RG108 attenuates acute kidney injury by inhibiting P38 MAPK/FOS and JNK/JUN pathways.

Acute kidney injury (AKI) is an important clinical syndrome characterised by a sudden decline in renal function, often accompanied by renal inflammation and tubular epithelial cell damage. It has been reported that inhibiting DNA methylation significantly suppress the progression of AKI. In the current study, we investigate the effect of the DNA methyltransferase (DNMT) inhibitor RG108 in cisplatin- and hypoxia-reoxygenation-induced AKI. The expression of kidney injury molecules and inflammatory factors was examined by immunofluorescence, Western blotting and Real-time PCR. The results demonstrated that RG108 treatment significantly reduced kidney inflammation and injury. Furthermore, RNA-seq analysis was performed to reveal the regulatory mechanism of RG108 in AKI. The expression of the FOS and JUN genes, which are downstream of the MAPK pathway, were significant increased in AKI. Meanwhile, the expression of FOS and JUN were both inhibited by RG108, which is similar to what we found treatment with a specific JNK inhibitor and a specific p38 MAPK inhibitor, and thus attenuated renal inflammation and injury. In conclusion, we suggest that RG108 inhibits P38 MAPK/FOS and JNK/JUN pathways and attenuates renal injury and inflammatory responses. In these results, RG108 may become a novel MAPK pathway inhibitor and a clinical candidate for the treatment of AKI.

CTsynther: Contrastive Transformer model for end-to-end retrosynthesis prediction.

Retrosynthesis prediction is a fundamental problem in organic chemistry and drug synthesis. We proposed an end-to-end deep learning model called CTsynther (Contrastive Transformer for single-step retrosynthesis prediction model) that could provide single-step retrosynthesis prediction without external reaction templates or specialized knowledge. The model introduced the concept of contrastive learning in Transformer architecture and employed a contrastive learning language representation model at the SMILES sentence level to enhance model inference by learning similarities and differences between various samples. Mixed global and local attention mechanisms allow the model to capture features and dependencies between different atoms to improve generalization. We further investigated the embedding representations of SMILES learned automatically from the model. Visualization results show that the model could effectively acquire information about identical molecules and improve prediction performance. Experiments showed that the accuracy of retrosynthesis reached 53.5% and 64.4% for with and without reaction types, respectively. The validity of the predicted reactants is improved, showing competitiveness compared with semi-template methods.

Functional reconstruction of tissue defects after total parotidectomy using a modified submandibular gland flap.

OBJECTIVE: Reconstruction of soft tissue defects after total parotidectomy requires a feasible and effective pedicled flap with sufficient volume. In this study, we introduce a modified submandibular gland flap (SMGF) for functional reconstruction of soft tissue defects resulting from total parotidectomy. MATERIALS AND METHODS: This study included 12 patients diagnosed with parotid gland carcinoma undergoing total parotidectomy and ipsilateral selective neck dissection. The modified SMGF was harvested and transferred to the parotid bed. This procedure was coupled with anastomosis between the parotid gland duct and Wharton's duct. The feasibility of the surgery, postoperative complications, facial profile restoration, and salivary secretion were assessed. RESULTS: All SMGFs pedicled only over the proximal facial artery survived without major complications. Facial profiles were well-restored, and salivary secretion was partially reserved. During the postoperative follow-up, no tumor recurrence was observed in any of the cases, and the volume of the SMGFs did not show obvious atrophy. CONCLUSIONS: The modified SMGF is a viable solution for volume restoration and functional reconstruction after total parotidectomy. CLINICAL RELEVANCE: This modified technique is simple and feasible for the functional reconstruction of soft tissue defects after total parotidectomy compared to other flaps and is worthy of clinical promotion.

A novel method to reconstruct the complex facial nerve defect after extended parotidectomy with masseteric nerve and descending hypoglossal nerve.

This study aims to present a novel technique for reconstructing complex facial nerve defects using the masseteric nerve and descending hypoglossal nerve. Here, we report a case involving a patient with locally advanced parotid malignancy who underwent extended parotidectomy with resection of the invaded facial nerve. Following tumor resection, the proximal end of the facial nerve was inaccessible, leading to the formation of multiple distal branch defects. Subsequently, we performed reconstruction of the complex facial nerve defect using the masseteric nerve for the zygomatic and upper buccal branches and the descending hypoglossal nerve for the lower buccal and submandibular branches. There were no significant operative or post-operative complications observed. Upon 18 months of follow-up, the facial function of the patient had been restored to House-Brackmann-III grade. In conclusion, this dual nerve transposition approach proves to be an effective method for reconstructing complex facial nerve defects subsequent to extended parotidectomy.

Reinforcement learning-driven exploration of peptide space: accelerating generation of drug-like peptides.

Using amino acid residues in peptide generation has solved several key problems, including precise control of amino acid sequence order, customized peptides for property modification, and large-scale peptide synthesis. Proteins contain unknown amino acid residues. Extracting them for the synthesis of drug-like peptides can create novel structures with unique properties, driving drug development. Computer-aided design of novel peptide drug molecules can solve the high-cost and low-efficiency problems in the traditional drug discovery process. Previous studies faced limitations in enhancing the bioactivity and drug-likeness of polypeptide drugs due to less emphasis on the connection relationships in amino acid structures. Thus, we proposed a reinforcement learning-driven generation model based on graph attention mechanisms for peptide generation. By harnessing the advantages of graph attention mechanisms, this model effectively captured the connectivity structures between amino acid residues in peptides. Simultaneously, leveraging reinforcement learning's strength in guiding optimal sequence searches provided a novel approach to peptide design and optimization. This model introduces an actor-critic framework with real-time feedback loops to achieve dynamic balance between attributes, which can customize the generation of multiple peptides for specific targets and enhance the affinity between peptides and targets. Experimental results demonstrate that the generated drug-like peptides meet specified absorption, distribution, metabolism, excretion, and toxicity properties and bioactivity with a success rate of over 90$\%$, thereby significantly accelerating the process of drug-like peptide generation.

Blood-brain barrier breakdown in dementia with Lewy bodies.

BACKGROUND: Blood-brain barrier (BBB) dysfunction has been viewed as a potential underlying mechanism of neurodegenerative disorders, possibly involved in the pathogenesis and progression of Alzheimer's disease (AD). However, a relation between BBB dysfunction and dementia with Lewy bodies (DLB) has yet to be systematically investigated. Given the overlapping clinical features and neuropathology of AD and DLB, we sought to evaluate BBB permeability in the context of DLB and determine its association with plasma amyloid-ß (Aß) using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). METHODS: For this prospective study, we examined healthy controls (n = 24, HC group) and patients diagnosed with AD (n = 29) or DLB (n = 20) between December 2020 and April 2022. Based on DCE-MRI studies, mean rates of contrast agent transfer from intra- to extravascular spaces (Ktrans) were calculated within regions of interest. Spearman's correlation and multivariate linear regression were applied to analyze associations between Ktrans and specific clinical characteristics. RESULTS: In members of the DLB (vs HC) group, Ktrans values of cerebral cortex (p = 0.024), parietal lobe (p = 0.007), and occipital lobe (p = 0.014) were significantly higher; and Ktrans values of cerebral cortex (p = 0.041) and occipital lobe (p = 0.018) in the DLB group were significantly increased, relative to those of the AD group. All participants also showed increased Ktrans values of parietal ( ß  = 0.391; p = 0.001) and occipital ( ß  = 0.357; p = 0.002) lobes that were significantly associated with higher scores of the Clinical Dementia Rating, once adjusted for age and sex. Similarly, increased Ktrans values of cerebral cortex ( ß  = 0.285; p = 0.015), frontal lobe ( ß  = 0.237; p = 0.043), and parietal lobe ( ß = 0.265; p = 0.024) were significantly linked to higher plasma Aß1-42/Aß1-40 ratios, after above adjustments. CONCLUSION: BBB leakage is a common feature of DLB and possibly is even more severe than in the setting of AD for certain regions of the brain. BBB leakage appears to correlate with plasma Aß1-42/Aß1-40 ratio and dementia severity.

The exciton dynamics and charge transfer in polymers with the effects of chlorine substituents.

Donor-acceptor (D-A) type conjugated polymers, particularly those with electron-withdrawing halogen substituents, have demonstrated high efficiency as donor materials in solar energy conversion. In our previous work, we have successfully synthesized three low-cost D-A type conjugated polymers (designated as PJ-1, PJ-2, and PJ-3) through a gradual chlorination process, of which, devices based on PJ-1 exhibited exceptional power conversion efficiency (15.01%) and figure-of-merit values (45.48). In this study, we further investigated the excited-state dynamics of the three donor polymers by transient absorption spectroscopy to explore the dynamic reasons behind the high power conversion efficiency of PJ-1. Our findings revealed that PJ-1 exhibited pronounced aggregation, which facilitated intermolecular interactions, thereby enhancing charge transport capability and suppressing trap-assisted recombination. Furthermore, the PJ-1-based heterojunction presented efficient exciton dissociation and enhanced hole transfer efficiency. These results underscore the potential of chlorine substitution in improving exciton dissociation and charge transfer via regulating aggregation behavior and energy level, offering a straightforward and effective approach to engineer high-performance conjugated polymer donor materials for photovoltaic applications.

Insulin-like growth factor-2 mRNA-binding protein 2 facilitates post-ischemic angiogenesis by increasing the stability of fibroblast growth factor 2 mRNA and its protein expression.

Background: Post-ischemic angiogenesis is crucial for reestablishing blood flow in conditions such as peripheral artery disease (PAD). The role of insulin-like growth factor-2 mRNA-binding protein 2 (IGF2BP2) in post-transcriptional RNA metabolism and its involvement in post-ischemic angiogenesis remains unclear. Methods: Using a human GEO database and a hind-limb ischemia (HLI) mouse model, the predominant isoform IGF2BP2 in ischemic gastrocnemius tissue was identified. Adeno-associated virus with the Tie1 promoter induced IGF2BP2 overexpression in the HLI model, evaluating the expression of vascular structural proteins (CD31 and α-SMA) and blood flow recovery after HLI. In vitro experiments with human umbilical vein endothelial cells (HUVECs) demonstrated that lentivirus-mediated IGF2BP2 overexpression upregulates cell proliferation, migration, and tube formation. GeneCards, RNAct databases, and subsequent reverse transcription quantitative polymerase chain reaction (RT-qPCR) predicted IGF2BP2 interactions with fibroblast growth factor 2 (FGF2) mRNA, and actinomycin D treatment, binding site predictions and CLIP-seq data further confirmed this interaction. Furthermore, western blotting, enzyme-linked immunosorbent assay, and RNA immunoprecipitation followed by RT-qPCR were performed to validate IGF2BP2's interaction with FGF2 mRNA and to assess its role in stabilizing FGF2 mRNA, as well as its impact on FGF2 protein expression. Results: HLI reduced IGF2BP2 expression in the gastrocnemius tissue, which gradually increased during blood flow recovery. IGF2BP2 overexpression in HLI mice accelerated blood flow recovery and increased capillary and small artery densities. The overexpression of IGF2BP2 in HUVECs stimulated proliferation, migration, and tube formation by interacting with FGF2 mRNA to increase its stability. This interaction resulted in increased levels of FGF2 protein and secretion, ultimately promoting angiogenesis. Conclusions: IGF2BP2 contributes to blood flow restoration post-ischemia in vivo and promotes angiogenesis in HUVECs by enhancing FGF2 mRNA stability and FGF2 protein expression and secretion. These findings underscore IGF2BP2's therapeutic potential in ischemic conditions, such as PAD.

A platelet-related signature for predicting the prognosis and immunotherapy benefit in bladder cancer based on machine learning combinations.

Background: Bladder cancer carries a large societal burden, with over 570,000 newly diagnosed cases and 210,000 deaths globally each year. Platelets play vital functions in tumor progression and therapy benefits. We aimed to construct a platelet-related signature (PRS) for the clinical outcome of bladder cancer cases. Methods: Ten machine learning techniques were used in the integrative operations to build PRS using the datasets from The Cancer Genome Atlas (TCGA), gene series expression (GSE)13507, GSE31684, GSE32894 and GSE48276. A number of immunotherapy datasets and prediction scores, including GSE91061, GSE78220, and IMvigor210, were utilized to assess how well the PRS predicted the benefit of immunotherapy. Vitro experiment was performed to verify the role of α1C-tubulin (TUBA1C) in bladder cancer. Results: Enet (alpha =0.4) algorithm-based PRS had the highest average C-index of 0.73 and it was suggested as the optimal PRS. PRS acted as an independent risk factor for bladder cancer and patients with high PRS score portended a worse overall survival rate, with the area under the curve of 1-, 3- and 5-year operating characteristic curve being 0.754, 0.779 and 0.806 in TCGA dataset. A higher level of immune-activated cells, cytolytic function and T cell co-stimulation was found in the low PRS score group. Low PRS score demonstrated a higher tumor mutation burden score and programmed cell death protein 1 & cytotoxic T-lymphocyte associated protein 4 immunophenoscore, lower tumor immune dysfunction and exclusion score, intratumor heterogeneity score and immune escape score in bladder cancer, suggesting the PRS as an indicator for predicting immunotherapy benefits. Vitro experiment showed that TUBA1C was upregulated in bladder cancer and knockdown of TUBA1C obviously suppressed tumor cell proliferation. Conclusions: The present study developed an ideal PRS for bladder cancer, which may be used as a predictor of prognosis, a risk classification system, and a therapy guide.

Machine learning-based analysis of Ebola virus' impact on gene expression in nonhuman primates.

Introduction: This study introduces the Supervised Magnitude-Altitude Scoring (SMAS) methodology, a novel machine learning-based approach for analyzing gene expression data from non-human primates (NHPs) infected with Ebola virus (EBOV). By focusing on host-pathogen interactions, this research aims to enhance the understanding and identification of critical biomarkers for Ebola infection. Methods: We utilized a comprehensive dataset of NanoString gene expression profiles from Ebola-infected NHPs. The SMAS system combines gene selection based on both statistical significance and expression changes. Employing linear classifiers such as logistic regression, the method facilitates precise differentiation between RT-qPCR positive and negative NHP samples. Results: The application of SMAS led to the identification of IFI6 and IFI27 as key biomarkers, which demonstrated perfect predictive performance with 100% accuracy and optimal Area Under the Curve (AUC) metrics in classifying various stages of Ebola infection. Additionally, genes including MX1, OAS1, and ISG15 were significantly upregulated, underscoring their vital roles in the immune response to EBOV. Discussion: Gene Ontology (GO) analysis further elucidated the involvement of these genes in critical biological processes and immune response pathways, reinforcing their significance in Ebola pathogenesis. Our findings highlight the efficacy of the SMAS methodology in revealing complex genetic interactions and response mechanisms, which are essential for advancing the development of diagnostic tools and therapeutic strategies. Conclusion: This study provides valuable insights into EBOV pathogenesis, demonstrating the potential of SMAS to enhance the precision of diagnostics and interventions for Ebola and other viral infections.

Constructing Multiscale Fibrous Morphology to Achieve 20% Efficiency Organic Solar Cells by Mixing High and Low Molecular Weight D18.

This study underscores the significance of precisely manipulating the morphology of the active layer in organic solar cells (OSCs). By blending polymer donors of D18 with varying molecular weights, a multiscale interpenetrating fiber network structure within the active layer is successfully created. The introduction of 10% low molecular weight D18 (LW-D18) into high molecular weight D18 (HW-D18) produces MIX-D18, which exhibits an extended exciton diffusion distance and orderly molecular stacking. Devices utilizing MIX-D18 demonstrate superior electron and hole transport, improves exciton dissociation, enhances charge collection efficiency, and reduces trap-assisted recombination compared to the other two materials. Through the use of the nonfullerene acceptor L8-BO, a remarkable power conversion efficiency (PCE) of 20.0% is achieved. This methodology, which integrates the favorable attributes of high and low molecular weight polymers, opens a new avenue for enhancing the performance of OSCs.

Fabrication and Temporal Dependency Osteogenic Regulation of Dual-Scale Hierarchical Microstructures on Medical Metal Surface.

The structural characteristics at the interface of bone implants can guide biological regulation. In this study, a dual-scale hierarchical microstructure is proposed and customized using hybrid machining to achieve temporal dependency osteogenic regulation. It is observed that osteoblasts induced by dual-scale hierarchical structure exhibit adequate protrusion development and rapid cell attachment through the modulation of mechanical forces in the cell growth environment, and further promot the upregulation of the cell membrane receptor PDGFR-α, which is related to cell proliferation. Afterward, transcriptomic analysis reveals that during the differentiation stage, the DSH structure regulates cellular signaling cascades primarily through integrin adhesion mechanisms and then accelerates osteogenic differentiation by activating the TGF-ß pathway and cAMP signaling pathway. Furthermore, the calcium nodules are preferentially deposited within the lower honeycomb-like channels, thereby endowing the proposed dual-scale hierarchical structure with the potential to induce oriented deposition and improve the long-term stability of the implant.

Fatigue life prediction of cracked cross beam of mining linear vibrating screen under cyclic load.

The cross beam of a mining linear vibrating screen is prone to cracking under long-term cyclic load. In order to accurately predict the fatigue life of the cracked cross beam, a coupled analysis method of vibration and crack propagation is proposed. A 2D dynamic model of the vibrating screen is established based on the finite element method, which is verified by the vibration test platform. The cracked Euler beam element is used to model the cracked cross beam. The effects of crack depth, amplitude of excitation force, frequency of excitation force, and crack location on the crack-tip stress intensity factor of the cracked cross beam are investigated in detail. In addition, an iterative method is proposed on the basis of the Paris model. The residual service life of the beam under different frequencies of excitation force, amplitudes of excitation force, spring stiffness, crack positions, and degrees of stiffness imbalance are discussed. The results demonstrate that the fatigue life of the beam increases as the frequency of excitation force and spring stiffness increase. The increase of the amplitude of excitation force and spring permanent deformation reduces the fatigue life. The conclusion obtained provide some theoretical guidance for the design and routine maintenance of mining linear vibrating screens.

Temporal trends in prevalence of liver cancer and etiology-specific liver cancer from 1990 to 2019.

BACKGROUND: Liver cancer (LC) remains a major cause of cancer death worldwide. Grasping prevalence trends is key to informing strategies for control and prevention. We analyzed the global, regional and national trends in LC prevalence and its major causes from 1990 to 2019. METHODS: We obtained LC age-standardized prevalence rate (ASPR) estimates from the Global Burden of Disease study 2019 and assessed trends using Joinpoint regression. LC cases were categorized into those due to hepatitis B virus (HBV), hepatitis C virus (HCV), alcohol use, nonalcoholic steatohepatitis (NASH) and other causes. RESULTS: While the ASPR of LC has shown a global decrease, there are specific regions where an increase in ASPR has been observed, with the highest rates in America. HBV remained the leading cause of LC (41.45 %) but significant increases occurred for HCV, alcohol use and NASH. Prevalence correlated with socioeconomic development. High-income countries had higher LC rates from HCV and alcohol but lower HBV-related LC. In high-income nations, LC prevalence climbs; the converse holds in middle- and low-income countries. CONCLUSIONS: Despite a global ASPR decrease, LC due to HCV, NASH, and alcohol is rising. Prevention strategies must prioritize HBV vaccination, HCV treatment, and alcohol regulation. IMPACT: The study informs targeted LC control policies and emphasizes the importance of continued monitoring and regional cooperation to combat LC.

Dynamics of a cross beam with a straight crack in a mining linear vibrating screen.

Cross beam fracture is one of the common failures of vibrating screens, and crack is the early manifestation of fracture, which is hard to detect. In order to meet the screening requirement of the vibrating screen and improve the service life of the cracked beam, the cracked Euler-Bernoulli beam model is established to investigate the dynamics of the cross beam with a straight crack under different weights of eccentric block, processing capacities, and Rayleigh damping coefficients based on the finite element method in this paper. The local flexibility coefficients are derived from the principles of fracture mechanics and strain release energy and solved by the adaptive five-point Gaussian Legende algorithm. The stiffness matrix of the cracked beam element is calculated through the inverse method of total flexibility. The four order Runge-Kutta algorithm and MATLAB tools are used to solve the dynamic equation of the cracked cross beam. The relationship between the vibration amplitude of the cracked cross beam and the weight of the eccentric block is studied by fitting formulas using the least squares method. The influence of different weights of eccentric block, processing capacities, and Rayleigh damping coefficients on the vibration amplitude and service life of the cracked beam are discussed. The results show that the greater the weight of the eccentric block, the shorter service life of the beam. When the damping is greater, the service life of the cracked beam is longer.

Cu(II)/Base Synergistic Promoted [2 + 1 + 3] Cyclization of Cyclic Ketones with α,ß-Unsaturated Aldehydes/Ketones and NH4I to Access Fused Pyridines.

Herein, a practical three-component [2 + 1 + 3] cyclization of various cyclic ketones with α,ß-unsaturated aldehydes/ketones and ammonium iodide (NH4I) to access highly functional fused pyridines has been developed. The features of this transformation include mild reaction conditions, readily available starting materials, and excellent chemoselectivity. This protocol is compatible with various functional groups, and the preliminary studies on the mechanism of the reaction are also provided.

Effects of the comprehensive elimination of Spartina alterniflora along China's coast on blue carbon and scenario prediction after ecological restoration.

Salt marshes cover the largest area among the three types of traditional blue carbon ecosystems in China's coastal zone, with the introduced smooth cordgrass (Spartina alterniflora Loisel.) being dominant in these marshes. The effects of eradicating S. alterniflora nationwide and the subsequent ecological restoration on blue carbon are unclear. This paper evaluates the variation in blue carbon during the national S. alterniflora eradication campaign, which involves mechanical tillage from 2022 to 2025, and proposes three scenarios for blue carbon changes after native vegetation is reestablished by 2050. The results show that, in 2025, plant carbon stock and soil carbon stock will decrease by 1.38 Tg C and 1.21 Tg C, respectively, in the areas where S. alterniflora has been removed and managed. Although blue carbon is reduced in coastal wetlands in 2025, carbon stock is expected to increase in restored native vegetated wetlands by 2050. S. alterniflora is resilient and competitive, posing a high risk in secondary invasion. Scenario Ⅰ suggests that S. alterniflora marshes could almost recover to their original state from 2022, with 7.70 Tg C stored in plant and soil carbon stocks. Scenario Ⅱ involves native vegetated wetlands coexisting with invasive S. alterniflora marshlands, with a total carbon stock estimated at 7.15 Tg C, reflecting a decrease of 0.39 Tg C in soil carbon stock and by 0.16 Tg C in plant carbon stock. In Scenario Ⅲ, mudflats dominant and native vegetated habitats are reestablished only in suitable sites, with the total carbon stock estimated at 5.63 Tg C, a 26.9% decrease compared to 2022 levels. While eradicating invasive S. alterniflora and restoring native vegetation in China's coast enhance the ecosystem services, it reduces blue carbon stocks. Therefore, developing additional strategies to increase carbon storage in coastal wetlands is necessary.

Great truths are always simple: A millimeter-sized macroscopic lanthanum-calcium dual crosslinked carboxymethyl chitosan aerogel bead as a promising adsorbent for scavenging oxytetracycline from wastewater.

Given their increasing environmental and health harms, it is crucial to develop green and sustainable techniques for scavenging antibiotics represented by oxytetracycline (OTC) from wastewater. In the present work, a structurally simple lanthanum-calcium dual crosslinked carboxymethyl chitosan (CMCS-La3+-Ca2+) aerogel was innovatively synthesized for adsorptive removal of OTC. It was found that CMCS and La3+ sites collaboratively participated in OTC elimination, and OTC removal peaked over the wide pH range of 4-7. The process of OTC sorption was better described by the pseudo-second-order kinetic model and Redlich-Peterson model, and the saturated uptake amount toward OTC was up to 580.91 mg/g at 303 K, which was comparable to the bulk of previous records. The as-fabricated composite also exerted exceptional capture capacity toward OTC in consecutive adsorption-desorption runs and high-salinity wastewater. Amazingly, its packed column continuously ran for over 60 h with a dynamic uptake amount of 215.21 mg/g until the adsorption was saturated, illustrating its great potential in scale-up applications. Mechanism studies demonstrated that multifarious spatially-isolated reactive sites of CMCS-La3+-Ca2+ cooperatively involved in OTC capture via multi-mechanisms, such as n-π EDA interaction, H-bonding, La3+-complexation, and cation-π bonding. All the above superiorities endow it as a promising adsorbent for OTC-containing wastewater decontamination.

[Effects of Long-term Biochar Addition on Denitrification N2O Emissions from Bacteria and Fungi in Paddy Soil].

Denitrification driven by bacteria and fungi is the main source of nitrous oxide （N2O） emissions from paddy soil. It is generally believed that biochar reduces N2O emissions by influencing the bacterial denitrification process, but the relevant mechanism of its impact on fungal denitrification is still unclear. In this study, the long-term straw carbonization returning experimental field in Changshu Agricultural Ecological Experimental Base of the Chinese Academy of Sciences was taken as the object. Through indoor anaerobic culture and molecular biology technology, the relative contributions of bacteria and fungi to denitrifying N2O production in paddy soil and the related microorganism mechanism were studied under different long-term biochar application amounts （blank, 2.25 t·hm-2, and 22.5 t·hm-2, respectively, expressed by BC0, BC1, and BC10）. The results showed that compared with that in BC0, biochar treatment significantly reduced N2O emission rate, denitrification potential, and cumulative N2O emissions, and the contribution of bacterial denitrification was greater than that of fungal denitrification in all three treatments. Among them, the relative contribution rate of bacterial denitrification in BC10 （62.9%） was significantly increased compared to BC0 （50.8%）, whereas the relative contribution rate of fungal denitrification in BC10 （37.1%） was significantly lower than that in BC0 （49.2%）. The application of biochar significantly increased the abundance of bacterial denitrification functional genes （nirK, nirS, and nosZ） but reduced the abundance of fungal nirK genes. The contribution rate of fungal denitrification was significantly positively correlated with the N2O emission rate and negatively correlated with soil pH, TN, SOM, and DOC. Biochar may have inhibited the growth of denitrifying fungi by increasing pH and carbon and nitrogen content, reducing the abundance of related functional genes, thereby weakening the reduction ability of NO to N2O during fungal denitrification process. This significantly reduces the contribution rate of N2O production during the fungal denitrification process and the denitrification N2O emissions from paddy soil. This study helps to broaden our understanding of the denitrification process in paddy soil and provides a theoretical basis for further regulating fungal denitrification N2O emissions.