Search Results (37)

Copper (Cu) is a naturally occurring element in soils, and at adequate concentrations, it is essential for plant survival. However, excessive Cu can lead to contamination, impairing soil quality and affecting the development of living organisms. The present study aimed to evaluate the physiological responses of Stizolobium aterrimum plants grown in soils contaminated with increasing doses of copper. The experiment was conducted in a greenhouse under controlled temperature conditions. Five treatments were applied (0, 30, 60, 240, and 480 mg dm⁻³). After 51 days of cultivation, the plants were harvested, and their tissues were separated into leaves, roots, and nodules. Nitrogen compounds were extracted, and the contents of total soluble amino acids, ureides, and soluble proteins were quantified. The activity of the nitrogenase enzyme was analyzed in vivo. The results indicate that Stizolobium aterrimum is partially tolerant to copper contamination, exhibiting adequate growth and metabolism in the presence of moderate Cu concentrations. However, increasing Cu levels in the soil reduce fresh biomass production and lead to higher copper accumulation in the root system. High soil Cu concentrations also affect the absorption of other nutrients, in addition to copper itself. Cu doses around 240 mg dm³ can already be considered toxic. Full article

Red clover (Trifolium pratense L.) is a well-appreciated grassland crop in temperate climates but suffers from increasingly frequent and severe drought periods. Molecular markers for drought resilience (DR) would benefit breeding initiatives for red clover, as would a better understanding of the genes involved in DR. Two previous studies, as follows, have: (1) identified phenotypic DR traits in a diverse set of red clover accessions; and (2) produced genotypic data using a pooled genotyping-by-sequencing (GBS) approach in the same collection. In the present study, we performed genome-wide association studies (GWAS) for DR using the available phenotypic and genotypic data. Single nucleotide polymorphism (SNP) calling was performed using GBS data and the following two red clover genome assemblies: the recent HEN-17 assembly and the Milvus assembly. SNP positions with significant associations were used to delineate flanking regions in both genome assemblies, while functional annotations were retrieved from Medicago truncatula orthologs. GWAS revealed 19 significant SNPs in the HEN-17-derived SNP set, explaining between 5.3 and 23.2% of the phenotypic variation per SNP–trait combination for DR traits. Among the genes in the SNP-flanking regions, we identified candidate genes related to cell wall structuring, genes encoding sugar-modifying proteins, an ureide permease gene, and other genes linked to stress metabolism pathways. GWAS revealed 29 SNPs in the Milvus-derived SNP set that explained substantially more phenotypic variation for DR traits, between 5.3 and 42.3% per SNP–trait combination. Candidate genes included a DEAD-box ATP-dependent RNA helicase gene, a P-loop nucleoside triphosphate hydrolase gene, a Myb/SANT-like DNA-binding domain protein, and an ubiquitin–protein ligase gene. Most accessions in this study are genetically more closely related to the Milvus genotype than to HEN-17, possibly explaining how the Milvus-derived SNP set yielded more robust associations. The Milvus-derived SNP set pinpointed 10 genomic regions that explained more than 25% of the phenotypic variation for DR traits. A possible next step could be the implementation of these SNP markers in practical breeding programs, which would help to improve DR in red clover. Candidate genes could be further characterized in future research to unravel drought stress resilience in red clover in more detail. Full article

Drought is the primary limiting factor affecting soybean productivity, and is exacerbated by climate change. In legumes like soybeans, biological nitrogen fixation (BNF) is the main form of nitrogen acquisition, with nitrogen being converted into ureides. A greenhouse experiment was conducted using the soybean cultivar BMX Zeus IPRO, with two water treatments applied during the vegetative phase: control (C) and water deficit (D). The relative water content and number of nodules were reduced in the D plants. Ureide concentrations (allantoin and allantoic acid) were higher in nodules under D conditions. However, no differences were observed in allantoin, total ureide, and soluble sugar concentrations in leaves. Our results suggest that reducing the number of nodules may be a key strategy for maintaining BNF under drought conditions and that ureide accumulation could be the primary metabolic response in this soybean cultivar. These findings indicate that the effects of water restriction on BNF are likely associated with local metabolic responses rather than a systemic ureide feedback mechanism inhibiting BNF. Full article

Brazilian soils are predominantly rich in aluminum, which becomes mobile at pH < 5, affecting sensitive plants; however, some species have developed aluminum tolerance mechanisms. The purpose of this study was to compare the physiological responses of Crotalaria genus species, family Fabaceae, which have the ability to associate with nitrogen-fixing bacteria under the influence of Al³⁺ in the soil. The soil used was Oxisol; the experimental design was in randomized blocks in a factorial scheme (2 × 3): soil factor (available toxic aluminum content; correction of dolomitic limestone—MgCO₃) and species factor (C. juncea; C. spectabilis; C. ochroleuca); cultivated within 43, 53, and 53 days, respectively, with five replications; 30 experimental samples. Mass and length, pigments, gas exchange, and changes in nitrogen metabolism were evaluated. C. juncea showed a higher concentration of amino acids in the leaves, internal carbon, and stomatal conductance in soil with Al³⁺, as well as higher production of ureides, allantoinic acid, allantoic acid, proteins, and amino acids in the nodules, with 78% of the Al³⁺ accumulation occurring in the roots. C. ochroleuca demonstrated greater shoot length and nodule number production in limed soil; in soil with Al³⁺, it showed a 91% increase in chlorophyll a content and 93% in carotenoids. C. spectabilis showed a 93% increase in ureide production in the leaves in soil with Al³⁺. Full article

The mechanism by which nitrate inhibits nitrogen fixation in soybean (Glycine max L.) is not fully understood. Accumulation of ureide in soybean plant tissues may regulate the nitrogen fixation capacity through a feedback pathway. In this study, unilaterally nodulated dual-root soybeans prepared by grafting were grown in sand culture. They were subjected to the removal of the nodulated side roots, and were given either nitrate supply or no supply to the non-nodulated side roots for 3 days (experiment I). Additionally, they received nitrate supply to the non-nodulated side roots for 1–14 days (experiment II). The results showed that nitrate supply increased the levels of asparagine and ureide in soybean shoots (Experiment I). In Experiment II, nodule dry weight, nodule number, nodule nitrogenase activity, and nodule urate oxidase activity decreased significantly after 3, 7, and 14 days of nitrate supply. Ureide content in the shoots and nodules increased after 1, 3, and 7 days of nitrate supply, but decreased after 14 days of nitrate supply. There was a significant positive correlation between urate oxidase activity and nitrogenase activity. Hence, we deduced that nitrate supply increased the asparagine content in soybean shoots, likely inhibiting ureide degradation, which induced the accumulation of ureide in soybean shoots and nodules, and, in turn, feedback inhibited the nodule nitrogen fixation. In addition, urate oxidase activity can be used to assess the nitrogen fixation capacity of nodules. Full article

Protein hydrolysates are plant biostimulants containing amino acids, oligopeptides, and peptides in their composition. When supplied to plants, protein hydrolysates (HPs) have been identified to improve nitrogen metabolism, enhance the activity of antioxidant enzymes, boost plant defense response to stresses, and positively impact the quantity and quality of products. Soybean is a crucial global commodity, with nitrogen being the primary nutrient for crop development as it directly affects productivity. This study aimed to evaluate the effect of an HP-based biostimulant on the N metabolism in nodulated soybean plants and their productivity. A greenhouse experiment was conducted to test two modes of application of the 0.20% HP-based biostimulant. Soybean plants, growing in pots, were treated with 0.20% HP either via seed treatment or foliar application (at growth stages V3 and V5). Activities of enzymes and compounds related to N metabolism, gene expression, and productivity components were analyzed. It was observed that the mode of application did not significantly influence the results. The application of HPs increased the concentration of nitrate, amino acids, and ureides in soybean leaves. It also positively altered the expression of genes such as nitrate reductase, urease, and asparagine. Additionally, it enhanced productivity, resulting in plants with a greater number and weight of pods and grains. Therefore, it is possible to consider HPs as a stimulator for increasing soybean productivity, even under non-stressing conditions. Full article

Ureide permeases (UPSs) mediate the transport of ureides, including allantoin and allantoate, which act as nitrogen-transporting compounds in plants and have recently been found to play a role in cellular signaling. To date, UPSs have not been reported in potato, and their identification is important for further function studies and for understanding molecular mechanisms of plant adverse responses. Based on potato genomic data, we identified 10 StUPS genes in potato (Solanum tuberosum L.). Then, we conducted a comprehensive study of the identified StUPS genes using bioinformatics methods. Genome phylogenetic and genomic localization analyses revealed that StUPSs can be classified into four categories, are highly homologous to Arabidopsis thaliana UPS members, and are distributed on three chromosomes. The six StUPS genes were investigated by RT–qPCR, and the findings indicated that all of these genes are involved in the response to several stresses, including low nitrogen, cold, ABA, salt, H₂O_2, and drought. This study establishes a strong theoretical framework for investigating the function of potato UPS genes, as well as the molecular mechanisms underlying the responses of these genes to various environmental stresses. Full article

Queuosine (Q) is a modification of the wobble base of tRNA harboring GUN anticodons with roles in decoding accuracy and efficiency. Its synthesis is complex with multiple enzymatic steps, and several pathway intermediates can be salvaged. The only two transporter families known to salvage Q precursors are QPTR/COG1738 and QrtT/QueT. Analyses of the distribution of known Q synthesis and salvage genes in human gut and oral microbiota genomes have suggested that more transporter families remain to be found and that Q precursor exchanges must occur within the structured microenvironments of the mammalian host. Using physical clustering and fusion-based association with Q salvage genes, candidate genes for missing transporters were identified and five were tested experimentally by complementation assays in Escherichia coli. Three genes encoding transporters from three different Pfam families, a ureide permease (PF07168) from Acidobacteriota bacterium, a hemolysin III family protein (PF03006) from Bifidobacterium breve, and a Major Facilitator Superfamily protein (PF07690) from Bartonella henselae, were found to allow the transport of both preQ₀ and preQ₁ in this heterologous system. This work suggests that many transporter families can evolve to transport Q precursors, reinforcing the concept of transporter plasticity. Full article

Phosphorus (P) is an essential major element for plants. The absorption and transport of P are important for soybean growth and yield, including nodule growth and N₂ fixation. Through an analysis of xylem sap, we investigated how nodulated soybean plants absorb PO₄ via the roots and transport it to the shoot. The nodulated soybean plants were treated with 0, 50, and 250 μM PO₄ concentrations for 1, 3, 7, and 15 days. The PO₄ concentration in the xylem sap significantly decreased after 1 day of P deprivation, and then it gradually decreased for 15 days. The high-concentration (250 μM PO₄) treatment increased the PO₄ concentrations in the xylem sap at 7- and 15-day timepoints but not at the 1- or 3-day timepoints. The soybean plants were treated with 0, 25, 50, 100, 150, 250, and 500 μM PO₄ for 3 days. The PO₄ absorption rate increased consistently in conjunction with the increase in the PO₄ concentration; however, the PO₄ concentrations in the xylem sap increased only from 0 to 50 μM PO₄ but were constant under higher P concentrations. The soybean plants accumulated extra PO₄ in the roots. The PO₄ concentration in the xylem sap immediately reflected the P deficiency conditions; thus, this index may be used as an indicator for the diagnosis of P deficiency. Full article

Previously, we demonstrated that the ¹⁷⁷Lu-labeled single-chain variable fragment of an anti-prostate-specific membrane antigen (PSMA) IgG D2B antibody (scFvD2B) showed higher prostate cancer (PCa) cell uptake and tumor radiation doses compared to ¹⁷⁷Lu-labeled Glu-ureide-based PSMA inhibitory peptides. To obtain a ^99mTc-/¹⁷⁷Lu-scFvD2B theranostic pair, this research aimed to synthesize and biochemically characterize a novel ^99mTc-scFvD2B radiotracer. The scFvD2B-Tag and scFvD2B antibody fragments were produced and purified. Then, two HYNIC derivatives, HYNIC-Gly-Gly-Cys-NH₂ (HYNIC-GGC) and succinimidyl-HYNIC (S-HYNIC), were used to conjugate the scFvD2B-Tag and scFvD2B isoforms, respectively. Subsequently, chemical characterization, immunoreactivity tests (affinity and specificity), radiochemical purity tests, stability tests in human serum, cellular uptake and internalization in LNCaP(+), PC3-PIP(++) or PC3(−) PCa cells of the resulting unlabeled HYNIC-scFvD2B conjugates (HscFv) and ^99mTc-HscFv agents were performed. The results showed that incorporating HYNIC as a chelator did not affect the affinity, specificity or stability of scFvD2B. After purification, the radiochemical purity of ^99mTc-HscFv radiotracers was greater than 95%. A two-sample t-test of ^99mTc-HscFv1 and ^99mTc-HscFv1 uptake in PC3-PIP vs. PC3 showed a p-value < 0.001, indicating that the PSMA receptor interaction of ^99mTc-HscFv agents was statistically significantly higher in PSMA-positive cells than in the negative controls. In conclusion, the results of this research warrant further preclinical studies to determine whether the in vivo pharmacokinetics and tumor uptake of ^99mTc-HscFv still offer sufficient advantages over HYNIC-conjugated peptides to be considered for SPECT/PSMA imaging. Full article

Soluble epoxide hydrolase (sEH) is an enzyme involved in the metabolism of bioactive lipid signaling molecules. sEH converts epoxyeicosatrienoic acids (EET) to virtually inactive dihydroxyeicosatrienoic acids (DHET). The first acids are “medicinal” molecules, the second increase the inflammatory infiltration of cells. Mitogen-activated protein kinases (p38 MAPKs) are key protein kinases involved in the production of inflammatory mediators, including tumor necrosis factor-α (TNF-α) and cyclooxygenase-2 (COX-2). p38 MAPK signaling plays an important role in the regulation of cellular processes, especially inflammation. The proto-oncogenic serine/threonine protein kinase Raf (c-Raf) is a major component of the mitogen-activated protein kinase (MAPK) pathway: ERK1/2 signaling. Normal cellular Raf genes can also mutate and become oncogenes, overloading the activity of MEK1/2 and ERK1/2. The development of multitarget inhibitors is a promising strategy for the treatment of socially dangerous diseases. We synthesized 1,3-disubstituted ureas and diureas containing a dichloroadamantyl moiety. The results of computational methods show that soluble epoxide hydrolase inhibitors can act on two more targets in different signaling pathways of mitogen-activated protein kinases p38 MAPK and c-Raf. The two chlorine atoms in the adamantyl moiety may provide additional Cl-π interactions in the active site of human sEH. Molecular dynamics studies have shown that the stability of ligand–protein complexes largely depends on the “spacer effect.” The compound containing a bridge between the chloroadamantyl fragment and the ureide group forms more stable ligand–protein complexes with sEH and p38 MAPK, which indicates a better conformational ability of the molecule in the active sites of these targets. In turn, a compound containing two chlorine atoms forms a more stable complex with c-Raf, probably due to the presence of additional halogen bonds of chlorine atoms with amino acid residues. Full article

New imidazolidine-2,4,5-triones with norabietic, nordehydroabietic, and adamantane substituents were synthesized by reacting oxalyl chloride and the corresponding ureas, providing good yields. Bioisosteric replacement of the ureide group with a parabanic acid fragment made it possible to increase the solubility of compounds and conduct biological studies. The compounds inhibit the DNA repair enzyme tyrosyl-DNA phosphodiesterase 1 in submicromolar concentrations. Cytotoxic concentrations were also studied on the glioblastoma cell line SNB19. Full article

Citrulline is a non-protein amino acid that acts as a metabolic intermediate in the urea cycle and arginine synthesis. It is present in some foods, although its name derives from watermelon (Citrullus vulgaris), from which it was first identified. Under normal conditions, Citrulline exists as a zwitterion in aqueous solutions since its carboxylic and amine groups can act as Lewis donors to chelate metal cations. In addition, Citrulline possesses in the aliphatic chain a terminal ureide group, which could also coordinate. Although Citrulline is comparable to other classical amino acids, its coordination chemistry has yet to be explored. Only two metal complexes have been reported, and the copper complex is a polymeric and insoluble material. As part of our search for active Casiopeina^® analogs, we created a more soluble complex by combining 2,2′-Bipyridine into a new mixed material, resulting in the mononuclear complex [Cu(Bipy)(Citr)(H₂O)(NO₃)]·H₂O. Single-crystal X-ray diffraction, spectroscopic methods (FT-IR, UV-Vis, Raman), and mass spectrometry characterized the material. Interestingly, both isomers of Citrulline, R(D), and S(L) are present in the same crystal. In addition, the molecular structure and electronic properties of the complex were calculated using density functional theory (DFT). Non-covalent interactions were characterized using the atoms-in-molecules (AIM) approach and Hirshfeld surface (HS) analysis. This ternary complex containing Citrulline and 2,2′-Bipyridine will be used for docking calculations and preliminary biological studies using calf thymus DNA (CT-DNA) and plasmid pUC19 as a first approximation to cytotoxic activity against cancer cell lines. Full article

Stress-induced alterations vary with the species of plants, the intensity and duration of the exposure, and stressors availability in nature or soil. Purine catabolism acts as an inherent defensive mechanism against various abiotic stresses and plays a pivotal role in the stress acclimatisation of plants. The intermediate metabolite of purine catabolism, allantoin, compensates for soil nitrogen deficiency due to the low carbon/nitrogen ratio, thereby maintaining nitrogen homeostasis and supporting plant growth and development. Allantoin accounts for 90% of the total nitrogenous compound in legumes, while it contributes only 15% in non-leguminous plants. Moreover, studies on a variety of plant species have reported the differential accumulation of allantoin in response to abiotic stresses, endowing allantoin as a stress modulator. Allantoin functions as signalling molecule to stimulate stress-responsive genes (P5CS; pyrroline-5-carboxylase synthase) and ROS (reactive oxygen species) scavenging enzymes (antioxidant). Moreover, it regulates cross-talk between the abscisic acid and jasmonic acid pathway, and maintains ion homeostasis by increasing the accumulation of putrescine and/or spermine, consequently enhancing the tolerance against stress conditions. Further, key enzymes of purine catabolism (xanthine dehydrogenase and allantoinase) have also been explored by constructing various knockdown/knockout mutant lines to decipher their impact on ROS-mediated oxidative injury in plants. Thus, it is established that allantoin serves as a regulatory signalling metabolite in stress protection, and therefore a lower accumulation of allantoin also reduces plant stress tolerance mechanisms. This review gives an account of metabolic regulation and the possible contribution of allantoin as a photo protectant, osmoprotectant, and nitrogen recycler to reduce abiotic-stress-induced impacts on plants. Full article