Search Results (208)

Background/Objectives: Nitrogen (N) is an essential macronutrient that strongly influences maize growth and metabolism. While many studies have focused on nitrogen responses during later developmental stages, early-stage physiological and metabolic responses remain less explored. This study investigated the effect of different nitrogen-deficient levels on maize seedling growth and primary metabolite profiles. Methods: Seedlings were treated with N-modified nutrient solution, which contained 0% to 120% of the standard nitrogen level (8.5 mM). Results: Nitrogen starvation (N0) significantly reduced plant height (by 11–14%), shoot fresh weight (over 30%) compared to the optimal N supply (N100). Total leaf nitrogen content under N0–N20 was less than half of that in N100, whereas moderate N deficiency resulted in moderate reductions in growth and nitrogen content. Metabolite analysis revealed that N deficiency induced the accumulation of soluble sugars and organic acids (up to threefold), while sufficient N promoted the synthesis of amino acids related to nitrogen assimilation and protein biosynthesis. Statistical analyses (PCA and ANOVA) showed that both genotypes (MB and TYC) and tissue type (upper vs. lower leaves) influenced the metabolic response to nitrogen, with MB displaying more consistent shifts and TYC exhibiting greater variability under moderate stress. Conclusions: These findings highlight the sensitivity of maize seedlings to early nitrogen deficiency, with severity influenced by nitrogen level, tissue-specific position, and genotype; thus underscore the close coordination between physiological growth and primary metabolic pathways in response to nitrogen availability. These findings expand current knowledge of nitrogen response mechanisms and offer practical insights for improving nitrogen use efficiency in maize cultivation. Full article

Serotoninomics is an expanding field that focuses on the comprehensive study of the serotoninergic system, including serotonin’s biosynthesis, metabolism, and regulation, as well as related scientific methodologies 5-hydroxytryptamine (5-HT). This field explores serotonin’s complex roles in various physiological and pathological contexts. The essential amino acid tryptophan (Trp) is a precursor for several metabolic and catabolic pathways, with the kynurenine (KYN) pathway being particularly significant, representing about 95% of Trp metabolism. In contrast, only a small portion (1–2%) of dietary Trp enters the serotonin pathway. Anthranilic acid (AA), a metabolite in the KYN pathway, has emerged as a potential biomarker and therapeutic target for schizophrenia. Elevated serum AA levels in patients with schizophrenia have been associated with neurotoxic effects and disruptions in neurotransmission, suggesting AA’s critical role in the disorder’s pathophysiology. Furthermore, the 5-HT_2A receptor’s involvement is particularly noteworthy, especially in relation to schizophrenia’s positive symptoms. Recent findings indicate that 5-HT_2A receptor hyperactivity is linked to positive symptoms of schizophrenia, such as hallucinations and delusions. This study investigates serotoninomics’ implications for neuropsychiatric disorders, focusing on AA in schizophrenia and analysing recent research on serotonin signalling pathways and AA’s neurochemical effects. Understanding the roles of the 5-HT_2A receptor and AA in neuropsychiatric disorders could lead to the development of more precise and less invasive diagnostic tools, specific therapeutic strategies, and improved clinical outcomes. Ongoing research is essential to uncover these pathways’ exact mechanisms and therapeutic potential, thereby advancing personalised medicine and innovative treatments in neuropsychiatry. Full article

Background/Objectives: Breast milk provides essential nutrition and immune protection to support infant growth and development. However, insufficient breast milk remains a serious issue, and bioactive peptides represent a potential strategy to promote lactation. In this study, we investigated the impact of a methionine-containing dipeptide, EM, on MCF-10A mammary epithelial cells. Methods: MCF-10A cells were treated with EM, and cell proliferation and the expression of key milk protein genes were assessed. Integrated transcriptomic and untargeted metabolomic analyses were performed to identify EM-induced changes in metabolic and gene expression pathways. Results: EM treatment significantly enhanced cell proliferation and upregulated the expression of key milk protein genes (CSN1S1 (casein alpha-S1, encoding alpha-S1 casein), CSN2 (casein beta, encoding beta-casein), and CSN3 (casein kappa, encoding kappa-casein)) at both transcriptional and protein levels compared to controls. Integrated transcriptomic and metabolomic analyses revealed that EM reprogrammed amino acid metabolism, lipid biosynthesis, and nutrient transport pathways. Core genes such as SLC7A11, APOE, and ABCA1 were identified as critical nodes linking metabolic and transcriptional networks. Conclusions: These findings indicate that EM may promote lactogenic activity by modulating metabolic and transcriptional networks in vitro, highlighting the potential of dipeptide-based nutritional interventions, which warrants further in vivo validation. Full article

This study investigated the metabolite dynamic changes and transformation pathways in Diqing Tibetan pig (DTP) hams during fermentation (0, 30, 90, 180, 360, 540 d) by widely targeted metabolomics. A total of 873 metabolites in 17 subclasses were detected, with significant changes in 448 metabolites. Additionally, 65 key metabolites were found to be involved in the top 10 pathways, with the top pathways for metabolite markers in mature hams including protein metabolism (2-oxocarboxylic acid metabolism, tryptophan metabolism and amino acid biosynthesis) and lipid metabolism (unsaturated fatty acid biosynthesis and linoleic acid metabolism). Overall, the unique DTP ham taste, flavor, and nutritional value may be contributed to by the significant accumulation of essential amino acids, MSG-like amino acids, free fatty acids (arachidonic acid, docosahexaenoic acid, and eicosapentaenoic acid), citric acid, oxaloacetic acid, succinic acid, and vitamin B. This study facilitates a comprehensive understanding of metabolic profiling and the transformation pathways of DTP hams during fermentation, providing novel insights into the biochemical mechanisms underlying traditional Tibetan pig hams, bridging traditional knowledge with modern omics technologies. Full article

Ophiocordyceps sinensis, is an entomopathogenic fungus renowned for its medicinal properties, thriving in the frigid and high-altitude regions of the Qinghai–Tibet plateau. Given the limited availability of wild resources and the increasing recognition of their medicinal value, the cultivation of O. sinensis was initiated. However, there is a paucity of research investigating the disparities in their quality. This study evaluated the primary physiological indicators of both wild and cultivated O. sinensis. It also employed proteome and untargeted metabolome approaches to elucidate the differences in quality and underlying mechanisms between the two types. The results revealed that the contents of key representative components, including polysaccharide, crude protein, adenosine, and mannitol, were higher in wild O. sinensis than in cultivated O. sinensis. A total of 499 differentially expressed proteins (DEPs), including 117 up-regulated and 382 down-regulated DEPs, were identified in wild and cultivated O. sinensis. Additionally, 369 up-regulated differentially accumulated metabolites (DAMs) and 737 down-regulated DAMs were also identified. Wild O. sinensis had higher relative levels of lysophospholipid metabolites, while cultivated O. sinensis had higher relative levels of aldehydes and carboxylic acids. Correlation analysis revealed that different habitats altered 47 pathways shared between the proteome and metabolome, including carbohydrate metabolism and energy metabolism. β-glucosidase and α-galactosidase play essential roles in carbohydrate catabolism and may indirectly influence amino acid synthesis through energy metabolic pathways. The differential expression of polyamine oxidase (PAO) could reflect variations in polyamine metabolism and ammonia production between wild and cultivated O. sinensis. These variations may consequently affect nitrogen homeostasis and the biosynthesis of nitrogen-containing compounds, ultimately leading to differences in nutritional quality. In conclusion, these findings offer a novel perspective on the applications of O. sinensis and serve as a reference for the targeted development of cultivated O. sinensis. Full article

L-leucine, an essential amino acid which cannot be synthesized in mammals, has extensive applications in various fields. However, the large-scale production of L-leucine still faces various challenges in terms of strain and process optimization. In this study, E. coli A211 was used as the initial strain, and a double enhancement strategy of CRISPR-associated transposase genome integration and a plasmid was employed to enhance the L-leucine metabolic pathway. We constructed four engineered strains—E. coli A101, E. coli B201, E. coli CD301, and E. coli bcd401. The transcriptional levels of key genes (leuA, leuCD, leuB, and bcd) in L-leucine biosynthesis were significantly upregulated to boost L-leucine production. Fermentation screening revealed that E. coli CD301 exhibited the highest L-leucine titer (0.57 ± 0.01 g/L), presenting a 97% increase compared with the parental strain. The fermentation process of E. coli CD301 was further optimized using single-factor optimization followed by response surface methodology of variables such as temperature, C/N ratio, and inoculum size, leading to an enhanced L-leucine titer of 0.89 ± 0.03 g/L, a 56.1% improvement over the pre-optimization level. This study demonstrated the effectiveness of CRISPR-associated transposase genome integration and plasmid double enhancement strategy, providing new insights into metabolic engineering approaches for improving L-leucine production via fermentation with E. coli. Full article

Molybdenum (Mo) is a vital micronutrient for nearly all living organisms, serving as a cofactor for molybdoenzymes that catalyze essential redox reactions in nitrogen metabolism. Among these enzymes, nitrate reductase plays a crucial role in nitrate assimilation. Maintaining Mo homeostasis—including uptake, storage, and utilization—is critical to avoid both deficiency and toxicity. Our research focuses on uncovering novel molecular components involved in Mo homeostasis, particularly in connection with nitrate assimilation, using Chlamydomonas reinhardtii, a model green microalga. To achieve this, we generated more than 5000 Chlamydomonas transformants through insertional mutagenesis using a paromomycin resistance cassette (AphVIII) and screened them for altered growth on nitrate and under different Mo concentrations. We identified four strains showing altered growth patterns when using nitrate as a nitrogen source or exhibiting increased sensitivity or resistance to Mo. The genomic alterations in these strains were identified. Notably, both a Mo-resistant and a Mo-sensitive transformant had disruptions in the genes that encoded ABC-type transport proteins, indicating a potential role for these proteins in Mo transport. Additionally, two strains were unable to grow on nitrate. One of them had a mutation in the CNX7, a gene involved in Mo cofactor biosynthesis, while the other had a mutation in BAT1, an amino acid transporter. The BAT1 mutant represents an interesting case study, as this gene has not previously been associated with nitrate metabolism. These findings enhance our understanding of Mo and nitrate homeostasis mechanisms and open new paths for engineering microalgae with improved nitrogen assimilation. Full article

The median lethal concentration value of alkalinity tolerance for Macrobrachium nipponense over 96 h is only 14.42 mmol/L with a safety value of 4.71 mmol/L, which is insufficient to perform the aquaculture program in a water environment with high alkalinity. Thus, the present study aims to explore the effects of alkalinity exposure on the gills of M. nipponense through identifying the changes in antioxidant enzymes, morphology, and gene expressions after 1 day, 4 days, and 7 days of exposure under an alkalinity of 10 mmol/L. The activities of MDA, GSH-PX, CAT, T-AOC, and Ca²⁺Mg²⁺-ATPase are significantly stimulated by 62.6%, 6.57%, 32.1%, 33.3%, and 14.9%, compared to those from Day 0 (control group), indicating that these antioxidant enzymes play essential roles in the protection of prawns from the damage of reactive oxygen species caused by alkalinity exposure. In addition, alkalinity exposure results in an increase in the hemolymph vessels, affecting the normal respiratory function of the gills. Transcriptome profiling analysis reveals that short-term alkali exposure (4 days) does not result in significant changes in gene expression in the present study. Furthermore, metabolic pathways, biosynthesis of amino acids, amino sugar and nucleotide sugar metabolism, lysosomes, glycolysis/gluconeogenesis, and phagosomes represent the main enriched metabolic pathways of differentially expressed genes (DEGs) between Day 4 and Day 7. Biosynthesis of amino acids, lysosomes, and phagosomes are immune-related metabolic pathways, while amino sugar and nucleotide sugar metabolism and glycolysis/gluconeogenesis are energy metabolism-related metabolic pathways, indicating that the processes of immune response and energy metabolism play essential roles in the response to alkalinity exposure in M. nipponense. Thus, the DEGs from these metabolic pathways are considered as candidate genes involved in the regulation of alkaline acclimation in M. nipponense. The present study provides valuable evidence for analysis of the adaptive mechanism when exposed to alkalinity, contributing to the survival rate and aquaculture of this species under water environments with high alkalinity. Full article

Selenium (Se) is an essential trace element for humans, and the production of Se-enriched rice (Oryza sativa) is a key approach for Se supplementation. Nevertheless, the effects of different Se forms and concentrations on the metabolism and aboveground absorption pathways of rice seedlings are not yet well-understood. Therefore, we conducted a hydroponic experiment and used transcriptome analysis to study the absorption and transformation processes of sodium selenite (Na₂SeO₃) and selenomethionine (SeMet) in rice at the seedling stage. The aboveground (stem + leaf) Se concentration at the seedling stage was higher under the SeMet treatments, and low Se applications (<25 μM) significantly promoted rice growth. Selenocysteine (SeCys) and SeMet were the primary forms of Se in rice, accounting for 57–86.35% and 7.6–31.5%, respectively, while selenate [Se (VI)] significantly increased when Se levels exceeded 25 μM. In the transcriptome, differentially expressed genes (DEGs) were significantly enriched in the following pathways: carbon metabolism, amino acid biosynthesis, and glutathione metabolism. In the Na₂SeO₃ treatments, genes encoding phosphoglycerate mutase (PGM), triosephosphate isomerase (TPI), phosphofructokinase (PFK), pyruvate kinase (PK), malate dehydrogenase (MDH), polyamine oxidase (PAO), aspartate aminotransferase (AST), and glutathione S-transferase (GST) were upregulated, and the expression levels of differentially expressed genes (DEGs) decreased with increasing Se levels. SeMet treatments upregulated genes encoding PFK, PK, glutamine synthetase (NADH-GOGAT), and L-ascorbate peroxidase (APX), and expression levels of DEGs increased with increasing Se levels. This study provides important insights into the molecular mechanisms of the uptake and metabolism of different Se forms in rice at the seedling stage. Full article

As a tropomyosin-binding component, troponin T (TnT) is essential for the Ca²⁺ regulation of striated muscles’ contraction and locomotion activity, but its impacts on the growth and development of insects have rarely been reported. In this study, TnT was identified and functionally characterized in Tribolium castaneum by RNA interference (RNAi) and transcriptome analysis. The TnT of T. castaneum contained a 1152 bp open reading frame encoding 383 amino acids. It displayed the highest expression in late pupae and was highly expressed in the integument and CNS. Both the larval and early pupal injection of dsTnT led to 100% cumulative mortality before the pupal–adult transition. Late pupal RNAi caused 26.01 ± 4.29% pupal mortality; the survivors successfully became adults, but 49.71 ± 6.51% died in 10 days with a dried and shriveled abdomen, poorly developed reproductive system and no offspring. Additionally, RNA sequencing results indicated that key ecdysteroid and juvenile hormone biosynthesis genes (CYP314A1, aldehyde dehydrogenase family 3 member B1 and farnesol dehydrogenase) were affected, as well as several cuticle protein, nutrition metabolism and immune-related genes, suggesting that TnT may play prominent roles in development, metabolism and reproduction by affecting these pathways. This study could provide a brand-new target gene in the RNAi strategy for pest control. Full article

Equine endurance exercise induces physiological changes that alter metabolism and molecular pathways to maintain balance after intense physical activity. However, the specific regulatory mechanisms remain under debate. Identifying differentially expressed genes (DEGs) and differential metabolites (DMs) associated with equine endurance is essential for elucidating these regulatory mechanisms. This study collected blood samples from six Yili horses before and after an 80 km race and conducted transcriptomics and metabolomics analyses, yielding 722 DEGs and 256 DMs. These DEGs were primarily enriched in pathways related to amino acid biosynthesis, cellular senescence, and lipid metabolism/atherosclerosis. The DMs were predominantly enriched in fatty acid biosynthesis and the biosynthesis of unsaturated fatty acids. The integrative transcriptomics and metabolomics analyses of DEGs and DMs highlight functional changes during the endurance race. The findings offer a holistic understanding of the regulatory mechanisms underlying equine endurance and a solid foundation for formulating training programs to optimize horse performance in endurance racing. Full article

Chloroplast biogenesis is a crucial biological process in plants. Endoribonuclease E (RNase E) functions in the RNA metabolism of chloroplast and plays a vital role for chloroplast development in Arabidopsis. However, despite sharing 44.7% of its amino acid sequence identity with Arabidopsis RNase E, the biological function of rice OsRNE (Oryza sativa RNase E) remains unknown. Here, we identified a white leaf and lethal 1 (wll1) mutant that displayed white leaves and died at the seedling stage. The causal gene OsRNE was isolated by MutMap+ method. CRISPR/Cas9-mediated knockout of OsRNE resulted in white leaves and seedling lethality, confirming OsRNE as the causal gene for the wll1 phenotype. The albino phenotype of osrne mutant was associated with decreased chlorophyll content and abnormal thylakoid morphology in the chloroplast. The absence of OsRNE led to a significant reduction in the Rubisco large subunit (RbcL), and the 23S and 16S chloroplast rRNAs were nearly undetectable in the osrne mutant. OsRNE transcripts were highly expressed in green tissues, and the protein was localized to chloroplasts, indicating its essential role in photosynthetic organs. Furthermore, transcriptome analysis showed that most of the genes associated with photosynthesis and carbohydrate metabolism pathways in the osrne mutant were significantly down-regulated compared with those in WT. Chlorophyll- and other pigment-related genes were also differentially expressed in the osrne mutant. Our findings demonstrated that OsRNE plays an important role in chloroplast development and chlorophyll biosynthesis in rice. Full article

Chitin synthase is an essential enzyme of the chitin synthesis pathway during molting. In this study, we identified and characterized a chitin synthase (EsCHS) gene in the Chinese mitten crab, Eriocheir sinensis. The spatio-temporal expression and functional role of EsCHS were investigated. The open reading frame of EsCHS was 4725 bp long and encoded 1574 amino acid residues that contained the typical domain structure of the glycosyltransferase family 2. Phylogenetic analysis revealed that EsCHS belongs to the group I chitin synthase family. The expression of EsCHS was found in regenerative limbs, the cuticle and the intestines. During the molting cycle, EsCHS began to increase in the pre-molt stage and reached a significant peak in the post-molt stage. The knockdown of EsCHS resulted in the significant downregulation of chitin biosynthesis pathway genes, including TRE, HK, G6PI, PAGM and UAP. Moreover, the long-term RNAi of EsCHS resulted in thinning procuticles, abnormal molting and high mortality, suggesting that EsCHS is indispensable for the formation of chitin in the cuticle during molting. In conclusion, EsCHS is involved in the chitin biosynthesis pathway and plays an important role in molting in E. sinensis. These findings highlight the potential of incorporating EsCHS into selective breeding programs to optimize molting regulation and improve growth performance in crustacean aquaculture. Full article

Helvella leucopus, an endangered wild edible fungus, is renowned for its distinct health benefits and nutritional profile, with notable differences in the bioactive and nutritional properties between its cap and stipe. To investigate the molecular basis of these tissue-specific variations, we conducted integrative transcriptomic and metabolomic analyses. Metabolomic profiling showed that the cap is particularly rich in bioactive compounds, including sterols and alkaloids, while the stipe is abundant in essential nutrients, such as glycerophospholipids and amino acids. Transcriptomic analysis revealed a higher expression of genes involved in sterol biosynthesis (ERG1, ERG3, ERG6) and energy metabolism (PGK1, ENO1, PYK1) in the cap, suggesting a more active metabolic profile in this tissue. Pathway enrichment analysis highlighted tissue-specific metabolic pathways, including riboflavin metabolism, pantothenate and CoA biosynthesis, and terpenoid backbone biosynthesis, as key contributors to the unique functional properties of the cap and stipe. A detailed biosynthetic pathway network further illustrated how these pathways contribute to the production of crucial bioactive and nutritional compounds, such as sterols, alkaloids, linoleic acid derivatives, glycerophospholipids, and amino acids, in each tissue. These findings provide significant insights into the molecular mechanisms behind the health-promoting properties of the cap and the nutritional richness of the stipe, offering a theoretical foundation for utilizing H. leucopus in functional food development and broadening our understanding of bioactive and nutritional distribution in edible fungi. Full article

Tetrahydrofolate (THF), the biologically active form of folate, serves as a crucial carrier of one-carbon units essential for synthesizing cellular components such as amino acids and purine nucleotides in vivo. It also acts as an important precursor for the production of pharmaceuticals, including folinate and L-5-methyltetrahydrofolate (L-5-MTHF). In this study, we developed an efficient enzyme cascade system for the production tetrahydrofolate from folate, incorporating NADPH recycling, and explored its application in the synthesis of L-5-MTHF, a derivative of tetrahydrofolate. To achieve this, we first screened dihydrofolate reductases (DHFRs) from various organisms, identifying SmDHFR from Serratia marcescens as the enzyme with the highest catalytic activity. We then conducted a comparative analysis of formate dehydrogenases (FDHs) from different sources, successfully establishing an NADPH recycling system. To further enhance biocatalytic efficiency, we optimized key reaction parameters, including temperature, pH, enzyme ratio, and substrate concentration. To address the challenge of pH mismatch in dual-enzyme reactions, we employed an enzymatic microenvironment regulation strategy. This involved covalently conjugating SmDHFR with a superfolder green fluorescent protein mutant carrying 30 surface negative charges (−30sfGFP), using the SpyCatcher/SpyTag system. This modification resulted in a 2.16-fold increase in tetrahydrofolate production, achieving a final yield of 4223.4 µM. Finally, we extended the application of this tetrahydrofolate synthesis system to establish an enzyme cascade for L-5-MTHF production with NADH recycling. By incorporating methylenetetrahydrofolate reductase (MTHFR), we successfully produced 389.8 μM of L-5-MTHF from folate and formaldehyde. This work provides a novel and efficient pathway for the biosynthesis of L-5-MTHF and highlights the potential of enzyme cascade systems in the production of tetrahydrofolate-derived compounds. Full article