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Hydrogen sulfide (H2S), an emerging gas transmitter, has been shown to be involved in multiple intracellular physiological and biochemical processes. In this study, the effects of hydrogen sulfide coupled with calcium on cadmium removal and resistance in Phanerochaete chrysosporium were examined. The results revealed that H2S enhanced the uptake of calcium by P. chrysosporium to resist cadmium stress. The removal and accumulation of cadmium by the mycelium was reduced by H2S and Ca2+ pretreatment. Moreover, oxidative damage and membrane integrity were alleviated by H2S and Ca2+. Corresponding antioxidative enzyme activities and glutathione were also found to positively respond to H2S and Ca2+, which played an important role in the resistance to cadmium-induced oxidative stress. The effects of hydroxylamine (HA; a hydrogen sulfide inhibitor) and ethylene glycol-bis-(2-aminoethylether)-N,N,N′,N′-tetraacetic acid (EGTA; a calcium chelator) toward H2S and Ca2+ and their cross-interactions confirmed the positive roles and the potential crosstalk of H2S and Ca2+ in cadmium stress resistance. These findings imply that the protective effects of H2S in P. chrysosporium under cadmium stress may occur through a reduction in the accumulation of cadmium and promotion of the antioxidant system, and the H2S-regulated pathway may be associated with the intracellular calcium signaling system. Key points • Altered monoterpenoid tolerance mainly related to altered activity of efflux pumps. • Increased tolerance to geranic acid surprisingly caused by decreased export activity. • Reduction of export activity can be beneficial for biotechnological conversions.

Chemokines are important regulators of the immune system, inducing specific cellular responses by binding to receptors on immune cells. In SLE patients, decreased expression of CCL2 on mesenchymal stem cells (MSC) prevents inhibition of B-cell proliferation, causing the characteristic autoimmune phenotype. Nevertheless, the intrinsic role of CCL2 on B-cell autoimmunity is unknown. In this study using Ccl2 KO mice, we found that CCL2 deficiency enhanced BCR signaling by upregulating the phosphorylation of the MST1-mTORC1-STAT1 axis, which led to reduced marginal zone (MZ) B cells and increased germinal center (GC) B cells. The abnormal differentiation of MZ and GC B cells were rescued by in vivo inhibition of mTORC1. Additionally, the inhibition of MST1-mTORC1-STAT1 with specific inhibitors in vitro also rescued the BCR signaling upon antigenic stimulation. The deficiency of CCL2 also enhanced the early activation of B cells including B-cell spreading, clustering and signalosome recruitment by upregulating the DOCK8-WASP-actin axis. Our study has revealed the intrinsic role and underlying molecular mechanism of CCL2 in BCR signaling, B-cell differentiation, and humoral response.

In the original published version of the article, the red squares in the figures which indicated the corrections.

As an important chemokine receptor, the role of CX3CR1 has been studied extensively on the migration of lymphocytes including T and B cells. Although CX3CR1+ B cells have immune suppressor properties, little is known about its role on the regulation of BCR signaling and B cell differentiation as well as the underlying molecular mechanism. We have used CX3CR1 KO mice to study the effect of CX3CR1 deficiency on BCR signaling and B cell differentiation. Interestingly, we found that proximal BCR signaling, such as the activation of CD19, BTK and SHIP was reduced in CX3CR1 KO B cells upon antigenic stimulation. However, the activation of mTORC signaling was enhanced. Mechanistically, we found that the reduced BCR signaling in CX3CR1 KO B cells was due to reduced BCR clustering, which is caused by the enhanced actin accumulation by the plasma membrane via increased activation of WASP. This caused an increased differentiation of MZ B cells in CX3CR1 KO mice and an enhanced generation of plasma cells (PC) and antibodies. Our study shows that CX3CR1 regulates BCR signaling via actin remodeling and affects B cell differentiation and the humoral immune response.

Due to the biomagnifying effect in the food chains, heavy metals will cause serious harm to the food produced in paddy soil, and then threaten human health. The remediation of soil heavy metals by the addition of amendments is a common method. However, the combination of the two amendments has been less studied and its effect is unknown. In this study, we investigated the effects of different concentrations of a lime and calcium-magnesium phosphate (CMP) amendments metal availability and paddy soil bacteria biodiversity. The experiment proves that the addition of 0.5 and 1.0‰ amendment can effectively reduce cadmium (Cd) availability and the cadmium content in rice to be below 0.2 mg/kg, meeting the national food safety level. The results demonstrate that increasing pH and phosphorous (P) in soil were two important factors decreasing available cadmium. Furthermore, biodiversity analysis of the treated soil showed that the amendment increased biodiversity. Proteobacteria and Chloroflex were the most abundant bacteria at the phylum level, followed by Acidobacterium and Nitrospirae. The abundance of Bacterodietes-vadinHA17, Syntrophaceae, and Thiobacillus increased as phosphorous increased. Cadmium passivation might induce those species.

Sanguinarine has strong inhibitory effects against the cyanobacterium Microcystis aeruginosa. However, previous studies were mainly limited to laboratory tests. The efficacy of sanguinarine for mitigation of cyanobacterial blooms under field conditions, and its effects on aquatic microbial community structure remain unknown. To elucidate these issues, we carried out in situ cyanobacterial bloom mitigation tests. Our results showed that sanguinarine decreased population densities of the harmful cyanobacteria Microcystis and Anabaena. The inhibitory effects of sanguinarine on these cyanobacteria lasted 17 days, after which the harmful cyanobacteria recovered and again became the dominant species. Concentrations of microcystins in the sanguinarine treatments were lower than those of the untreated control except during the early stage of the field test. The results of community DNA pyrosequencing showed that sanguinarine decreased the relative abundance of the prokaryotic microorganisms Cyanobacteria, Actinobacteria, Planctomycetes and eukaryotic microorganisms of Cryptophyta, but increased the abundance of the prokaryotic phylum Proteobacteria and eukaryotic microorganisms within Ciliophora and Choanozoa. The shifting of prokaryotic microbial community in water column was directly related to the toxicity of sanguinarine, whereas eukaryotic microbial community structure was influenced by factors other than direct toxicity. Harmful cyanobacteria mitigation efficacy and microbial ecological effects of sanguinarine presented in this study will inform the broad application of sanguinarine in cyanobacteria mitigation.

Chitosan-stabilized FeS magnetic (MC-FeS) composites were successfully prepared to address the easily oxidization of FeS and enhance Cr(VI) removal from water. Results showed that the MC-FeS composites enhanced the Cr(VI) removal capacity as compared to bare FeS. Further investigation using X-ray photoelectron spectroscopy showed that FeOOH, S8, Cr2O3, Cr2S3, and a Fe(III)-Cr(III) complex were apparently introduced by Cr(VI), Fe(II), and S(−II), respectively. The sorption kinetics could be interpreted using a pseudo-second-order kinetic model, whereas the isotherms were simulated using the Redlich‒Peterson isotherm model indicating Cr(VI) removal by MC-FeS composites was a hybrid chemical reaction‒sorption process. In addition, the MC-FeS composite presented high stability against aging and performed well in a long-term reaction system and typical natural water environment. The effective performance of MC-FeS composites shows their great potential in wastewater remediation contaminated by heavy metals.

In this study, magnetic graphene oxide modified zeolite (Cu-Z-GO-M) composites with two different ratios of GO to zeolite (named Cu-Z-GO-M 1:2 and Cu-Z-GO-M 1:1) were synthesized by solid-state dispersion (SSD) method. The properties of zeolite-based composites were characterized by SEM, XRD, FTIR, XPS, and magnetization curves. In order to understand the pollutant removal performance of the as-prepared composites, methylene blue (MB) was used as the target pollutant in adsorption experiments. The removal efficiency of MB onto Cu-Z-GO-M composite was enhanced obviously with pH > 9. The adsorption capacities of MB onto Cu-Z-GO-M 1:1 were 82.147, 89.315, 97.346 mg/g at 298, 308, and 318 K, respectively. The removal ability of MB increased with the increase of GO content in modified composites. The adsorption behavior can be well described using a pseudo-second-order kinetic and Freundlich isotherm model. The thermodynamic analysis indicated the MB adsorption by Cu-Z-GO-M was a spontaneous and endothermic reaction. The results showed that the prepared Cu-Z-GO-M composite could be a promising adsorbent with good adsorption capacity and reusability for MB removal from wastewater.

Oil spills result in severe environmental pollution and inflict serious ecological damage, which makes the development of facile, low-cost, high-capacity, and sustainable oil absorbents to be a task of high practical significance. In this study, a kaolin-modified hydrophobic melamine sponge (K-MS) was prepared via simple soaking method, which can be applied to clean up oil spills and organic solvents leaks. The properties of the K-MS were characterized by a range of instrumental techniques. The addition of fluorizated kaolin not only endowed commercially available melamine sponge hydrophobic properties and enhanced its adsorption capacity to various oils and organic solvents. The K-MS exhibited the high adsorption capacity (up to 87–194 g/g) and excellent recyclability (>90%). The equilibrium adsorption time was fast within 1 s for diesel. Moreover, the as-prepared sponge adsorption performance was examined in harsh environment, which has remarkable chemical stability and compressive properties. Thus, this study presents a low-cost facile strategy to produce promising absorbent for large-scale oil and organic solvents cleanups and recovery. Furthermore, this approach can be extended to a series of clay minerals in rich source, thus could open up new prospects for design hydrophobic materials to address oil pollution.

In this work, the immobilization of silver nanoparticles on lignosulfonate functionalized kaolin composite (LS-kaolin-Ag) was fabricated by a facile reduction method without additional reductant and stabilizer. Transmission electron microscopy, X-ray powder diffraction, and X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy (FTIR) were used to confirm the successful preparation of LS-kaolin-Ag composite. The catalytic reduction tests on both cationic dye rhodamine B and anionic dye Congo red indicated the high catalytic activities of this as-prepared LS-kaolin-Ag composite. Meanwhile, this catalyst showed good recyclability for dye decolorization with just a little decrease of conversion percent in five successive reactions. These results suggest that LS-kaolin-Ag composite as an efficient and cost-effective catalyst shows great application potential for the decolorization of various organic dyes.

Microcystis aeruginosa has several morphological and physiological traits that frequently enable it to dominate in eutrophic waters. Sanguinarine is a promising algaecide of biological origin that ...

To explore the approach for further enhancing the dye removal performance of polydopamine (PDA) coated materials, a novel composite of PDA-kaolin with reduced graphene oxide hybridization (PDA-rGO-kaolin) was synthesized and selected as a model adsorbent for methylene blue (MB) removal. The BET characteristic analysis showed that the introduction of rGO significantly increased the surface area of PDA-kaolin by 3.1 times. A series of comparative experiments on PDA-kaolin and PDA-rGO-kaolin towards MB removal in various conditions were carried out. Adsorption experiment indicated that PDA-rGO-kaolin was more satisfactory for MB removal. Kinetic analysis showed that the adsorption followed a pseudo-second-order kinetic model. The adsorption behavior could be better described by Langmuir isotherm model. Compared with PDA-kaolin, PDA-rGO-kaolin showed higher maximum adsorption capacity towards MB (39.663 mg/g). Furthermore, the adsorption of MB molecules on adsorbents was spontaneous and endothermic process according to thermodynamic experiment. Moreover, PDA-rGO-kaolin showed a good regeneration performance for MB removal. These results show that the introduction of graphene is a feasible and efficient method to improve the adsorption performance of PDA coated kaolin composite.

Microcystis aeruginosa frequently forms cyanobacterial blooms in eutrophic water bodies, resulting in high concentrations of extracellular polymeric substances (EPS) in the water column. The effects of M. aeruginosa EPS (MA-EPS) on the adsorption behavior of Cu(II) onto kaolinite and the possible mechanisms were investigated in this study. The results of potentiometric titration and Fourier transform infrared (FT-IR) spectroscopy determination show that carboxyl, phosphoryl and amino/hydroxyl groups were the main adsorption groups on MA-EPS. The combination of EPS with kaolinite created new adsorption sites. MA-EPS increased the adsorption of Cu(II) by kaolinite mainly through complexation. The adsorption kinetics of Cu(II) by kaolinite or kaolinite + EPS composite (Kao + EPS) was well fitted by a pseudo-second order kinetic model. The adsorption isotherm analyses show that the incorporation of MA-EPS onto kaolinite increased its surface heterogeneity. Rather than intercalating into the kaolinite interlayers, MA-EPS and/or Cu(II) were adsorbed onto the surface of this clay.

Sixteen treatments of soil contaminated by Cu, Pb, and Zn by the addition of a different percentage of biochar and compost were incubated for 120 days. The abundance of denitrifying genes such as narG, nirK, nirS and nosZ and the ammonia-oxidizing amoA genes of ammonia-oxidizing archaea/bacteria (AOA/AOB), soil nitrite reductase activity (S-NiR) and their shaping factors were also determined. The relationships between functional genes, S-NiR, and physico-chemical parameters were analyzed using the Pearson correlation method. The study found that the changes in physico-chemical parameters, including water-soluble organic carbon (WSC), nitrate (NO3−) and ammonium (NH4+), were predominant in different treatments. The abundance of nirK and narG genes is most sensitive to the changes in the properties of the soil sample. Bacterial 16S rDNA gene abundance was significantly affected by NO3− and S-NiR (P

In recent years, 2, 5-furandicarboxylic acid (FDCA) has attracted much attention as the precursor of bio-polyester materials. A coupled process of ultrasonic-assisted dilute acid pretreatment and MnO2 was designed in this study to directly produce FDCA from lignocellulosic biomass, which is different from the traditional preparation process. Moreover, the critical parameters in the process were analyzed and optimized by the response surface method. The yield of FDCA could reach 52.1% under the optimal conditions. The reaction mechanism indicated that heavy metal elements in lignocellulosic biomass could play the role of the Lewis acid catalyst to promote the formation of FDCA to a certain extent. With the increase of temperature, the heavy metals transfer in biomass from the solid phase to the liquid phase increased, but most of them remain in the former. Therefore, further purification and treatment measures are worthy of attention.

This study presents a one-step synthetic approach for magnetic biochar (MBC) photo-degradation of diethyl phthalate (DEP). The results showed that MBC exhibited better catalytic property for DEP degradation than BC, and its catalytic performance was influenced by the amount of Fe doping. Electron paramagnetic resonance (EPR), quenching experiments, and chemical probe studies confirmed the presence of persistent free radicals (PFRs), hydroxyl radicals (·OH), and superoxide anion radical (·O2-) in both of BC and MBC. Solar light promoted the formation of PFRs in BC system, which transferred electrons to oxygen to form ·O2-, thus yielding ·OH. On the other hand, electron transfer occurred between PFRs and Fe3+ for MBC, Fe2+ played an important role in activation of O2 and ·O2- production. Subsequently, photo-Fenton reaction was primarily responsible for ·OH formation. This work compared the different generation pathways for ROS between BC and MBC and provides new insight into the possible mediatory roles of BC in O2 activation under solar light by transition metals.

As an aliphatic amino acid, cysteine (CYS) is diffuse in the living cells of plants and animals. However, little is known of its role in the reactivity of nano-sized zero-valent iron (NZVI) in the degradation of pollutants. This study shows that the introduction of CYS to the NZVI system can help improve the efficiency of reduction, with 30% more efficient degradation and a reaction rate constant nine times higher when nitrobenzene (NB) is used as probe compound. The rates of degradation of NB were positively correlated with the range of concentrations of CYS from 0 to 10 mmol/L. The introduction of CYS increased the maximum concentration of Fe(III) by 12 times and that of Fe(II) by four times in this system. A comparison of systems featuring only CYS or Fe(II) showed that the direct reduction of NB was not the main factor influencing its CYS-stimulated removal. The reduction in the concentration of CYS was accompanied by the generation of cystine (CY, the oxidized form of cysteine), and both eventually became stable. The introduction of CY also enhanced NB degradation due to NZVI, accompanied by the regeneration of CYS. This supports the claim that CYS can accelerate electron transfer from NZVI to NB, thus enhancing the efficiency of degradation of NB.

Quinclorac (3,7-dichloroquinoline-8-carboxylic acid, QNC) is a highly selective auxin herbicide that is typically applied to paddy rice fields. Its residue is a serious problem in crop rotations. In this study, Oryza sativa L. seedlings was used as a model plant to explore its biochemical response to abiotic stress caused by QNC and nZVI coexposure, as well as the interactions between QNC and nZVI treatments. Exposure to 5 and 10 mg/L QNC reduced the fresh biomass by 26.6% and 33.9%, respectively, compared to the control. The presence of 50 and 250 mg/L nZVI alleviated the QNC toxicity, but the nZVI toxicity was aggravated by the coexist of QNC. Root length was enhanced upon exposure to low or medium doses of both QNC and nZVI, whereas root length was inhibited under high-dose coexposure. Both nZVI and QNC, either alone or in combination, significantly inhibited the biosynthesis of chlorophyll, and the inhibition rate increased with elevated nZVI and QNC concentration. It was indicated that nZVI or QNC can affect the plant photosynthesis, and there was a significant interaction between the two treatments. Effects of QNC on the antioxidant response of Oryza sativa L. differed in the shoots and roots; generally, the introduction of 50 and 250 mg/L nZVI alleviated the oxidative stress (POD in shoots, SOD and MDA in roots) induced by QNC. However, 750 mg/kg nZVI seriously damaged Oryza sativa L. seedlings, which likely resulted from active iron deficiency. QNC could be removed from the culture solution by nZVI; as a result, nZVI suppressed QNC uptake by 20%–30%.

Carbon nanotubes can interact with proteins or enzymes upon penetration into cell membranes of living organisms that may affect the protein-protein interactions in vivo. Here, three structural models composed of four-chain esterase from Hungatella hathewayi with and without pristine or carboxylated single-walled carbon nanotube (SWCNT) are constructed to investigate the changes in protein-protein interactions and SWCNT orientations by molecular dynamics simulations. The results show that the protein-protein interact very tightly to protect them from the separation by the carboxylated or pristine SWCNTs, as shown by the calculations of binding affinity and the distances between the centers of mass of different protein chains. Both pristine and carboxylated SWCNTs cause structural changes in the esterase. In addition, functionalization (e.g., carboxylation) can regulate the SWCNT orientation when positioned near the esterase.

Background AKT2 is one of the key molecules that involves in the insulin-induced signaling and the development of cancer. In B cells, the function of AKT2 is unclear. Methods In this study, we used AKT2 knockout mice model to study the role of AKT2 in BCR signaling and B cell differentiation. Results AKT2 promotes the early activation of B cells by enhancing the BCR signaling and actin remodeling. B cells from AKT2 KO mice exhibited defective spreading and BCR clustering upon stimulation in vitro. Disruption of Btk-mediated signaling caused the impaired differentiation of germinal center B cells, and the serum levels of both sepecific IgM and IgG were decreased in the immunized AKT2 KO mice. In addition, the actin remodeling was affected due to the decreased level of the activation of WASP, the actin polymerization regulator, in AKT2 KO mice as well. As a crucial regulator of both BCR signaling and actin remodeling during early activation of B cells, the phosphorylation of CD19 was decreased in the AKT2 absent B cells, while the transcription level was normal. Conclusions AKT2 involves in the humoral responses, and promotes the BCR signaling and actin remodeling to enhance the activation of B cells via regulating CD19 phosphorylation.

In this work, a facile and cost-effective method was reported to fabricate a novel, robust, and superhydrophobic kaolinite modified graphene oxide-melamine sponge (K-GOMS). The GO sheets were used to increase the roughness of the sponge smooth surface. The hydrophobic kaolinite adhered on GO sheets significantly enhanced the superhydrophobicity of the K-GOMS surface with a water contact angle of 152.3°. Several organic solvents and oils were selected to test the adsorption performance of the obtained adsorbents. The results revealed that the superhydrophobic K-GOMS exhibited not only superior adsorption capacity for various organic solvents and oils, from 60 to 113 times of its own weight, but also outstanding recyclability with an adsorption capacity retention higher than 94% after 30 cycles of diesel oil adsorption, and excellent environmental tolerance in wide range of pH values and temperatures. Therefore, this study provides an effective way for constructing facile, low-cost, and large-scale production of superhydrophobic adsorbents for oil-water separation.

Toxicity effects of silver nanoparticles (AgNPs) on the freshwater bivalve Corbicula fluminea (C. fluminea) were investigated through experiments. In this study, C. fluminea promoted the sedimentation of AgNPs and affected the fate and transformation of AgNPs. A series of biomarkers of C. fluminea in vivo were evaluated after 14 days exposure to various doses (0–2 mg L−1) of polyvinyl pyrrolidone (PVP) coated AgNPs. The levels of antioxidants increased obviously in 2 mg L−1 AgNPs treatments to protect C. fluminea from oxidative damage. Glutathione peroxidase (GPx) and glutathione (GSH) played important roles in tissues detoxification in 0.1 and 0.5 mg L−1 exposure, respectively. The biological behaviors (feeding rate, ammonia excretion rate) were inhibited at 0.1 mg L−1, inducted at 0.5 mg L−1, and inhibited again at 2 mg L-1 AgNPs, which indicated that AgNPs influenced the physiological metabolism of C. fluminea. Ag contents in tissue and shell of C. fluminea were much higher than blank groups. In addition, in vivo tissues were more sensitive to low AgNPs concentration compared with shells, indicating that C. fluminea could be used as a good indicator for AgNPs freshwater pollution. No Ag was detected in feces probably implying that nanoparticles had long gut retention time in C. fluminea. Overall, this study reveals the interactions between AgNPs and C. fluminea and provides important implications about the fate and toxicity of AgNPs in natural aquatic environment.

In this study, graphene oxide modified kaolin (GO-kaolin) composites (named 2% GK, 5% GK, and 10% GK) were synthesized by a facile method. Characterization results indicated the successful modification of GO on kaolin surface. To understand the dye removal performance of kaolin with GO modification, batch adsorption experiments were carried out using methylene blue (MB) as a model dye pollutant in various experimental conditions The adsorption results showed that the increase of GO content in modified kaolin composite could effectively enhance the removal of MB from aqueous solution in each experiment condition, which was attributed to the increase of special surface area and active adsorption sites. Kinetic analysis of MB adsorption by GO-kaolin samples was shown a better fitting to pseudo-second-order kinetic models. The adsorption isotherm data were better fitted to Langmuir isotherm models. The values of thermodynamics constants suggested that the adsorption reaction was endothermic in nature. Furthermore, adsorption process of MB on kaolin was changed after the introduction of GO. An excellent regeneration performance of 10% GK was observed via the regeneration experiment. The results show that kaolin modified with suitable GO content is a high-efficiency and reusable adsorbent in the removal of MB from wastewater.

In this work, P. chrysogenum strain F1-ferrihydrite composites (PFC) were applied to the bioremediation of polluted mimic wastewater with high concentration (50–500 mg/L) of arsenic. An interesting phenomenon was discovered that the PFC was formed in situ in the process of removal of As(III), which can greatly improve their practical application in separation and reutilization. The results showed that optimum removal efficiency achieved 81.23% for As(III) at an initial concentration of 100 mg/L that also could be up to 75.00% at 200 mg/L with composite sorbent PFC. According to the adsorption isotherms and kinetics experiments, the adsorption reaction included both physical adsorption and chemical adsorption. The formation of composite PFC significantly promoted the sorption of As(III) ion between biomass and ferrihydrite from aqueous. The adsorption rates and capacities for arsenic were both enhanced markedly than biomass and ferrihydrite individually as well. Adsorption-desorption experiment indicated PFC maintained to a dominant with 74.47% of removal efficiency over 3 cycles. This research demonstrated that PFC has great potential in removing high concentration of As(III) from wastewater.

The Mg/Al layered double hydroxide (Mg/Al-LDH) intercalated with the [Formula: see text] (MoS4-LDH) impregnated into poly(acrylamide-co-sodium acrylate) (PP) was synthesized as layered double hydroxides-PP (LDHS-PP), whose characterization, adsorption properties and mechanisms were investigated. The maximum adsorption capacity (qm) for Cd(II) was ∼2789.58 mg/g by 1% LDHS-PP, while it was ∼1893.09 mg/g by PP, which indicated that the MoS4-LDH greatly improved the Cd(II) uptake for PP in aqueous solution. In strongly acidic conditions (∼pH 3.0), there was still a good removal efficiency of about 45.65% by the 1% LDHS-PP, while that of PP was almost zero. At pH 5.0 the removal efficiency increased to 85.17% by the 1% LDHS-PP. The sorption kinetics for the 1% LDHS-PP was described well by a pseudo-second-order kinetic model. X-ray photoelectron spectrometry (XPS) and elemental distribution maps further confirmed the presence of MoS4-LDH in the PP and most of the Cd(II) chemisorption based on the Cd-S bonding. Due to its high removal efficiency and acid resistance, LDHS-PP is a promising in-situ fixation agent for the remediation of agricultural soil polluted with Cd(II) at low pH.

Potential transformations of silver nanoparticles (AgNPs) upon interaction with naturally ubiquitous organic ligands in aquatic environments influence their transport, persistence, bioavailability, and subsequent toxicity to organisms. In this study, differential behaviors of AgNPs and silver ions (Ag+) towards cysteine (Cys), an amino acid representative of thiol ligands that easily coordinate to Ag+ and graft to nanoparticle surfaces, were investigated in the aspects of bioremediation and their toxicity to Phanerochaete chrysosporium. Total Ag removal, 2,4-dichlorophenol (2,4-DCP) degradation, extracellular protein secretion, and cellular viability were enhanced to some extent after supplement of various concentrations of cysteine under stress of AgNPs and Ag+. However, an obvious decrease in total Ag uptake was observed after 5–50 μM cysteine addition in the groups treated with 10 μM AgNPs and 1 μM Ag+, especially at a Cys:Ag molar ratio of 5. More stabilization in uptake pattern at this ratio was detected under Ag+ exposure than that under AgNP exposure. Furthermore, in the absence of cysteine, all Ag+ treatments stimulated the generation of reactive oxygen species (ROS) more significantly than high-dose AgNPs did. However, cysteine supply under AgNP/Ag+ stress aggravated ROS levels, albeit alleviated at 100 μM Ag+, indicating that the toxicity profiles of AgNPs and Ag+ to P. chrysosporium could be exacerbated or marginally mitigated by cysteine. The results obtained were possibly associated with the lability and bioavailability of AgNP/Ag+-cysteine complexes.

This study investigated the influence of silver ions (Ag + ) on the cytotoxicity of silver nanoparticles (AgNPs) in Phanerochaete chrysosporium and noted the degree of extracellular secretions in response to the toxicant's stress. Oxalate production was elicited with moderate concentrations of 2,4-dichlorophenol (2,4-DCP) and AgNPs reaching a plateau at 10 mg/L and 10 μM, respectively. Increased oxalate accumulation was accompanied by higher activities of manganese peroxidase (MnP) and lignin peroxidase (LiP). However, the secretion of oxalate, MnP and LiP was significantly inhibited owing to Ag + incorporation into AgNP solution. Production of extracellular polymeric substances (EPS) significantly elevated with an increase in 2,4-DCP concentrations; however, after 24 h of exposure to 100 mg/L 2,4-DCP, an obvious decrease in EPS occurred, indicating that part of EPS could be consumed as carbon and energy sources to ameliorate biological tolerance to toxic stress. Furthermore, AgNP-induced “particle-specific” cytotoxicity was substantially enhanced with additional Ag + as evidenced by its significant negative impact on cellular growth, plasma membrane integrity, and morphological preservation compared with AgNPs at equal Ag concentration.

Although humic acid (HA) plays an important role in the fate and transport of nanoparticles in subsurface environments, the roles of specific fractions of HA in the transport of nanoparticles are still not well understood. In this study, quantum dots (QDs) with carboxyl and amino modifications (QD–COOH and QD–NH2) were used as typical nanoparticles to understand the effects of molecular weight (MW) fractionated humic acid (Mf-HA) on the transport and retention behaviour of nanoparticles. Transport experiments on QDs were performed both in the absence and presence of pristine- and Mf-HA in both NaCl and CaCl2 solutions at pH 7.0. The Mf-HA had distinct effects on the transport and retention behavior of QDs, which were highly dependent on the MW of the Mf-HA. In addition, the surface coating of the QDs and cation types also showed significant effects on the transport behavior of QDs. In NaCl solution, the transport of QD–NH2 was dramatically enhanced in the presence of pristine- and Mf-HA, and the high MW Mf-HA (>100 kDa and 30–100 kDa) could enhance the mobility of the QDs more significantly than the low MW Mf-HA (10–30 kDa, 3–10 kDa, and

Dissolved organic matter (DOM) originated from livestock manure often co-exists with cadmium ion (Cd) in livestock effluent. However, the effects of DOM on removal efficiency of Cd by adsorbent remain unknown. This study investigated the effects of DOM originated from cattle manure on adsorption behaviors of Cd by periphyton, and the possible mechanisms were also explored through desorption analyses, Fourier transform infrared spectroscopy (FTIR) determination, and histochemical staining. The adsorption kinetics and isotherm of Cd by periphyton could be explained by pseudo-second-order model and Freundlich model, respectively. DOM addition did not change the adsorption kinetics and isotherm of periphyton toward Cd, but it decreased the adsorption capacity of Cd by periphyton. Ion exchange and complexation were the main binding forces for the adsorption of Cd by periphyton, while the adsorption of Cd by DOM mainly through complexation. Amide and hydroxyl in the DOM were involved in its adsorption toward Cd, and may contribute to the competition for Cd with periphyton. Thus, the decrease of DOM concentration in livestock effluent is helpful to remove Cd by periphyton adsorption.

Heavy metal passivators could reduce the transfer of heavy metal ions from soil to crops and exhibit great potential in safe cropping in heavy metal contaminated agricultural soils. However, the effects of heavy metal passivators on microbial diversity and microorganisms-based biogeochemical processes in agricultural soil are poorly explored. In this study, the effects of three heavy metal passivators, viz. lime, silicon (Si) fertilizer, and gypsum, on the structure and function of microorganisms in cadmium (Cd) contaminated paddy soils were investigated through activity of soil enzyme, microbial abundance and community structure by an in situ paddy field plot experiment. Our results showed that lime application changed the activity of phosphatase and urease through increasing bio-available phosphorus (AP) content in soil and soil pH, respectively. Lime application increased abundance and richness of the prokaryotic microbes in paddy soil, while gypsum application increased evenness of the eukaryotic microbes. Si fertilizer application resulted in the increase of evenness of both prokaryotic and eukaryotic microbes. The results presented in this study suggest that application of heavy metal passivator lime, Si fertilizer, and gypsum could improve microbial diversity and function in Cd contaminated paddy soil.

The extensive use of neonicotinoid pesticides in the past two decades caused serious impacts on many kinds of living beings. Therefore, it has been strongly suggested to detoxify and eliminate neonicotinoids’ residual levels in environment. Here, the degradation and detoxification of thiamethoxam (THX) by white-rot fungus Phanerochaete chrysosporium was conducted. Results shown that P. chrysosporium can tolerate THX and degraded 49% of THX after incubation for 15 days, and then 98% for 25 days at the initial concentration of 10 mg/L, which indicates the excellent degradation ability of this fungus to THX. Based on the by-products identified, THX underwent dechlorination, nitrate reduction, and C–N cleavage between the 2-chlorothiazole ring and oxadiazine. (Z)-N-(3-methyl-1,3,5-oxadiazinan-4-ylidene)nitramide and 3-methyl-1,3,5-oxadiazinan-4-imine were identified as the main metabolites. The impacts of THX and its corresponding degradation intermediates on the growth of E. coil and Microcystis aeruginosa as well as the germination of rape and cabbage demonstrated that P. chrysosporium effectively degrades THX into metabolites and reduces its biotoxicity. The present work demonstrates that P. chrysosporium can be effectively used for degradation and detoxification of THX.

Being that the influence of organic ligands on contaminant removal by nanoscale zero valent iron (nZVI) has been explored in quite a few studies, there is little information on reaction mechanisms of the ZVI-ligand system under different aeration conditions. The degradation of nitrobenzene (NB) by nZVI-oxalic acids (OA) was investigated under N2, O2 and without aeration conditions. From the findings, it was evident that OA dramatically improved NB degradation by nZVI with all of the aeration conditions. Approximately 100% of NB was degraded by nZVI-OA+N2 system after 60 min of reaction, followed in effectiveness by nZVI-OA+ without aeration (95%) as well as nZVI-OA+O2 (85%). Operation parameters including OA concentration and pH had significant effect on the removal of NB in the nZVI-OA system. 3 mM OA concentration and pH 3.0 were found to be favourable. The Fe2+, total dissolved iron concentrations, pH and ORP values in the nZVI-OA systems had also been monitored. Intermediates and trapping experiments showed that reduction played a fundamental role in the NB degradation by nZVI-OA under N2 or without aeration conditions. The formation of Fe(OA)0 and Fe(OA)22− complexes had lower standard ORP, which could improve the strength of reductant in the systems, and thus resulting in an increased degradation efficiency of NB by nZVI-OA+N2. Under O2 aeration condition, the NB degradation process could be regarded as an oxidation. In the meantime, OA promoted the production of reactive oxidants species by speeding up the oxidation rates of Fe2+ by O2 and H2O2. Summarily, the improved reactivity of nZVI was largely as a result of the strong complexation ability of OA.

The growing potential of quantum dots (QDs) in biomedical applications has raised considerable concerns regarding their toxicological impact. Consequently, there has been a need to understand the underlying toxicity mechanism of QDs. In this work, we comprehensively investigated the bioaccumulation and toxicity of three CdSe/ZnS QDs (COOH CdSe/ZnS 525, NH2 CdSe/ZnS 525, and NH2 CdSe/ZnS 625) in Phanerochaete chrysosporium (P. chrysosporium) using confocal laser scanning microscopy, reactive oxygen species (ROS) measurements, and cell viability assays. Confocal laser scanning microscopy analytical results indicated that all the CdSe/ZnS QDs, with the concentration ranging from 10 to 80nM, could accumulate largely in the hyphae and induce the generation of ROS, showing a direct toxicity to P. chrysosporium. And the bioaccumulation and toxicity of CdSe/ZnS QDs presented dose-dependent and time-dependent effects on P. chrysosporium. Furthermore, the CdSe/ZnS QDs-induced cytotoxicity was also related to their physicochemical properties, including particle size and surface charges: NH2 CdSe/ZnS 525 with small size was more cytotoxic as compared to NH2 CdSe/ZnS 625 with large size, and the smaller negative charged NH2 CdSe/ZnS 525 resulted in greater cytotoxicity than the larger negative charged COOH CdSe/ZnS 525. The obtained results provide valuable information for exploring and understanding of toxicity mechanism of QDs in living cells.

Biologically derived algicidal substances are regarded as environmentally friendly in the control of harmful cyanobacterial blooms. To evaluate the possible control of Microcystis-based water blooms using fruit from Macleaya cordata (MC-fruit), the effects of MC-fruit on the growth, polyphasic chlorophyll fluorescence transients, microcystin production and efficacy of in situ cyanobacterial bloom removal were investigated. The results showed that MC-fruit could effectively inhibit the growth of M. aeruginosa PCC7806 at a concentration of 1 mg l−1. MC-fruit stress caused severe damage to photosynthesis of M. aeruginosa and decreased the content of cellular microcystin-LR. The results of an in situ field test showed that MC-fruit effectively reduced the biomass of Microcystis and improved water quality. Accordingly, MC-fruit may be a useful biologically derived algicide for cyanobacterial bloom control.

Red mud and compost are two inexpensive and effective materials available for the in situ treatment of soil contaminated with heavy metals. In order to investigate the specific process involved, a detailed analysis of the synergistic effects of combined red mud and compost was carried out. The efficiency of three different treatment systems, namely compost (C), red mud (R), and a mixture of compost and red mud (R + C), on the movability, ecological risk, and biological effective Cu, Zn, Cd, and Pb over time of incubation in agricultural soil was evaluated. Results showed that the pH, water extractable organic carbon (WEOC) and total organic carbon (TOC) showed significant changes after addition of these amendment materials to the target soil. The combination of red mud and compost mixture as amendment material (R + C) resulted in the largest reduction in efficiency of the available heavy metals. In addition, the microbial biomass in the treated soil increased after addition of the amendment materials, highest increase was observed with R + C. The results indicate that these amendment materials, especially R + C could lower the ecological risk of heavy metals in soil.

Biochar and compost have been widely used for pollution remediation of heavy metals in soil. However, little research was conducted to explore the efficiency of biochar, compost and their combination to reduce heavy metals availability, and the effects of their additive on soil biological properties are often neglected. Therefore, this study investigated the effects of biochar, compost and their combination on availability of heavy metals, physicochemical features and enzyme activities in soil. Results showed that adding amendments to polluted soil significantly altered soil properties. Compared to the separate addition of biochar or compost, their combined application was more effective to improve soil pH, organic matter (OM), organic carbon (TOC) and available potassium (AK). All amendments significantly decreased the availability of Cd and Zn, but slightly activated As and Cu. In addition, soil enzyme activities were activated by compost and inhibited by biochar, but exhibited highly variable responses to their combinations. Pearson correlation analysis indicated that electrical conductivity (EC) and AK were the most important environmental factors affecting metal availability and soil enzyme activities including dehydrogenase, catalase, β-glucosidase, urease, acid and alkaline phosphatase, arylsulfatase except for protease and invertase. Availability of As, Cu, Cd and Zn affected dehydrogenase, catalase and urease activities. These results indicated that biochar, compost and their combination have significant effects on physicochemical features, metals availability and enzyme activities in heavy metal-polluted soil.

The ecological implications of livestock production intensification have received sustained attention across the globe. Anaerobic digestion is the main process for livestock waste treatment. However, the ecological consequences of dissolved organic matter originating from anaerobic digestion (AD-DOM) in eutrophic water bodies remain elusive. In this study, the physiological responses of a bloom-forming cyanobacterium, Microcystis aeruginosa , to AD-DOM were investigated. Moreover, the composition of AD-DOM was identified by using thermochemolysis followed by gas chromatography–mass spectrometry (GC–MS) analysis. The growth of M. aeruginosa FACHB905 was not sensitive to low levels (0.625–1.25%, V/V) of AD-DOM but was inhibited by high levels (2.5–5%, V/V) of AD-DOM, resulting from photoinhibition damage to photosystem II (PSII). The main target of AD-DOM in PSII was the electron accepting side ( ψ 0 ) or the electron donor side ( φ P 0 ), depending on time variables. The reactive oxygen species (ROS) level showed a positive correlation with AD-DOM addition; however, it was higher than that of the control for 3.75–5% AD-DOM on the 6th day. The intracellular microcystin contents (including MC-LR and Dha 7 -MC-LR) decreased in response to AD-DOM addition, but extracellular microcystin increased after 6 days of exposure. In addition, GC–MS detection showed that AD-DOM is mainly composed of lignin-derived aromatic compounds, alkanes/alkene, nitrogen­containing compounds, and sterols. The results presented in this study suggested that AD-DOM released from the livestock industry may play a subtle role in affecting harmful algal blooms through level-dependent variables. In addition, the ecological consequences of microcystin released by toxin-producing species under AD-DOM stress are still worth considering.

The traditional high-salinity organic wastewater treatment process is cumbersome and costly, and involves an independent process for removing pollutants and salinity. A flow-through coupled system of electro-Fenton and electrosorption processes was designed in this work. The simultaneous purification and desalination of high concentration wastewater were effectively achieved through the cooperation of various electrochemical reactions, which avoids the complex processes of desalination and dilution in advance when treating high-salinity organic wastewater, and the removal performance was improved. The influence of key parameters, including voltage, initial pH, plate spacing, H2O2 concentration, and flow rate, were systematically investigated. The findings show that actual wastewater passing through the coupled system promptly turns to clean water with significantly decreased COD, TN, and salinity, with removal efficiencies reaching 96.5%, 98.2%, and 46.2%, respectively, under the optimal conditions (voltage intensity 1.5 V, initial pH 4, plate spacing 1 cm, flow rate 40 mL/min, H2O2 concentration 50 mM). The reaction mechanism study suggested that both the Fenton reaction, direct electron transfer, and indirect oxidation by active chlorine contributed to the removal of COD and TN, while the decrease in salinity mainly occurred in the process of electrosorption. Moreover, the regeneration of the ACF and the operational stability of the coupled system were good after five cycles. The economic analysis indicated that the cost of the flow-through coupled system was only $1.18/m3, which has important benefits.

A novel composite of carbon disulfide-modified magnetic ion-imprinted chitosan-Fe(III), i.e., MMIC-Fe(III) composite, was prepared as an efficient adsorbent for the simultaneous removal of tetracycline (TC) and Cd(II). This adsorbent showed excellent performance in removing TC and Cd(II) due to its rapid kinetics, high adsorption capacity, good reusability, and was well suited for use with real water samples. Kinetics studies demonstrated that the adsorption proceeded according to a pseudo-second order model. The adsorption isotherms were well described by the Langmuir model, with maximum adsorption capacity for TC and Cd(II) being 516.29 and 194.31 mg/g, respectively. The synergistic effect of TC and Cd(II) adsorption might be due to the formation of TC-Cd(II) complex bridging the adsorbate and adsorbent. These properties demonstrate the potential application of MMIC-Fe(III) for the simultaneous removal of TC and Cd(II), and may provide some information for the synergistic removal of antibiotics and heavy metals from aquatic environments.

The growing potential of quantum dots (QDs) in biological and biomedical applications has raised considerable concern due to their toxicological impact. Consequently, it is urgent to elucidate the underlying toxicity mechanism of QDs. In this work, we comprehensively investigated the cellular uptake of four CdSe/ZnS QDs (COOH CdSe/ZnS 525, COOH CdSe/ZnS 625, NH2 CdSe/ZnS 525, and NH2 CdSe/ZnS 625) and induced physiological responses in Phanerochaete chrysosporium (P. chrysosporium) through inductively coupled plasma optical emission spectroscopy, confocal laser scanning microscopy, and the determination of malondialdehyde content, superoxide level, superoxide dismutase activity, catalase activity and glutathione level. The results showed that the four CdSe/ZnS QDs accumulated largely in the hyphae and caused oxidative stress to P. chrysosporium in the tested concentration range (10–80 nM). Furthermore, the cellular uptake and cytotoxicity were related to the physicochemical properties of the QDs, such as particle size and surface charges. Negatively charged CdSe/ZnS QDs with small size could be more easily ingested by P. chrysosporium than large ones; thus small size CdSe/ZnS QDs were more cytotoxic to P. chrysosporium. On the other hand, small negatively charged CdSe/ZnS QDs resulted in greater cytotoxicity than large negatively charged CdSe/ZnS QDs. The obtained results offer valuable information for revealing the toxicity mechanism of QDs in living cells.

The phytogenic algicide sanguinarine shows strong inhibitory effects on some bloom-forming cyanobacteria and exhibits great potential in cyanobacterial bloom mitigation. To evaluate the possible ecological effects of sanguinarine on microalgae, the effects and possible mechanisms of sanguinarine on the competition between bloom-forming cyanobacterium Raphidiopsis raciborskii (formerly named Cylindrospermopsis raciborskii) and green alga Scenedesmus obliquus were investigated through co-culture competition test and comparative toxicological study including growth characteristics, chlorophyll fluorescence transients, activities of antioxidant enzymes, and lipid peroxidation. The results of Raphidiopsis-Scenedesmus co-culture competition test showed that sanguinarine decreased the competition ability of R. raciborskii, which benefitted S. obliquus in winning the competition. Toxicological studies have shown that sanguinarine exhibited high inhibitory effects on the growth and photosynthesis of R. raciborskii but no obvious toxicity on S. obliquus at concentrations of no more than 80 μg L−1. Oxidative damage partially contributed but was not the primary mechanism for the toxicity of sanguinarine on R. raciborskii. The results presented in this study indicate that sanguinarine may be a good algicidal candidate in mitigation of Raphidiopsis-based water bloom.

This study systematically investigated the advanced oxidation processes driven by the white-rot fungus (WRF) Phanerochaete chrysosporium in the removal of the neonicotinoid pesticide imidacloprid (IMI). The quinone redox cycling driven by P. chrysosporium promotes the degradation of IMI in presence of Mn2+ and Fe (III)-oxalate. Results showed that the degradation efficiency varied with the type of quinine mediator, and gallic acid (GA) was a more effective mediator than 1,4-benzoquinone (BQ). The removal rate of IMI was increased by 1.8-fold in the presence of 100 μM of Mn2+ compared with that of the system without Mn2+. The addition of oxalic acid and EDTA promoted the degradation of IMI, and the effect of oxalic acid was more pronounced at the later stage (day 5 and day 6); the optimal Fe3+/oxalate ratio was 1:3. Time-course experiments revealed the maximum removal rates of IMI were 97.37%, 82.0% and 73.52% at the initial IMI concentration of 10, 20, and 30 mg/L, respectively, in the presence of 100 μM Mn2+, 100 μM Fe3+-300 μM of oxalate and 500 μM gallic acid. Under quinone redox cycling conditions, the good correlation between ·OH production rates and the enzymes activity was concluded, the quinines redox cycles promote enzyme activity, as well as the rate of ·OH production. Results from this study indicated the GA mediator-based system using P. chrysosporium offers a new method to advance the bio-oxidation process owing to its simple culture system, low-cost precursors, unique fungi, and degradation stability.

Phthalate esters (PAEs) are one of the most frequently detected organic pollutants in soils. In this work, the adsorption behaviors of di-ethyl phthalate (DEP) and dibutyl phthalate (DBP) on soils, humins (HM) and Clay organo-mineral complexes (Clay-OM) from four regions in China, Changchun (CC), Cangzhou (CZ), Yinchuan (YC), and Changsha (CS) were studied. The surface and structural properties of these sorbents were characterized using Brunauer-Emmett-Teller specific surface area, Fourier transform infrared spectroscopy, X-ray diffraction spectroscopy, and 13C nuclear magnetic resonance methods. The results showed that the CC soil has the largest pore volume (PV) and specific surface area (SSA). PV, SSA, and aliphatic carbon content of the samples ranked as Clay-OM > HM > soil. Adsorption experiments indicated that the Clay-OM exhibited the strongest adsorption affinity for both DBP and DEP, followed by HM, and then the soil samples. Furthermore, DEP and DBP adsorption amounts on the samples declined as follows: CC > CS > CZ > YC. To illustrate the dominant mechanisms for PAEs adsorption onto soil, the soil organic carbon content normalized adsorption coefficient (LogKoc) was correlated with several possible parameters using multiple parameter linear regression and significance testing. The R2 values of the DBP and DEP in multi-regression equations were 0.825 and 0.741 respectively, and the significance test suggested that pore structure and specific surface area had crucial influences on the adsorption progress.

In this study, influences of cations (Na+, K+, Ca2+, and Mg2+), anions (NO3-, Cl-, and SO42-), and humic acid (HA) on the antimicrobial efficacy of silver nanoparticles (AgNPs)/Ag+ against Phanerochaete chrysosporium were investigated by observing cell viability and total Ag uptake. K+ enhanced the antimicrobial toxicity of AgNPs on P. chrysosporium, while divalent cations decreased the toxicity considerably, with preference of Ca2+ over Mg2+. Impact caused by a combination of monovalent and divalent electrolytes was mainly controlled by divalent cations. Compared to AgNPs, however, Ag+ with the same total Ag content exhibited stronger antimicrobial efficacy towards P. chrysosporium, regardless of the type of electrolytes. Furthermore, HA addition induced greater microbial activity under AgNP stress, possibly originating from stronger affinity of AgNPs over Ag+ to organic matters. The obtained results suggested that antimicrobial efficacy of AgNPs was closely related to water chemistry: addition of divalent electrolytes and HA reduced the opportunities directly for AgNP contact and interaction with cells through formation of aggregates, complexes, and surface coatings, leading to significant toxicity reduction; however, in monovalent electrolytes, the dominating mode of action of AgNPs could be toxic effects of the released Ag+ on microorganisms due to nanoparticle dissolution.

Phthalate esters (PAEs) are among the frequently detected organic pollutants in agricultural soils. Here, we investigated adsorption and biodegradation behaviors of di-ethyl phthalate (DEP) and dibutyl phthalate (DBP) in the soils collected from four regions in China: Changchun (CC), Changsha (CS), Cangzhou (CZ), and Yinchuan (YC). The results demonstrated that soil organic matter content crucially influenced the adsorption progress. However, the calculated degradation rates of PAEs in the four soils had no significant correlation with their adsorption capacity, suggesting that PAEs' bioavailability might be not the limiting factor governing their degradation. Furthermore, homogeneous biodegradation experiments were performed in the soil solutions extracted from different regional soils. Results showed that biodegradation of PAEs was influenced by the soil solution's pH and its concentration of dissolved organic matter (DOM). To better understand the accelerating mechanism of DOM, bacterial growth and enzyme activity in the presence of Humic acid (HA) and Fulvic acid (FA) were determined, and the degradation of PAEs by intracellular enzymes were also investigated. These results suggested that HA, FA, and other forms of DOM were actively involved in this biodegradation process in two ways: namely, via nutritional support and sequestration of PAEs. We conclude that the actual impact of soil organic matter (SOM) upon PAEs' biodegradation in soils arose from the net outcome of these two opposing effects.

Background B-cell receptor (BCR) signaling, combined with CD19 and CD21 signals, imparts specific control of B-cell responses. Dedicator of cytokinesis protein 2 (DOCK2) is critical for the migration and motility of lymphocytes. Although absence of DOCK2 leads to lymphopenia, little is known about the signaling mechanisms and physiologic functions of DOCK2 in B cells. Objective We sought to determine the underlying molecular mechanism of how DOCK2 regulates BCR signaling and peripheral B-cell differentiation. Methods In this study we used genetic models for DOCK2, Wiskott–Aldrich syndrome protein (WASP), and lymphoid enhancer–binding factor 1 deficiency to study their interplay in BCR signaling and B-cell differentiation. Results We found that the absence of DOCK2 led to downregulation of proximal and distal BCR signaling molecules, including CD19, but upregulation of SH2-containing inositol 5 phosphatase 1, a negative signaling molecule. Interestingly, DOCK2 deficiency reduced CD19 and CD21 expression at the mRNA and/or protein levels and was associated with reduced numbers of marginal zone B cells. Additionally, loss of DOCK2 reduced activation of WASP and accelerated degradation of WASP, resulting into reduced actin accumulation and early activation of B cells. Mechanistically, the absence of DOCK2 upregulates the expression of lymphoid enhancer–binding factor 1. These differences were associated with altered humoral responses in the absence of DOCK2. Conclusions Overall, our study has provided a novel underlying molecular mechanism of how DOCK2 deficiency regulates surface expression of CD21, which leads to downregulation of CD19-mediated BCR signaling and marginal zone B-cell differentiation.

In this study, interaction of oxytetracycline (OTC) onto nano-hydroxyapatite (nHAP) was evaluated as affected by pH and metal ions. Results showed that the adsorption process of OTC was highly pH- and metallic species-dependent. The amount of sorbed OTC at four pH were in the order of pH 8.0 > pH 10.0 > pH 5.5 > pH 3.0 and reached equilibrium around 120 min, indicating adsorption affinity of four species to nHAP followed the order of OTC− > OTC2− > OTC± > OTC+. Adding metal ions greatly increased the distribution coefficient (Kd) of OTC between adsorbents and aqueous phases, following the order of Fe3+ > Cu2+ > Pb2+ > Cd2+ = Ca2+ in the pH range of 3.0–10.0. Moreover, the co-adsorption behavior of OTC and heavy metals onto nHAP was also explored at pH 5.5 for the first time. OTC adsorption was significantly enhanced with the co-existence of 0.25 mmol/L Cu2+ or Pb2+. Inversely, the presence of 0.25 mmol/L OTC slightly led to the improvement of Cu2+ adsorption and depression of Pb2+ adsorption, yet Pb2+ adsorption was obviously promoted with the co-existence of 0.1 mmol/L OTC. Meanwhile, adsorption of OTC and Cd2+ showed unapparent variation in single or binary systems. The bridging effect involving metal ions, O- and N- containing groups in OTC molecules, and CaOH or POH sites of nHAP resulted in the formation of ternary complexes which were responsible for the promotion of their adsorption, while dissolution-precipitation was another key mechanism with the co-existence of Pb2+.

Hydrogen sulfide (H2S), an important cellular signaling molecule, plays vital roles in mediating responses to biotic/abiotic stresses. Influences of H2S on metal removal, cell viability, and antioxidant response of Phanerochaete chrysosporium upon exposure to heavy metals and silver nanoparticles (AgNPs) in the present study were investigated. An enhancement in Pb(ΙΙ) removal with an increase in concentration of the H2S donor sodium hydrosulfide (NaHS) was observed, and the maximum removal efficiencies increased by 31% and 17% under 100 and 200 mg/L Pb(ΙΙ) exposure, respectively, in the presence of 500 μM NaHS. Application of 500 μM NaHS increased the cell viability by 15%–39% under Pb(II) stress (10–200 mg/L) with relative to the untreated control. Increase in total Ag uptake and cell survival was also elicited by NaHS in a concentration-dependent manner under AgNP stress. Meanwhile, activities of superoxide dismutase and catalase were significantly enhanced with the introduction of NaHS under stresses of Pb(II), Cd(II), Cu(II), Zn(II), Ni(II), and AgNPs. The inhibition in lipid peroxidation and oxidative stress was observed in P. chrysosporium cells exposed to these toxicants following NaHS pretreatment, which could be attributed to the upregulation in antioxidant enzymes. The results obtained suggest that H2S can alleviate heavy metals and AgNP-induced toxicity to P. chrysosporium and improve the removal efficiency of these toxicants from wastewater.

In this work, silver nanoparticles supported on polydopamine-kaolin composite (PDA-kaolin-Ag) was fabricated by an in-situ reduction method with PDA as both reductant and stabilizer. The morphology, composition, and structure of PDA-kaolin-Ag composite were characterized by transmission electron microscopy (TEM), X-ray powder diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The catalytic reduction tests confirmed the importance of PDA modification and high catalytic activities of this as-prepared PDA-kaolin-Ag composite towards a model dye Rhodamine B. The catalytic reduction processes followed pseudo-first order kinetics. Meanwhile, this catalyst showed excellent stability and recyclability for dye decoloration. Furthermore, this composite also exhibited good catalytic performance on methylene blue, methyl orange, and Congo red. These results suggest that PDA-kaolin-Ag composites can be used as efficient and cost-effective catalyst for the decoloration of various organic dyes.

Antioxidative response of Phanerochaete chrysosporium induced by silver nanoparticles (AgNPs) and their toxicity mechanisms were comprehensively investigated in a complex system with 2,4-dichlorophenol (2,4-DCP) and Ag+. Malondialdehyde content was elevated by 2,4-DCP, AgNPs, and/or Ag+ in concentration- and time-dependent manners within 24 h, indicating an increase in lipid peroxidation. However, beyond 48 h of exposure, lipid peroxidation was alleviated by upregulation of intracellular protein production and enhancement in the activities of superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD). Comparatively, POD played more major roles in cell protection against oxidative damage. Furthermore, the dynamic change in reactive oxygen species (ROS) level was parallel to that of oxidized glutathione (GSSG), and ROS levels correlated well with GSSG contents (R2 = 0.953) after exposure to AgNPs for 24 h. This finding suggested that elimination of oxidative stress resulted in depletion of reduced glutathione. Coupled with the analyses of anoxidative responses of P. chrysosporium under the single and combined treatments of AgNPs and Ag+, HAADF-STEM, SEM, and EDX demonstrated that AgNP-induced cytotoxicity could originate from the original AgNPs, rather than dissolved Ag+ or the biosynthesized AgNPs.