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1.
Annu Rev Biochem ; 91: 1-32, 2022 06 21.
Artigo em Inglês | MEDLINE | ID: mdl-35320683

RESUMO

Cryo-electron microscopy (cryo-EM) continues its remarkable growth as a method for visualizing biological objects, which has been driven by advances across the entire pipeline. Developments in both single-particle analysis and in situ tomography have enabled more structures to be imaged and determined to better resolutions, at faster speeds, and with more scientists having improved access. This review highlights recent advances at each stageof the cryo-EM pipeline and provides examples of how these techniques have been used to investigate real-world problems, including antibody development against the SARS-CoV-2 spike during the recent COVID-19 pandemic.


Assuntos
COVID-19 , Pandemias , Microscopia Crioeletrônica/métodos , Humanos , SARS-CoV-2 , Imagem Individual de Molécula
2.
Cell ; 167(6): 1610-1622.e15, 2016 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-27912064

RESUMO

The ribosome is a complex macromolecular machine and serves as an ideal system for understanding biological macromolecular assembly. Direct observation of ribosome assembly in vivo is difficult, as few intermediates have been isolated and thoroughly characterized. Herein, we deploy a genetic system to starve cells of an essential ribosomal protein, which results in the accumulation of assembly intermediates that are competent for maturation. Quantitative mass spectrometry and single-particle cryo-electron microscopy reveal 13 distinct intermediates, which were each resolved to ∼4-5 Å resolution and could be placed in an assembly pathway. We find that ribosome biogenesis is a parallel process, that blocks of structured rRNA and proteins assemble cooperatively, and that the entire process is dynamic and can be "re-routed" through different pathways as needed. This work reveals the complex landscape of ribosome assembly in vivo and provides the requisite tools to characterize additional assembly pathways for ribosomes and other macromolecular machines.


Assuntos
Escherichia coli/química , Escherichia coli/metabolismo , Subunidades Ribossômicas Maiores de Bactérias/química , Subunidades Ribossômicas Maiores de Bactérias/metabolismo , Microscopia Crioeletrônica , Espectrometria de Massas , Modelos Moleculares , Multimerização Proteica , RNA Bacteriano/metabolismo , RNA Ribossômico/metabolismo
3.
Mol Cell ; 80(6): 938-939, 2020 12 17.
Artigo em Inglês | MEDLINE | ID: mdl-33338409

RESUMO

The goal of structural biology is to understand biological macromolecules in as much detail as possible. Depending on the resolution of the structure obtained, insights will range from understanding interactions at the level of proteins, domains, or atoms. The three mainstay structural biology techniques are X-ray crystallography, nuclear magnetic resonance (NMR) imaging, and cryogenic electron microscopy (cryo-EM). Cryo-EM has rapidly gained popularity in recent years due to a combination of hardware and software advances, leading to the so-called Resolution Revolution (Kühlbrandt, 2014).


Assuntos
Microscopia Crioeletrônica , Biologia Molecular/métodos , Proteínas/ultraestrutura , Cristalografia por Raios X , Imageamento Tridimensional , Software
4.
Mol Cell ; 78(4): 683-699.e11, 2020 05 21.
Artigo em Inglês | MEDLINE | ID: mdl-32386575

RESUMO

Mycobacterium tuberculosis causes tuberculosis, a disease that kills over 1 million people each year. Its cell envelope is a common antibiotic target and has a unique structure due, in part, to two lipidated polysaccharides-arabinogalactan and lipoarabinomannan. Arabinofuranosyltransferase D (AftD) is an essential enzyme involved in assembling these glycolipids. We present the 2.9-Å resolution structure of M. abscessus AftD, determined by single-particle cryo-electron microscopy. AftD has a conserved GT-C glycosyltransferase fold and three carbohydrate-binding modules. Glycan array analysis shows that AftD binds complex arabinose glycans. Additionally, AftD is non-covalently complexed with an acyl carrier protein (ACP). 3.4- and 3.5-Å structures of a mutant with impaired ACP binding reveal a conformational change, suggesting that ACP may regulate AftD function. Mutagenesis experiments using a conditional knockout constructed in M. smegmatis confirm the essentiality of the putative active site and the ACP binding for AftD function.


Assuntos
Proteína de Transporte de Acila/metabolismo , Proteínas de Bactérias/química , Proteínas de Bactérias/metabolismo , Membrana Celular/metabolismo , Microscopia Crioeletrônica/métodos , Glicosiltransferases/metabolismo , Mycobacterium smegmatis/enzimologia , Proteína de Transporte de Acila/genética , Proteínas de Bactérias/genética , Domínio Catalítico , Parede Celular/metabolismo , Galactanos/metabolismo , Glicosiltransferases/genética , Lipopolissacarídeos/metabolismo , Mutação , Mycobacterium smegmatis/genética , Mycobacterium smegmatis/crescimento & desenvolvimento , Filogenia , Conformação Proteica , Especificidade por Substrato
5.
Nature ; 577(7790): 426-431, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31775157

RESUMO

The organization of genomic DNA into nucleosomes profoundly affects all DNA-related processes in eukaryotes. The histone chaperone known as 'facilitates chromatin transcription' (FACT1) (consisting of subunits SPT16 and SSRP1) promotes both disassembly and reassembly of nucleosomes during gene transcription, DNA replication and DNA repair2. However, the mechanism by which FACT causes these opposing outcomes is unknown. Here we report two cryo-electron-microscopic structures of human FACT in complex with partially assembled subnucleosomes, with supporting biochemical and hydrogen-deuterium exchange data. We find that FACT is engaged in extensive interactions with nucleosomal DNA and all histone variants. The large DNA-binding surface on FACT appears to be protected by the carboxy-terminal domains of both of its subunits, and this inhibition is released by interaction with H2A-H2B, allowing FACT-H2A-H2B to dock onto a complex containing DNA and histones H3 and H4 (ref. 3). SPT16 binds nucleosomal DNA and tethers H2A-H2B through its carboxy-terminal domain by acting as a placeholder for DNA. SSRP1 also contributes to DNA binding, and can assume two conformations, depending on whether a second H2A-H2B dimer is present. Our data suggest a compelling mechanism for how FACT maintains chromatin integrity during polymerase passage, by facilitating removal of the H2A-H2B dimer, stabilizing intermediate subnucleosomal states and promoting nucleosome reassembly. Our findings reconcile discrepancies regarding the many roles of FACT and underscore the dynamic interactions between histone chaperones and nucleosomes.


Assuntos
Proteínas de Ciclo Celular/química , Proteínas de Ciclo Celular/metabolismo , Proteínas de Ligação a DNA/química , Proteínas de Ligação a DNA/metabolismo , Proteínas de Grupo de Alta Mobilidade/química , Proteínas de Grupo de Alta Mobilidade/metabolismo , Nucleossomos/química , Nucleossomos/metabolismo , Fatores de Transcrição/química , Fatores de Transcrição/metabolismo , Fatores de Elongação da Transcrição/química , Fatores de Elongação da Transcrição/metabolismo , Microscopia Crioeletrônica , DNA/química , DNA/metabolismo , Histonas/química , Histonas/metabolismo , Humanos , Modelos Moleculares , Estrutura Quaternária de Proteína , Estrutura Terciária de Proteína
6.
Nature ; 576(7786): 315-320, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31776516

RESUMO

The emergence and spread of drug-resistant Plasmodium falciparum impedes global efforts to control and eliminate malaria. For decades, treatment of malaria has relied on chloroquine (CQ), a safe and affordable 4-aminoquinoline that was highly effective against intra-erythrocytic asexual blood-stage parasites, until resistance arose in Southeast Asia and South America and spread worldwide1. Clinical resistance to the chemically related current first-line combination drug piperaquine (PPQ) has now emerged regionally, reducing its efficacy2. Resistance to CQ and PPQ has been associated with distinct sets of point mutations in the P. falciparum CQ-resistance transporter PfCRT, a 49-kDa member of the drug/metabolite transporter superfamily that traverses the membrane of the acidic digestive vacuole of the parasite3-9. Here we present the structure, at 3.2 Å resolution, of the PfCRT isoform of CQ-resistant, PPQ-sensitive South American 7G8 parasites, using single-particle cryo-electron microscopy and antigen-binding fragment technology. Mutations that contribute to CQ and PPQ resistance localize primarily to moderately conserved sites on distinct helices that line a central negatively charged cavity, indicating that this cavity is the principal site of interaction with the positively charged CQ and PPQ. Binding and transport studies reveal that the 7G8 isoform binds both drugs with comparable affinities, and that these drugs are mutually competitive. The 7G8 isoform transports CQ in a membrane potential- and pH-dependent manner, consistent with an active efflux mechanism that drives CQ resistance5, but does not transport PPQ. Functional studies on the newly emerging PfCRT F145I and C350R mutations, associated with decreased PPQ susceptibility in Asia and South America, respectively6,9, reveal their ability to mediate PPQ transport in 7G8 variant proteins and to confer resistance in gene-edited parasites. Structural, functional and in silico analyses suggest that distinct mechanistic features mediate the resistance to CQ and PPQ in PfCRT variants. These data provide atomic-level insights into the molecular mechanism of this key mediator of antimalarial treatment failures.


Assuntos
Microscopia Crioeletrônica , Resistência a Medicamentos/efeitos dos fármacos , Proteínas de Membrana Transportadoras/química , Proteínas de Membrana Transportadoras/ultraestrutura , Plasmodium falciparum/química , Proteínas de Protozoários/química , Proteínas de Protozoários/ultraestrutura , Cloroquina/metabolismo , Cloroquina/farmacologia , Resistência a Medicamentos/genética , Concentração de Íons de Hidrogênio , Malária Falciparum/tratamento farmacológico , Malária Falciparum/parasitologia , Proteínas de Membrana Transportadoras/genética , Proteínas de Membrana Transportadoras/metabolismo , Modelos Moleculares , Mutação , Plasmodium falciparum/genética , Plasmodium falciparum/ultraestrutura , Proteínas de Protozoários/genética , Proteínas de Protozoários/metabolismo , Quinolinas/metabolismo , Quinolinas/farmacologia
7.
Proteomics ; 24(12-13): e2300210, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38727198

RESUMO

Cancer harbours extensive proteomic heterogeneity. Inspired by the prior success of single-cell RNA sequencing (scRNA-seq) in characterizing minute transcriptomics heterogeneity in cancer, researchers are now actively searching for information regarding the proteomics counterpart. Therefore recently, single-cell proteomics by mass spectrometry (SCP) has rapidly developed into state-of-the-art technology to cater the need. This review aims to summarize application of SCP in cancer research, while revealing current development progress of SCP technology. The review also aims to contribute ideas into research gaps and future directions, ultimately promoting the application of SCP in cancer research.


Assuntos
Espectrometria de Massas , Neoplasias , Proteômica , Análise de Célula Única , Proteômica/métodos , Análise de Célula Única/métodos , Humanos , Neoplasias/metabolismo , Espectrometria de Massas/métodos , Animais
8.
BMC Plant Biol ; 24(1): 205, 2024 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-38509465

RESUMO

BACKGROUND: Gynostemma pentaphyllum, an ancient Chinese herbal medicine, serves as a natural source of gypenosides with significant medicinal properties. Basic helix-loop-helix (bHLH) transcription factors play pivotal roles in numerous biological processes, especially in the regulation of secondary metabolism in plants. However, the characteristics and functions of the bHLH genes in G. pentaphyllum remain unexplored, and their regulatory role in gypenoside biosynthesis remains poorly elucidated. RESULTS: This study identified a total of 111 bHLH members in G. pentaphyllum (GpbHLHs), categorizing them into 26 subgroups based on shared conserved motif compositions and gene structures. Collinearity analysis illustrated that segmental duplications predominately lead to the evolution of GpbHLHs, with most duplicated GpbHLH gene pairs undergoing purifying selection. Among the nine gypenoside-related GpbHLH genes, two GpbHLHs (GpbHLH15 and GpbHLH58) were selected for further investigation based on co-expression analysis and functional prediction. The expression of these two selected GpbHLHs was dramatically induced by methyl jasmonate, and their nuclear localization was confirmed. Furthermore, yeast one-hybrid and dual-luciferase assays demonstrated that GpbHLH15 and GpbHLH58 could bind to the promoters of the gypenoside biosynthesis pathway genes, such as GpFPS1, GpSS1, and GpOSC1, and activate their promoter activity to varying degrees. CONCLUSIONS: In conclusion, our findings provide a detailed analysis of the bHLH family and valuable insights into the potential use of GpbHLHs to enhance the accumulation of gypenosides in G. pentaphyllum.


Assuntos
Gynostemma , Extratos Vegetais , Gynostemma/genética , Gynostemma/química , Gynostemma/metabolismo , Extratos Vegetais/química , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo
9.
J Neurosci Res ; 102(1)2024 01.
Artigo em Inglês | MEDLINE | ID: mdl-38284835

RESUMO

Bone metastasis pain (BMP) is a severe chronic pain condition. Our previous studies on BMP revealed functional brain abnormalities. However, the potential effect of BMP on brain structure and function, especially gray matter volume (GMV) and related functional networks, have not yet been clearly illustrated. Voxel-based morphometry and functional connectivity (FC) analysis methods were used to investigate GMV and intrinsic FC differences in 45 right-handed lung cancer patients with BMP(+), 37 lung cancer patients without BMP(-), and 45 healthy controls (HCs). Correlation analysis was performed thereafter with all clinical variables by Pearson correlation. Compared to HCs, BMP(+) group exhibited decreased GMV in medial frontal gyrus (MFG) and right middle temporal gyrus (MTG). Compared with BMP(-) group, BMP(+) group exhibited reduced GMV in cerebelum_6_L and left lingual gyrus. However, no regions with significant GMV differences were found between BMP(-) and HCs groups. Receiver operating characteristic analysis indicated the potential classification power of these aberrant regions. Correlation analysis revealed that GMV in the right MTG was positively associated with anxiety in BMP(+) group. Further FC analysis demonstrated enhanced interactions between MFG/right MTG and cerebellum in BMP(+) patients compared with HCs. These results showed that BMP was closely associated with cerebral alterations, which may induce the impairment of pain moderation circuit, deficits in cognitive function, dysfunction of emotional control, and sensorimotor processing. These findings may provide a fresh perspective and further neuroimaging evidence for the possible mechanisms of BMP. Furthermore, the role of the cerebellum in pain processing needs to be further investigated.


Assuntos
Dor Crônica , Neoplasias Pulmonares , Humanos , Substância Cinzenta/diagnóstico por imagem , Neoplasias Pulmonares/complicações , Córtex Cerebral , Lobo Temporal
10.
Crit Rev Biotechnol ; : 1-21, 2024 Jan 21.
Artigo em Inglês | MEDLINE | ID: mdl-38246753

RESUMO

Stress tolerance is a vital attribute for all living beings to cope with environmental adversities. IrrE (also named PprI) from Deinococcus radiodurans enhances resistance to extreme radiation stress by functioning as a global regulator, mediating the transcription of genes involved in deoxyribonucleic acid (DNA) damage response (DDR). The expression of IrrE augmented the resilience of various species to heat, radiation, oxidation, osmotic stresses and inhibitors, encompassing bacterial, fungal, plant, and mammalian cells. Moreover, IrrE was employed in a global regulator engineering strategy to broaden its applications in stress tolerance. The regulatory impacts of heterologously expressed IrrE have been investigated at the molecular and systems level, including the regulation of genes, proteins, modules, or pathways involved in DNA repair, detoxification proteins, protective molecules, native regulators and other aspects. In this review, we discuss the regulatory role and mechanism of IrrE in the antiradiation response of D. radiodurans. Furthermore, the applications and regulatory effects of heterologous expression of IrrE to enhance abiotic stress tolerance are summarized in particular.

11.
Exp Physiol ; 2024 Aug 20.
Artigo em Inglês | MEDLINE | ID: mdl-39163874

RESUMO

Previous studies demonstrated that acute fatiguing exercise transiently reduces whole-muscle stiffness, which might contribute to increased risk of injury and impaired contractile performance. We sought to elucidate potential intracellular mechanisms underlying these reductions. To that end, the cellular passive Young's modulus was measured in muscle fibres from healthy, young males and females. Eight volunteers (four male and four female) completed unilateral, repeated maximal voluntary knee extensions until task failure, immediately followed by bilateral percutaneous needle muscle biopsy of the post-fatigued followed by the non-fatigued control vastus lateralis. Muscle samples were processed for mechanical assessment and separately for imaging and phosphoproteomics. Fibres were passively (pCa 8.0) stretched incrementally to 156% of initial sarcomere length to assess Young's modulus, calculated as the slope of the resulting stress-strain curve at short (sarcomere length = 2.4-3.0 µm) and long (sarcomere length = 3.2-3.8 µm) lengths. Titin phosphorylation was assessed by liquid chromatography followed by high-resolution mass spectrometry. The passive modulus was significantly reduced in post-fatigued versus control fibres from male, but not female, participants. Post-fatigued samples showed altered phosphorylation of five serine residues (four located within the elastic region of titin) but did not exhibit altered active tension or sarcomere ultrastructure. Collectively, these results suggest that acute fatigue is sufficient to alter phosphorylation of skeletal titin in multiple locations. We also found reductions in the passive modulus, consistent with prior reports in the literature investigating striated muscle stiffness. These results provide mechanistic insight contributing to the understanding of dynamic regulation of whole-muscle tissue mechanics in vivo. HIGHLIGHTS: What is the central question of this study? Previous studies have shown that skeletal muscle stiffness is reduced following a single bout of fatiguing exercise in whole muscle, but it is not known whether these changes manifest at the cellular level, and their potential mechanisms remain unexplored. What is the main finding and its importance? Fatiguing exercise reduces cellular stiffness in skeletal muscle from males but not females, suggesting that fatigue alters tissue compliance in a sex-dependent manner. The phosphorylation status of titin, a potential mediator of skeletal muscle cellular stiffness, is modified by fatiguing exercise. Previous studies have shown that passive skeletal muscle stiffness is reduced following a single bout of fatiguing exercise. Lower muscle passive stiffness following fatiguing exercise might increase risk for soft-tissue injury; however, the underlying mechanisms of this change are unclear. Our findings show that fatiguing exercise reduces the passive Young's modulus in skeletal muscle cells from males but not females, suggesting that intracellular proteins contribute to reduced muscle stiffness following repeated loading to task failure in a sex-dependent manner. The phosphorylation status of the intracellular protein titin is modified by fatiguing exercise in a way that might contribute to altered muscle stiffness after fatiguing exercise. These results provide important mechanistic insight that might help to explain why biological sex impacts the risk for soft-tissue injury with repeated or high-intensity mechanical loading in athletes and the risk of falls in older adults.

12.
Cryobiology ; 114: 104843, 2024 03.
Artigo em Inglês | MEDLINE | ID: mdl-38158171

RESUMO

Coolant-assisted liquid nitrogen (LN) flash freezing of frozen tissues has been widely adopted to preserve tissue morphology for histopathological annotations in mass spectrometry-based spatial proteomics techniques. However, existing coolants pose health risks upon inhalation and are expensive. To overcome this challenge, we present our pilot study by introducing the EtOH-LN workflow, which demonstrates the feasibility of using 95 % ethanol as a safer and easily accessible alternative to existing coolants for LN-based cryoembedding of frozen tissues. Our study reveals that both the EtOH-LN and LN-only cryoembedding workflows exhibit significantly reduced freezing artifacts compared to cryoembedding in cryostat (p < 0.005), while EtOH-LN (SD = 0.56) generates more consistent results compared to LN-only (SD = 1.29). We have modified a previously reported morphology restoration method to incorporate the EtOH-LN workflow, which successfully restored the tissue architecture from freezing artifacts (p < 0.05). Additional studies are required to validate the impact of the EtOH-LN workflow on the molecular profiles of tissues.


Assuntos
Artefatos , Proteômica , Congelamento , Projetos Piloto , Fluxo de Trabalho , Criopreservação/métodos , Etanol , Espectrometria de Massas , Nitrogênio
13.
Proc Natl Acad Sci U S A ; 118(51)2021 12 21.
Artigo em Inglês | MEDLINE | ID: mdl-34916296

RESUMO

The human extracellular calcium-sensing (CaS) receptor controls plasma Ca2+ levels and contributes to nutrient-dependent maintenance and metabolism of diverse organs. Allosteric modulation of the CaS receptor corrects disorders of calcium homeostasis. Here, we report the cryogenic-electron microscopy reconstructions of a near-full-length CaS receptor in the absence and presence of allosteric modulators. Activation of the homodimeric CaS receptor requires a break in the transmembrane 6 (TM6) helix of each subunit, which facilitates the formation of a TM6-mediated homodimer interface and expansion of homodimer interactions. This transformation in TM6 occurs without a positive allosteric modulator. Two modulators with opposite functional roles bind to overlapping sites within the transmembrane domain through common interactions, acting to stabilize distinct rotamer conformations of key residues on the TM6 helix. The positive modulator reinforces TM6 distortion and maximizes subunit contact to enhance receptor activity, while the negative modulator strengthens an intact TM6 to dampen receptor function. In both active and inactive states, the receptor displays symmetrical transmembrane conformations that are consistent with its homodimeric assembly.


Assuntos
Cálcio/metabolismo , Regulação da Expressão Gênica/fisiologia , Homeostase/fisiologia , Receptores de Detecção de Cálcio/metabolismo , Microscopia Crioeletrônica , Células HEK293 , Humanos , Modelos Moleculares , Conformação Proteica , Domínios Proteicos , Receptores de Detecção de Cálcio/genética , Transdução de Sinais
14.
J Assist Reprod Genet ; 41(4): 1087-1096, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38321265

RESUMO

PURPOSE: Decreased ovarian reserve function is mainly characterized by female endocrine disorders and fertility decline. Follicular fluid (FF) exosomal microRNAs (miRNAs) have been shown to regulate the function of granulosa cells (GCs). The present study explored differentially expressed miRNAs (DEmiRNAs) in patients with diminished ovarian reserve (DOR). METHODS: FF was collected from 12 DOR patients and 12 healthy controls. DEmiRNAs between the two groups were identified and analyzed using high-throughput sequencing technology and validated by real-time quantitative PCR (RT-qPCR). RESULTS: A total of 592 DEmiRNAs were identified using high-throughput miRNA sequencing, of which 213 were significantly upregulated and 379 were significantly downregulated. The sequencing results were further validated by RT-qPCR. These DEmiRNA target genes were mainly involved in the cancer pathway, phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT) signaling pathway, regulation of actin cytoskeleton signaling pathway, and biological processes related to protein binding, nucleoplasm, cytoplasm, and cell membrane. CONCLUSION: FF exosomal miRNAs are significantly differentially expressed in DOR patients versus non-DOR patients, underscoring their crucial role in regulating the pathogenesis of DOR.


Assuntos
Exossomos , Líquido Folicular , MicroRNAs , Reserva Ovariana , Humanos , Feminino , Líquido Folicular/metabolismo , MicroRNAs/genética , Exossomos/genética , Exossomos/metabolismo , Reserva Ovariana/genética , Adulto , Células da Granulosa/metabolismo , Células da Granulosa/patologia , Infertilidade Feminina/genética , Infertilidade Feminina/metabolismo , Infertilidade Feminina/patologia , Transdução de Sinais/genética , Sequenciamento de Nucleotídeos em Larga Escala , Regulação da Expressão Gênica/genética , Perfilação da Expressão Gênica
15.
Sensors (Basel) ; 24(10)2024 May 09.
Artigo em Inglês | MEDLINE | ID: mdl-38793849

RESUMO

The origin of agricultural products is crucial to their quality and safety. This study explored the differences in chemical composition and structure of rice from different origins using fluorescence detection technology. These differences are mainly affected by climate, environment, geology and other factors. By identifying the fluorescence characteristic absorption peaks of the same rice seed varieties from different origins, and comparing them with known or standard samples, this study aims to authenticate rice, protect brands, and achieve traceability. The study selected the same variety of rice seed planted in different regions of Jilin Province in the same year as samples. Fluorescence spectroscopy was used to collect spectral data, which was preprocessed by normalization, smoothing, and wavelet transformation to remove noise, scattering, and burrs. The processed spectral data was used as input for the long short-term memory (LSTM) model. The study focused on the processing and analysis of rice spectra based on NZ-WT-processed data. To simplify the model, uninformative variable elimination (UVE) and successive projections algorithm (SPA) were used to screen the best wavelengths. These wavelengths were used as input for the support vector machine (SVM) prediction model to achieve efficient and accurate predictions. Within the fluorescence spectral range of 475-525 nm and 665-690 nm, absorption peaks of nicotinamide adenine dinucleotide (NADPH), riboflavin (B2), starch, and protein were observed. The origin tracing prediction model established using SVM exhibited stable performance with a classification accuracy of up to 99.5%.The experiment demonstrated that fluorescence spectroscopy technology has high discrimination accuracy in tracing the origin of rice, providing a new method for rapid identification of rice origin.


Assuntos
Algoritmos , Oryza , Espectrometria de Fluorescência , Máquina de Vetores de Suporte , Oryza/química , Oryza/classificação , Espectrometria de Fluorescência/métodos , Riboflavina/análise , NADP/química , NADP/análise , NADP/metabolismo , Amido/análise , Amido/química , Sementes/química
16.
J Environ Manage ; 352: 120117, 2024 Feb 14.
Artigo em Inglês | MEDLINE | ID: mdl-38237336

RESUMO

With China being the world's largest emitter of greenhouse gases and its aviation sector burgeoning, the environmental performance of Chinese airlines has global significance. Amidst rising demands for eco-friendly practices from both customers and regulators, the interplay between airport infrastructure and environmental performance becomes pivotal. This research offers an innovative methodology to gauge the environmental performance of Chinese airlines, emphasizing the distance traveled between airports using weighted additive utility functions. Leveraging neural networks, the study investigates the impact of various airport infrastructural characteristics on environmental performance. Noteworthy findings indicate that ground control measures, automatic information services at origin airports, surface concrete on runways at both ends, and a centerline lighting system in destination airports positively influence environmental performance. In contrast, longer and wider runways at origin airports, increased distances to control towers, and asphalt runways at destination airports adversely affect it. These insights not only underscore the importance of strategic infrastructure enhancements for reducing carbon footprints but also hold profound policy implications. As global climate change remains at the forefront, fostering sustainable airport infrastructure in China can significantly contribute to worldwide mitigation efforts.


Assuntos
Poluentes Atmosféricos , Aviação , Poluentes Ambientais , Gases de Efeito Estufa , Aeroportos , Poluentes Atmosféricos/análise
17.
J Environ Manage ; 360: 121132, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38754191

RESUMO

In the context of global climate change threatening human survival, and in a post-pandemic era that advocates for a global green and low-carbon economic recovery, conducting an in-depth analysis to assess whether green finance can effectively support low-carbon economic development from a dynamic perspective is crucial. Unlike existing research, which focuses solely on the average effects of green credit (GC) on carbon productivity (CP), we introduce a non-parametric panel data model to investigate GC's impact on CP across 30 provinces in China from 2003 to 2021, verifying a significant time-varying effect. Specifically, during the first phase (2003-2008), GC negatively impacted CP. In the second phase (2009-2014), this negative influence gradually diminished and transformed into a positive effect. In the third phase (2015-2021), GC continued to positively influence CP, although this effect became insignificant during the pandemic. Further subgroup analysis reveals that in the regions with low environmental regulations, GC did not significantly boost CP throughout the sample period. In contrast, in the regions with high environmental regulations, GC's positive effect persisted in the mid to late stages of the sample period. Additionally, compared to the regions with low levels of marketization, the impact of GC on CP was more pronounced in highly marketized regions. This indicates that the promoting effect of GC on CP depends on strong support from environmental regulations and well-functioning market mechanisms. By adopting a non-parametric approach, this study reveals variations in the impact of GC on CP across different stages and under the influence of the pandemic shock, offering new insights into the relationship between GC and China's CP.


Assuntos
Carbono , Mudança Climática , China , Carbono/análise
18.
J Environ Manage ; 367: 121955, 2024 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-39096728

RESUMO

This study aims to address a critical gap in the literature by examining the incorporation of uncertainty in measuring carbon emissions using the greenhouse gas (GHG) Protocol methodology across all three scopes. By comprehensively considering the various dimensions of CO2 emissions within the context of organizational activities, our research contributes significantly to the existing body of knowledge. We address challenges such as data quality issues and a high prevalence of missing values by using information entropy, techniques for order preference by similarity to ideal solution (TOPSIS), and an artificial neural network (ANN) to analyze the contextual variables. Our findings, derived from the data sample of 56 companies across 18 sectors and 13 Brazilian states between 2017 and 2019, reveal that Scope 3 emissions exhibit the highest levels of information entropy. Additionally, we highlight the pivotal role of public policies in enhancing the availability of GHG emissions data, which, in turn, positively impacts policy-making practices. By demonstrating the potential for a virtuous cycle between improved information availability and enhanced policy outcomes, our research underscores the importance of addressing uncertainty in carbon emissions measurement for advancing effective climate change mitigation strategies.


Assuntos
Mudança Climática , Gases de Efeito Estufa , Gases de Efeito Estufa/análise , Brasil , Entropia , Monitoramento Ambiental/métodos , Incerteza , Dióxido de Carbono/análise
19.
Compr Rev Food Sci Food Saf ; 23(3): e13341, 2024 05.
Artigo em Inglês | MEDLINE | ID: mdl-38720590

RESUMO

New food sources and production systems (NFPS) are garnering much attention, driven by international trade, changing consumer preferences, potential sustainability benefits, and innovations in climate-resilient food production systems. However, NFPS can introduce new challenges for food safety agencies and food manufacturers. Most food safety hazards linked to new foods have been identified in traditional foods. However, there can be some food safety challenges that are unique to new foods. New food ingredients, inputs, and processes can introduce unexpected contaminants. To realize the full potential of NFPS, there is a need for stakeholders from governments, the food industry, and the research community to collectively work to address and communicate the safety of NFPS products. This review outlines known food safety hazards associated with select NFPS products on the market, namely, plant-derived proteins, seaweeds, jellyfish, insects, microbial proteins, as well as foods derived from cell-based food production, precision fermentation, vertical farming, and 3D food printing. We identify common elements in emerging NFPS regulatory frameworks in various countries/regions. Furthermore, we highlight current efforts in harmonization of terminologies, use of recent scientific tools to fill in food safety knowledge gaps, and international multi-stakeholder collaborations to tackle safety challenges. Although there cannot be a one-size-fits-all approach when it comes to the regulatory oversight for ensuring the safety of NFPS, there is a need to develop consensus-based structured protocols or workflows among stakeholders to facilitate comprehensive, robust, and internationally harmonized approaches. These efforts increase consumers' confidence in the safety of new foods and contribute toward fair practices in the international trade of such foods.


Assuntos
Inocuidade dos Alimentos , Humanos , Animais , Abastecimento de Alimentos/normas , Contaminação de Alimentos/prevenção & controle
20.
Fa Yi Xue Za Zhi ; 40(3): 284-290, 2024 Jun 25.
Artigo em Inglês, Chinês | MEDLINE | ID: mdl-39166310

RESUMO

The quality of Japanese forensic experts has been widely recognized around the world, which cannot be separated from the "ripple effect" caused by the rapid rise of the modern forensic education in Japan. By continuously adopting foreign forensic education resources and teaching experience, it has finally formed a forensic professional talent training model with a clear hierarchy of basic education and professional training, as well as classroom teaching and case studies complementing each other; and it continuously improves the comprehensive quality of practitioners through domestic training and international exchange and cooperation, providing talented professionals for the development of the Japanese forensic industry. In this context, this article takes the development history of Japanese forensic medicine as the starting point to study how it gradually formed the embryonic form of forensic education in modern times. Based on this, it analyzes the characteristics of Japan's modern forensic medicine talent training model, summarizes excellent experiences for localized transformation, such as emphasizing the role of practical teaching, exerting the effectiveness of vocational skills training, and promoting international exchange and cooperation, to provide reference and inspiration for the training of relevant professional talents in China.


Assuntos
Medicina Legal , Humanos , Japão , Medicina Legal/educação , Modelos Educacionais , Competência Profissional , China , Currículo , Ensino , Aptidão
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