize. Results: NO3-/NH4+ ratio with 3:1 improved the enzymatic activity of N metabolism and non-structural carbohydrate accumulation, which strongly promoted the transfer of DM and N in vegetative organs to reproductive organs and improved the pre-anthesis DM and nitrogen translocation efficiency. The enzymatic activities of nitrate reductase, nitrite reductase, glutamine synthetase, glutamine oxoglutarate aminotransferase, and nonstructural carbohydrate accumulation under N4 treatment were increased by 9.30%-32.82%, 13.19%-37.94%, 4.11%-16.00%, 11.19%-30.82%, and 14.89%-31.71% compared with the other treatments. Mixed NO3--N and NH4+-N increased the total DM accumulation at the anthesis and maturity stages, simultaneously decreasing the DM partitioning of stem, increasing total DM, DM translocation efficiency (DMtE), and contribution of pre-anthesis assimilates to the grain (CAPG) in 2015 and 2017, promoting the transfer of DM from stem to grain. Furthermore, the grain yield increased by 3.31%-9.94% (2015), 68.6%-26.30% (2016), and 8.292%-36.08% (2017) under the N4 treatment compared to the N1, N2, and N3 treatments. Conclusion: The study showed that a NO3-/NH4+ ratio of 3:1 is recommended for high-yield and sustainable maize management strategies in Northwestern China. [ABSTRACT FROM AUTHOR]

Multidrug-resistant tuberculosis (MDR-TB) is an essential cause of tuberculosis treatment failure and death of tuberculosis patients. The rapid and reliable profiling of Mycobacterium tuberculosis (MTB) drug resistance in the early stage is a critical research area for public health. Then, most traditional approaches for detecting MTB are time-consuming and costly, leading to the inappropriate therapeutic schedule resting on the ambiguous information of MTB drug resistance, increasing patient economic burden, morbidity, and mortality. Therefore, novel diagnosis methods are frequently required to meet the emerging challenges of MTB drug resistance distinguish. Considering the difficulty in treating MDR-TB, it is urgently required for the development of rapid and accurate methods in the identification of drug resistance profiles of MTB in clinical diagnosis. This review discussed recent advances in MTB drug resistance detection, focusing on developing emerging approaches and their applications in tangled clinical situations. In particular, a brief overview of antibiotic resistance to MTB was present, referred to as intrinsic bacterial resistance, consisting of cell wall barriers and efflux pumping action and acquired resistance caused by genetic mutations. Then, different drug susceptibility test (DST) methods were described, including phenotype DST, genotype DST and novel DST methods. The phenotype DST includes nitrate reductase assay, RocheTM solid ratio method, and liquid culture method and genotype DST includes fluorescent PCR, GeneXpert, PCR reverse dot hybridization, ddPCR, next-generation sequencing and gene chips. Then, novel DST methods were described, including metabolism testing, cell-free DNA probe, CRISPR assay, and spectral analysis technique. The limitations, challenges, and perspectives of different techniques for drug resistance are also discussed. These methods significantly improve the detection sensitivity and accuracy of multidrug-resistant tuberculosis (MRT) and can effectively curb the incidence of drug-resistant tuberculosis and accelerate the process of tuberculosis eradication. [ABSTRACT FROM AUTHOR]

Nonsymbiotic phytoglobins (nsHbs) are a diverse superfamily of hemoproteins grouped into three different classes (1, 2, and 3) based on their sequences. Class 1 Hb are expressed under hypoxia, osmotic stress, and/or nitric oxide exposure, while class 2 Hb are induced by cold stress and cytokinins. Both are mainly six-coordinated. The deoxygenated forms of the class 1 and 2 nsHbs from A. thaliana (AtHb1 and AtHb2) are able to reduce nitrite to nitric oxide via a mechanism analogous to other known globins. NsHbs provide a viable pH-dependent pathway for NO generation during severe hypoxia via nitrite reductase-like activity with higher rate constants compared to mammalian globins. These high kinetic parameters, along with the relatively high concentrations of nitrite present during hypoxia, suggest that plant hemoglobins could indeed serve as anaerobic nitrite reductases in vivo. The third class of nsHb, also known as truncated hemoglobins, have a compact 2/2 structure and are pentacoordinated, and their exact physiological role remains mostly unknown. To date, no reports are available on the nitrite reductase activity of the truncated AtHb3. In the present work, three representative nsHbs of the plant model Arabidopsis thaliana are presented, and their nitrite reductase-like activity and involvement in nitrosative stress is discussed. The reaction kinetics and mechanism of nitrite reduction by nsHbs (deoxy and oxy form) at different pHs were studied by means of UV-Vis spectrophotometry, along with EPR spectroscopy. The reduction of nitrite requires an electron supply, and it is favored in acidic conditions. This reaction is critically affected by molecular oxygen, since oxyAtHb will catalyze nitric oxide deoxygenation. The process displays unique autocatalytic kinetics with metAtHb and nitrate as end-products for AtHb1 and AtHb2 but not for the truncated one, in contrast with mammalian globins. [ABSTRACT FROM AUTHOR]

Size-tunable Cu nanoparticles on porous N -doped hexagonal carbon nanorods was reasonably developed. The optimal Cu 30% @NH exhibits an ultrahigh yield for NH 3 electrosynthesis due to the favorable adsorption for NO 3 –* key reaction species. [Display omitted] Electrocatalytic nitrate reduction (NO 3 RR) technique has emerged as a hotspot in NH 3 production, for its practicability, and a series of advanced electrocatalysts with high activity and robust stability needed to be constructed in today's era. In this work, size-tunable Cu nanoparticles on porous nitrogen-doped hexagonal carbon nanorods (Cu@NHC) were reasonably designed and served for catalyzing NO 3 RR in neutral media. Especially, Cu 30% @NHC demonstrated a remarkable electroactivity for NH 3 production as it showed a suitable grain size with massive catalytic centers and favorable d band structure with faster *NO 3 −-to-*NO 2 − catalytic dynamics. As expected, Cu 30% @NHC (3628.28 µg h−1 mg cat. −1) had a much higher NH 3 yield than those for Cu 20% @NHC (1268.42 µg h−1 mg cat. −1) and Cu 40% @NHC (725.03 µg h−1 mg cat. −1). And those collected NH 3 products indeed derived from NO 3 RR process revealed by 15N isotope-labeling and systemic control tests. Moreover, Cu 30% @NHC was also durable for NO 3 RR bulk electrolysis with minor loss in activity. This work offered an effective modifying tactics to boost NO 3 RR catalysis and could guide the design of other advanced electrocatalysts via size-induced surface engineering. [ABSTRACT FROM AUTHOR]

Denitrifying bacteria harboring the nitrate reductase S (nirS) gene convert active nitrogen into molecular nitrogen, and alleviate eutrophication in aquaculture water. Suspended particulate matter (SPM) is an important component of aquaculture water and a carrier for denitrification. SPM with different particle sizes were collected from a coastal high-altitude aquaculture pond in Maoming City, China. Diversity, community structure, abundance of nirS-type denitrifying bacteria on SPM and environmental influencing factors were studied using high-throughput sequencing, fluorescence quantitative PCR, and statistical analysis. Pseudomonas, Halomonas, and Wenzhouxiangella were the dominant genera of nirS-type denitrifying bacteria on SPM from the ponds. Network analysis revealed Pseudomonas and Halomonas as the key genera involved in the interaction of nirS-type denitrifying bacteria on SPM in the ponds. qPCR indicated a trend toward greater nirS gene abundance in progressively larger SPM. Dissolved oxygen, pH, temperature, and SPM particle size were the main environmental factors influencing changes in the nirS-type denitrifying bacterial community on SPM in coastal high-altitude aquaculture pond water. These findings increase our understanding of the microbiology of nitrogen cycle processes in aquaculture ecosystem, and will help optimize aquatic tailwater treatment strategies. [ABSTRACT FROM AUTHOR]

Introduction: Remote ischemic conditioning upregulates endogenous protective pathways in response to ischemia-reperfusion injury. This study tested the hypothesis that limb remote ischemic per- conditioning (RIPerC) exerts cardioprotective effects via the renin-angiotensin system (RAS)/inducible nitric oxide synthase (iNOS)/apelin pathway. Methods: Renal ischemia-reperfusion injury (I/R) was induced by bilateral occlusion of the renal pedicles for 60 minutes, followed by 24 hours of reperfusion; sham-operated rats served as controls. RIPerC was induced by four cycles (5 minutes) of limb ischemia-reperfusion along with bilateral renal ischemia. The functional disturbance was evaluated by renal (BUN and creatinine) and cardiac (troponin I and lactate dehydrogenase) injury biomarkers. Results: Renal I/R injury increased renal and cardiac injury biomarkers that were reduced in the RIPerC group. Histopathological findings of the kidney and heart were also suggestive of amelioration injury-induced changes in the RIPerC group. Assessment of cardiac electrophysiology revealed that RIPerC ameliorated the decline in P wave duration without significantly affecting other cardiac electrophysiological changes. Further, renal I/R injury increased the plasma (322.40±34.01 IU/L), renal (8.27±1.10 mIU/mg of Protein), and cardiac (68.28±10.28 mIU/mg of protein) angiotensin-converting enzyme (ACE) activities in association with elevations in the plasma and urine nitrite (25.47±2.01 & 16.62±3.05 μmol/L) and nitrate (15.47±1.33 & 5.01±0.96 μmol/L) levels; these changes were reversed by RIPerC. Further, renal ischemia-reperfusion injury significantly (P =0.047) decreased the renal (but not cardiac) apelin mRNA expression, while renal and cardiac ACE2 (P <0.05)>P=0.043) mRNA expressions were significantly increased compared to the sham group; these effects were largely reversed by RIPerC. Conclusion: Our results indicated that RIPerC protects the heart against renal ischemia- reperfusion injury, likely via interaction of the apelin with the RAS/iNOS pathway. [ABSTRACT FROM AUTHOR]

Nitrogen and brassinosteroids (BRs) play a vital role in modulating the growth, development, and yield of rice. However, the influences of BRs on nitrogen assimilation and metabolism in rice are not fully understood. In this study, we analyzed the impact of BRs on nitrogen utilization in rice using the indica variety 'Zhongjiazao 17' and the japonica variety 'Nipponbare' in hydroponic conditions. The results showed that BR treatment could efficiently elevate nitrate and ammonium nitrogen accumulation in both shoots and roots. Furthermore, some genes involved in the uptake of nitrate and ammonium in roots were stimulated by BRs, though we noted subtle variances between the two rice cultivars. Moreover, BRs augmented the activity of nitrate reductase (NR) and glutamine synthetase (GS) in roots, along with NR in shoots. Interestingly, BRs also spiked the total free amino acid content in both the shoots and roots. Gene expression analysis uncovered a robust induction by BRs of NR genes and GS-related genes in the roots of both 'Nipponbare' and 'Zhongjiazao 17'. Collectively, our data suggest that BRs significantly enhance the accumulation of both nitrate and ammonium in rice and trigger a series of reactions related to nitrogen utilization. [ABSTRACT FROM AUTHOR]

Denitrification is a key process in soil available nitrogen (N) loss. However, the effects of different water-saving irrigation systems on soil N components and denitrifying bacterial communities are still unclear. In this study, quantitative fluorescence PCR and Illumina MiSeq sequencing were used to investigate the effects of three main irrigation systems, conventional flooding irrigation (FP), shallow buried drip irrigation (DI), and mulched drip irrigation (MF), on the abundance, community composition, and diversity of soil nirK- and nirS-type denitrifying bacteria in the semi-arid area of Northeast China, and to clarify the driving factors of nirK- and nirS-type denitrifying bacterial community variations. The results showed that, compared with FP, MF significantly increased soil moisture, alkaline hydrolyzed nitrogen (AHN), nitrate nitrogen (NO3−-N), non-acid hydrolyzed nitrogen (AIN), and amino sugar nitrogen (ASN), but significantly decreased the contents of ammonium nitrogen (NH4+-N) and acid hydrolyzed ammonium nitrogen (AN). The irrigation system changed the relative abundance of the dominant genera of denitrifying bacteria, DI and MF significantly increased nitrate reductase (NR) and nitrite reductase (NiR) activities, and MF significantly increased the diversity of nirK- and nirS-type denitrifying bacteria but significantly decreased the richness. The community structure of nirK- and nirS-type denitrifying bacteria was significantly different among the three irrigation systems. NO3−-N was the main driving factor affecting the community structure of nirS-type denitrifying bacteria, and moisture significantly affected the community structure of nirK-type denitrifying bacteria. DI and MF significantly increased the abundance of nirK- and nirS-type denitrifying bacteria and also increased the abundance ratio of nirS/nirK genes. Therefore, although DI and MF significantly increased the abundance of denitrifying microorganisms, they did not lead to an increase in the N2O emission potential. [ABSTRACT FROM AUTHOR]

Fatty acid and central carbon metabolism are crucial energy metabolism reactions. However, to date, few studies have examined their distribution characteristics within the alfalfa–rhizobia symbiotic system. To clarify the distributional differences and accumulation rates of fatty acids and central carbon with this system, we measured the plant phenotype, nodule formation, nitrogen fixation capacity, and key nitrogen metabolism enzyme activities of Medicago sativa 'Gannong No. 9' 35 days post-inoculation (dpi) with Sinorhizobia meliloti LL11. Additionally, we employed targeted metabolomics to analyze central carbon and fatty acid metabolites in various tissue samples of symbiotic and control (C.K.) plants, as well as in S. meliloti LL11. We found that plant height; root length; aboveground fresh and dry weights; underground fresh and dry weights; and nitrate reductase, nitrogen reductase, glutamine synthetase, and glutamate synthase activities were significantly higher in the leaves and roots of symbiotic plants than in those of C.K. plants. Compared to symbiotic plants, C.K. plants exhibited higher total central carbon and fatty acid metabolite content, accounting for 38.61% and 48.17% of C.K. plants, respectively. We detected 32 central carbon and 40 fatty acid metabolites in S. meliloti LL11, with succinate (343,180.8603 ng·mL−1) and hexadecanoic acid (4889.7783 ng·mL−1) being the most. In both symbiotic and C.K. plants, central carbon metabolite was considerably higher than the fatty acid metabolite central. Moreover, the carbon metabolites found in symbiotic plants were primarily distributed in pink nodule roots (PNRs), with malate exhibiting the highest content (4,800,612.3450 ng·g−1), accounting for 53.09% of total central carbon metabolite content. Fatty acid metabolites were mainly found in pink root nodules (P.N.s), which are sites of nitrogen fixation. Trans-10-nonadecenoic acid and hexadecanoic acid exhibited the highest contents, comprising >15% of the total fatty acid metabolite content. We found that petroselaidic acid is only present in P.N., which seems to be closely related to the nitrogen fixation reaction in P.N. In general, symbiotic plants transfer central carbon metabolites to nodules via PNRs to drive nitrogen fixation. However, in P.N.s, these metabolites are limited, leading to accumulation in PNRs. Fatty acid metabolites, crucial for nitrogen fixation, are prevalent in P.N.s. Conversely, C.K. plants without nitrogen fixation distribute these metabolites primarily to the stems, emphasizing growth. This study provides new insights into the energy metabolism of symbiotic nitrogen fixation. [ABSTRACT FROM AUTHOR]

Aims: Copper (Cu) is essential for enzymatic systems, electron transport during photosynthesis, and lignin synthesis, affecting plant metabolism and growth. Cu deficiency is observed in young tree orchards, possibly induced by interaction with other mineral nutrients, although visual symptoms are not easily characterized. This study evaluated the induction of Cu deficiency in citrus, due to high nitrogen (N) fertilization, based on the assessment of biochemical parameters, gas exchange, and anatomy of plant tissues. Methods: Valencia orange trees were submitted to levels of Cu supply via fertigation in addition to foliar spraying (control without Cu or with 2.4 g plant−1 of Cu), and N (medium = 8.6 or high = 25.9 g plant−1 of N) for 210 days. Results: Plants well supplied with Cu exhibited higher electron transport rate, net CO2 assimilation, transpiration, and stomatal conductance, in comparison to the control without Cu. Those grown with high N exhibited greater electron transport rate compared to medium N. Plants without Cu and high N supply exhibited the lowest nitrate reductase activity, whereas plants fertilized with Cu and high N exhibited the greatest increase in the activity of this enzyme, in addition to the highest levels of total free amino acids. Furthermore, plants without Cu and high N exhibited the lowest Cu/Zn-SOD II isoform activity. Loose parenchyma structures of leaves and branches were associated with visual symptoms of Cu deficiency. Conclusion: Plant responses demonstrated how Cu deficiency is induced in citrus trees by excess N, thus highlighting the importance of establishing best nutrient management for sustainable fruit production. [ABSTRACT FROM AUTHOR]

The present study aimed to investigate the effects of chitosan application on the yield and quality of rockets. "Bengi" rocket variety was used as a plant material and chitosan was applied to leaves at four different doses (0 (control)-75-150-300 ppm). The results revealed that the yield values varied between 1691-1914 g m-2, plant height between 24.33-27.92 cm, and leaf width between 4.56-5.71 cm among the applications. The total dry matter, chlorophyll, total phenolics, vitamin C, and antiradical activity values were determined to range between 7.71% and 8.68%, 34.15 and 36.68 SPAD, 104.67 and 180.84 mg 100 g-1, 126.63 and 143.51 mg 100 g-1, and 63.77% and 71.87%, respectively. The highest total phenolic and antiradical activity values were obtained at the 300 ppm application and the highest vitamin C values were obtained from the control group. a* and h° values varied between -17.87 to -18.71 and 124.09 to 125.78. Chitosan applications decreased nitrate accumulation compared to the control group. It was determined that the 75 ppm chitosan dose used in the study was better in terms of yield, plant height, leaf width, total dry matter, chlorophyll, a*, h°, and nitrate accumulation parameters and was the recommended dose for rocket cultivation. [ABSTRACT FROM AUTHOR]

Increasing N use efficiency (NUE) is desirable in turfgrass management. Traditional definition of NUE in turfgrass is essentially the inverse of nitrogen concentration in the clippings and is often evaluated once in a growing season. In this experiment, we followed the Brenderse and Aerts' definition of NUE as the product of mean residence time (MRT) and nitrogen productivity (NP). The objective of this experiment was to identify NP changes over time in Kentucky bluegrass cultivars at different N levels under deficit irrigation. Nine Kentucky bluegrass (Poa pratensis L.) and two hybrid bluegrass cultivars from 10 phenotypic classes were tested under N rates of 10 and 40 g m−2. Deficit irrigation at 60% of the evapotranspiration was imposed. The results showed interaction effects on NP from N level, irrigation, and cultivar. Low‐N treatment resulted in higher NP values as compared to high‐N for 'Merit' and 'Martha'. No NP difference existed between N or irrigation levels for 'Blue ghost', 'Geronimo', 'Heidi', 'Bandera', 'Impact', 'Fielder', 'Jackrabbit', and 'Park'. 'Rhythm' showed lower NP values in high‐N combined with full irrigation compared to other treatments. In general, increasing N levels resulted in lower NP, but higher nitrate reductase activity (NaR) and higher net photosynthesis. No N by irrigation interaction effect was detected for effective quantum yield or NaR. In conclusion, leaf‐level NP was shown to be an effective parameter for in‐season monitoring of the above‐ground NUE of Kentucky bluegrass, which provided more dynamic information than clipping yields or a one‐time NUE calculation based on traditional definition. [ABSTRACT FROM AUTHOR]

Nitrate (NO3−) is the primary source of nitrogen preferred by most arable crops, including wheat. The pioneering experiment on primary nitrate response (PNR) was carried out three decades ago. Since then, much research has been carried out to understand the NO3− signaling. Nitrate is sensed by the dual affinity NO3− transceptor NPF6.3, which further relays the information to a master regulator NIN-like protein 7 (NLP7) through calcium-dependent protein kinases (CPK10, CPK30, CPK32), highlighting the importance of calcium ion (Ca2+) as one of the important secondary messengers in relaying the NO3− signaling in Arabidopsis. In a previous study, we found that Ca2+ regulates nitrogen starvation response in wheat. In this study, 10 days old NO3−-starved wheat seedlings were exposed to various treatments. Our study on time course changes in expression of PNR sentinel genes; NPF6.1, NPF6.2, NRT2.1, NRT2.3, NR, and NIR in wheat manifest the highest level of expression at 30 min after NO3− exposure. The use of Ca2+ chelator EGTA confirmed the involvement of Ca2+ in the regulation of transcription of NPFs and NRTs as well the NO3− uptake. We also observed the NO3− dose-dependent and tissue-specific regulation of nitrate reductase activity involving Ca2+ as a mediator. The participation of Ca2+ in the PNR and NO3− signaling in wheat is confirmed by pharmacological analysis, physiological evidences, and protoplast-based Ca2+ localization. [ABSTRACT FROM AUTHOR]

The low efficiency of nitrogen (N) fertilizers is a frequent problem in agriculture that impacts the environment. Omeprazole (OMP) has been reported to promote N uptake and assimilation in tomato, basil, and corn. However, information about the effect of omeprazole on N assimilation, recovery, and N use efficiency parameters for bean plants is limited. Therefore, the objective of the present study was to determine the effect of foliar applications of OMP at 0, 1, 10, and 100 µM on nitrogen assimilation, growth, yield, nitrogen use efficiency parameters, and recovery percentage in green bean plants. Green bean plants cv. Strike grown in pots were used. Biomass, yield, nitrate reductase activity, photosynthetic pigments concentration, soluble amino acids and protein concentrations, total nitrogen concentration, nitrogen use efficiency parameters, and nitrogen recovery were analyzed. The results obtained indicate that the application of OMP at 1 µM increased yield and biomass, promoted N assimilation through higher NR enzyme activity, higher amino acid concentration, higher N use efficiency coefficient, and allowed a more efficient nitrogen recovery percentage. [ABSTRACT FROM AUTHOR]

Cushion plants are one kind of unique specie in alpine ecosystems. They have a compact perennial cushion structure and play a role in facilitating the survival of other associated species by improving the local micro-environment. They are called "engineers" in the alpine ecosystem and their enhancement of soil nutrient availability is one of the ways of their engineering effect. In this study, Androsace tapete, a species of cushion plant widely distributed on the Qinghai-Tibet Plateau, was selected to investigate the dynamics of this process during the growing season at elevations of 4500 m and 4800 m on the southern slope of the Nyenchenthanglha mountains in Damxung. The effects of A. tapete on soil nutrient availability were analyzed by comparing the inorganic nitrogen content, net nitrogen mineralization rate and soil enzyme activities during the growing season in the soil under A. tapete and ambient grassland (CK). The results showed three important aspects of this system. (1) Soil nitrate nitrogen and ammonium nitrogen did not show significant differences at 4500 m, but the contents of nitrate nitrogen and inorganic nitrogen under the A. tapete soil significantly increased in the middle of the growing season at 4800 m, with nitrate nitrogen increasing by 56% and inorganic nitrogen increasing by 74.5%. (2) The trend and rate of soil nitrogen mineralization were both changed under A. tapete. In the 4500 m sample site, soil net nitrogen mineralization under A. tapete was negative (nitrogen immobilization) in the middle of the growing season, and the rate was –0.11 µg g–1 d–1, while that of CK was positive (nitrogen mineralization) and the rate was 0.61 µg g–1 d–1; and the difference between them was significant. However, both were positive in the early and late growing season, and the difference did not reach a significant level. In the 4800 m sample site, the soil net nitrogen mineralization under A. tapete was positive in the early part of the growing season, and the rate was 0.07 µg g–1 d–1, while the mineralization for CK was negative, and the rate was –1.17 µg g–1 d–1; and the difference was significant. In the middle of the growing season, both of them were negative, but the soil net nitrogen mineralization rate under A. tapete (–1.95 µg g–1 d–1) was significantly lower than that of CK (–0.02 µg g–1 d–1). At the late stage of the growing season, both of them were negative, and the difference was not significant. (3) Activities of nitrate reductase and nitrite reductase in the soil were significantly increased under A. tapete. Compared to CK at the 4500 m sample site, the activities of nitrate reductase and nitrite reductase under A. tapete were increased by 9.1% and 15.7%, respectively; and they were increased by 22.5% and 16.1%, respectively, at the 4800 m sample site. The activities of these two enzymes were significantly correlated with the dynamics of inorganic nitrogen in the soil. These results indicated that, compared to CK, the cushion plant A. tapete can change the process of soil nitrogen mineralization and the content of inorganic nitrogen, but that change had seasonal dynamics and spatial differences, which implies that this process was affected not only by the engineering of the cushion plant but also by changes in the local environment. Therefore, the engineering effect of cushion plant A. tapete was not constant during the growing seasons, and further studies are needed to clarify this process, especially considering the rapidly changing climate on the Qinghai-Tibet Plateau. [ABSTRACT FROM AUTHOR]

Tea (Camellia sinensis L.) is one of the most important and traditional economic crops widely cultivated in the subtropical regions of China, which are usually developed from forestland. Soil enzyme activity is an important indicator of soil fertility and nutrient transformation. The purpose of this study is to investigate the seasonal dynamic characteristics of soil properties and enzyme activities of different planting patterns in Wuyishan city, and to provide theoretical basis for reasonable evaluation of soil ecological effects of organic tea cultivation. In this paper, three different planting patterns (forestland, conventional and organic tea gardens) were selected as the research objects. Soil samples were collected in May, August, November and February from 2021 to 2022. The soil properties and enzyme activities (urease, nitrate reductase, polyphenol oxidase, catalase, invertase and acid phosphatase) were determined in different seasons, and the dynamic changes with seasons were also investigated. The results show that: comparing with the forestland, the contents of soil ammonium nitrogen, total phosphorus, available phosphorus and available potassium increased significantly in the conventional tea garden, while the total potassium and pH decreased significantly. Compared with the conventional tea garden, the soil organic matter and total nitrogen contents increased significantly in the organic tea garden. The soil total phosphorus, available phosphorus, total potassium and available potassium contents decreased significantly. The soil pH also increased, and the proportion of soil nutrients was more coordinated. The effects of planting pattern and season and their interactions on urease and peroxidase activities were significant. Compared with the forestland, the soil urease, polyphenol oxidase, catalase and acid phosphatase activities decreased by 12.05% to 63.55% in the conventional tea garden, while urease activities significantly increased by 324.95% in the organic tea garden, and the soil nitrate reductase activities were not changed by planting mode. In general, the soil urease, polyphenol oxidase, invertase and acid phosphatase activities were significantly higher in summer and autumn (May and August) than those in winter and spring (November and February). The highest soil nitrate reductase and catalase activities were found in spring (February). The results of permutational multivariate analysis of variance show that the effect of planting pattern on the overall soil physical and chemical properties was much greater than that of seasonal changes. Redundancy analysis shows that soil environmental factors explained 77.03% of the variation in soil enzyme activity, and the soil organic matter, total nitrogen, ammonium nitrogen, total phosphorus, soil available phosphorus, total potassium, available potassium and pH were the main driving factors of soil enzymes. In summary, the conversion of forestland into tea gardens has a significant impact on soil properties and enzyme activities. Conventional planting leads to the accumulation of available phosphorus and potassium in tea garden soil and the decrease of soil enzyme activity, while organic planting improves soil enzyme activity and enhances soil carbon and nitrogen nutrient supply capacity, and thus is beneficial for maintaining a sustainable ecosystem in tea garden soil. [ABSTRACT FROM AUTHOR]

Nitrate accumulation is a common problem in most leafy vegetables and it happens when the amount of nitrate absorption exceeds the amount consumed by the plant. This study was conducted as a factorial experiment in the form of a completely randomized design and in three replications. The first factor included adding nitrate (calcium nitrate) to Hoagland's standard solution at three levels of 0, 10 and 20%, and the second factor was adding different concentrations of molybdenum from sodium molybdate salt at four levels of 0, 0.5, 1.5 and 3 µM. The measured traits included traits of some growth characteristics, total phenol and flavonoids, ascorbic acid, spinach leaf nitrate. According to the obtained results, fresh and dry weight of leaf, dry weight of root and percentage of dry matter increased by increasing calcium nitrate concentration up to 20% and molybdenum application up to 3 µM in nutrient solution. The simultaneous application of molybdenum and nitrogen had no significant effect on total phenolic, total flavonoid and ascorbic acid traits, and the highest amount of these traits was observed in 3 µM molybdenum. The highest amount of leaf nitrate (3247.4 mg kg-1 FW) was observed in the treatment of 20% additional nitrate along with molybdenum. Based on the results, the use of molybdenum in nutrient solution had a reducing effect on nitrate accumulation in spinach leaf, therefore adding 3 µM sodium molybdate to Hoagland nutrient solution in hydroponic system for spinach production is recommended to obtain the maximum amount of antioxidant compounds and the minimum amount of nitrate accumulation. Introduction Plants take nitrogen (N) either as nitrate (NO3-) or ammonium (NH4+) form for various growth and developmental processes; however, NO3- is more important for such processes. For most of the crop plants, the nitrate form is mobile, less toxic, and can be stored in vacuoles. However, Nitrate must be reduced to NH4+ before it can be utilized for the synthesis of amino acids, proteins, and other nitrogenous compounds in plant cells. Nitrate reductase (NR) and nitrite reductase (NiR), the key nitrate assimilatory enzymes, are located in cytosol and chloroplasts and catalyze nitrate reduction to NO2- followed by NO2- to NH4+, respectively, in the leaf tissues. However, NH4+ is directly assimilated to produce different amino acids by the mutual actions of glutamine synthetase (GS) and glutamate synthase (GOGAT) enzymes in a cyclic manner within the plant cells. Nitrate accumulation is a common problem in most leafy vegetables and it happens when the amount of nitrate absorption exceeds the amount consumed by the plant. Molybdenum (Mo) is an essential microelement for higher plants and also a metal component of the Mo-cofactor, (Moco) biosynthesis. Moco binds to Mo-requiring enzymes and optimizes their activities for normal functioning of plant growth and developmental processes. Molybdenum plays a significant role in N metabolism, which includes nitrate reduction, assimilation, and fixation, by regulating the NR and GS enzymes activities and expressions. During symbiotic N fixation, Mo acts as a cofactor for nitrogenase enzymes to catalyze the redox reaction to convert elemental N into ammonium ions. Materials and methods This study was conducted as a factorial experiment in the form of a completely randomized design and in three replications. The first factor included adding nitrate (calcium nitrate) to Hoagland's standard solution at three levels of 0, 10 and 20%, and the second factor was adding different concentrations of molybdenum from sodium molybdate salt at four levels of 0, 0.5, 1.5 and 3 µM. This research was conducted in the research greenhouse of Campus of Agriculture and Natural Resources Razi University. Senator spinach seeds were obtained from Fardin Kasht Alborz Institute. Spinach seeds were disinfected with 1% sodium hypochlorite for 5 minutes and then planted in seedling trays containing cocopeat and perlite with a volume ratio of 1:1. The measured traits included traits of some growth characteristics, total phenol and flavonoids, ascorbic acid, spinach leaf nitrate. Results and discussion According to the obtained results, fresh and dry weight of leaf, dry weight of root and percentage of dry matter increased by increasing calcium nitrate concentration up to 20% and molybdenum application up to 3 µM in nutrient solution. The simultaneous application of molybdenum and nitrogen had no significant effect on total phenolic, total flavonoid and ascorbic acid traits, and the highest amount of these traits was observed in 3 µM molybdenum. The highest amount of leaf nitrate (3247.4 mg kg-1 FW) was observed in the treatment of 20% additional nitrate along with molybdenum. The most important point in this research was the use of molybdenum to control nitrate accumulation, and the use of molybdenum in concentrations of 1.5 and 3 µM was able to reduce the amount of nitrate accumulation in the aerial parts to some extent, thus neutralizing the toxicity of excess nitrate. The use of sodium molybdate can be one of the recommended ways to reduce the accumulation of nitrates and at the same time enrich molybdenum in spinach and increase the nutritional value of this plant. Conclusion Nitrate and ammonium are the major forms of N that plants use for different growth and developmental processes. The present study revealed that Mo fertilizer plays a key role in N metabolism through regulating the activities and expressions of N-assimilating enzymes. In general, the results of this research showed that the increase in molybdenum concentration in hydroponic culture affected the growth and biochemical characteristics of spinach. Based on the results, the use of molybdenum in nutrient solution had a reducing effect on nitrate accumulation in spinach leaf, therefore adding 3 µM sodium molybdate to Hoagland nutrient solution in hydroponic system for spinach production is recommended to obtain the maximum amount of antioxidant compounds and the minimum amount of nitrate accumulation. [ABSTRACT FROM AUTHOR]

Background Glutamine synthetase (GS), glutamate synthase (GOGAT), and nitrate reductase (NR) are key enzymes involved in nitrogen assimilation and metabolism in plants. However, the systematic analysis of these gene families lacked reports in soybean (Glycine max (L.) Merr.), one of the most important crops worldwide. Methods In this study, we performed genome-wide identification and characterization of GS, GOGAT, and NR genes in soybean under abiotic and nitrogen stress conditions. Results We identified a total of 10 GS genes, six GOGAT genes, and four NR genes in the soybean genome. Phylogenetic analysis revealed the presence of multiple isoforms for each gene family, indicating their functional diversification. The distribution of these genes on soybean chromosomes was uneven, with segmental duplication events contributing to their expansion. Within the nitrogen assimilation genes (NAGs) group, there was uniformity in the exon-intron structure and the presence of conserved motifs in NAGs. Furthermore, analysis of cis-elements in NAG promoters indicated complex regulation of their expression. RT-qPCR analysis of seven soybean NAGs under various abiotic stresses, including nitrogen deficiency, drought-nitrogen, and salinity, revealed distinct regulatory patterns. Most NAGs exhibited up-regulation under nitrogen stress, while diverse expression patterns were observed under salt and drought-nitrogen stress, indicating their crucial role in nitrogen assimilation and abiotic stress tolerance. These findings offer valuable insights into the genomic organization and expression profiles of GS, GOGAT, and NR genes in soybean under nitrogen and abiotic stress conditions. The results have potential applications in the development of stress-resistant soybean varieties through genetic engineering and breeding.

This study aimed to determine the Activity of Nitrate Reductase (ANR) of soybean in Saturated Soil Culture (SSC) and Watering Cultivation (WC) in tidal land and its correlation with aspects of soybean yield of the Anjasmoro cultivar. Treatment applications were arranged in a randomized block design (RBD) with three replications. The height of standing water in the trench in the Saturated Soil Culture system (SSC) as a treatment in this study was 15 cm, 20 cm, and 25 cm from the soil surface. WC actors were selected from 3 farmer groups. Soybean seeds were planted in experimental plots measuring 3 m x 2 m with a spacing of 30 cm x 20 cm, according to the spacing used by farmers. SP36, KCl, and Urea fertilizers were given as basic fertilizers at the recommended dosage. Observation variables included: ANR, number of filled pods/plant, dry seed weight/100 seeds, and dry seed weight/plant. The results showed that the height of standing water in the ditch in SSC affected the ANR and soybean yield. There was no difference in ANR for the height of the water in the ditch 15 cm and 20 cm from the soil surface, 12.76 mol NO2, respectively g-1hour-1 and 13.43 mol NO2. g-1. hour-1. The lowest ANR was obtained at the treatment level with the height of the puddle in the ditch 25 cm from the soil surface, namely 11.52 mol NO2. g-1.h-1, but still higher than the ANR in WC. There was no difference in the number of filled pods/plant, dry seed weight/100 seeds, and dry seed weight/plant between the height of standing water in the 15 cm trench and 20 cm from the soil surface.

Molybdenum (Mo) is an essential micronutrient across all kingdoms of life, where it functions as a key component of the active centers of molybdenum-dependent enzymes. For these enzymes to gain catalytic activity, Mo must be complexed with a pterin scaffold to form the molybdenum cofactor (Moco). The final step of Moco biosynthesis is catalyzed by the enzyme Mo-insertase. This review focuses on eukaryotic Mo-insertases, with an emphasis on those found in plants and mammals, which have been instrumental in advancing the understanding of Mo biochemistry. Additionally, a historical perspective is provided, tracing the discovery of Mo-insertase from the early 1960s to the detailed characterization of its reaction mechanism in 2021. This review also highlights key milestones in the study of Mo-insertase, including mutant characterization, gene cloning, structural elucidation at the atomic level, functional domain assignment, and the spatial organization of the enzyme within cellular protein networks.

The transmembrane nitrate reductase (Nar) is the first enzyme in the dissimilatory alternate anaerobic nitrate respiratory chain in denitrifying bacteria. To date, there has been no real-time method to determine its specific activity embedded in its native membrane; here, we describe such a new method, which is useful with the inside-out membranes of Paracoccus denitrificans and other denitrifying bacteria. This new method takes advantage of the native coupling of the endogenous NADH dehydrogenase or Complex I with the reduction of nitrate by Nar through the quinone pool of the inner membranes of P. denitrificans. This is achieved under previously reached anaerobic conditions. Inner controls confirming the specific Nar activity determined by this new method were made by the total inhibition of the Nar enzyme by sodium azide and cyanide, well-known Nar inhibitors. The estimation of the Michaelis–Menten affinity of Nar for NO3− using this so-called Nar-JJ assay gave a Km of 70.4 μM, similar to previously determined values. This new Nar-JJ assay is a suitable, low-cost, and reproducible method to determine in real-time the endogenous Nar activity not only in P. denitrificans, but in other denitrifying bacteria such as Brucella canis, and potentially in other entero-pathogenic bacteria.