Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 37
Filtrar
Más filtros

Banco de datos
Tipo del documento
Intervalo de año de publicación
1.
J Am Chem Soc ; 2024 Jul 02.
Artículo en Inglés | MEDLINE | ID: mdl-38952302

RESUMEN

Precise manipulation of the coordination configuration within substances can modulate the band structure and catalytic properties of the target material. Metal-covalent organic frameworks (MCOFs), a crystal material amalgamating the benefits of metal-organic frameworks (MOFs) and covalent organic frameworks (COFs), can integrate a predetermined coordination environment into the frameworks for amplifying the catalytic effect. In this study, we delicately synthesize isomeric MCOFs using bis(glycinato)copper as the aminoligand via kinetically and thermodynamically favorable pathways to yield cis-MCOF and trans-MCOF products, respectively, thereby introducing a cis-trans isomeric coordination field into the framework. Moreover, the twisted skeleton derived from the flexibility of amino acid and ß-ketoenamine linkages endows trans-MCOF with surprising water dispersibility. Compared to cis-MCOF, the trans isomerism displays a significant enhancement in cathodic electrochemiluminescence via the catalysis of Cu nodes toward K2S2O8. The density of states analysis shows that the d-band center of trans-MCOF is closer to the Fermi level, leading to more stable adsorption binding to promote the catalysis. This study is the first report on constructing predesign coordination configuration MCOFs via an easy-handling method, which gives the guidelines for the design of amino acid-based MCOF materials.

2.
J Am Chem Soc ; 2024 Jun 05.
Artículo en Inglés | MEDLINE | ID: mdl-38837248

RESUMEN

Electrochemiluminescence (ECL) involves charge transfer between electrochemical redox intermediates to produce an excited state for light emission. Ensuring precise control of charge transfer is essential for decoding ECL fundamentals, yet guidelines on how to achieve this for conventional emitters remain unexplored. Molecular ratchets offer a potential solution, as they enable the directional transfer of energy or chemicals while impeding the reverse movement. Herein, we designed 10 pairs of imine-based covalent organic frameworks as reticular ratchets to delicately manipulate the intrareticular charge transfer for directing ECL transduction from electric and chemical energies. Aligning the donor and acceptor (D-A) directions with the imine dipole effectively facilitates charge migration, whereas reversing the D-A direction impedes it. Notably, the ratchet effect of charge transfer directionality intensified with increasing D-A contrast, resulting in a remarkable 680-fold improvement in the ECL efficiency. Furthermore, dipole-controlled exciton binding energy, electron/hole decay kinetics, and femtosecond transient absorption spectra identified the electron transfer tendency from the N-end toward the C-end of reticular ratchets during ECL transduction. An exponential correlation between the ECL efficiency and the dipole difference was discovered. Our work provides a general approach to manipulate charge transfer and design next-generation electrochemical devices.

3.
Phys Rev Lett ; 132(7): 073802, 2024 Feb 16.
Artículo en Inglés | MEDLINE | ID: mdl-38427883

RESUMEN

The exotic physics associated with exceptional points (EPs) is always under the scrutiny of theoretical and experimental science. Recently, considerable effort has been invested in the combination of nonlinearity and non-Hermiticity. The concept of nonlinear EPs (NEPs) has been introduced, which can avoid the loss of completeness of the eigenbasis in dynamics while retaining the key features of linear EPs. Here, we present the first direct experimental demonstration of a NEP based on two non-Hermition coupled circuit resonators combined with a nonlinear saturable gain. At the NEP, the response of the eigenfrequency to perturbations demonstrates a third-order root law and the eigenbasis of the Hamiltonian governing the system dynamics is still complete. Our results bring this counterintuitive aspect of the NEP to light and possibly open new avenues for applications.

4.
Dev Biol ; 490: 110-116, 2022 10.
Artículo en Inglés | MEDLINE | ID: mdl-35809631

RESUMEN

The development of the dendrite and the axon during neuronal polarization underlies the directed flow of information in the brain. Seminal studies on axon development have dominated the mechanistic analysis of neuronal polarization. These studies, many originating from examinations in cultured hippocampal and cortical neurons in vitro, have established a prevalent view that axon formation precedes and is necessary for neuronal polarization. There is also in vivo evidence supporting this view. Nevertheless, the establishment of bipolar polarity, the leading edge, and apical dendrite development in pyramidal neurons in vivo occur when axon formation is prevented. Furthermore, recent mounting evidence suggest that directed mechanisms might mediate bipolar polarity/leading process and subsequent apical dendrite development. In the presence of spatially directed extracellular cues in the developing brain, these events may operate independently of axon forming events. In this perspective we summarize evidence in support of these evolving views in neuronal polarization and highlight recent findings on dedicated mechanisms acting in apical dendrite development.


Asunto(s)
Polaridad Celular , Neuronas , Axones/fisiología , Polaridad Celular/fisiología , Dendritas/fisiología , Neurogénesis , Neuronas/fisiología
5.
Anal Chem ; 95(44): 16392-16397, 2023 11 07.
Artículo en Inglés | MEDLINE | ID: mdl-37885198

RESUMEN

Photocurrent polarity reversal is a switching process between the anodic and cathodic pathways and is critical for eliminating false positivity and improving detection sensitivity in photoelectrochemical (PEC) sensing. In this study, we construct a PEC sensor with excellent photocurrent polarity reversal induced by ascorbic acid (AA) as an electron donor with the energy level matching the photoactive material zirconium metal-organic framework (ZrMOF). The ZrMOF-modified electrode demonstrates cathodic photocurrent in the presence of O2 as an electron acceptor, while the anodic photocurrent is generated in the presence of AA, achieving photocurrent polarity reversal. By the in situ release of AA from AA-encapsulated apoferritin modified with DNA 2 (AA@APO-S2) as a detection tag in the presence of trypsin after the recognition of hairpin DNA-modified indium tin oxide to the reaction product of aptamer/DNA 1 with the target protein and the following rolling cycle amplification for introducing the detection tag to the sensing interface, the reversed photocurrent shows an enhanced photocurrent response to the target protein, leading to a highly sensitive PEC sensing strategy. This strategy realizes the detection of vascular endothelial growth factor 165 with good specificity, a wide linear range, and a low detection limit down to 5.3 fM. The actual sample analysis offers the detection results of the proposed PEC sensor comparable to those of commercial enzyme-linked immunosorbent assay tests, indicating the promising application of the photocurrent polarity reversal-based PEC sensing strategy in biomolecule detection and clinical diagnosis.


Asunto(s)
Aptámeros de Nucleótidos , Técnicas Biosensibles , Factor A de Crecimiento Endotelial Vascular/análisis , Electrones , ADN , Aptámeros de Nucleótidos/química , Técnicas Electroquímicas/métodos , Límite de Detección
6.
Phys Rev Lett ; 130(26): 266901, 2023 Jun 30.
Artículo en Inglés | MEDLINE | ID: mdl-37450800

RESUMEN

Exceptional points (EPs) are special spectral singularities at which two or more eigenvalues, and their corresponding eigenvectors, coalesce and become identical. In conventional wisdom, the coalescence of eigenvectors inevitably leads to the loss of completeness of the eigenbasis. Here, we show that this scenario breaks down in general at nonlinear EPs (NEPs). As an example, we realize a fifth-order NEP (NEP_{5}) within only three coupled resonators with both a theoretical model and simulations in circuits. One stable and another four auxiliary steady eigenstates of the nonlinear Hamiltonian coalesce at the NEP_{5}, and the response of eigenfrequency to perturbations demonstrates a fifth-order root law. Intriguingly, the biorthogonal eigenbasis of the Hamiltonian governing the system dynamics is still complete, and this fact is corroborated by a finite Petermann factor instead of a divergent one at conventional EPs. Consequently, the amplification of noise, which diverges at other EPs, converges at our NEP_{5}. Our finding transforms the understanding of EPs and shows potential for miniaturizing various key applications operating near EPs.

7.
Zhongguo Zhong Yao Za Zhi ; 48(2): 374-381, 2023 Jan.
Artículo en Zh | MEDLINE | ID: mdl-36725227

RESUMEN

This study aims to screen a strain from Armillaria for the cultivation of Gastrodia elata. Specifically, Armillaria strains were isolated from different producing areas of G. elata and identified. Based on the growth characteristics of the strains and the experiment on the cultivation of G. elata, an optimal A. gallica strain was screened out. The specific process is as follows. The fungus-gro-wing materials of G. elata were collected from four producing areas and the Armillaria strains were isolated(G,Y,S,H). The strains were then identified based on morphological observation and phylogeny analysis and the commonly used strains were determined. The sucrase genotypes of the strains were identified according to our previous research findings, and the growth characteristics of the strains, such as growth rate, diameter, dry weight, and polysaccharide content of the rhizomorphs, were measured. According to the biological characteristics and sucrase genotypes, two strains were selected for the cultivation of G. elata. The tuber yield and the content of gastrodin and p-hydroxybenzyl alcohol in the tuber of G. elata were measured to select the optimal strain. The results showed that the four strains were all A. gallica. The rhizomorphs of strains G and H of the same sucrase genotype had larger/higher length, growth rate, diameter, branch number, dry weight, and polysaccharide content than those of strains S and Y of the same sucrase genotype. The tuber yield and the total content of gastrodin and p-hydroxybenzyl alcohol in tuber of G. elata cultivated with strain H were 6.528 kg·m~(-2) and 0.566%, respectively, which were 4.58 and 1.30 folds those of G. elata cultivated with strain S. Strains H and S were screened out from four strains of A. gallica based on the growth characteristics and sucrase genotype. According to the tuber yield and content of total gastrodin and p-hydroxybenzyl alcohol in the tuber of G. elata, strain H was identified as the optimal one. The findings in this study are expected to lay a basis for cultivating G. elata with high yield and quality of tubers.


Asunto(s)
Armillaria , Gastrodia , Armillaria/genética , Polisacáridos
8.
Zhongguo Zhong Yao Za Zhi ; 48(12): 3149-3155, 2023 Jun.
Artículo en Zh | MEDLINE | ID: mdl-37381997

RESUMEN

This study explored the preservation effect of strigolactone analogs on Gastrodia elata tubers and screened out the suitable preservation measures of G. elata to provide a safer and more effective method for its storage and preservation. Fresh G. elata tubers were treated with 7FGR24, 2,4-D isooctyl ester, and maleic hydrazide, respectively. The growth of flower buds, the activities of CAT, and MDA, and the content of gastrodin and p-hydroxybenzyl alcohol were measured to compare the effects of different compounds on the storage and preservation of G. elata. The effects of different storage temperatures on the preservation of 7FGR24 were compared and analyzed. The gibberellin signal transduction receptor gene GeGID1 was cloned, and the effect of 7FGR24 on the expression level of GeGID1 was analyzed by quantitative polymerase chain reaction(qPCR). The toxicity of the G. elata preservative 7FGR24 was analyzed by intragastric administration in mice to evaluate its safety. The results showed that compared with 2,4-D isooctyl ester and maleic hydrazide, 7FGR24 treatment had a significant inhibitory effect on the growth of G. elata flower buds, and the CAT enzyme activity of G. elata was the highest, indicating that its preservation effect was stronger. Different storage temperatures had different effects on the preservation of G. elata, and the preservation effect was the strongest at 5 ℃. The open reading frame(ORF) of GeGID1 gene was 936 bp in length, and its expression level was significantly down-regulated after 7FGR24 treatment, indicating that 7FGR24 may inhibit the growth of flower buds by inhibiting the gibberellin signal of G. elata, thereby exerting a fresh-keeping effect. Feeding preservative 7FGR24 had no significant effect on the behavior and physiology of mice, indicating that it had no obvious toxicity. This study explored the application of the strigolactone analog 7FGR24 in the storage and preservation of G. elata and preliminarily established a method for the storage and preservation of G. elata, laying a foundation for the molecular mechanism of 7FGR24 in the storage and preservation of G. elata.


Asunto(s)
Gastrodia , Hidrazida Maleica , Animales , Ratones , Giberelinas , Ésteres
9.
Zhongguo Zhong Yao Za Zhi ; 48(12): 3140-3148, 2023 Jun.
Artículo en Zh | MEDLINE | ID: mdl-37381996

RESUMEN

The gene GeDTC encoding the dicarboxylate-tricarboxylate carrier protein in Gastrodia elata was cloned by specific primers which were designed based on the transcriptome data of G. elata. Bioinformatics analysis on GeDTC gene was carried out by using ExPASY, ClustalW, MEGA, etc. Positive transgenic plants and potato minituber were obtained by virtue of the potato genetic transformation system. Agronomic characters, such as size, weight, organic acid content, and starch content, of potato minituber were tested and analyzed and GeDTC gene function was preliminarily investigated. The results showed that the open reading frame of GeDTC gene was 981 bp in length and 326 amino acid residues were encoded, with a relative molecular weight of 35.01 kDa. It was predicted that the theoretical isoelectric point of GeDTC protein was 9.83, the instability coefficient was 27.88, and the average index of hydrophilicity was 0.104, which was indicative of a stable hydrophilic protein. GeDTC protein had a transmembrane structure and no signal peptide and was located in the inner membrane of mitochondria. The phylogenetic tree showed that GeDTC was highly homologous with DTC proteins of other plant species, among which GeDTC had the highest homology with DcDTC(XP_020675804.1) in Dendrobium candidum, reaching 85.89%. GeDTC overexpression vector pCambia1300-35Spro-GeDTC was constructed by double digests, and transgenic potato plants were obtained by Agrobacterium-mediated gene transformation. Compared with the wild-type plants, transgenic potato minituber harvested by transplanting had smaller size, lighter weight, lower organic acid content, and no significant difference in starch content. It is preliminarily induced that GeDTC is the efflux channel of tricarboxylate and related to the tuber development, which lays a foundation for further elucidating the molecular mechanism of G. elata tuber development.


Asunto(s)
Gastrodia , Gastrodia/genética , Filogenia , Aminoácidos , Clonación Molecular
10.
Chemistry ; 28(31): e202200305, 2022 Jun 01.
Artículo en Inglés | MEDLINE | ID: mdl-35307887

RESUMEN

A core-shell heterogeneous metal-organic framework (MOF) hybrid is sequentially designed by a photosensitized porous coordination network (PCN)-typed MOF as core and Cu2+ -centered zeolitic imidazolate framework (ZIF-67) as shell encapsulating cyanine 3-labelled siRNA. The heterogeneous MOF hybrid realized stimulus-responsive photodynamic therapy (PDT) and controllable siRNA delivery through 1 O2 -assistant endosomal escape for imaging-guided photodynamic-gene synergetic theranostics.


Asunto(s)
Estructuras Metalorgánicas , Fotoquimioterapia , Apoptosis , Glutatión , Fármacos Fotosensibilizantes , ARN Interferente Pequeño
11.
Prenat Diagn ; 42(1): 49-59, 2022 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-34648206

RESUMEN

OBJECTIVE: Advances in artificial intelligence (AI) have demonstrated potential to improve medical diagnosis. We piloted the end-to-end automation of the mid-trimester screening ultrasound scan using AI-enabled tools. METHODS: A prospective method comparison study was conducted. Participants had both standard and AI-assisted US scans performed. The AI tools automated image acquisition, biometric measurement, and report production. A feedback survey captured the sonographers' perceptions of scanning. RESULTS: Twenty-three subjects were studied. The average time saving per scan was 7.62 min (34.7%) with the AI-assisted method (p < 0.0001). There was no difference in reporting time. There were no clinically significant differences in biometric measurements between the two methods. The AI tools saved a satisfactory view in 93% of the cases (four core views only), and 73% for the full 13 views, compared to 98% for both using the manual scan. Survey responses suggest that the AI tools helped sonographers to concentrate on image interpretation by removing disruptive tasks. CONCLUSION: Separating freehand scanning from image capture and measurement resulted in a faster scan and altered workflow. Removing repetitive tasks may allow more attention to be directed identifying fetal malformation. Further work is required to improve the image plane detection algorithm for use in real time.


Asunto(s)
Inteligencia Artificial/normas , Anomalías Congénitas/diagnóstico , Ultrasonografía Prenatal/instrumentación , Adulto , Inteligencia Artificial/tendencias , Anomalías Congénitas/diagnóstico por imagen , Femenino , Edad Gestacional , Humanos , Embarazo , Estudios Prospectivos , Reproducibilidad de los Resultados , Ultrasonografía Prenatal/métodos , Ultrasonografía Prenatal/normas
12.
Analyst ; 146(6): 1859-1864, 2021 Mar 21.
Artículo en Inglés | MEDLINE | ID: mdl-33443249

RESUMEN

The detection of telomerase is of great significance for monitoring cell canceration. The conventional methods depend on the extension of telomerase towards its primer to conduct signal transduction. Herein, a specific and reliable detection strategy based on stepwise recognition was developed for tandem detection of metal ions and enzymes. We first synthesized an electrically active metal-organic framework (MIL-101(Fe)), which can act directly as a signal reporter in phosphate buffered saline after being modified with capture DNA (cDNA). When the zinc ion is added as a coenzyme factor, the modified hairpin DNA on the electrode is cleaved by DNAzyme to yield the activated primer. After the addition of telomerase, the cleaved DNA strand would be extended, and the resulting sequence will be hybridized with the signal label of MIL-101(Fe)-cDNA. Therefore, a signal-on strategy for the detection of telomerase was achieved based on the direct electrochemical analysis of MIL-101(Fe). Moreover, this electrochemical biosensor can discriminate telomerase activity among different cell lines. The stepwise recognition ensured the advantages of an electrochemical biosensor such as high sensitivity and specificity during the detection process, providing a novel method for monitoring and diagnosis of diseases.


Asunto(s)
Técnicas Biosensibles , ADN Catalítico , Estructuras Metalorgánicas , Telomerasa , Técnicas Electroquímicas , Límite de Detección , Telomerasa/metabolismo
13.
Anal Chem ; 92(7): 4726-4730, 2020 04 07.
Artículo en Inglés | MEDLINE | ID: mdl-32167303

RESUMEN

In this work, a cleancap-regulated aggregation-induced emission (AIE) strategy based on copper nanoclusters (CuNCs) was developed with stepwise recognition for highly specific analysis of the enzyme. The dissolved CuNCs with AIE characteristics in alkaline solution were prepared by using p-mercaptophenylboronic acid as the reducing agent and the stabilizing ligand. The prepared CuNCs can specifically conjugate with glucose (Glu) to connect with each other via the rapid boronate esters formation between boronic acids of CuNCs and a pair of cis-diols on Glu. The cleancap-regulated AIE strategy was further identified by modification of CuNCs with d-glucose 6-phosphate (P-Glu) as the capper and substrate. Introduction of alkaline phosphatase to the P-Glu/CuNCs complex can induce the cleavage of phosphate group to activate the 5,6-diol of Glu on the CuNCs. The decapped complexes could be aggregated through further conjugation between 5,6-diol and boronic acid of two CuNCs, resulting in strong red AIE luminescence. The dual recognitions of enzymatic cleavage and cis-diols/boronic acid conjugation endow the designed method with highly specific detection and cell imaging of enzymatic activity. The cleancap-regulated AIE strategy provides a universal tool for regulation of AIE phenomenon in trace analysis.


Asunto(s)
Fosfatasa Alcalina/análisis , Fosfatasa Alcalina/metabolismo , Cobre/química , Células HCT116 , Células Hep G2 , Humanos , Nanopartículas del Metal/química , Microscopía Confocal , Estructura Molecular , Imagen Óptica , Agregado de Proteínas
14.
Mol Biol Rep ; 47(12): 9301-9311, 2020 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-33190199

RESUMEN

Lonicera japonica is used in Chinese herbal medicines with a wide spectrum of pharmacological properties associated with chlorogenic acid, flavonoid and iridoid. The biosynthesis of these compounds could be affected by genetic inheritance and epigenetic modification. However, the mechanisms that regulate the expression of genes involved in the biosynthesis of these compounds are rarely known. The results of qRT-PCR showed that the biosynthesis gene expression of these compounds was related to histone H3K4 and H3K9 methylation levels. These active compounds content of L. japonica were measured by UPLC-MS/MS. H3K4me3 showed a positive correlation with chlorogenic acid and loganic acid content, and H3K9me positively correlated with luteolin content. The correlation between histone methylation levels and the levels of luteolin and loganic acid in L. japonica from different producing areas validate the regulatory role of histone methylation in biosynthesis of bioactive compounds. Our study demonstrated a potential regulatory network of H3K9/H3K4 methylation to gene expression and content of secondary metabolites, and provided a basis for understanding the mechanism underlying the variation of major bioactive compounds in L. japonica.


Asunto(s)
Ácido Clorogénico/metabolismo , Flavonoides/biosíntesis , Histonas/metabolismo , Iridoides/metabolismo , Lonicera/genética , Lonicera/metabolismo , Proteínas de Plantas/metabolismo , Cromatografía Líquida de Alta Presión , Medicamentos Herbarios Chinos , Expresión Génica , Regulación de la Expresión Génica de las Plantas , Redes Reguladoras de Genes , Metilación , Hojas de la Planta/genética , Hojas de la Planta/metabolismo , Reacción en Cadena en Tiempo Real de la Polimerasa , Transducción de Señal/genética , Espectrometría de Masas en Tándem
15.
Zhongguo Zhong Yao Za Zhi ; 44(24): 5352-5357, 2019 Dec.
Artículo en Zh | MEDLINE | ID: mdl-32237379

RESUMEN

In order to improve the quality and yield of Gastrodia elata f. glauca,determine the suitable Armillaria strains for the accompanying experiment in Xiaocaoba,Yiliang,four Armillaria strains were selected. They were used for G. elata cultivation,and the gene sequence,r DNA-ITS,ß-tubulin and EF1-α of four Armillaria strains,were compared and analyzed. The yield was mesured in November which was based on previous laboratory research. The tubers were washed and steamed,then dried and powdered. The content of gastrodin and p-hydroxybenzyl alcohol was determined by UPLC,the polysaccharide was determined by phenol-concentrated sulfuric acid method. The results showed that the strains M1,M2,M3 and M4 were Armillaria gallica group but there were differences in the yield and active ingredient content when they were cultivated with the same G. elata. The yield of G. elata( Jian Ma) was the lowest when cultivated with Armillaria strain M3,but it was not the same when used M1,0. 981 kg·m-2,the highest yield in the four stains.The content of gastrodin was 0. 581%,the total content of gastrodin and p-hydroxybenzyl alcohol was 0. 595%,when accompanied with M1 strains. It was higher than other strains. The content of G. elata polysaccharide was 2. 132%,which was similar to the content of M3 strain,higher than that of M2 and M4 strain. Selecting phylogenesis of Armillaria strians,the content of active ingredient,and the yield as indicators,it was concluded concerned that the M1 strain was the best of four strains. The results will provide a theoretical basis and guidance for higher yield and quality in cultivation of G. elata in Yiliang.


Asunto(s)
Armillaria/fisiología , Gastrodia/química , Gastrodia/microbiología , Tubérculos de la Planta/química , Armillaria/clasificación , Filogenia , Plantas Medicinales/química , Plantas Medicinales/microbiología
16.
Angew Chem Int Ed Engl ; 58(23): 7808-7812, 2019 06 03.
Artículo en Inglés | MEDLINE | ID: mdl-30957318

RESUMEN

Encapsulation of active biomolecules and/or nanoparticles in metal-organic frameworks (MOFs) remains a great challenge in biomedical applications. In this work, through a stepwise in situ growth method, a black phosphorus quantum dot (BQ) and catalase were precisely encapsulated into the inner and outer layers of MOFs, respectively. The integrated MOF system as a tandem catalyst could convert H2 O2 into O2 in MOF-stabilized catalase outer layer, and then O2 was directly injected into MOF-sensitized BQ inner, leading to high quantum yield of singlet oxygen. Upon internalization, the photodynamic therapy efficiency of the MOF system was 8.7-fold greater than that without catalase, showing an enhanced therapeutic effect against hypoxic tumor cells. Furthermore, by coupling with photothermal therapy of BQs, photodynamic-thermal synergistic therapy was realized both in vitro and in vivo.


Asunto(s)
Hipoxia , Estructuras Metalorgánicas/química , Nanopartículas/administración & dosificación , Fotoquimioterapia , Puntos Cuánticos , Neoplasias del Cuello Uterino/terapia , Animales , Catalasa/química , Catalasa/metabolismo , Proliferación Celular , Femenino , Humanos , Ratones , Nanopartículas/química , Fósforo/química , Fósforo/metabolismo , Oxígeno Singlete/metabolismo , Células Tumorales Cultivadas , Neoplasias del Cuello Uterino/patología , Ensayos Antitumor por Modelo de Xenoinjerto
17.
J Hazard Mater ; 474: 134655, 2024 Aug 05.
Artículo en Inglés | MEDLINE | ID: mdl-38805822

RESUMEN

Arsenic (As) can be transferred along the food chain, while little is known about the toxic effects of dietborne As on marine copepods. In this study, we investigated the short-term and long-term effects of waterborne and dietborne As exposure on the bioaccumulation and biotransformation, as well as developmental toxicity of Tigriopus japonicus. Under acute As exposure, As bioaccumulation increased and reached a plateau with increasing exposure concentration. Moreover, As accumulation at dietborne exposure was 4.3 and 5.7 times greater than that at control group for AsIII and AsV, respectively. At chronic As exposure, As accumulation increased continuously with exposure time, with a 2.8-day extension of development time and a 45% reduction in 10-d fecundity under dietborne exposure compared to control, whereas 2.3-day extension of development time and a 20% reduction in 10-d fecundity were observed under waterborne exposure. Among As species, inorganic As had the highest concentrations, but the proportion of inorganic As decreased from 89% to 63% during 4 to 21 d of exposure, suggesting the conversion of inorganic As to organic As. The organic As was dominated by arsenobetaine (AsB, 13-25%), followed by monomethylarsenic (MMA, 8-25%). These results suggest that dietborne exposure has more pronounced toxic effects on T. japonicus, but the toxicity of As could be reduced through biotransformation under chronic exposure. Therefore, the arsenic species should be considered when assessing As toxicity.


Asunto(s)
Arsénico , Biotransformación , Copépodos , Contaminantes Químicos del Agua , Animales , Contaminantes Químicos del Agua/toxicidad , Contaminantes Químicos del Agua/metabolismo , Copépodos/metabolismo , Copépodos/efectos de los fármacos , Arsénico/toxicidad , Arsénico/metabolismo , Bioacumulación
18.
Artículo en Inglés | MEDLINE | ID: mdl-38717883

RESUMEN

While humans can excel at image classification tasks by comparing a few images, existing metric-based few-shot classification methods are still not well adapted to novel tasks. Performance declines rapidly when encountering new patterns, as feature embeddings cannot effectively encode discriminative properties. Moreover, existing matching methods inadequately utilize support set samples, focusing only on comparing query samples to category prototypes without exploiting contrastive relationships across categories for discriminative features. In this work, we propose a method where query samples select their most category-representative features for matching, making feature embeddings adaptable and category-related. We introduce a category alignment mechanism (CAM) to align query image features with different categories. CAM ensures features chosen for matching are distinct and strongly correlated to intra-and inter-contrastive relationships within categories, making extracted features highly related to their respective categories. CAM is parameter-free, requires no extra training to adapt to new tasks, and adjusts features for matching when task categories change. We also implement a cross-validation-based feature selection technique for support samples, generating more discriminative category prototypes. We implement two versions of inductive and transductive inference and conduct extensive experiments on six datasets to demonstrate the effectiveness of our algorithm. The results indicate that our method consistently yields performance improvements on benchmark tasks and surpasses the current state-of-the-art methods.

19.
J Fungi (Basel) ; 10(6)2024 May 27.
Artículo en Inglés | MEDLINE | ID: mdl-38921372

RESUMEN

The sclerotium of the edible mushroom Polyporus umbellatus (Zhuling) exhibits various medicinal properties. However, given its long growth cycle and overexploitation, wild resources are facing depletion. Macrofungal growth depends on diverse microbial communities; however, the impact of soil bacteria on P. umbellatus development is unknown. Here, we combined high-throughput sequencing and pure culturing to characterize the diversity and potential function of bacteria and fungi inhabiting the P. umbellatus sclerotium and tested the bioactivities of their isolates. Fungal operational taxonomic units (OTUs) were clustered and classified, revealing 1275 genera. Bacterial OTUs yielded 891 genera. Additionally, 81 bacterial and 15 fungal strains were isolated from P. umbellatus sclerotia. Antagonism assays revealed three bacterial strains (FN2, FL19, and CL15) promoting mycelial growth by producing indole-3-acetic acid, solubilizing phosphate, and producing siderophores, suggesting their role in regulating growth, development, and production of active compounds in P. umbellatus. FN2-CL15 combined with bacterial liquid promoted growth and increased the polysaccharide content of P. umbellatus mycelia. This study reports new bioactive microbial resources for fertilizers or pesticides to enhance the growth and polysaccharide accumulation of P. umbellatus mycelia and offers guidance for exploring the correlation between medicinal macrofungi and associated microbial communities.

20.
Foods ; 13(2)2024 Jan 11.
Artículo en Inglés | MEDLINE | ID: mdl-38254541

RESUMEN

Enzyme inactivation is crucial for enhancing the shelf life of lightly milled rice (LMR), yet the impact of diverse superheated steam (SS) treatment conditions on lipolytic enzyme efficiency, physicochemical properties, and volatile profiles of LMR remains unclear. This study investigated varying SS conditions, employing temperatures of 120 °C, 140 °C, and 160 °C and exposure times of 2, 4, 6, and 8 min. The research aimed to discern the influence of these conditions on enzyme activities, physicochemical characteristics, and quality attributes of LMR. Results indicated a significant rise in the inactivation rate with increased treatment temperature or duration, achieving a notable 70% reduction in enzyme activities at 120 °C for 6 min. Prolonged exposure to higher temperatures also induced pronounced fissures on LMR surfaces. Furthermore, intensive SS treatment led to a noteworthy 5.52% reduction in the relative crystallinity of LMR starch. GC/MS analysis revealed a consequential decrease, ranging from 44.7% to 65.7%, in undesirable odor ketones post-SS treatment. These findings underscore the potential of SS treatment in enhancing the commercial attributes of LMR.

SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA