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This study aimed to compare the effects of various dietary selenium (Se) sources (0.5 mg/kg) on performance, meat quality, and antioxidant capacity in broilers as well as essential trace elements concentrations in their blood and tissues. A total of 360 one-day-old male yellow-feathered chickens (37.00 ± 0.17 g) were randomly allocated to 5 diet treatments: the basal diet (CON) and 4 diets supplemented with sodium selenite (SS), selenomethionine (SM), selenium-enriched yeast (SY), and nano-selenium (NS) for 56 d, respectively, with 6 replicates per treatment and 12 chickens per replicate. Dietary Se supplementation did not affect growth performance and carcass characteristics in broilers (P > 0.05). Supplemental SM enhanced the redness in the pectoral muscle compared to CON and NS (P < 0.05). Supplementation of SY and NS improved the concentrations of Se, copper, manganese, and zinc in the serum (P < 0.05). Supplemental SS also elevated the zinc content in the serum (P < 0.05). Broilers fed the SY diet showed increased Se content in the liver and pectoral muscle compared to those fed CON, SM, and NS diets (P < 0.05). Also, SY improved the pectoral muscle Se concentration compared to SS (P < 0.05). Besides, dietary Se supplementation increased the Se content in the thigh muscle (P < 0.05), with SY showing highest Se deposition. Dietary supplementation with SS, SM, and NS improved the activities of total superoxide dismutase and total antioxidant capacity (T-AOC) in the serum (P < 0.05). Supplemental SY also elevated the T-AOC in the serum (P < 0.05). Additionally, SS and SM enhanced the T-AOC in the liver (P < 0.05). In conclusion, supplemental SM affected meat color. Supplementing diets with various Se sources increased antioxidant capacity and Se content in the thigh muscle of broilers, with SY showing a more pronounced deposition efficiency. Besides, diets supplemented with different Se sources had variable effects on the concentrations of essential trace elements in the serum and tissues of broilers.
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Ração Animal , Antioxidantes , Galinhas , Dieta , Suplementos Nutricionais , Carne , Selênio , Oligoelementos , Animais , Galinhas/crescimento & desenvolvimento , Ração Animal/análise , Antioxidantes/metabolismo , Dieta/veterinária , Carne/análise , Suplementos Nutricionais/análise , Oligoelementos/metabolismo , Oligoelementos/administração & dosagem , Selênio/administração & dosagem , Masculino , Distribuição Aleatória , Selenometionina/administração & dosagem , Selenito de Sódio/administração & dosagem , Fenômenos Fisiológicos da Nutrição Animal/efeitos dos fármacosRESUMO
Deafness mainly results from irreversible impairment of hair cells (HCs), which may relate to oxidative stress, yet therapeutical solutions is lacked due to limited understanding on the exact molecular mechanism. Herein, mimicking the molecular structure of natural enzymes, a palladium (Pd) single-atom nanozyme (SAN) was fabricated, exhibiting superoxide dismutase and catalase activity, transforming reactive oxygen species (ROS) into O2 and H2O. We examined the involvement of Pd in neomycin-induced HCs loss in vitro and in vivo over zebrafish. Our results revealed that neomycin treatment induced apoptosis in HCs, resulting in substantial of ROS elevation in HEI-OC1 cells, decrease in mitochondrial membrane potential, and increase in lipid peroxidation and iron accumulation, ultimately leading to iron-mediated cell death. Noteworthy, Pd SAN treatment exhibited significant protective effects against HCs damage and impaired HCs function in zebrafish by inhibiting ferroptosis. Furthermore, the application of iron death inducer RSL3 resulted in notable exacerbation of neomycin-induced harm, which was mitigated by Pd administration. Our investigation demonstrates that antioxidants is promising for inhibiting ferroptosis and repairing of mitochondrial function in HCs and the enzyme-mimic SAN provides a good strategy for designing drugs alleviating neomycin-induced ototoxicity.
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Ferroptose , Células Ciliadas Auditivas , Perda Auditiva , Neomicina , Paládio , Espécies Reativas de Oxigênio , Peixe-Zebra , Animais , Neomicina/farmacologia , Paládio/química , Paládio/farmacologia , Ferroptose/efeitos dos fármacos , Perda Auditiva/induzido quimicamente , Perda Auditiva/prevenção & controle , Perda Auditiva/tratamento farmacológico , Células Ciliadas Auditivas/efeitos dos fármacos , Células Ciliadas Auditivas/metabolismo , Células Ciliadas Auditivas/patologia , Espécies Reativas de Oxigênio/metabolismo , Linhagem Celular , Apoptose/efeitos dos fármacos , Potencial da Membrana Mitocondrial/efeitos dos fármacosRESUMO
Vascular endothelial cells (ECs) are monolayers of cells arranged in the inner walls of blood vessels. Under normal physiological conditions, ECs play an essential role in angiogenesis, homeostasis and immune response. Emerging evidence suggests that abnormalities in EC metabolism, especially aerobic glycolysis, are associated with the initiation and progression of various diseases, including multiple cancers. In this review, we discuss the differences in aerobic glycolysis of vascular ECs under normal and pathological conditions, focusing on the recent research progress of aerobic glycolysis in tumor vascular ECs and potential strategies for cancer therapy.
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Células Endoteliais , Glicólise , Neoplasias , Neovascularização Patológica , Humanos , Neoplasias/metabolismo , Neoplasias/patologia , Neoplasias/terapia , Células Endoteliais/metabolismo , Neovascularização Patológica/metabolismo , AnimaisRESUMO
Transforming growth factor-ß (TGF-ß) is strongly associated with the cell adhesion signaling pathway in cell differentiation, migration, etc. Mechanistically, TGF-ß is secreted in an inactive form and localizes to the extracellular matrix (ECM) via the latent TGF-ß binding protein (LTBP). However, it is the release of mature TGF-ß that is essential for the activation of the TGF-ß signaling pathway. This progress requires specific integrins (one of the main groups of cell adhesion molecules (CAMs)) to recognize and activate the dormant TGF-ß. In addition, TGF-ß regulates cell adhesion ability through modulating CAMs expression. The aberrant activation of the TGF-ß signaling pathway, caused by abnormal expression of key regulatory molecules (such as Smad proteins, certain transcription factors, and non-coding RNAs), promotes tumor invasive and metastasis ability via epithelial-mesenchymal transition (EMT) during the late stages of tumorigenesis. In this paper, we summarize the crosstalk between TGF-ß and cell adhesion signaling pathway in cancer and its underlying molecular mechanisms.
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Adesão Celular , Transição Epitelial-Mesenquimal , Neoplasias , Transdução de Sinais , Fator de Crescimento Transformador beta , Humanos , Fator de Crescimento Transformador beta/metabolismo , Neoplasias/patologia , Neoplasias/metabolismo , Neoplasias/genética , Transição Epitelial-Mesenquimal/genética , Integrinas/metabolismo , Matriz Extracelular/metabolismo , Regulação Neoplásica da Expressão GênicaRESUMO
Uridine diphosphate glycosyltransferase(UGT) is involved in the glycosylation of a variety of secondary metabolites in plants and plays an important role in plant growth and development and regulation of secondary metabolism. Based on the genome of a diploid Chrysanthemum indicum, the UGT gene family from Ch. indicum was identified by bioinformatics methods, and the physical and chemical properties, subcellular localization prediction, conserved motif, phylogeny, chromosome location, gene structure, and gene replication events of UGT protein were analyzed. Transcriptome and real-time fluorescence quantitative polymerase chain reaction(PCR) were used to analyze the expression pattern of the UGT gene in flowers and leaves of Ch. indicum. Quasi-targeted metabolomics was used to analyze the differential metabolites in flowers and leaves. The results showed that a total of 279 UGT genes were identified in the Ch. indicum genome. Phylogenetic analysis showed that these UGT genes were divided into 8 subfamilies. Members of the same subfamily were distributed in clusters on the chromosomes. Tandem duplications were the main driver of the expansion of the UGT gene family from Ch. indicum. Structural domain analysis showed that 262 UGT genes had complete plant secondary metabolism signal sequences(PSPG box). The analysis of cis-acting elements indicated that light-responsive elements were the most ubiquitous elements in the promoter regions of UGT gene family members. Quasi-targeted metabolome analysis of floral and leaf tissue revealed that most of the flavonoid metabolites, including luteolin-7-O-glucoside and kaempferol-7-O-glucoside, had higher accumulation in flowers. Comparative transcriptome analysis of flower and leaf tissue showed that there were 72 differentially expressed UGT genes, of which 29 genes were up-regulated in flowers, and 43 genes were up-regulated in leaves. Correlation network and phylogenetic analysis showed that CindChr9G00614970.1, CindChr2G00092510.1, and CindChr2G00092490.1 may be involved in the synthesis of 7-O-flavonoid glycosides in Ch. indicum, and real-time fluorescence quantitative PCR analysis further confirmed the reliability of transcriptome data. The results of this study are helpful to understand the function of the UGT gene family from Ch. indicum and provide data reference and theoretical basis for further study on the molecular regulation mechanism of flavonoid glycosides synthesis in Ch. indicum.
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Chrysanthemum , Glicosiltransferases , Glicosiltransferases/genética , Glicosiltransferases/metabolismo , Chrysanthemum/genética , Difosfato de Uridina , Filogenia , Reprodutibilidade dos Testes , Plantas/metabolismo , Flavonoides , Glicosídeos , Regulação da Expressão Gênica de PlantasRESUMO
Fecal samples from 20 healthy adults were collected for in vitro fermentation experiments to investigate the effects of combined probiotics on the utilization of grape seed extract in humans. After fermenting for 24 h, short-chain fatty acids, metabolites, and gut microbiota composition were analyzed. Short-chain fatty acids in the grape seed extract probiotics group were significantly higher than those in the grape seed extract group. Probiotics significantly enhanced the conversion and utilization of catechins and epicatechins in grape seed extract group and increased the production of 3-hydroxyphenylacetic acid. The 16S rRNA sequencing results revealed that compound probiotics significantly increased the relative abundance of Lacticaseibacillus, HT002, Bifidobacterium, and Lactobacillus and reduced that of Escherichia-Shigella. Our findings showed considerable individual variability in the metabolic utilization of grape seed extract in humans. The consumption of probiotics appears to significantly enhance the utilization.
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Extrato de Sementes de Uva , Probióticos , Adulto , Humanos , Polifenóis , RNA Ribossômico 16S , Ácidos Graxos Voláteis/metabolismoRESUMO
The combination of Bifidobacterium longum and Pediococcus pentosaceus is a clinically effective probiotic formulation for alleviating infantile colic; however, their utilization characteristics and mechanism of action surrounding their combined use of sugar sources remains unclear. Using in vitro simulation technology, this study set up individual and mixed cultures of the two probiotics at unique concentrations, and different types of prebiotics, carbohydrates and polyols were added. Gas and short-chain fatty acid production, substrate utilization, as well as growth of the individual and mixed probiotics were detected at the beginning of fermentation, 24â h, and 48â h. Further, the mechanism of the syntrophic effect of the two probiotics was explored based on their growth characteristics. It was found that neither strain produced gas after 24â h and 48â h of cultivation, but could synergistically utilize fructo oligosaccharides (FOS) when mixed. There was an increasing trend of acetic acid production for B. longum in yeast extract, casitone and fatty acid (YCFA) and FOS medium with increasing of bacterial concentrations at 24â h and 48â h; whereas the trend for P. pentosaceus was less obvious. When bacterial concentrations were >5 billion CFU·g-1, the mixed culture showed significantly lower acetic acid production than B. longum alone. By adding lactic and acetic acids to the YCFA medium and observing P. pentosaceus growth, the results suggested that Pediococcus pentosaceus could use the acetic acid and lactic acid produced by Bifidobacterium longum for growth. When the bacterial concentration was 5 billion CFU·g-1, the acetic acid production of B. longum was significantly higher in the mixed cultures in lactulose, lactose, FOS, galactooligosaccharide, and inulin medium; whereas the reverse was true for culturing in xylitol, carboxymethyl cellulose sodium, and sorbitol medium. Further, the mixed cultures produced significantly more acetic acid than B. longum alone. In summary, through in vitro simulation experiments, the optimal ratio and potential interaction mechanisms between B. longum and P. pentosaceus were revealed here, offers a basis for understanding how the probiotic combinations may improve infant colic symptoms by influencing the gut pH and regulating the gut microbiota mechanisms.
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Genotype imputation is a powerful technique employed by next-generation sequencing (NGS) and genotyping arrays, which can significantly enhance the cost-effectiveness and efficiency of genomic selection. The accuracy of imputation is largely determined by the choice of reference panel, with previous studies generally demonstrating that a closely related population as a reference panel leads to greater accuracy than a more distantly related population. Various strategies have been proposed for selecting desirable individuals via targeted resequencing, but their efficiencies need further improvement. In this study, we present a practical broiler selection methodology for a local Chinese chicken line that integrates established methods based on pedigree, genomics, and random sampling, and leverages genotype and pedigree information from the yellow-plumage dwarf chicken line. The efficacy of these selection strategies was assessed by evaluating their ability to accurately impute masked genotypes from data obtained using a 600K chip. Our findings reveal that the pedigree-based method yields superior accuracy in genotype imputation, whereas the haplotype-based method exhibits greater stability. Nonetheless, the impact of these targeted methods for selecting key individuals is slightly different when initiating a new sequencing project in a production context. Overall, this study highlights the advantages of using the pedigree-based approach as the preferred method for optimizing genotype imputation in broiler chickens.
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Galinhas , Polimorfismo de Nucleotídeo Único , Animais , Galinhas/genética , Genótipo , Genoma , Genômica/métodosRESUMO
ABBREVIATIONS: AMBRA1 autophagy and beclin 1 regulator 1; ATG14 autophagy related 14; ATG5 autophagy related 5; ATG7 autophagy related 7; BECN1 beclin 1; BECN2 beclin 2; CC coiled-coil; CQ chloroquine CNR1/CB1R cannabinoid receptor 1 DAPI 4',6-diamidino-2-phenylindole; dCCD delete CCD; DRD2/D2R dopamine receptor D2 GPRASP1/GASP1 G protein-coupled receptor associated sorting protein 1 GPCR G-protein coupled receptor; ITC isothermal titration calorimetry; IP immunoprecipitation; KD knockdown; KO knockout; MAP1LC3/LC3 microtubule associated protein 1 light chain 3; NRBF2 nuclear receptor binding factor 2; OPRD1/DOR opioid receptor delta 1 PIK3C3/VPS34 phosphatidylinositol 3-kinase catalytic subunit type 3; PIK3R4/VPS15 phosphoinositide-3-kinase regulatory subunit 4; PtdIns3K class III phosphatidylinositol 3-kinase; PtdIns3P phosphatidylinositol-3-phosphate; RUBCN rubicon autophagy regulator; SQSTM1/p62 sequestosome 1; UVRAG UV radiation resistance associated; VPS vacuolar protein sorting; WT wild type.
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A unique hybridized intumescent flame retardant named reduced-graphene-oxide-modified ammonium polyphosphate (RGO-APP) was successfully synthesized via the simple hydrothermal method and reduced process. Then, the obtained RGO-APP was applied in epoxy resin (EP) for flame retardancy reinforcement. The addition of RGO-APP results in a significant reduction in heat release and smoke production from the EP, which is attributed to EP/RGO-APP producing a more compact and intumescent char against the heat transfer and combustible decomposition, thus enhancing the fire safety of EP, as confirmed by char residue analysis. Especially, the EP containing 15 wt% RGO-APP acquires a limiting oxygen index (LOI) value of 35.8% and shows a 83.6% reduction in peak heat release rate and a 74.3% reduction in peak smoke production rate compared with those of pure EP. The tensile test exhibits that the presence of RGO-APP favors the enhancement in tensile strength and elastic modulus of EP due to the good compatibility between flame retardant and epoxy matrix, as supported by differential scanning calorimetry (DSC) and scanning electron microscope (SEM) analyses. This work provides a new strategy for the modification of APP, thus facilitating a promising application in polymeric materials.
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Mobile crowdsensing leverages the ubiquitous sensors of smart devices to facilitate various sensing applications. Users who participate in contributing data usually get rewards from the task requester, while there is a potential risk that someone would preempt the task and provide a forged sensing report for seeking revenue with minimal effort. Thus, trust assessment is essential to identify those irregular sensing reports. The existing methods mainly consider users' reputations and estimate the trustworthiness upon the difference from the aggregated result. However, they still face a severe problem when a majority of reports are invalid or low-quality caused by the repeated submission, e.g., a user can switch multiple accounts on a single device to repeatedly submit forged reports. To tackle this problem, we design a trust assessment scheme with an enhanced device fingerprinting algorithm. Briefly, to reduce the influence of the repeated sensing reports, we first compute their unique fingerprints derived from the intrinsic characteristics of sensors and assign an initial trust weight for each report. Then, to improve the accuracy of the assessment, we further compute the similarity of the reports to obtain their final trust values. Extensive evaluations are conducted to justify the effectiveness of our proposed design.
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Caohai Lake is a typical natural lake-type karst plateau wetland, which is sensitive to environmental changes, and the release of dissolved organic nitrogen (DON) in sediment is a potential factor of nitrogen pollution in this lake. Therefore, we aimed to reveal the temporal and spatial distribution characteristics and source analysis of DON in karst lake sediment. Surface sediment samples were collected from Caohai Lake in southwest China, and the sample locations were distributed across almost the entire wetland area, during both the wet and dry seasons. The DON content and fluorescence spectroscopy were determined and analysed using a three-dimensional fluorescence-parallel factor analysis (3DEEM-PARAFAC) model. The mean DON content in the sediment during the dry season (67.79 ± 42.96 mg/kg) was higher than that in the wet season (28.57 ± 20.97 mg/kg). There were four fluorescent components of DON in the sediment: C1 (tyrosine-like protein), C2 (terrestrial humus), C3 (tryptophan-like protein) and C4 (terrestrial humus). The DON in the surface sediment of Caohai Lake was influenced by terrestrial sources and biological activities. These findings help reveal the circulation mechanism of endogenous nitrogen in the lake and provide theoretical support for the prevention and control of nitrogen pollution in Caohai Lake.
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Monitoramento Ambiental , Lagos , Lagos/química , Matéria Orgânica Dissolvida , Nitrogênio/análise , China , Espectrometria de FluorescênciaRESUMO
The effects of an α-Al2O3 nanoparticle filler in the SiC matrix on the mechanical properties and failure mechanism of the unidirectional, laminated carbon fiber-reinforced SiC composites were investigated in this work. First, α-Al2O3 nanoparticles were added to the carbon fiber bundles using a slurry impregnation method, and then the Cf/SiC composite with an α-Al2O3 nanoparticle filler (Cf/SiC-Al2O3) was fabricated using a precursor infiltration and pyrolysis method. The microstructure of the Cf/SiC-Al2O3 composite showed chemical compatibility between the α-Al2O3 and the pyrolysis SiC. The Cf/SiC-Al2O3 composite with a low porosity of ~6.67% achieved a good flexural strength of 629.3 MPa and a good fracture toughness of 25.2 MPa·m1/2. The interlaminar shear strength of the Cf/SiC-Al2O3 composite was 11.7 MPa. The SiC-Al2O3 matrix also presented a considerable Young's modulus of 138.2 ± 8.66 GPa and hardness of 10.3 ± 1.03 GPa. Further analysis indicated that the good mechanical properties with the addition of an α-Al2O3 filler were not only related to the dense matrix and the improvement of the mechanical properties of the matrix. They also originated from the thermal residual compressive stress in the SiC matrix close to the α-Al2O3 nanoparticles caused by the thermal expansion mismatch, which could reflect and close the cracks in the matrix. The findings of this study provide more methods for designing new composites exhibiting a good performance.
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An efficient copper-iodine cocatalyzed intermolecular C-H aminocyanation of indoles with a broad substrate scope has been developed for the first time. This method enables highly step-economic access to 2-amino-3-cyanoindoles in moderate to good yields and provides a complementary strategy for the regioselective difunctionalization of carbonâcarbon double bonds of interest in organic synthesis and related areas. Mechanistic studies suggest that these transformations are initiated by iodine-mediated C2-H amination with azoles, followed by copper-catalyzed C3-H cyanation with ethyl cyanoformate.
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Indóis , Iodo , Azóis/química , Catálise , Cobre/química , Indóis/química , Iodetos , Iodo/químicaRESUMO
Acrylamide-methacrylic acid copolymer named P (AM-co-MAA) was synthesized via aqueous solution polymerization, and then mixed with crosslinker, flame retardants and initiators to prepare multifunctional transparent flame-retarded hydrogels with transparency, fire resistance and anti-ageing property. The results show that the application of multifunctional transparent flame-retarded hydrogel imparts high level of transparency and excellent fire resistance to the fire-resistant glass, and the light transmittance and fire resistance of the flame-retarded hydrogel increases with the increasing mass ratio of AM to MAA in P(AM-co-MAA). When the mass ratio of AM to MAA is 4:1, the obtained P(AM-co-MAA) imparts the lowest backside temperature of 130 °C at 3600 s and highest light transmittance of 86.1% to the transparent flame-retarded hydrogel. TG and DSC analysis show that the addition of P(AM-co-MAA) increases the thermal stability of the transparent flame-retarded hydrogels due to the formation of numerous hydrogen bonds via the complexation between amide and carboxyl groups. Accelerated ageing test indicates that the transparent flame-retarded hydrogel containing P(AM-co-MAA) exerts durable fire resistance and transparency, and the ageing resistance of the transparent flame-retarded hydrogel depends on the mass ratio of AM to MAA in P(AM-co-MAA). Therefore, this study provides a promising strategy to prepare a novel multifunctional transparent flame-retarded hydrogel with excellent light transmittance, fire resistance and anti-ageing properties.
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A unique mono-component intumescent flame retardant, named PPy-MAPP, of which melamine-coated ammonium polyphosphate (MAPP) was microencapsulated by polypyrrole (PPy), was synthesized and carefully characterized. The obtained PPy-MAPP was applied to epoxy resin (EP) for obtaining flame-retarded EP composites. The results show that PPy-MAPP imparts better flame retardancy and smoke suppression properties to EP compared to the same addition of MAPP. The EP composite with 15 wt% PPy-MAPP easily passes the UL94 V-0 rating and achieves an LOI value of 42.4%, accompanied by a 61.9% reduction in total heat release (THR) and a 73.9% reduction in total smoke production (TSP) when compared with pure EP. The char residue analysis shows that PPy-MAPP can promote a generation of more phosphorus-rich structures in the condensed phase that improve the integrity and intumescence of char against fire. The mechanical test indicates that PPy-MAPP has a less negative effect on the tensile strength and elastic modulus of epoxy resin due to the good compatibility between PPy-MAPP and the EP matrix, as supported by differential scanning calorimetry (DSC) analyses. In this paper, these attractive features of PPy-MAPP provide a new strategy to prepare satisfactory flame retardant and super flame retarding EP composites.
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Chrysanthemum indicum var. aromaticum (CIA) is an endemic plant that occurs only in the high mountain areas of the Shennongjia Forest District in China. The whole plant, in particular the flowers of CIA, have intense fragrance, making it a novel resource plant for agricultural, medicinal, and industrial applications. However, the volatile metabolite emissions in relation to CIA flower development and the molecular mechanisms underlying the generation of floral scent remain poorly understood. Here, integrative metabolome and transcriptome analyses were performed to investigate floral scent-related volatile compounds and genes in CIA flowers at three different developmental stages. A total of 370 volatile metabolites, mainly terpenoids and esters, were identified, of which 89 key differential metabolites exhibited variable emitting profiles during flower development. Transcriptome analysis further identified 8,945 differentially expressed genes (DEGs) between these samples derived from different flower developmental stages and KEGG enrichment analyses showed that 45, 93, and 101 candidate DEGs associated with the biosynthesis of phenylpropanoids, esters, and terpenes, respectively. Interestingly, significant DEGs involved into the volatile terpenes are only present in the MEP and its downstream pathways, including those genes encoding ISPE, ISPG, FPPS, GPPS, GERD, ND and TPS14 enzymes. Further analysis showed that 20 transcription factors from MYB, bHLH, AP2/EFR, and WRKY families were potentially key regulators affecting the expressions of floral scent-related genes during the CIA flower development. These findings provide insights into the molecular basis of plant floral scent metabolite biosynthesis and serve as an important data resources for molecular breeding and utilization of CIA plants in the future.
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A novel diaminodiphenylmethane (DDM) modified ammonium polyphosphate (APP) flame retardant, DDP, was successfully synthesized via ion-exchange reaction. DDP was introduced into epoxy resins (EPs) to reduce flammability. A comparable level of DDP exerts better flame-retardant and smoke suppression efficiencies in EP than APP. An EP blend containing 15 wt% DDP displays a limiting oxygen index (LOI) value of 37.1% and a UL 94 V-0 rating, and further exhibits a 32.3% reduction in total heat release and a 48.0% reduction in total smoke production compared with pure EP. The presence of DDP greatly facilitates char formation during combustion, and the char mass from thermal decomposition of an EP blend is 37.8% smaller than that of an EP blend containing 15 wt% DDP at 800 °C. The incorporation of DDP into EP blends has a smaller impact on the glass transition temperature and tensile strength than those of a comparable level of APP. This reflects the better compatibility of DDP with the EP matrix compared with that for APP.
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Nitrate is one of the most common pollutants in aquatic ecosystems, particularly in highly vulnerable karst aquifers. In Caohai Lake, an important karst wetland in southwestern China, karst surface water and groundwater are important recharge water sources, and nitrates flow into the wetland along with the surface water and groundwater, degrading the wetland water quality. Therefore, identifying the sources of nitrate in the surface water and groundwater in the Caohai catchment is of great significance to the protection of the wetland water environment. In this study, the nitrate concentrations, hydrochemistry and multiple stable isotope ratios (δ18O-H2O, δD-H2O, δ15N-NO3- and δ18O-NO3-) were used to identify the sources and fate of the NO3- in the groundwater and inflowing rivers around the Caohai wetland. The results showed that the NO3- concentrations in the groundwater samples from the southern side exceeded the WHO limit during the wet season, while other samples did not exceed the limit. The mean concentrations of NO3- in groundwater were higher than those in the inflowing river water, and NO3- concentrations decreased in the order of wet season>dry season>normal season in the groundwater and inflowing rivers. The hydrochemistry and multiple isotope ratios suggest that the nitrate transformation was dominated by nitrification processes, while denitrification had an influence on the transformation of NO3- (as evidenced by isotopes) in groundwater during the dry season. According to the analyses based on a stable isotope analysis in R (SIAR), sewage and manure were the main sources of NO3- in the groundwater, while sewage, manure and chemical fertilizer were the major sources of NO3- in the inflowing river water; therefore, the scientific use of farmland fertilizers and the treatment of domestic sewage should be strengthened to safeguard groundwater quality and control the NO3- concentrations in rivers.
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Água Subterrânea , Poluentes Químicos da Água , China , Ecossistema , Monitoramento Ambiental , Nitratos/análise , Isótopos de Nitrogênio/análise , Rios , Poluentes Químicos da Água/análise , Áreas AlagadasRESUMO
The Caohai Lake wetland in Weining County, Guizhou Province, is the largest karst wetland in China, and karst groundwater is an essential source of recharge and material. This study collected groundwater from the Caohai Lake catchment during the wet season, dry season, and flat season, and the main ion components of the groundwater were analyzed. The hydrochemistry characteristics and main ion sources of the groundwater were revealed, and the preliminary estimates of the karst carbon sink flux in the Caohai Lake catchment were calculated based on the solute load method. The results indicated that the water chemistry of the groundwater in the Caohai Lake catchment is primarily the HCO3-Ca type, and individual groundwater points in the southeast are the SO4-Ca type during the flat season. The dominant ions in the groundwater are Ca2+, Mg2+, and HCO3-. Seasonally, the average concentrations of SO42- and Mg2+ decreased in the order of flat season>dry season>wet season, while the average concentration of NO3- decreased in the order of wet season>dry season>flat season, and the seasonal variation of the other ions were not significant. Spatially, the concentrations of Ca2+ and HCO3- in the groundwater in the northern part of Caohai Lake, of K+, Na+, and Cl- in the southwest, and of Mg2+, NO3-, and SO42- in the southeast were relatively high. Ca2+, Mg2+, and HCO3- in the groundwater were primarily controlled by the dissolution of carbonate rocks, and carbonic acid, sulfuric acid and nitric acid were all involved in the weathering of carbonate rocks in the catchment. Most of the NO3- in the groundwater was affected mostly by the soil nitrogen and domestic sewage, while NO3- in the southeast groundwater was primarily affected by agricultural activities. The sources of K+, Na+, Cl-, and SO42- exhibited no obvious temporal and spatial differences, and the K+, Na+, and Cl- were mainly affected by human activities, while SO42- was mostly derived from the dissolution of sulfur compounds in the formation. The studied area has a high proportion of allogenic acids (sulfuric acid and nitric acid) participating in the weathering of carbonate rocks, which is the highest in the flat season and the lowest in wet season. After deducting the proportion of allogenic acids participating in the weathering of carbonate rocks, the average inorganic carbon flux in the Caohai Lake catchment is preliminarily estimated to be approximately 181.5 t·a-1, and the average karst groundwater transport of HCO3- to Caohai Lake is approximately 1144.1 t·a-1.