Enhanced Circular Dichroism for Achiral Sensing Based on a DNA-Origami-Empowered Anapole Metasurface.

Circular dichroism (CD) spectroscopy has been extensively utilized for detecting and distinguishing the chirality of diverse substances and structures. However, CD spectroscopy is inherently weak and conventionally associated with chiral sensing, thus constraining its range of applications. Here, we report a DNA-origami-empowered metasurface sensing platform through the collaborative effect of metasurfaces and DNA origami, enabling achiral/slightly chiral sensing with high sensitivity via the enhanced ΔCD. An anapole metasurface, boasting over 60 times the average optical chirality enhancement, was elaborately designed to synergize with reconfigurable DNA origami. We experimentally demonstrated the detection of achiral/slightly chiral DNA linker strands via the enhanced ΔCD of the proposed platform, whose sensitivity was a 10-fold enhancement compared with the platform without metasurfaces. Our work presents a high-sensitivity platform for achiral/slightly chiral sensing through chiral spectroscopy, expanding the capabilities of chiral spectroscopy and inspiring the integration of multifunctional artificial nanostructures across diverse domains.

Association between the use of statins and in-hospital mortality risk in patients with sepsis-induced coagulopathy during ICU stays: a study based on medical information mart for intensive care database.

BACKGROUND: The objective of this study was to explore the correlation between statin administration in the intensive care unit (ICU) setting and the in-hospital mortality risk of patients suffering from sepsis-induced coagulopathy (SIC). METHODS: Utilizing a retrospective cohort study design, this investigation collected data from the Medical Information Mart for Intensive Care (MIMIC)-IV spanning 2008 to 2019. The diagnosis of SIC was established based on a SIC score of 4 or above. Statin usage during the ICU period was extracted from the prescription records based on the keywords of statin medications. The primary endpoint analyzed was the in-hospital mortality within the ICU, characterized by any death occurring during the ICU admission. RESULTS: During the follow-up, which had a median duration of approximately 7.28 days, 18.19% of the 4,777 SIC patients died in the ICU. Statin was linked with a decrease in the risk of in-hospital mortality for SIC patients in the ICU [hazard ratio (HR): 0.73, 95% confidence interval (CI): 0.60-0.89, P = 0.002]. Relative to rosuvastatin, the use of atorvastatin (HR: 0.54, 95% CI: 0.34-0.85, P = 0.008) or simvastatin (HR: 0.55, 95% CI: 0.33-0.92, P = 0.024), as well as combinations of multiple statins (HR: 0.36, 95% CI: 0.15-0.86, P = 0.022), was associated with a reduction in ICU in-hospital mortality risk. Subgroup analysis also suggested that the use of atorvastatin, simvastatin, or a combination of statins had an advantage over rosuvastatin in reducing ICU in-hospital mortality in SIC patients older than 65 years of age or SIC patients with respiratory failure or cardiogenic shock (all P < 0.05). CONCLUSION: The present study supports the potential benefits of statin use in mortality in SIC patients during ICU stays. The study encourages clinicians to consider the benefits of statins and supports the ongoing exploration of statins for enhanced outcomes in critical care settings.

Amorphous hollow manganese silicate nanosphere oxidase mimic for ultrasensitive and high-reliable colorimetric detection of biothiols.

Metal-based nanozymes with exceptional physicochemical property and intrinsic enzymatic properties have been widely used in industrial, medical, and diagnostic fields. However, low substrate affinity results in unsatisfying catalytic kinetic and instability in complicated conditions, which significantly decreases their sensitivity and reliability. Herein, an amorphous hollow manganese silicate nanosphere (defined as AHMS) has been successfully synthesized via a facile one-step hydrothermal method and utilized in the archetype for colorimetric detection of biothiols with high sensitivity and high reliability. The experimental data demonstrates that ultrafast affinity of the substrate contributes to enhanced sensitivity with outstanding catalytic kinetic features (Km = 27.1 µM) and low limit of detection (LODGSH = 20 nM). The designed sensor demonstrates a reliable applicability for analysis of biological liquids (fetal calf serum and Staphylococcus aureus) and design of visual logic gates. Therefore, AHMS provides a promising strategy for ultrasensitive and high-reliable biosensing.

Clinical Application of CAD/CAM-Guided Modified Dautrey's Procedure in Recurrent Temporomandibular Joint Luxation.

This study aimed to introduce the clinical application of the CAD/CAM-guided modified Dautrey's procedure in recurrent anterior temporomandibular joint luxation and evaluate its clinical effects. Four selected patients were treated by the CAD/CAM-guided modified Dautrey's procedure and were followed-up to access their curative effect. Joint pain and sound, recurrence rate, mandibular function, maximum mouth opening (MMO), symptoms of facial nerve injury, and changes in zygomatic facial appearance were observed in postoperative follow-up. The followed-up period ranged from 3 months to 1 year with an average time of 7.5 months. There was no recurrence in all 4 patients, and no symptoms of facial nerve injury and zygomaticofacial appearance changes were found. All patients showed improvement in MMO, with a mean preoperative and postoperative MMO of 4.74 and 3.74 cm, respectively. All of them showed relief of joint pain or sound 3 months or more after the operation and could exercise mandibular normally. This results showed that the CAD/CAM-guided modified Dautrey's procedure was effective in the treatment of recurrent temporomandibular joint luxation and could be used as a good alternative treatment for it.

The performance of OPC water model in prediction of the phase equilibria of methane hydrate.

Molecular dynamics (MD) simulations were performed to determine the three-phase coexistence line of sI methane hydrates. The MD simulations were carried out at four different pressures (4, 10, 40, and 100 MPa) by using the direct phase coexistence method. In current simulations, water was described by either TIP4P/Ice or "optimal" point charge (OPC) models and methane was described as a simple Lennard-Jones interaction site. Lorentz-Berthelot (LB) combining rules were used to calculate the parameters of the cross interactions. For the OPC model, positive deviations from the energetic LB rule were also considered based on the solubility of methane in water. For the TIP4P/Ice water model, the obtained three phase coexistence temperatures showed good agreement with experiment data at higher pressures, which is consistent with previous predictions. For the OPC water model, simulations using the classic and the modified LB parameters both showed negative deviations to the experimental values. Our results also indicated that the deviation of the T3 prediction by the OPC model was not closely correlated with the predicted melting point of ice. At 4 MPa, the modified OPC model showed a better prediction of hydrate equilibrium temperature, even better than the prediction by TIP4P/Ice. Considering the relatively higher accuracy in biomolecular MD of the OPC model, it is suggested that this model may have a better performance in hydrate MD simulations of biomolecule-based additives.

Increased photoluminescence and photodynamic therapy efficiency of hydroxyapatite-ß-cyclodextrin-methylene blue@carbon powders with the favor of hydrogen bonding effect.

To meet the requirements of theranostics with diagnosis and treatment, photodynamic-based therapy is simultaneously enabled with the incorporation of methylene blue (MB) as imaging agent and photosensitizer in core-shell structured drug vehicles. Citrate-modified hydroxyapatite (HAp) powders are first grafted with ß-cyclodextrin (CD), then combined with MB molecules through electrostatic interactions, and finally encapsulated with carbon shells through hydro-thermal carbonization of glucose to prepare HAp-CD-MB@C powders. Processing parameters of carbonization temperature, glucose addition, reaction time and CD addition are varied to prepare drug carriers with modulated crystallite degrees and photo-physical properties. Increased crystallite sizes of HAp are accompanied with the formation of C=O, C=C and C-OH groups in carbon shell, endowing sustainable release behaviors of MB through carbonous structures. High photoluminescence intensities are fairly related with red-shifted vibration peaks of groups in tightly combined MB molecules through hydrogen bonds. This hydrogen bonding effect is significantly increased for HAp-CD-MB@C140 with the splitting of CH3-involved vibration peaks in infrared spectra, which causes increase in photoluminescence intensity and four-fold increase in generation ratio of singlet oxygen. The present studies shed light on preparation of core-shell structured drug carriers, modulation of aggregate states of MB molecules, enhancement of photo-physical properties and improvement of generation ratio of singlet oxygen during photodynamic-based therapy.

Higher erythrocyte n-3 polyunsaturated fatty acid were associated with a better profile of DXA-derived body fat and fat distribution in adults.

BACKGROUND: Previous studies have reported that high-dose supplementation of n-3 polyunsaturated fatty acids (PUFAs) may reduce the risk of metabolic diseases, but there is limited evidence of an effect on body fat. We examined the associations of erythrocyte n-3 PUFAs with body fat and fat distribution in a general population consuming a normal diet. METHODS: This community-based cross-sectional study included 3075 Chinese (68% women, 40-75 years) recruited between 2008 and 2013. We collected general information and measured anthropometric indices; erythrocyte n-3 PUFAs (including α-C18:3, C20:5, C22:5 and C22:6) by gas-chromatography, and fat mass (FM) and %FM at the total body (TB), android (A) and gynoid (G) regions by dual-energy X-ray absorptiometry (DXA). RESULTS: Both minimally and maximally adjusted models showed dose-dependent inverse associations of total and individual levels of erythrocyte n-3 PUFAs (except C20:5 n-3[EPA]) with adiposity indices. In the full model, the mean differences between quartiles 4 and 1 of total n-3 PUFAs were -1.60% (BMI), -4.06% (TB FM), -5.38% (A FM), -2.05% (G FM), -2.05% (TB %FM), -3.39% (A %FM) and -2.50% (% A/G); the ORs (95% CI) of %FM-derived obesity (≥25% for men, ≥35% for women) for the highest (vs. lowest) quartile were 0.70 (0.57, 0.86) for total n-3 PUFAs and 0.71 (0.58, 0.87), 0.96(0.78, 1.18), 0.82(0.67, 1.00), 0.66 (0.54, 0.81) for α-C18:3/C20:5/C22:5/C22:6 n-3, respectively. The favourable associations were more pronounced for the DXA-derived FM indices, measurements at the android region and for C22:6 n-3. No significant associations between C20:5 n-3 and the adiposity indices were observed. CONCLUSIONS: Higher levels of circulating n-3 PUFAs were dose-dependently associated with better profiles of body fat and fat distribution, particularly in the abdominal regions in this population.

[Treatment of rheumatoid arthritis with flavonoids of Echinps latifolius Tausch in rat model].

OBJECTIVE: To investigate the effect of Flavonoids extracted from Echinps latifolius Tausch(FELT) on rheumatoid arthritis (RA) in rat model. METHOD: Fifty SD rats were randomly divided into model group, control group, and low, medium, and high-dose FELT groups (n=10 in each group). Complete Freund's adjuvant (0.1 mL) was used to induce RA in rats. FELT in doses of 50 mg/kg, 100 mg/kg, 150 mg/kg was given to rats in low, medium and high-dose FELT groups by gavage, and same volume of PBS was given to rats in control group. The arthritis score and the paw swelling score were measured to evaluate the therapeutic effect of FELT. Real time qPCR was used to detect the mRNA expression of fibronectin and MMP3 in synovial tissue and the mRNA expression of caspase 3, Bcl-2 and Bcl-2 associated X protein (Bax) in fibroblast-like synoviocytes (FLS). RESULTS: The arthritis score and the paw swelling score were significantly decreased in three FELT groups compared to RA model rats (P <0.05). The relative expression levels of FN and MMP3 mRNA in synovium of three FELT-treatment groups were significantly lower than those in model group (1.80, 1.76 and 1.67 vs 2.53; 1.69, 1.46 and 1.45 vs 2.67, respectively, all P <0.05). The relative expression levels of Bax and caspase 3 mRNA in FLSs of three FELT groups were higher than those in model group (0.56, 0.58 and 0.60 vs 0.30; 0.54, 0.56 and 0.59 vs 0.29, respectively, all P <0.05); while the relative expression levels of Bcl-2 mRNA in FELT groups were lower than that in model group (2.20, 2.08 and 2.08 vs 4.04, respectively, P <0.05). CONCLUSION: FELT may inhibit the synovium proliferation in RA model rats through promoting the FLS apoptosis.

[Effect of Phellinus Polysaccharide on Canonical Wnt Signaling in Synovium in Rats with Rheumatoid Arthritis].

OBJECTIVE: To investigate the role of Phellinus Polysaccharide (FPS) in activating canonical Wnt signaling in rats with rheumatoid arthritis (RA). METHODS: Male SD rats were randomly divided into three groups (normal group, RA model group and PPS treated RA group), each with 10 rats. The RA model rats were prepared through intradermal injection of 0. 1 mL complete Freund's adjuvant into the right rear toes of the rats. The PPS treated RA rats were given 50 mg/kg PPS by gavage eight days after the introduction of RA. All rats were evaluated with arthritis score and paw swelling score at day 16, 20, 24, 28, 32. At day 28, the expressions of fibronectin gene, Wnt signal pathway negative regulation gene SFRP1,2 and Wnt key gene ß-catenin, C-myc, and ccndl were detected by real time qPCR. RESULTS: PPS significantly reduced the arthritis score and paw swelling score of RA model rats. Lower levels of expression of SFRP1, 2 and higher levels of expression of ß-catenin, C-myc, ccndl and fibronectin were found in the RA model rats compared with the normal controls. PPS increased the expression of SFRP1, 2 and decreased the expression of ß-catenin, C-myc, ccndl and fibronectin in the RA rats. CONCLUSION: PPS has significant therapeutic effect on RA model rats through inhibiting canonical Wnt signaling.

[Effect of pulchinenoside on FZD8 expression of adjuvant arthritis rats].

To study the effect of pulchinenoside (PULC) on the Frizzled (FZD) expression of adjuvant arthritis ( AA) rats. AA rats were prepared through the toe injection with complete Freund's adjuvant to culture fibroblast-like synoviocytes (FLS). The effect of the oral administration with PULC on the FZD8 expression was detected by the real time qPCR. The effect of FZD8 knockout on the expressions of IL-1, IL-6, IL-8 were detected by MTT and ELISA. The role of miR-375 in the abnomal expression of FZD8 was detected by the real time qPCR. The results showed signfiicant decrease in the FZD8 expression among AA rats, FLS proliferation ater FZD8 knockout and IL-1, IL-6, IL-8 expressions and notable increase in miR-375 expression after the oral administration with PULC. The up-regulated miR-375 expression can inhibit the FZD8 expression. PULC may inhibit the FZD8 expression by up-regulating the miR-375 expression.

[Flavonoids of Echinps latifolius suppress Wnt signaling in adjuvant arthritis rats].

The role of flavonoids of Echinps latifolius (FELT) in Wnt signaling was investigated in adjuvant arthritis (AA) rats. The therapeutic effects of FELT on AA rats were detected by rat arthritis score and MTT. The effect of FELT gavage treatment on the Wnt signaling key gene ß-catenin, C-myc and cyclin D1 in synovium from AA rats was detected by Real-time qPCR, and the effects of FELT gavage treatment on the upstream negative regulation gene SFRP 1,2,4,5 in synovium from AA rats were detected by Real-time qPCR. The results showed that FELT gavage treatment significantly inhibited arthritis score and MTT values in AA rats, significantly inhibited the expression of the Wnt signaling gene ß-catenin, C-myc and cyclin D1, significantly up-regulated the expression of the up- stream negative regulation gene SFRP 1,2,4. FELT has a better therapeutic effect for AA rats.

[Pulchinenoside inhibits the fibroblast-like synoviocytes apoptosis in adjuvant arthritis rats].

OBJECTIVE: To explore the eff ect of pulchinenoside (PULC) on fi broblast-like synoviocytes (FLS) apoptosis in adjuvant arthritis (AA) rats. METHODS: A total of 60 SD rats were randomly divided into 8 groups: A normal control group, an AA group, a low PULC group (50 mg/kg), a middle PULC group (100 mg/kg) or a high PULC group (150 mg/kg) and an ibuprofen (8 mg/kg) group (n=10 per group). FLS from the AA rats was cultured. The expression of Bcl-2, Bax, caspase-3 and the FLS proliferation were detected by the real time qPCR and MTT, respectively. The expression of IL-6 and IL-8 in culture medium was detected by ELISA. RESULTS: Compared with the AA group, the Bcl-2 expression was down-regulated (all P<0.05), the Bax and caspase-3 expression was up-regulated (all P<0.05), and the FLS proliferation was inhibited (all P<0.05). The IL-6 and IL-8 expression was suppressed in the FLS in the PULC groups at different dosages (all P<0.05) as well as in the ibuprofen group (P<0.05). CONCLUSION: PULC may inhibit the FLS proliferation in AA rats by increase in FLS apoptosis.

[Pulchinenoside control MeCP2 expression in FLS from RA model rats].

The role of pulchinenoside (PULC) in the regulation of MeCP2 expression was investigated in RA model rats. Adjuvant arthritis rats were used as RA model rats, and fibroblast-like synoviocytes (FLS) from the RA model rats were cultured. The effect of 100 mg x kg(-1) PULC gavage treatment on the MeCP2 expression and the effect of MeCP2 siRNA on the expression of SFRP2 and ß-catenin were detected by real time qPCR and Western blotting. The role of PULC in the FLS proliferation was detected by MTT. The results showed that the MeCP2 expression was down-regulated, the SFRP2 expression was up-regulated and the FLS proliferation was inhibited in FLS after therapy. MeCP2 siRNA significantly inhibited the MeCP2 expression, up-regulated the SFRP2 expression and inhibited the ß-catenin expression in FLS from RA model rats. PULC may increase the SFRP2 expression, inhibit the Wnt signaling and inhibit the FLS proliferation in FLS from the RA model rats by inhibiting the MeCP2 expression.

A multi-orientation system for characterizing microstructure changes and mechanical responses of fine-grained gassy sediments associated with gas hydrates.

Fine-grained marine sediments containing veiny and nodular gas hydrates will evolve into fine-grained gassy sediments after hydrate dissociation due to climate-driven ocean warming. The mechanical properties of the fine-grained gassy sediments are basically acquired by ocean engineering design. However, they have not been fully understood, largely due to the lack of microstructure visualization. In this paper, a new system is developed to jointly conduct x-ray computed tomography scans, oedometer tests, and seismic wave testing on a single specimen with temperature being well controlled, allowing varieties of experimental data to be acquired effectively and automatically. The results show that stress history can hardly affect the undrained stiffness of fine-grained gassy sediments, while the drained stiffness of fine-grained sediments without gas bubbles is stress history dependent. After being unloaded, many microstructure changes remain, and examples include the free gas distribution being more concentrated and the connectivity among gas bubbles becoming much better. The multi-orientation system lays the foundation for further studies on the microstructure changes and mechanical responses of fine-grained gassy sediments associated with gas hydrates.

Gubra Amylin-NASH Diet Induced Nonalcoholic Fatty Liver Disease Associated with Histological Damage, Oxidative Stress, Immune Disorders, Gut Microbiota, and Its Metabolic Dysbiosis in Colon.

SCOPE: The overall changes of colon under nonalcoholic fatty liver disease (NAFLD) remain to be further elucidated. METHODS AND RESULTS: This study establishes a mouse model of NAFLD through a long-term Gubra Amylin-nonalcoholic steatohepatitis (NASH) diet (GAN diet). The results show that GAN diet significantly induces weight gain, liver steatosis, colonic oxidative stress, and lipid accumulation in blood, liver, and adipose tissue in mice. GAN feeding reduces the diversity of the gut microbiota, alters the composition and abundance of the gut microbiota, and leads to an increase in microbial metabolites such as long-chain fatty acids (LCFAs) and secondary bile acids (BAs), as well as a decrease in short-chain fatty acids (SCFAs). The RNA-seq and immunofluorescence results reveal that the GAN diet alters the expression of proteins and their coding genes involved in oxidative stress, immune response, and barrier function in colon tissue, such as lipocalin-2 (Lcn2, p < 0.05), heme oxygenase-1 (HO-1/Hmox1, p < 0.05), interferon-gamma (IFN-γ), and claudin-3/7. In addition, correlation analysis indicates a strong correlation between the changes in gut microbiota and lipid biomarkers. Additionally, the expression of immune related genes in colon tissue is related to the LCFAs produced by microbial metabolism. CONCLUSION: GAN-induced NAFLD is related to microbiota and its metabolic imbalance, oxidative stress, immune disorders, and impaired barrier function in colon.

Chicken Hypothalamic and Ovarian DNA Methylome Alteration in Response to Forced Molting.

Epigenetic modifications play an important role in regulating animal adaptation to external stress. To explore how DNA methylation regulates the expression levels of related genes during forced molting (FM) of laying hens, the hypothalamus and ovary tissues were analyzed at five periods using Whole-Genome Bisulfite Sequencing. The results show that methylation levels fluctuated differently in the exon, intron, 5'UTR, 3'UTR, promoter, and intergenic regions of the genome during FM. In addition, 16 differentially methylated genes (DMGs) regulating cell aging, immunity, and development were identified in the two reversible processes of starvation and redevelopment during FM. Comparing DMGs with differentially expressed genes (DEGs) obtained in the same periods, five hypermethylated DMGs (DSTYK, NKTR, SMOC1, SCAMP3, and ATOH8) that inhibited the expression of DEGs were found. Therefore, DMGs epigenetically modify the DEGs during the FM process of chickens, leading to the rapid closure and restart of their reproductive function and a re-increase in the egg-laying rate. Therefore, this study further confirmed that epigenetic modifications could regulate gene expression during FM and provides theoretical support for the subsequent optimization of FM technology.

Molecular Dynamics Simulation of the Three-Phase Equilibrium Line of CO2 Hydrate with OPC Water Model.

The three-phase coexistence line of the CO2 hydrate was determined using molecular dynamics (MD) simulations. By using the classical and modified Lorentz-Berthelot (LB) parameters, the simulations were carried out at 10 different pressures from 3 to 500 MPa. For the OPC water model, simulations with the classic and the modified LB parameters both showed negative deviations from the experimental values. For the TIP4P/Ice water model, good agreement with experimental equilibrium data can be achieved when the LB parameter is adjusted based on the solubility of CO2 in water. Our results also show that the influence of the water model on the equilibrium prediction is much larger than the CO2 model. Current simulations indicated that the H2O-H2O and H2O-CO2 cross-interactions' parameters might contribute equally to the accurate prediction of T3. According to our simulations, the prediction of T3 values showed relatively higher accuracy while using the combination of TIP4P/Ice water and EPM2 CO2 with modified LB parameter. Furthermore, varied χ values are recommended for accurate T3 estimation over a wide pressure range. The knowledge obtained in this study will be helpful for further accurate MD simulation of the process of CO2/CH4 replacement.

Dietary supplementation of coated sodium butyrate improves growth performance of laying ducks by regulating intestinal health and immunological performance.

Introduction: This study was conducted to assess the effects of dietary supplementation of coated sodium butyrate (CSB) on the growth performance, serum antioxidant, immune performance, and intestinal microbiota of laying ducks. Methods: A total of 120 48-week-old laying ducks were randomly divided into 2 treatment groups: the control group (group C fed a basal diet) and the CSB-treated group (group CSB fed the basal diet + 250 g/t of CSB). Each treatment consisted of 6 replicates, with 10 ducks per replicate, and the trial was conducted for 60 days. Results: Compared with the group C, the group CSB showed a significant increase in the laying rate (p<0.05) of the 53-56 week-old ducks. Additionally, the serum total antioxidant capacity, superoxide dismutase activity and immunoglobulin G level were significantly higher (p<0.05), while the serum malondialdehyde content and tumor necrosis factor (TNF)-a level were significantly lower (p<0.05) in the serum of the group CSB compared to the group C. Moreover, the expression of IL-1b and TNF-a in the spleen of the group CSB was significantly lower (p<0.05) compared to that of the group C. In addition, compared with the group C, the expression of Occludin in the ileum and the villus height in the jejunum were significantly higher in the group CSB (p<0.05). Furthermore, Chao1, Shannon, and Pielou-e indices were higher in the group CSB compared to the group C (p<0.05). The abundance of Bacteroidetes in the group CSB was lower than that in the group C (p<0.05), while the abundances of Firmicutes and Actinobacteria were higher in the group CSB compared to the group C (p<0.05). Conclusions: Our results suggest that the dietary supplementation of CSB can alleviate egg-laying stress in laying ducks by enhancing immunity and maintaining the intestinal health of the ducks.

Association of residual feed intake with intestinal microbiome and metabolome in laying period of ducks.

Introduction: Residual feed intake (RFI) is a indicator to evaluate animal feed. This experiment was explored to study the relationship between intestinal microbiome and metabolome of ducks with different residual feed intake during laying period. Methods: A total of 300 Shaoxing ducks aged 42 weeks were randomly selected and fed a diet of 60 d. At the end of the trial, 20 samples were selected according to the phenotype of RFI and divided into two groups (HRFI and LRFI). The cecal microbiota composition was explored by 16S ribosomal RNA gene sequencing and rectal metabolomics uses liquid chromatography-mass spectrometry (LC-MS) to identify the composition of metabolites in a non-targeted manner. Results: Results show feed intake and feed conversion ratio in the group HRFI were significantly higher than those in the group LRFI (p < 0.05). Chao1 indices were higher in the group LRFI than in the HRFI (p < 0.05), Shannon and Simpson indices were higher in the group LRFI than in the HRFI (p < 0.01). After linear discriminant analysis effect size (p < 0.05, LDA score > 3), Rikenellaceae, Rikenellaceae_RC9_gut_group, Lactobacillales and Ruminococcus_2, etc. were significantly enriched in the group LRFI at the genus level, while Prevotellaceae_NK3B31_group and Bacteria were significantly enriched in the group HRFI. After LC-MS analysis we found 338 metabolic difference products and 10 metabolic pathways, including the ABC transporter system, cysteine and methionine metabolism, arginine and proline metabolism, and vitamin B6 metabolism, were identified to be associated with the significantly differentially expressed between the groups LRFI and HRFI (p < 0.05). We hypothesize that the difference between ducks with different RFIs is mainly due to the fact that ducks with LRFI have more SCFAs-producing bacteria in their gut microorganisms, which regulate the RFI of animals. This process we found that Phascolarctobaterium and Anaerobiospirillum may provide energy for ABC transporter system by producing SCFAs, and regulate RFI to improve feed utilization efficiency. Discussion: These results revealed the relationship between microbiome and metabonomics in laying ducks with different RFI, and provided theoretical basis for further study on the relationship between them.