Low-dose M.tb infection but not BCG or MTBVAC vaccination enhances heterologous antibody titres in non-human primates.

Introduction: Mycobacteria are known to exert a range of heterologous effects on the immune system. The mycobacteria-based Freund's Complete Adjuvant is a potent non-specific stimulator of the immune response used in immunization protocols promoting antibody production, and Mycobacterium bovis Bacille Calmette Guérin (BCG) vaccination has been linked with decreased morbidity and mortality beyond the specific protection it provides against tuberculosis (TB) in some populations and age groups. The role of heterologous antibodies in this phenomenon, if any, remains unclear and under-studied. Methods: We set out to evaluate antibody responses to a range of unrelated pathogens following infection with Mycobacterium tuberculosis (M.tb) and vaccination with BCG or a candidate TB vaccine, MTBVAC, in non-human primates. Results: We demonstrate a significant increase in the titer of antibodies against SARS-CoV-2, cytomegalovirus, Epstein-Barr virus, tetanus toxoid, and respiratory syncytial virus antigens following low-dose aerosol infection with M.tb. The magnitude of some of these responses correlated with TB disease severity. However, vaccination with BCG administered by the intradermal, intravenous or aerosol routes, or intradermal delivery of MTBVAC, did not increase antibody responses against unrelated pathogens. Discussion: Our findings suggest that it is unlikely that heterologous antibodies contribute to the non-specific effects of these vaccines. The apparent dysregulation of B cell responses associated with TB disease warrants further investigation, with potential implications for risk of B cell cancers and novel therapeutic strategies.

Imaging study of coccygeal morphology in adolescent idiopathic scoliosis.

The correlation between scoliosis and sagittal curvature of the cervical, thoracic, and lumbar spine have already been reported in previous studies. However, as a part of the spine, the change in coccygeal morphology in AIS patients has not yet been studied. In this study, a retrospective analysis was performed on 400 patients who were divided into a non-scoliotic group (206 patients) and an AIS group (194 patients). The Postacchini coccygeal radiological classification that was modified by Nathan was used to observe and compare the sagittal coccygeal morphology between the two groups. The results showed that the non-scoliotic group had the highest percentage (52.4%) of patients with type I and the lowest (3.4%) proportion of patients with type V; moreover, the AIS group had the highest percentage (69.1%) of patients with type I and the lowest (1.5%) proportion of patients with type V. The coccygeal morphology was significantly different between the non-scoliotic group and the AIS group (P = 0.001). No significant differences in coccygeal morphology were found between the males and females in the two groups (mild and moderate scoliosis and different segmental scoliosis). In addition, a significant correlation between coccygeal morphology and scoliosis (P = 0.035) was found. In conclusion, coccygeal morphology significantly differs between AIS patients and non-scoliotic adolescents. There was a smaller proportion of patients with a type I coccyx and a larger proportion of patients with a type II or type III coccyx in the AIS group than in the non-scoliotic group. In other words, the presence of a more pronounced coccygeal curve in AIS patients may be caused by an incorrect sitting position and an imbalance in the contraction of the pelvic muscles. It should be further studied whether correcting the sitting position and muscular imbalances could change coccygeal morphology and subsequently affect the development of AIS.

[Imaging study on thoracic and lumbar physiological curvature in adolescent idiopathic scoliosis].

OBJECTIVE: To observe the alteration of thoracic and lumbar physiological curvature in adolescent idiopathic scoliosis(AIS) and the difference of physiological curvature between different types of scoliosis. METHODS: A retrospective analysis was conducted on 305 adolescent patients taken full spine X-ray in our hospital from January 2017 to December 2021. The patients were divided into normal group and scoliosis group. The normal group was composed of 179 patients, 79 males and 100 females, aged 10 to 18 years old with an average of (12.84±2.10) years old, with cobb agle less than 10 degrees. The scoliosis group was composed of 126 patients, 33 males and 93 females, aged 10 to 18 years old with an average of (13.92±2.20) years old. The gender, age, Risser sign, thoracic kyphosis(TK) and lumbar lordosis(LL) in 2 groups were compared, and the TK and LL were also compared between different genders, different degrees of scoliosis and different segments of scoliosis. RESULTS: The female ratio(P=0.001) and age (P<0.001) in scoliosis group were higher than them in normal group; the ratio of low-grade ossification was higher in normal group than in scoliosis group(P=0.038). TK was significantly smaller in scoliosis group than in normal group(P<0.001), but there was no significant difference in LL between the 2 groups(P=0.147). There were no significant difference in TK and LL between male and female. The TK was significantly bigger in mild AIS patients than in moderate AIS patients(P<0.05), but there was no significant difference in LL between mild and moderate patients(P>0.05). The TK and LL in different segments scoliosis were not found significant difference. CONCLUSION: The physiological curvature of thoracic and lumbar spine is independent of gender. The thoracic physiological curvature becomes smaller in AIS patients, but lumbar curvature remains unchanged. The thoracic physiological curvature in mild AIS patients is greater than that in moderate AIS patients, but the lumbar curvature is almost unchanged between mild and moderate scoliosis and is similar with that in normal adolescent. The alteration of thoracic and lumbar physiological curvature in AIS patients may be related to relative anterior spinal overgrowth, and the specific detailed mechanism needs to be further studied.

Study on the relationship between scoliosis and vision problems: A narrative review.

Adolescent scoliosis is one of the most common surgical disorders of the pediatric spine. With timely detection and early treatment, most scoliotic children can avoid major and expensive surgery. Vision problems are also frequently found at an early age and can take a toll on individuals quality of life. However, scoliosis, a severe health hazard to adolescents, is often accompanied by vision problems clinically, including myopia, astigmatism, strabismus, amblyopia, horizontal paralysis, and blindness. And people with genetic defects have a higher probability of suffering both spinal problems and vision problems than those with nongenetic defects. However, many individuals viewed scoliosis and vision problems as 2 irrelevant diseases. This review searched PubMed, China National Knowledge Infrastructure, and Web of Science for studies on adolescent, scoliosis, eye diseases, myopia, strabismus, spinal disorders, and vision problems for almost 3 decades, and thus confirmed the potential relationship between adolescent scoliosis and vision problems.

[Correlation analysis of Cobb angle and linear spinous process angle in adolescent idiopathic scoliosis].

OBJECTIVE: To analyze the correlation between Cobb angle and spinous process angle (SPA) on X-ray film and body surface in patients with mild to moderate adolescent idiopathic scoliosis(AIS). To explore the possibility of linear SPA to assess scoliosis. METHODS: Retrospective study for correlation of Cobb angle and linear SPA on X-ray film. AIS patients treated and taken full spine anteroposterior X-ray from January 2019 to December 2021 were analyzed correlation of Cobb angle and linear SPA on X-ray film. Prospective study for correlation of Cobb angle and body linear SPA. AIS patients treated and taken full spine anteroposterior X-ray from December 1 to December 9 this year were analyzed correlation of Cobb angle and body linear SPA. RESULTS: A total of 113 AIS patients with age an average of (14.02±2.16) years old(ranged from 10 to 18 years old) were recruited in retrospective study, involving 26 males and 87 females;there were 71 patients with mild AIS and 42 patients with moderate AIS. Cobb angle in AIS patients was significantly inversely associated with SPA(r=-0.564, P<0.001), the linear regression equation was:Cobb angle=169.444-0.878×SPA. Cobb angles in patients with mild scoliosis were significantly and inversely associated with SPA(r=-0.269, P=0.012), the linear regression equation was:Cobb angle=46.832-0.185×SPA. Cobb angles in patients with moderate scoliosis were also clearly correlated with SPA(r=-0.417, P=0.003), the linear regression equation was:Cobb angle=113.889-0.516×SPA. Thirty-eight patients were recruited in prospective study. The mean Cobb angle and body linear SPA were(18.70±6.98)°, ranged from 11.3° to 36.0° and (170.34±4.57)°, ranged from 162.1° to 177.7° respectively. There was significantly negative correlation(r=-0.651, P<0.001), the linear regression equation is:Cobb angle=187.91-0.99×SPA. CONCLUSION: Linear SPA on X-ray film or on the body was significantly negatively correlated with Cobb angles, but the regression equation fits poorly, so it's not suitable for diagnosis of scoliosis;however, linear SPA is appropriate for self-controlled assessment of scoliotic therapy or for dynamic assessment of spinal flexibility.

The single and combined effects of sulfamethazine and cadmium on soil nitrification and ammonia-oxidizing microorganisms.

The coexistence of antibiotics and heavy metals in soil has attracted increasing attention due to their negative effects on microorganisms. However, how antibiotics and heavy metals affect functional microorganisms related to nitrogen cycle remains unclear. The goals of this work were to explore the individual and combined effects of sulfamethazine (SMT) and cadmium (Cd), selected as target pollutants in soil, on potential nitrification rates (PNR) and ammonia oxidizers (ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB)) structure and diversity by 56-day cultivation experiment. Results showed that PNR in Cd- or SMT-treated soil decreased at the beginning of the experiment and then increased over time. PNR was significantly correlated with AOA and AOB-amoA relative abundance (P < 0.01). SMT addition (10 and 100 mg kg-1) significantly improved AOA activity by 13.93% and 17.93%, respectively, and had no effect on AOB at day 1. Conversely, Cd at 10 mg kg-1 significantly inhibited AOA and AOB by 34.34% and 37.39%, respectively. Moreover, the relative abundance of AOA and AOB in combined SMT and Cd addition clearly higher relative to single Cd at 1 day. The single and combined Cd and SMT increased and reduced the community richness of AOA and AOB, respectively, but reduced the diversity of both after 56 days. Cd and SMT treatments significantly changed the relative abundance of AOA phylum levels and AOB genus levels in the soil. It was mainly manifested in reducing the relative abundance of AOA Thaumarchaeota, and increasing the relative abundance of AOB Nitrosospira. Besides, AOB Nitrosospira was more tolerant to the compound addition of both than single application.

Microbial nutrient limitations limit carbon sequestration but promote nitrogen and phosphorus cycling: A case study in an agroecosystem with long-term straw return.

Soil fertility can be increased by returning crop residues to fields due to the cooperative regulation of microbial metabolism of carbon (C) and nutrients. However, the dose-effect of straw on the soil C and nutrient retention and its underlying coupled microbial metabolic processes of C and nutrients remain poorly understood. Here, we conducted a comprehensive study on soil nutrients and stoichiometry, crop nutrient uptake and production, microbial metabolic characteristics and functional attributes using a long-term straw input field experiment. We estimated the microbial metabolic limitations and efficiency of C and nitrogen (N) use (CUE and NUE) via an enzyme-based vector-TER model, biogeochemical-equilibrium model and mass balance equation, respectively. In addition, the absolute abundances of 20 functional genes involved in the N- and P-cycles were quantified by quantitative PCR-based chip technology. As expected, straw input significantly increased C and N stocks, C: nutrients, crop nutrient uptake and growth. However, the C sequestration efficiency decreased by approximately 6.1 %, and the N2O emission rate increased by 0.5-1.0 times with the increase in straw input rate. Interestingly, the microbial metabolism was more limited by P when straw input was <8 t ha-1 but was reversed when straw input was 12 t ha-1. The enhanced nutrient limitation reduced both the CUE and the NUE of microbes and then upregulated genes associated with the hydrolysis of C, the mineralization of N and P, and denitrification, which consequently influenced C and N losses as well as crop growth. This study highlights that soil C and nutrient cycling are strongly regulated by microbial metabolic limitation, suggesting that adding the appropriate limiting nutrients to reduce nutrient imbalances caused by straw input is conducive to maximizing the ecological benefits of straw return.

A novel steroid hydroxylase from Nigrospora sphaerica with various hydroxylation capabilities to different steroid substrates.

Fungal hydroxylation of steroids is a key step in the industrial production of various steroid drugs. The main enzymes that enable these reactions are Cytochrome P450s (CYP), though very few industrially important CYPs have been identified and characterized. In this study, we identified a CYP enzyme (CYP-N2) and a cytochrome P450 reductase (CPRns) from Nigrospora sphaerica 722 by a combination of transcriptome sequencing and heterologous expression in Pichia pastoris. Gene CYP-N2 co-expressed with CPRns in Pichia pastoris GS115 showed 6ß- and 15α-hydroxylation activities on progesterone. Different hydroxylation specificity of CYP-N2 was observed on different steroid substrates. CYP-N2 showed 1α-hydroxylation on cortisone and 1α-hydroxylation and 6ß-hydroxylation activities on androstenedione (AD). With dehydroepiandrosterone (DHEA) as a substrate, the hydroxylated products of CYP-N2 included 7α-hydroxy-DHEA and 7α,15α-dihydroxy-DHEA. In order to precisely elucidate CYP-N2 biological function and find out the key amino acids influencing its hydroxylation capabilities in the binding pocket, new generation artificial intelligence technology AlphaFold 2 was used to predict the function-structure of CYP-N2 with high reliability. Through molecular docking, it was concluded that the residues almost binding all substrates were located in the same substrate binding pocket and the various hydroxylation abilities might be due to the different binding conformations of different substrates in the binding pocket. Alanine scanning mutagenesis was used to verify key amino acids identified by the molecular docking with steroid substrates. The 128 THR mutation resulted in conversion rate increase for substrates AD and cortisone by 2.6-fold and 2.1-fold respectively. The information obtained in this study is beneficial to facilitating the engineering of more efficient steroid hydroxylases for industrial applications.

Inflammation and immune activation are associated with risk of Mycobacterium tuberculosis infection in BCG-vaccinated infants.

Tuberculosis vaccine development is hindered by the lack of validated immune correlates of protection. Exploring immune correlates of risk of disease and/or infection in prospective samples can inform this field. We investigate whether previously identified immune correlates of risk of TB disease also associate with increased risk of M.tb infection in BCG-vaccinated South African infants, who became infected with M.tb during 2-3 years of follow-up. M.tb infection is defined by conversion to positive reactivity in the QuantiFERON test. We demonstrate that inflammation and immune activation are associated with risk of M.tb infection. Ag85A-specific IgG is elevated in infants that were subsequently infected with M.tb, and this is coupled with upregulated gene expression of immunoglobulin-associated genes and type-I interferon. Plasma levels of IFN-[Formula: see text]2, TNF-[Formula: see text], CXCL10 (IP-10) and complement C2 are also higher in infants that were subsequently infected with M.tb.

Auto-segmentation and time-dependent systematic analysis of mesoscale cellular structure in ß-cells during insulin secretion.

The mesoscale description of the subcellular organization informs about cellular mechanisms in disease state. However, applications of soft X-ray tomography (SXT), an important approach for characterizing organelle organization, are limited by labor-intensive manual segmentation. Here we report a pipeline for automated segmentation and systematic analysis of SXT tomograms. Our approach combines semantic and first-applied instance segmentation to produce separate organelle masks with high Dice and Recall indexes, followed by analysis of organelle localization based on the radial distribution function. We demonstrated this technique by investigating the organization of INS-1E pancreatic ß-cell organization under different treatments at multiple time points. Consistent with a previous analysis of a similar dataset, our results revealed the impact of glucose stimulation on the localization and molecular density of insulin vesicles and mitochondria. This pipeline can be extended to SXT tomograms of any cell type to shed light on the subcellular rearrangements under different drug treatments.

In silico and in vitro protocols for quantifying gene expression noise modulated by microRNAs.

Characterizing the noise modulation pattern of microRNA is valuable for both microRNA function analysis and synthetic biology applications. Here we propose a coarse-grained model to simulate how the properties of microRNAs, competing RNAs, and microRNA response elements affect gene expression noise. We also detail an experimental protocol based on synthetic gene circuits and flow cytometry to quantify the noise. This framework is easy-to-use for the study and application of both microRNA and gene expression noise. For complete details on the use and execution of this protocol, please refer to Wei et al. (2021).

Single-cell Transcriptomes Reveal Characteristics of MicroRNAs in Gene Expression Noise Reduction.

Isogenic cells growing in identical environments show cell-to-cell variations because of the stochasticity in gene expression. High levels of variation or noise can disrupt robust gene expression and result in tremendous consequences for cell behaviors. In this work, we showed evidence from single-cell RNA sequencing data analysis that microRNAs (miRNAs) can reduce gene expression noise at the mRNA level in mouse cells. We identified that the miRNA expression level, number of targets, target pool abundance, and miRNA-target interaction strength are the key features contributing to noise repression. miRNAs tend to work together in cooperative subnetworks to repress target noise synergistically in a cell type-specific manner. By building a physical model of post-transcriptional regulation and observing in synthetic gene circuits, we demonstrated that accelerated degradation with elevated transcriptional activation of the miRNA target provides resistance to extrinsic fluctuations. Together, through the integrated analysis of single-cell RNA and miRNA expression profiles, we demonstrated that miRNAs are important post-transcriptional regulators for reducing gene expression noise and conferring robustness to biological processes.

Characterizing microRNA-mediated modulation of gene expression noise and its effect on synthetic gene circuits.

MicroRNAs (miRNAs) have been shown to modulate gene expression noise, but less is known about how miRNAs with different properties may regulate noise differently. Here, we investigate the role of competing RNAs and the composition of miRNA response elements (MREs) in modulating noise. We find that weak competing RNAs could introduce lower noise than strong competing RNAs. In comparison with a single MRE, both repetitive and composite MREs can reduce the noise at low expression, but repetitive MREs can elevate the noise remarkably at high expression. We further observed the behavior of a synthetic cell-type classifier with miRNAs as inputs and find that miRNAs and MREs that could introduce higher noise tend to enhance cell state transition. These results provide a systematic and quantitative understanding of the function of miRNAs in controlling gene expression noise and the utilization of miRNAs to modulate the behavior of synthetic gene circuits.

Toxicological effects of single and joint sulfamethazine and cadmium stress in soil on pakchoi (Brassica chinensis L.).

The combined pollution of heavy metals and antibiotics in soil has attracted increasing attention due to their negative effects on plant growth. The aims of this study were to evaluate the phytotoxicity of single and combined sulfamethazine (SMT) and cadmium (Cd), selected as target pollutants in soil, on growth and physiological response of pakchoi (Brassica chinensis L.). Results revealed that the soil spiked with 10 mg kg-1 Cd inhibited the pakchoi growth regardless of SMT addition. The combined effect of SMT and Cd stress on uptake of SMT or Cd by pakchoi were concerned with their combined concentration. The combined influence of high concentrations SMT and Cd (1 and 10 mg kg-1) exposure on the Cd content of pakchoi showed antagonistic effects and synergistic effects, respectively. Besides, oxidative substances and enzyme activity of pakchoi tissue were affected by Cd and SMT exposure in the soil, particularly by their joint stress. This mainly expressed as the increase of malondialdehyde (MDA), H2O2 content and antioxidant enzyme activity (superoxide dismutase (SOD), peroxidase (POD), catalase (CAT)), which could be ascribed to the induction of Cd and SMT stress. Additionally, the SMT-Cd combined stress caused more reduction in nutrients (vitamin C and sugar) of pakchoi than the correspondingly single Cd stress. In conclusion, the SMT and Cd in soil lead to their accumulation and oxidative damage in pakchoi, which disturb the antioxidant defense system and ultimately adversely affect growth and quality of pakchoi.

Induction of Functional Specific Antibodies, IgG-Secreting Plasmablasts and Memory B Cells Following BCG Vaccination.

Tuberculosis (TB) is a major global health problem and the only currently-licensed vaccine, BCG, is inadequate. Many TB vaccine candidates are designed to be given as a boost to BCG; an understanding of the BCG-induced immune response is therefore critical, and the opportunity to relate this to circumstances where BCG does confer protection may direct the design of more efficacious vaccines. While the T cell response to BCG vaccination has been well-characterized, there is a paucity of literature on the humoral response. We demonstrate BCG vaccine-mediated induction of specific antibodies in different human populations and macaque species which represent important preclinical models for TB vaccine development. We observe a strong correlation between antibody titers in serum versus plasma with modestly higher titers in serum. We also report for the first time the rapid and transient induction of antibody-secreting plasmablasts following BCG vaccination, together with a robust and durable memory B cell response in humans. Finally, we demonstrate a functional role for BCG vaccine-induced specific antibodies in opsonizing mycobacteria and enhancing macrophage phagocytosis in vitro, which may contribute to the BCG vaccine-mediated control of mycobacterial growth observed. Taken together, our findings indicate that the humoral immune response in the context of BCG vaccination merits further attention to determine whether TB vaccine candidates could benefit from the induction of humoral as well as cellular immunity.

Experimental supporting data on seasonal dynamics of different soil nitrogen pools affected by long-term fertilization regimes.

The data presented in this article are related to the research paper entitled "Changes in N supply pathways under different long-term fertilization regimes in Northeast China" [1]. Seasonal dynamics of soil NH4 +-N, NO3 --N, soil microbial biomass nitrogen (N) and fixed NH4 + were provided on the basis of a 26-year long-term experiment, including six treatments: no fertilizer (CK), recycled manure (M), N and P fertilizers (NP), P and K fertilizers (PK), N, P and K fertilizers (NPK), and NPK fertilizers with recycled manure (NPKM). The presentation of potential N retention and supply through soil microbial biomass N and fixed NH4 + pools at different growth stages is helpful for comparing the effects of different N pools on soil N transformation and assessing synchronies between crop N demand and soil N supply through different N pools.

Synthetic promoter design in Escherichia coli based on a deep generative network.

Promoter design remains one of the most important considerations in metabolic engineering and synthetic biology applications. Theoretically, there are 450 possible sequences for a 50-nt promoter, of which naturally occurring promoters make up only a small subset. To explore the vast number of potential sequences, we report a novel AI-based framework for de novo promoter design in Escherichia coli. The model, which was guided by sequence features learned from natural promoters, could capture interactions between nucleotides at different positions and design novel synthetic promoters in silico. We combined a deep generative model that guides the search for artificial sequences with a predictive model to preselect the most promising promoters. The AI-designed promoters were optimized based on the promoter activity in E. coli and the predictive model. After two rounds of optimization, up to 70.8% of the AI-designed promoters were experimentally demonstrated to be functional, and few of them shared significant sequence similarity with the E. coli genome. Our work provided an end-to-end approach to the de novo design of novel promoter elements, indicating the potential to apply deep learning methods to de novo genetic element design.

Evaluation of Different Types and Amounts of Amendments on Soil Cd Immobilization and its Uptake to Wheat.

Using amendments is a cost-effective method to soil cadmium (Cd) remediation, whereas knowledge about how different amendments and rates affect remediation efficiency remains limited. This study aimed to evaluate the impacts of different types and amounts of amendments on soil Cd immobilization and its uptake by plants. Biochar (BC), zeolite (ZE), humic acid (HA), superphosphate (SP), lime (L), and sodium sulfide (SS) were applied at three rates (low, medium, and high) ranging from 0.5 to 5%. The concentration of CaCl2-extractable Cd was considerably affected by the amendments, except HA, and the high doses achieved better immobilization effects than the low doses did. The addition of amendments decreased weak acid soluble Cd by 4.1-44.0% but slightly increased the fractions of oxidizable and residual Cd. These amendments (except BC and HA dose of 1%) decreased Cd accumulation in grains by 1.3-68.8% and (except SP) in roots by 16.3-65.5% compared with the control. The SP efficiently immobilized Cd but posed a potential soil acidification risk. Moreover, SS treatment increased the soil electrical conductivity (EC) value and restricted the growth of wheat, possibly due to high-salt stress. BC, ZE, and L exerted significant effects on the reduction in available Cd as the application rate increased. These amendments enhanced Cd immobilization mainly by changing Cd availability in soil and influencing its redistribution in different fractions in soil and root uptake by plants. This study concluded that BC-5%, ZE-1%, and L-0.5% can be used for Cd immobilization in acidic or neutral soils.

Effects of apple branch biochar on soil C mineralization and nutrient cycling under two levels of N.

The incorporation of biochar into soil has been proposed as a strategy for enhancing soil fertility and crop productivity. However, there is limited information regarding the responses of soil respiration and the C, N and P cycles to the addition of apple branch biochar at different rates to soil with different levels of N. A 108-day incubation experiment was conducted to investigate the effects of the rate of biochar addition (0, 1, 2 and 4% by mass) on soil respiration and nutrients and the activities of enzymes involved in C, N and P cycling under two levels of N. Our results showed that the application of apple branch biochar at rates of 2% and 4% increased the C-mineralization rate, while biochar amendment at 1% decreased the C-mineralization rate, regardless of the N level. The soil organic C and microbial biomass C and P contents increased as the rate of biochar addition was increased to 2%. The biochar had negative effects on ß-glucosidase, N-acetyl-ß-glucosaminidase and urease activity in N-poor soil but exerted a positive effect on all of these factors in N-rich soil. Alkaline phosphatase activity increased with an increase in the rate of biochar addition, but the available P contents after all biochar addition treatments were lower than those obtained in the treatments without biochar. Biochar application at rates of 2% and 4% reduced the soil nitrate content, particularly in N-rich soil. Thus, apple branch biochar has the potential to sequester C and improve soil fertility, but the responses of soil C mineralization and nutrient cycling depend on the rate of addition and soil N levels.