SIRT2 regulates high mobility group protein B1 nucleoplasmic shuttle and degradation via deacetylation in microglia.

High mobility group protein B1 (HMGB1) acts as a pathogenic inflammatory response to mediate ranges of conditions such as epilepsy, septic shock, ischemia, traumatic brain injury, Parkinson's disease, Alzheimer's disease and mass spectrometry. HMGB1 promotes inflammation during sterile and infectious damage and plays a crucial role in disease development. Mobilization from the nucleus to the cytoplasm is the first important step in the release of HMGB1 from activated immune cells. Here, we demonstrated that Sirtuin 2 (SIRT2) physically interacts with and deacetylates HMGB1 at 43 lysine residue at nuclear localization signal locations, strengthening its interaction with HMGB1 and causing HMGB1 to be localized in the cytoplasm. These discoveries are the first to shed light on the SIRT2 nucleoplasmic shuttle, which influences HMGB1 and its degradation, hence revealing novel therapeutic targets and avenues for neuroinflammation treatment.

Damage-Free Silica Coating for Colloidal Nanocrystals Through a Proactively Water-Generating Amidation Reaction at High Temperature.

Silica is a promising shell coating material for colloidal nanoparticles due to its excellent chemical inertness and optical transparency. To encapsulate high-quality colloidal nanocrystals with silica shells, the silane coupling hydrolysis is currently the most effective approach. However, this reaction requires water, which often adversely affects the intrinsic physicochemical properties of nanocrystals. Achieving a damage-free silica encapsulation process to nanocrystals by hydrolysis is a huge challenge. Here, a novel strategy is developed to coat colloidal nanocrystals with a denser silica shell via a proactively water-generating reaction at high temperature. In this work, water molecules are continuously and proactively released into the reaction system through the amidation reaction, followed by in situ hydrolysis of silane, completely avoiding the impacts of water on nanocrystals during the silica coating process. In this work, water sensitive perovskite nanocrystals (CsPbBr3) are selected as the typical colloidal nanocrystals for silica coating. Notably, this high-temperature in situ encapsulation technology greatly improves the optical properties of nanocrystals, and the silica shells exhibit a denser structure, providing nanocrystals with better protection. This method overcomes the challenge of the influence of water on nanocrystals during the hydrolysis process, and provides an important reference for the non-destructive encapsulation of colloidal nanocrystals.

Entropy-Driven Ostwald Ripening Reversal Promotes the Formation of Low-Platinum Intermetallic Fuel Cell Catalysts.

Strain engineering has been widely used to optimize platinum-based oxygen reduction reaction (ORR) catalysts for proton exchange membrane fuel cells (PEMFCs). PtM3 (M is base metals), a well-known high-compressive-strain intermetallic alloy, shows promise as a low platinum ORR catalyst due to high intrinsic activity. However, during the alloying of Pt with a threefold amount of M, a notable phase separation between Pt and M may occur, with M particles rapidly sintering while Pt particles grow slowly, posing a challenge in achieving a well-defined PtM3 intermetallic alloy. Here, an entropy-driven Ostwald ripening reversal phenomenon is discovered that enables the synthesis of small-sized Pt(FeCoNiCu)3 intermetallic ORR catalysts. High entropy promotes the thermodynamic driving force for the alloying Pt with M, which triggers the Ostwald ripening reversal of sintered FeCoNiCu particles and facilitates the formation of uniform Pt(FeCoNiCu)3 intermetallic catalysts. The prepared Pt(FeCoNiCu)3 catalysts exhibit a high specific activity of 3.82 mA cm-2, along with a power density of ≈1.3 W cm-2 at 0.67 V and 94 °C with a cathode Pt loading of 0.1 mg cm-2 in H2-air fuel cell.

Emergence of a clinical Salmonella enterica serovar 1,4,[5], 12: i:-isolate, ST3606, in China with susceptibility decrease to ceftazidime-avibactam carrying a novel blaCTX-M-261 variant and a blaNDM-5.

PURPOSE: The detection rate of Salmonella enterica serovar 1,4,[5], 12: i: - (S. 1,4,[5], 12: i: -) has increased as the most common serotype globally. A S. 1,4,[5], 12: i: - strain named ST3606 (sequence type 34), isolated from a fecal specimen of a child with acute diarrhea hospitalized in a tertiary hospital in China, was firstly reported to be resistant to carbapenem and ceftazidime-avibactam. The aim of this study was to characterize the whole-genome sequence of S. 1,4,[5], 12: i: - isolate, ST3606, and explore its antibiotic resistance genes and their genetic environments. METHODS: The genomic DNA of S. 1,4,[5], 12: i: - ST3606 was extracted and performed with single-molecule real-time sequencing. Resistance genes, plasmid replicon type, mobile elements, and multilocus sequence types (STs) of ST3606 were identified by ResFinder 3.2, PlasmidFinder, OriTfinder database, ISfinder database, and MLST 2.0, respectively. The conjugation experiment was utilized to evaluate the conjugation frequency of pST3606-2. Protein expression and enzyme kinetics experiments of CTX-M were performed to analyze hydrolytic activity of a novel CTX-M-261 enzyme toward several antibiotics. RESULTS: Single-molecule real-time sequencing revealed the coexistence of a 109-kb IncI1-Iα plasmid pST3606-1 and a 70.5-kb IncFII plasmid pST3606-2. The isolate carried resistance genes, including blaNDM-5, sul1, qacE, aadA2, and dfrA12 in pST3606-1, blaTEM-1B, aac(3)-lld, and blaCTX-M-261, a novel blaCTX-M-1 family member, in pST3606-2, and aac(6')-Iaa in chromosome. The blaCTX-M-261 was derived from blaCTX-M-55 by a single-nucleotide mutation 751G>A leading to amino acid substitution of Val for Met at position 251 (Val251Met), which conferred CTX-M increasing resistance to ceftazidime verified by antibiotics susceptibility testing of transconjugants carrying pST3606-2 and steady-state kinetic parameters of CTX-M-261. pST3606-1 is an IncI1-α incompatibility type that shares homology with plasmids of pC-F-164_A-OXA140, pE-T654-NDM-5, p_dm760b_NDM-5, and p_dmcr749c_NDM-5. The conjugation experiment demonstrated that pST3606-2 was successfully transferred to the Escherichia coli recipient C600 with four modules of OriTfinder. CONCLUSION: Plasmid-mediated horizontal transfer plays an important role in blaNDM-5 and blaCTX-M-261 dissemination, which increases the threat to public health due to the resistance to most ß-lactam antibiotics. This is the first report of blaCTX-M-261 and blaNDM-5 in S. 1,4,[5], 12: i: -. The work provides insights into the enzymatic function and demonstrates the ongoing evolution of CTX-M enzymes and confirms urgency to control resistance of S. 1,4,[5], 12: i: -.

Photoexcitation-Enhanced High-Ionic Conductivity in Polymer Electrolytes for Flexible, All-Solid-State Lithium-Metal Batteries Operating at Room Temperature.

Designing solid polymer electrolytes (SPEs) with high ionic conductivity for room-temperature operation is essential for advancing flexible all-solid-state energy storage devices. Innovative strategies are urgently required to develop SPEs that are safe, stable, and high-performing. In this work, we introduce photoexcitation-modulated heterojunctions as catalytically active fillers within SPEs, guided by photocatalytic design principles, and employ natural bacterial cellulose to enhance the mechanical properties of the inorganic-filled SPEs. In-situ photothermal experiments and theoretical calculations reveal that the strong photogenerated electric field produced by trace heterojunctions within poly(ethylene oxide) electrolytes under photoexcitation significantly enhances lithium salt dissociation, increasing the concentration of mobile Li+. This results in a substantial increase in ionic conductivity, reaching 0.135 mS cm-1 at 25 °C, with a Li+ transference number as high as 0.46. The flexible all-solid-state lithium-metal pouch cells exhibit an impressive discharge capacity of 178.8 mAh g-1 even after repeated bending and folding, and demonstrate exceptional long-term cycling stability, retaining 86.7% of their initial capacity after 250 cycles at 1 C (25 °C). This research offers a novel approach to developing high-performance flexible lithium-metal batteries.

Fluorine Passivation Inhibits "Particle Talking" Behaviors under Thermal and Electrical Conditions of Pure Blue Mixed Halide Perovskite Nanocrystals.

Owing to outstanding optoelectronic properties, lead halide perovskite nanocrystals (PNCs) are considered promising emitters for next-generation displays. However, the development of pure blue (460-470 nm) perovskite nanocrystal light-emitting diodes (PNC-LEDs), which correspond to the requirements of Rec. 2020 standard, lag far behind that of their green and red counterparts. Here, pure blue CsPb(Br/Cl)3 nanocrystals with remarkable optical performance are demonstrated by a facile fluorine passivation strategy. Prominently, the fluorine passivation on halide vacancies and strong bonding of Pb-F intensely enhance crystal structure stability and inhibit "particle talking" behaviors under both thermal and electrical conditions. Fluorine-based PNCs with high resistance of luminescence thermal quenching retain 70% of photoluminescent intensity when heated to 343 K, which can be attributed to the elevated activation energy for carrier trapping and unchanged grain size. Fluorine-based PNC-LEDs also exhibit stable pure blue electroluminescence (EL) emission with sevenfold promoted luminance and external quantum efficiencies (EQEs), where the suppression of ion migration is further evidenced by a lateral structure device with applied polarizing potential.

Foliar Spraying of Chlorpyrifos Triggers Plant Production of Linolenic Acid Recruiting Rhizosphere Bacterial Sphingomonas sp.

Plants have developed an adaptive strategy for coping with biotic or abiotic stress by recruiting specific microorganisms from the soil pool. Recent studies have shown that the foliar spraying of pesticides causes oxidative stress in plants and leads to changes in the rhizosphere microbiota, but the mechanisms by which these microbiota change and rebuild remain unclear. Herein, we provide for the first-time concrete evidence that rice plants respond to the stress of application of the insecticide chlorpyrifos (CP) by enhancing the release of amino acids, lipids, and nucleotides in root exudates, leading to a shift in rhizosphere bacterial community composition and a strong enrichment of the genus Sphingomonas sp. In order to investigate the underlying mechanisms, we isolated a Sphingomonas representative isolate and demonstrated that it is both attracted by and able to consume linolenic acid, one of the root exudates overproduced after pesticide application. We further show that this strain selectively colonizes roots of treated plants and alleviates pesticide stress by degrading CP and releasing plant-beneficial metabolites. These results indicate a feedback loop between plants and their associated microbiota allowing to respond to pesticide-induced stress.

Investigating the effect of substrate binding on the catalytic activity of xylanase.

XynAF1 from Aspergillus fumigatus Z5 is an efficient thermophilic xylanase belonging to glycoside hydrolase family 10 (GH10). The non-catalytic amino acids N179 and R246 in its catalytic center formed one and three intermolecular H-bonds with the substrate in the aglycone region, respectively. Here we purified XynAF1-N179S and XynAF1-R246K, and obtained the protein-product complex structures by X-ray diffraction. The snapshots indicated that mutations at N179 and R246 had decreased the substrate-binding ability in the aglycone region. XynAF1-N179S, XynAF1-R246K, and XynAF1-N179S-R246K lost one, three, and four H-bonds with the substrate in comparison with the wild-type XynAF1, respectively, but this had little influence on the protein structure. As expected, N179S, R246K, and N179S-R246K led to a gradual decrease of substrate affinity of XynAF1. Interestingly, the enzyme assay showed that N179S increased catalytic efficiency, while both R246K and N179S-R246K had decreased catalytic efficiency. KEY POINTS: • The non-catalytic amino acids of XynAF1 could form H-bonds with the substrate. • The protein-product complex structures were obtained by X-ray diffraction. • The enzyme-substrate-binding capacity could affect enzyme catalytic efficiency.

Comparison of Different Chemical Extraction Methods for Predicting the Bioavailability and Phytotoxicity of Soil PAEs to Green Vegetables (Brassica Rapa Var. Chinensis).

The aim of the present study was to compare the predictive ability of four chemical extraction methods, i.e., Tenax, hydroxypropyl[ß]cyclodextrin (HPCD), n-butanol and low-molecular-weight-organic-acids (LMWOA), for predicting the bioavailability and phytotoxicity of soil phthalic acid esters to the green vegetable Shanghaiqing (SHQ). Results showed that the extraction ability of different extraction methods varies significantly. For dibutyl phthalate (DBP), the extraction ability followed the order of Tenax > LMWOA > HPCD > n-butanol. For di-(2-ethylhexyl) phthalate (DEHP), the order of the extraction ability was n-butanol > HPCD > Tenax > LMWOA. All the extraction methods underestimated the DBP concentration while overestimating the DEHP concentration accumulated by SHQ. The concentrations of DBP and DEHP extracted by Tenax were most related to the concentrations accumulated by SHQ and the phytotoxicity indicators of SHQ. Tenax can serve as a good chemical extractant to assess the bioavailability and phytotoxicity of soil DBP and DEHP to SHQ.

Stable Lead-Free Tin Halide Perovskite with Operational Stability >1200 h by Suppressing Tin(II) Oxidation.

Sn-based perovskites are the most promising alternative materials for Pb-based perovskites to address the toxicity problem of lead. However, the development of SnII -based perovskites has been hindered by their extreme instability. Here, we synthesized efficient and stable lead-free Cs4 SnBr6 perovskite by using SnF2 as tin source instead of easily oxidized SnBr2 . The SnF2 configures a fluorine-rich environment, which can not only suppress the oxidation of Sn2+ in the synthesis, but also construct chemically stable Sn-F coordination to hinder the electron transfer from Sn2+ to oxygen within the long-term operation process. The SnF2 -derived Cs4 SnBr6 perovskite shows a high photoluminescence quantum yield of 62.8 %, and excellent stability against oxygen, moisture, and light radiation for 1200 h, representing one of the most stable lead-free perovskites. The results pave a new pathway to enhance the optical properties and stability of lead-free perovskite for high-performance light emitters.

Phosphoproteome Profiling Revealed the Importance of mTOR Inhibition on CDK1 Activation to Further Regulate Cell Cycle Progression.

The mammalian target of rapamycin (mTOR) functions as a critical regulator of cell cycle progression. However, the underlying mechanism by which mTOR regulates cell cycle progression remains elusive. In this study, we used stable isotope labeling of amino acids in cell culture with a two-step strategy for phosphopeptide enrichment and high-throughput quantitative mass spectrometry to perform a global phosphoproteome analysis of mTOR inhibition by rapamycin. By monitoring the phosphoproteome alterations upon rapamycin treatment, downregulation of mTOR signaling pathway was detected and enriched. Further functional analysis of phosphoproteome revealed the involvement of cell cycle events. Specifically, the elevated profile of cell cycle-related substrates was observed, and the activation of CDK1, MAPK1, and MAPK3 kinases was determined. Second, pathway interrogation using kinase inhibitor treatment confirmed that CDK1 activation operated downstream from mTOR inhibition to further regulate cell cycle progression. Third, we found that the activation of CDK1 following 4-12 h of mTOR inhibition was accompanied by the activation of the Greatwall-endosulfine complex. In conclusion, we presented a high-confidence phosphoproteome map inside the cells upon mTOR inhibition by rapamycin. Our data implied that mTOR inhibition could contribute to CDK1 activation for further regulating cell cycle progression, which was mediated by the Greatwall-endosulfine complex.

Rice recruits Sphingomonas strain HJY-rfp via root exudate regulation to increase chlorpyrifos tolerance and boost residual catabolism.

Inoculation with pollution-degrading endophytes boosts the catabolism of residual contaminants and promotes the pollution adaptation of host plants. We investigated the interaction pattern between Sphingomonas strain HJY-rfp, a chlorpyrifos-degrading endophytic bacterium, and rice (Oryza sativa) under pesticide stress using hydroponic cultivation. We observed a notable trend of endophytic root colonization in rice plants treated with 10 mg l-1 chlorpyrifos solution, and after 24 h the migration of HJY-rfp enhanced the chlorpyrifos degradation rate in leaves and stems by 53.36% and 40.81%, respectively. Critically, the rice root exudate profile (organic acids and amino acids) changed under chlorpyrifos stress, and variations in the contents of several components affected the chemotactic behaviour of HJY-rfp. HJY-rfp colonization dramatically activated defensive enzymes, which enabled efficient scavenging of reactive oxygen species, and led to 9.8%, 22.5%, and 41.9% increases in shoot length, fresh weight, and accumulation of total chlorophyll, respectively, in rice suffering from oxidative damage by chlorpyrifos. Endophytic colonization caused up-regulation of detoxification genes that have shown a significant positive correlation with chlorpyrifos degradation in vivo. Collectively, our results demonstrate that agrochemical stress causes plants to actively recruit specific symbiotic microbes to detoxify contaminants and survive better under pollution conditions.

Characterization and structural analysis of a thermophilic GH11 xylanase from compost metatranscriptome.

Xylanase is efficient for xylan degradation and widely applied in industries. We found a GH11 family xylanase (Xyn11A) with high thermostability and catalytic activity from compost metatranscriptome. This xylanase has the optimal reaction temperature at 80 °C with the activity of 2907.3 U/mg. The X-ray crystallographic structure shows a typical "right hand" architecture, which is the characteristics of the GH11 family enzymes. Comparing it with the mesophilic XYN II, a well-studied GH11 xylanase from Trichoderma reesei, Xyn11A is more compact with more H-bonds. Our mutagenic results show that the electrostatic interactions in the thumb and palm region of Xyn11A could result in its high thermostability and activity. Introducing a disulfide bond at the N-terminus further increased its optimal reaction temperature to 90 °C with augmented activity. KEY POINTS: • A hyperthermophilic xylanase with high activity was discovered using the metatranscriptomic method. • The mechanisms of thermophilicity and high activity were revealed using X-ray crystallography, mutagenesis, and molecular dynamics simulations. • The thermostability and activity were further improved by introducing a disulfide bond.

Significantly improving the thermostability of a hyperthermophilic GH10 family xylanase XynAF1 by semi-rational design.

Xylanases have a broad range of applications in industrial biotechnologies, which require the enzymes to resist the high-temperature environments. The majority of xylanases have maximum activity at moderate temperatures, which limited their potential applications in industries. In this study, a thermophilic GH10 family xylanase XynAF1 from the high-temperature composting strain Aspergillus fumigatus Z5 was characterized and engineered to further improve its thermostability. XynAF1 has the optimal reaction temperature of 90 °C. The crystal structure of XynAF1 was obtained by X-ray diffraction after heterologous expression, purification, and crystallization. The high-resolution X-ray crystallographic structure of the protein-product complex was obtained by soaking the apo-state crystal with xylotetraose. Structure analysis indicated that XynAF1 has a rigid skeleton, which helps to maintain the hyperthermophilic characteristic. The homologous structure analysis and the catalytic center mutant construction of XynAF1 indicated the conserved catalytic center contributed to the high optimum catalytic temperature. The amino acids in the surface of xylanase XynAF1 which might influence the enzyme thermostability were identified by the structure analysis. Combining the rational design with the saturation mutation at the high B-value regions, the integrative mutant XynAF1-AC with a 6-fold increase of thermostability was finally obtained. This study efficiently improved the thermostability of a GH10 family xylanase by semi-rational design, which provided a new biocatalyst for high-temperature biotechnological applications. KEY POINTS: • Obtained the crystal structure of GH10 family hyperthermophilic xylanase XynAF1. • Shed light on the understanding of the GH10 family xylanase thermophilic mechanism. • Constructed a 6-fold increased thermostability recombinant xylanase.

Seed priming and foliar application with jasmonic acid enhance salinity stress tolerance of soybean (Glycine max L.) seedlings.

BACKGROUND: Jasmonic acid (JA) is an important molecule that has a regulatory effect on many physiological processes in plant growth and development under abiotic stress. This study investigated the effect of 60 µmol L-1 of JA in seed priming (P) at 15 °C in darkness for 24 h, foliar application (F), and/or their combination effect (P + F) on two soybean cultivars - 'Nannong 99-6' (salt tolerant) and 'Lee 68' (salt sensitive) - under salinity stress (100 mmol L-1 sodium chloride (NaCl)). RESULTS: Salinity stress reduced seedling growth and biomass compared with that in the control condition. Priming and foliar application with JA and/or their combination significantly improved water potential, osmotic potential, water use efficiency, and relative water content of both cultivars under salinity stress. Similarly, seed priming with JA, foliar application of JA, and/or their combination significantly improved the following properties under salinity stress compared with the untreated seedlings: net photosynthetic rate by 68.03%, 59.85%, and 76.67% respectively; transpiration rate by 74.85%, 55.10%, and 80.26% respectively; stomatal conductance by 69.88%, 78.25%, and 26.24% respectively; intercellular carbon dioxide concentration by 61.64%, 40.06%, and 65.79% respectively; and total chlorophyll content by 47.41%, 41.02%, and 55.73% respectively. Soybean plants primed, sprayed with JA, or treated with their combination enhanced the chlorophyll fluorescence, which was damaged by salinity stress. JA treatments improved abscisic acid, gibberellic acid, and JA levels by 60.57%, 62.50% and 52.25% respectively under salt stress compared with those in the control condition. The transcriptional levels of the FeSOD, POD, CAT, and APX genes increased significantly in the NaCl-stressed seedlings irrespective of JA treatments. Moreover, JA treatment resulted in a reduction of sodium ion concentration and an increase of potassium ion concentrations in the leaf and root of both cultivars regardless of salinity stress. Monodehydroascorbate reductase, dehydroascorbate reductase, and proline contents decreased in the seedlings treated with JA under salinity stress, whereas the ascorbate content increased with JA treatment combined with NaCl stress. CONCLUSION: The application of 60 µmol L-1 JA improved plant growth by regulating the interaction between plant hormones and hydrogen peroxide, which may be involved in auxin signaling and stomatal closure under salt stress. These methods could efficiently protect early seedlings and alleviate salt stress damage and provide possibilities for use in improving soybean growth and inducing tolerance against excessive soil salinity. © 2020 Society of Chemical Industry.

The KBTBD6/7-DRD2 axis regulates pituitary adenoma sensitivity to dopamine agonist treatment.

Pituitary adenoma (PA) is one of the most common intracranial tumors, and approximately 40% of all PAs are prolactinomas. Dopamine agonists (DAs), such as cabergoline (CAB), have been successfully used in the treatment of prolactinomas. The expression of dopamine type 2 receptor (DRD2) determines the therapeutic effect of DAs, but the molecular mechanisms of DRD2 regulation are not fully understood. In this study, we first demonstrated that DRD2 underwent proteasome-mediated degradation. We further employed the yeast two-hybrid system and identified kelch repeat and BTB (POZ) domain containing 7 (KBTBD7), a substrate adaptor for the CUL3-RING ubiquitin (Ub) ligase complex, as a DRD2-interacting protein. KBTBD6/7 directly interacted with, and ubiquitinated DRD2 at five ubiquitination sites (K221, K226, K241, K251, and K258). CAB, a high-affinity DRD2 agonist, induced DRD2 internalization, and cytoplasmic DRD2 was degraded via ubiquitination under the control of KBTBD6/7, the activity of which attenuated CAB-mediated inhibition of the AKT/mTOR pathway. KBTBD7 knockout (KO) mice were generated using the CRISPR-Cas9 technique, in which the static level of DRD2 protein was elevated in the pituitary gland, thalamus, and heart, compared to that of WT mice. Consistently, the expression of KBTBD6/7 was negatively correlated with that of DRD2 in human pituitary tumors. Moreover, KBTBD7 was highly expressed in dopamine-resistant prolactinomas, but at low levels in dopamine-sensitive prolactinomas. Knockdown of KBTBD6/7 sensitized MMQ cells and primary pituitary tumor cells to CAB treatment. Conversely, KBTBD7 overexpression increased CAB resistance of estrogen-induced in situ rat prolactinoma model. Together, our findings have uncovered the novel mechanism of DRD2 protein degradation and shown that the KBTBD6/7-DRD2 axis regulates PA sensitivity to DA treatment. KBTBD6/7 may thus become a promising therapeutic target for pituitary tumors.

Transfer Learning for Wireless Fingerprinting Localization Based on Optimal Transport.

Wireless fingerprinting localization (FL) systems identify locations by building radio fingerprint maps, aiming to provide satisfactory location solutions for the complex environment. However, the radio map is easy to change, and the cost of building a new one is high. One research focus is to transfer knowledge from the old radio maps to a new one. Feature-based transfer learning methods help by mapping the source fingerprint and the target fingerprint to a common hidden domain, then minimize the maximum mean difference (MMD) distance between the empirical distributions in the latent domain. In this paper, the optimal transport (OT)-based transfer learning is adopted to directly map the fingerprint from the source domain to the target domain by minimizing the Wasserstein distance so that the data distribution of the two domains can be better matched and the positioning performance in the target domain is improved. Two channel-models are used to simulate the transfer scenarios, and the public measured data test further verifies that the transfer learning based on OT has better accuracy and performance when the radio map changes in FL, indicating the importance of the method in this field.

Use of Bacillus-siamensis-inoculated biochar to decrease uptake of dibutyl phthalate in leafy vegetables.

Dibutyl phthalate (DBP) is a frequently detected farmland contaminant that is harmful to the environment and human health. In this study, a DBP-degrading endophytic Bacillus siamensis strain T7 was immobilized in rice husk-derived biochar for bioremediation of DBP-polluted agricultural soils. The effects of this microbe-biochar composite on the soil prokaryotic community and the mechanism by which it regulates DBP degradation, were also investigated. A supplement of T7-biochar composite not only significantly boosted DBP biodegradation in soil by raising the DBP degradation rate constant and half-life from 0.1979 d-1 and 2.3131 d to 0.2434 d-1 and 2.1062 d, respectively, but also impeded DBP uptake by leafy vegetables. The general bioremediation effect of T7-biochar alliance excelled pure T7 suspensions and biochar, by trapping more DBP and boosting its complete degradation in soil. Besides, the combination of strain T7 and biochar can increase the proportion of some beneficial bacteria and boost the functional diversity of soil prokaryotic community, then to a certain extent may reverse the negative effect of DBP pollution on the agricultural soils. These results indicate that the rice-husk-derived biochar is a proper media when utilizing functional microbes into environmental treatment. Overall, T7-biochar composite is a promising soil modifier for soil bioremediation and the production of DBP-free crops.

Major factors dominating the fate of dibutyl phthalate in agricultural soils.

Dibutyl phthalate (DBP) is a ubiquitous soil contaminant. We have investigated the sorption, degradation and residue of DBP in 20 types of agricultural soils and aimed to identify the major soil properties that dominate the fate of DBP. Sorption isotherms of DBP in all soils were fitted well with the Freundlich model. The sorption coefficient (Kf) varied between 3.99 and 36.1 mg1-1/nL1/n/kg. Path analysis indicated that 59.9% of variation in Kf could be explained by the combination of pH, organic carbon (OC) and clay content. Degradation of DBP in the 20 soils was well described by the first-order kinetic model, with half-lives (t1/2) ranging from 0.430 to 4.99 d. The residual DBP concentration after 60 d of incubation (R60) ranged from 0.756 to 2.15 mg/kg and the residual rates ranged from 3.97% to 9.63%. The Kf value was significantly positively correlated with t1/2 and R60. Moreover, soil pH, microbial biomass carbon (Cmic) and OC were identified as dominating factors that explained 84.4% of variation in t1/2. The R60 data indicated 72.2% of its variability attributable to the combination of OC and Cmic. The orders of the relative importance of dominating factors on the Kf, t1/2 and R60 were OC > pH > clay, Cmic > pH > OC and OC > Cmic, respectively. This work contributes to better understand the fate of DBP in soils and make scientific decisions about accelerating its dissipation in different soils.

Uptake, translocation and subcellular distribution of pesticides in Chinese cabbage (Brassica rapa var. chinensis).

The extensive application of pesticides in agricultural activities has raised increasing concerns on crop contamination by pesticide residues. Vegetables seem more susceptible to pesticide contamination given the high-intensive application of pesticides during their entire growth, while information about transfer and cell diffusion characteristics of pesticides in vegetables is currently insufficient. Here, we investigated the uptake, translocation and subcellular distribution behaviors of four commonly used pesticides in Chinese cabbage (Brassica rapa var. chinensis) under laboratory hydroponic conditions. Root uptake of pesticides followed the order of fenbuconazole > avermectin > thiamethoxam > spirotetramat. Thiamethoxam was more readily to be translocated from vegetable root to shoot, while spirotetramat, fenbuconazole and avermectin preferentially accumulated in vegetable root. Cell soluble components were the dominant storage compartment for thiamethoxam. The majority of spirotetramat, fenbuconazole and avermectin were partitioned into the cell walls. Hopefully, results of this study would extend the current knowledge of pesticide bioconcentration behavior in food-crops and assist in properly evaluating the threats of pesticide residues to human health via food chain.