Biosynthesis of silver nanoparticles using Burkholderia contaminans ZCC and mechanistic analysis at the proteome level.

The biogenic synthesis of silver nanoparticles (AgNPs) by microorganisms has been a subject of increasing attention. Despite extensive studies on this biosynthetic pathway, the mechanisms underlying the involvement of proteins and enzymes in AgNPs production have not been fully explored. Herein, we reported that Burkholderia contaminans ZCC was able to reduce Ag+ to AgNPs with a diameter of (10±5) nm inside the cell. Exposure of B. contaminans ZCC to Ag+ ions led to significant changes in the functional groups of cellular proteins, with approximately 5.72% of the (C-OH) bonds being converted to (C-C/C-H) (3.61%) and CO (2.11%) bonds, and 4.52% of the CO (carbonyl) bonds being converted to (C-OH) bonds. Furthermore, the presence of Ag+ and AgNPs induced the ability of extracellular electron transfer for ZCC cells via specific membrane proteins, but this did not occur in the absence of Ag+ ions. Proteomic analysis of the proteins and enzymes involved in heavy metal efflux systems, protein secretion system, oxidative phosphorylation, intracellular electron transfer chain, and glutathione metabolism suggests that glutathione S-transferase and ubiquinol-cytochrome c reductase iron-sulfur subunit play importance roles in the biosynthesis of AgNPs. These findings contribute to a deeper understanding of the functions exerted by glutathione S-transferase and ferredoxin-thioredoxin reductase iron-sulfur subunits in the biogenesis of AgNPs, thereby hold immense potential for optimizing biotechnological techniques aimed at enhancing the yield and purity of biosynthetic AgNPs.

Distributed Control for Nonlinear Time-Delay Multiagent Systems: Hybrid Saturation-Constraint Impulsive Approach.

This article mainly studies the problem of impulse consensus of multiagent systems under communication constraints and time delay. Considering the limited communication bandwidth of the agent, global and partial saturation constraints are considered. In addition, so as to further improve communication efficiency by reducing communication frequency, the novel control protocol combining event-triggered strategy and general impulse control protocol is proposed. Under this kind of novel control protocol, the communication frequency of multiagent systems can be reduced while avoiding "Zeno behavior." Through theoretical analysis, sufficient conditions for the systems to achieve consensus are obtained for the above two saturation constraint cases. In the end, the effectiveness of the novel protocols is proved by providing two different simulation instances.

[Effects of Modified Distiller's Lees Biochar on Nutrients and Enzyme Activities in Purple Soil].

In order to investigate the effects of distiller's lees biochar and different modified distiller's lees biochars on soil properties, pot experiments were conducted to study the effects of different soil amendments (CK:no amendment, JZ:distiller's lees biochar, TiO2/JZ:Nano-TiO2 supported by distiller's lees biochar, and Fe/TiO2/JZ:titanium dioxide supported by iron-modified distiller's lees biochar) and the application rates of different amendments (1%, 3%, and 5%) on the characteristics of soil nutrients and enzyme activities under irrigation-drought rotation. The results showed the following:①the modified distiller's lees biochar significantly increased soil pH and CEC (P<0.05). At the 5% Fe-TiO2/JZ addition level, the soil pH reached 7.95 during the rice season, an increase of 2.3 units compared with that in the CK treatment; the CEC reached 12.06 cmol·kg-1, increasing by 21.38%; the soil pH reached 5.99 during the cabbage season and increased by 1.5 units compared with that in the CK treatment; and CEC reached 8.91 cmol·kg-1 at 3% Fe-TiO2/JZ addition and increased by 13.11%. ②At the same time, the contents of soil total nitrogen and available phosphorus were significantly increased (P<0.05). Compared with that in the CK treatment, the soil total nitrogen of 5% JZ, 5% TiO2/JZ, and 5% Fe-TiO2/JZ increased by 20.56%, 85.04%, and 59.61% in the rice season and 12.39%, 22.68%, and 23.70% in the cabbage season, respectively. In the rice season, the increase in soil available P under 5% Fe-TiO2/JZ was the highest, reaching 10.49 mg·kg-1, which was 1.64 times that under CK treatment. In the cabbage season, the soil available phosphorus (P) reached 90.15 mg·kg-1 under 5% TiO2/JZ addition, which increased by 93.38% compared with that in the CK treatment. ③Modified distiller's lees biochar increased catalase and urease activities and decreased alkali-hydrolytic nitrogen content and acid phosphatase activity. At the 3% addition level, catalase activity increased by 12.19%, 48.17%, and 37.30% in the rice season and 5.95%, 8.34%, and 17.42% in the cabbage season, respectively. In the rice season, the soil urease activity reached the maximum under 5% Fe-TiO2/JZ addition, which was increased by 40.90% compared with that in the CK treatment. In the cabbage season, the soil urease activity reached the maximum under 5% TiO2/JZ addition, which was increased by 58.53% compared with that in the CK treatment. The activity of acid phosphatase decreased by 5.39%-24.66% in the rice season and by 54.46%-61.40% in the cabbage season. Distiller's lees biochar and modified distiller's lees biochar could effectively increase soil pH and soil nutrient content, thus affecting soil enzyme activities. The application of iron modified-titanium dioxide-loaded distiller's lees biochar of 3% to 5% in acidic purple soil is more suitable.

Antioxidant CeO2 doped with carbon dots enhance ammonia production by an electroactive Azospirillum humicireducens SgZ-5T.

Microbial nitrogen fixation is a fundamental process in the nitrogen cycle, providing a continuous supply of biologically available nitrogen essential for life. In this study, we combined cerium oxide-doped carbon dots (CeO2/CDs) with electroactive nitrogen-fixing bacterium Azospirillum humicireducens SgZ-5T to enhance nitrogen fixation through ammonium production. Our research demonstrates that treatment of SgZ-5T cells with CeO2/CDs (0.2 mg mL-1) resulted in a 265.70% increase in ammonium production compared to SgZ-5T cells alone. CeO2/CDs facilitate electron transfer in the biocatalytic process, thereby enhancing nitrogenase activity. Additionally, CeO2/CDs reduce the concentration of reactive oxygen species in SgZ-5T cells, leading to increased ammonium production. The upregulation of nifD, nifH and nifK gene expression upon incorporation of CeO2/CDs (0.2 mg mL-1) into SgZ-5T cells supports this observation. Our findings not only provide an economical and environmentally friendly approach to enhance biological nitrogen fixation but also hold potential for alleviating nitrogen fertilizer scarcity.

Numerical simulation analysis of heat and mass transfer of saline wastewater in a falling film evaporation tube based on different inlet modes.

Falling film evaporation technology is widely used in the treatment of salt-containing wastewater in coal chemical industry. However, there is still a lack of research on the inlet method of vertical falling film evaporation tubes. In this paper, the heat and mass transfer processes of saline wastewater under vertical and tangential inlets were investigated using numerical simulations. On this basis, the differences in flow and heat transfer processes between saline wastewater and pure water under tangential inlet were investigated. The results showed that the flow velocity of saline wastewater with a falling film evaporation tube in a tangential inlet mode was larger. Meanwhile, the turbulence in this way was more intense and the fluid temperature in the vertical tube was higher. Saline wastewater has higher temperature and smaller liquid volume fraction than pure water liquid membrane in the range of 193-1,000 mm from the inlet. The use of tangential inlet method to treat salt-containing wastewater has higher evaporation efficiency and is a very effective way to guide the improvement of heat transfer efficiency.

Self-Assembled Biohybrid: A Living Material To Bridge the Functions between Electronics and Multilevel Biological Modules/Systems.

Exoelectrogens are known to be specialized in reducing various extracellular electron acceptors to form conductive nanomaterials that are integrated with their cell bodies both structurally and functionally. Utilizing this unique capacity, we created a strategy toward the design and fabrication of a biohybrid electronic material by exploiting bioreduced graphene oxide (B-rGO) as the structural and functional linker to facilitate the interaction between the exoelectrogen community and external electronics. The metabolic functions of exoelectrogens encoded in this living hybrid can therefore be effectively translated toward corresponding microbial fuel cell applications. Furthermore, this material can serve as a fundamental building block to be integrated with other microorganisms for constructing various electronic components. Toward a broad impact of this biohybridization strategy, photosynthetic organelles and cells were explored to replace exoelectrogens as the active bioreducing components and as formed materials exhibited 4- and 8-fold improvements in photocurrent intensities as compared with native bioelectrode interfaces. Overall, a biologically driven strategy for the fabrication and assembly of electronic materials is demonstrated, which provides a unique opportunity to precisely probe and modulate desired biofunctions through deterministic electronic inputs/outputs and revolutionize the design and manufacturing of next-generation (bio)electronics.

Three-dimensional self-supporting superstructured double-sided nanoneedles arrays of iron carbide nanoclusters embedded in manganese, nitrogen co-doped carbon for highly efficient oxygen reduction reaction.

Nitrogen- and transition metal-dual doped carbon materials with low cost and high catalytic performances are considered as one of promising alternatives for noble metal catalysts in acceleration of oxygen reduction reaction (ORR). In this work, three-dimensional (3D) self-supporting superstructures of iron carbide (Fe3C) nanoclusters entrapped in manganese (Mn)- and nitrogen (N)-dual doped carbon nanosheets covered with double-sided nanoneedles carbon arrays (Fe3C/Mn,N-NCAs) are simply synthesized by a coordination pyrolysis method, in which dicyandiamide mainly behaves as nitrogen source and 1-(2-pyridylazo)-2-naphthol (PAN) as carbon source. Integration of the unique 3D self-supporting superstructures and synergistic effects of the multi-compositions, the as-obtained catalyst displays appealing ORR performance such as the much positive onset potential (Eonset = 0.98 V vs. RHE) and half-wave potential (E1/2 = 0.88 V vs. RHE), as well as a just 10 mV negative shift in E1/2 after 2000 cycles, surpassing commercial Pt/C. This work provides some valuable perspectives for preparation of high-efficiency and low-cost non-noble metal ORR electrocatalysts in energy transformation and storage correlated systems.

Au(III)-induced extracellular electron transfer by Burkholderia contaminans ZCC for the bio-recovery of gold nanoparticles.

The biorecovery of gold (Au) by microbial reduction has received increasing attention, however, the biomolecules involved and the mechanisms by which they operate to produce Au nanoparticles have been not resolved. Here we report that Burkholderia contaminans ZCC is capable of reduction of Au(III) to Au nanoparticles on the cell surface. Exposure of B. contaminans ZCC to Au(III) led to significant changes in the functional group of cell proteins, with approximately 11.1% of the (C-C/C-H) bonds being converted to CO (8.1%) and C-OH (3.0%) bonds and 29.4% of the CO bonds being converted to (C-OH/C-O-C/P-O-C) bonds, respectively. In response to Au(III), B. contaminans ZCC also displayed the ability of extracellular electron transfer (EET) via membrane proteins and could produce reduced riboflavin as verified by electrochemical and liquid chromatography-mass spectrometric results, but did not do so without Au(III) being present. Addition of exogenous reduced riboflavin to the medium suggested that B. contaminans ZCC could utilize indirect EET via riboflavin to enhance the rate of reduction of Au(III). Transcriptional analysis of the riboflavin genes (ribBDEFH) supported the view of the importance of riboflavin in the reduction of Au(III) and its importance in the biorecovery of gold.

Extrapolymeric substances (EPS) in Mucilaginibacter rubeus P2 displayed efficient metal(loid) bio-adsorption and production was induced by copper and zinc.

Strains of the genus Mucilaginibacter, belonging to the phylum Bacteroidetes, have been noted for exhibiting high genome plasticity and for the vigorous production of extracellular polymeric substances (EPS). Here we analyzed the composition and properties of EPS generated by M. rubeus P2, isolated from a gold-copper mine and exhibiting extremely high resistance to multiple heavy metals. Production of EPS increased significantly upon exposure to elevated concentrations of Cu(II) and Zn(II), but not Au(III). In addition, the EPS produced by M. rubeus P2 displayed extremely high bio-adsorption of As(III), Cu(II) and Au(III), but not of Zn(II). Moreover, EPS production in Mucilaginibacter rubeus P2 exposed to 1 mM of Cu(II) was 8.5 times higher than EPS production in the same strain without metal (loid)-exposure. These findings constitute the basis for a future use of these EPS-overproducing bacteria in bioremediation of heavy metal contaminated environments. The functional groups, especially -SH, CO, and N-H/C-N in the fingerprint zone of glutathione (GSH) and polysaccharides-like components of EPS, were the main components of EPS involved in both Zn(II) and Cu(II) binding and removal. Around 31.22% and 5.74% of Cu(II)-treated EPS was shown to exist as (CO) structures and these structures were converted into C-OH and O-C-O upon exposure to Cu(II), respectively. In contrast, (C-OH/C-O-C/P-O-C) groups in EPS were observed to be positively correlated to increasing concentrations of Zn(II) in strain P2. Furthermore, the complete genome of M. rubeus P2 helped us to identify 350 genes involved in carbohydrate metabolism, some of which are predicted to be involved in EPS production and modification. This work describes the first detailed biochemical and biophysical analysis of EPS from any strain of Mucilaginibacter with unique heavy metal binding properties. The results will be useful for a better understanding of how microorganisms such as M. rubeus P2 adapt to heavy metal polluted environments and how this knowledge can potentially be harnessed in biotechnological applications such as industrial waste water purification, bioremediation of heavy metal contaminated soil and beneficial plant microbe interactions. The toolbox provided in this paper will provide a valuable basis for future studies.

Liposoluble quinone promotes the reduction of hydrophobic mineral and extracellular electron transfer of Shewanella oneidensis MR-1.

A large number of reaction systems are composed of hydrophobic interfaces and microorganisms in natural environment. However, it is not clear how microorganisms adjust their breathing patterns and respond to hydrophobic interfaces. Here, Shewanella oneidensis MR-1 was used to reduce ferrihydrite of a hydrophobic surface. Through Fe(II) kinetic analysis, it was found that the reduction rate of hydrophobic ferrihydrite was 1.8 times that of hydrophilic one. The hydrophobic surface of the mineral hinders the way the electroactive microorganism uses the water-soluble electron mediator riboflavin for indirect electron transfer and promotes MR-1 to produce more liposoluble quinones. Ubiquinone can mediate electron transfer at the hydrophobic interface. Ubiquinone-30 (UQ-6) increases the reduction rate of hydrophobic ferrihydrite from 38.5 ± 4.4 to 52.2 ± 0.8 µM·h-1. Based on the above experimental results, we propose that liposoluble electron mediator ubiquinone can act on the extracellular hydrophobic surface, proving that the metabolism of hydrophobic minerals is related to endogenous liposoluble quinones. Hydrophobic modification of minerals encourages electroactive microorganisms to adopt differentiated respiratory pathways. This finding helps in understanding the electron transfer behavior of the microbes at the hydrophobic interface and provides new ideas for the study of hydrophobic reactions that may occur in systems, such as soil and sediment.

Potential of cadmium resistant Burkholderia contaminans strain ZCC in promoting growth of soy beans in the presence of cadmium.

Bioremediation of Cd contaminated environments can be assisted by plant-growth-promoting bacteria (PGPB) enabling plant growth in these sites. Here a gram-negative Burkholderia contaminans ZCC was isolated from mining soil at a copper-gold mine. When exposed to Cd(II), ZCC displayed high Cd resistance and the minimal inhibitory concentration was 7 mM in LB medium. Complete genome analysis uncovered B. contaminans ZCC contained 3 chromosomes and 2 plasmids. One of these plasmids was shown to contain a multitude of heavy metal resistance determinants including genes encoding a putative Cd-translocating PIB-type ATPase and an RND-type related to the Czc-system. These additional heavy metal resistance determinants are likely responsible for the increased resistance to Cd(II) and other heavy metals in comparison to other strains of B. contaminans. B. contaminans ZCC also displayed PGPB traits such as 1-aminocyclopropane-1-carboxylate deaminase activity, siderophore production, organic and inorganic phosphate solubilization and indole acetic acid production. Moreover, the properties and Cd(II) binding characteristics of extracellular polymeric substances was investigated. ZCC was able to induce extracellular polymeric substances production in response to Cd and was shown to be chemically coordinated to Cd(II). It could promote the growth of soybean in the presence of elevated concentrations of Cd(II). This work will help to better understand processes important in bioremediation of Cd-contaminated environment.

Consensus of Nonlinear Multiagent Systems With Grouping Via State-Constraint Impulsive Protocols.

In this article, the consensus problem of nonlinear multiagent systems with grouping via state-constraint impulsive protocols is investigated. Two types of cases with and without leader agent are studied by using two kinds of protocols. A judgement strategy is designed to decide to group in the nonlinear multiagent systems, and two kinds of state-constraint impulsive control protocols, which include partial state constraint and full state constraint, are proposed to make this system cut down the cost of communication and reduce irreversible damage to equipment. Then, based on the algebraic graph theory, the Lyapunov stability theory, and the matrix theory, some sufficient conditions are established to deal with the consensus problem in the nonlinear multiagent systems. The presented results can be used to solve the consensus problem in the nonlinear multiagent systems with grouping. Finally, some important simulations are presented to illustrate the feasibility of the theoretical results.

Serine restriction alters sphingolipid diversity to constrain tumour growth.

Serine, glycine and other nonessential amino acids are critical for tumour progression, and strategies to limit their availability are emerging as potential therapies for cancer1-3. However, the molecular mechanisms driving this response remain unclear and the effects on lipid metabolism are relatively unexplored. Serine palmitoyltransferase (SPT) catalyses the de novo biosynthesis of sphingolipids but also produces noncanonical 1-deoxysphingolipids when using alanine as a substrate4,5. Deoxysphingolipids accumulate in the context of mutations in SPTLC1 or SPTLC26,7-or in conditions of low serine availability8,9-to drive neuropathy, and deoxysphinganine has previously been investigated as an anti-cancer agent10. Here we exploit amino acid metabolism and the promiscuity of SPT to modulate the endogenous synthesis of toxic deoxysphingolipids and slow tumour progression. Anchorage-independent growth reprogrammes a metabolic network involving serine, alanine and pyruvate that drives the endogenous synthesis and accumulation of deoxysphingolipids. Targeting the mitochondrial pyruvate carrier promotes alanine oxidation to mitigate deoxysphingolipid synthesis and improve spheroid growth, similar to phenotypes observed with the direct inhibition of SPT or ceramide synthesis. Restriction of dietary serine and glycine potently induces the accumulation of deoxysphingolipids while decreasing tumour growth in xenograft models in mice. Pharmacological inhibition of SPT rescues xenograft growth in mice fed diets restricted in serine and glycine, and the reduction of circulating serine by inhibition of phosphoglycerate dehydrogenase (PHGDH) leads to the accumulation of deoxysphingolipids and mitigates tumour growth. The promiscuity of SPT therefore links serine and mitochondrial alanine metabolism to membrane lipid diversity, which further sensitizes tumours to metabolic stress.

Electrochemiluminescence for the identification of electrochemically active bacteria.

Electrochemically active bacteria (EAB) use extracellular electron transfer (EET) to exchange electron with extracellular acceptors. Previous studies regarding the measurement of EAB were based on either extracellular reduction or oxidation. In this work, we developed a simple electrochemiluminescence (ECL) assay for the identification and detection of EAB. The results of this proposed method revealed that EET of EAB influenced the content of dissolved oxygen and the formation of Ru(bpy)32+• thus leading to qualitative changes of the ECL signal. EAB with the ability of extracellular reduction (such as Shewanella oneidensis MR-1) gave enhanced signal on ECL emission while those displaying the ability of extracellular oxidation (i.e., Sulfobacillus acidophilus) showed the opposite effect on ECL emission, but non-EAB (i.e., Escherichia coli) did not. These changes in ECL intensity were also proportional to the cell density that could be quantitatively detected in the concentration range of (1.1 ±â€¯1) × 105-212 ±â€¯2 CFU/mL (i.e. Shewanella oneidensis MR-1). Moreover, the measurement of the ability of EAB using this approach was in agreement with measurements using the dissimilatory Fe(III) reduction method. Compared to previous reports, this method displayed a continual and steady ECL signal that allowed accurate measurements of EAB. Most important, only a low cell density was needed in this Ru(bpy)32+ - based ECL method, which is beneficial for cell detection.

Hemp seed polysaccharides protect intestinal epithelial cells from hydrogen peroxide-induced oxidative stress.

The purpose of this study was to investigate structure of Hemp seed polysaccharide (HSP) and the protective effect of HSP from H2O2-induced oxidative damage in IPEC-1 cells and the possible mechanism of this protection. Analysis of monosaccharide composition and structure of two fractions HSP0 and HSP0.2 from polysaccharide of Hemp seed (HSPc) were analyzed by high performance liquid chromatography (HPLC) and Fourier transform infrared spectroscopy (FT-IR). The results showed that both HSP0 and HSP0.2 contain sulfate groups, which are sulfated polysaccharides. In IPEC-1 cells model, the release of LDH and MDA was significantly decreased, and the activities of SOD, GSH-Px and CAT were significantly increased in HSP0 and HSP0.2-treated group. HSP0.2 dramatically increased the gene expression of antioxidant enzymes and phase II detoxification enzymes measured by real-time fluorescent quantitative reverse transcription-polymerase chain reaction (qRT-PCR). In addition, HSP0.2 up-regulated the expression level of intracellular transcription factor Nuclear factor erythroid-2-related factor 2 (Nrf2) and inhibited the level of Kelch-like ECH-associated protein 1 (Keap1) with Western blot analysis. Collectively, the present study suggested that HSP0.2 has the protective effect of IPEC-1 cells against H2O2-induecd oxidative stress. This protection mechanism may be related to activation of the Keap1/Nrf2 signaling pathway.

Effects of an Electric Field on the Conformational Transition of the Protein: A Molecular Dynamics Simulation Study.

The effect of the electric field on the conformational properties of the protein 1BBL was investigated by molecular dynamics simulations. Our simulation results clearly capture the structural transitions of the protein sample from helix to turn or random coil conformation induced by the increasing strength of the electric field. During our analysis, we found that the conformational stability is weakened, and the protein sample is stretched as an unfolded structure when it was exposed in a sufficiently high electric field. The characteristic time when the jump occurs in the time evolution curves of root mean square deviation (RMSD) and radius of gyration Rg decreases with increasing electric strength, which demonstrates the rapidly conformational transition that occurs. The number of intra-protein hydrogen bonds, which is the key factor for stabilizing the protein structure, is related to the overall size of the protein. The value of the dipole moment and characteristic time are both influenced by the strength, but are independent of the direction of the external field. The protein sample becomes rotated with the electric field direction. These conclusions provide a theoretical realization of understanding the protein conformational transition in an electric field and the guidance for anticipative applications.

Extracellular electron transfer of Enterobacter cloacae SgZ-5T via bi-mediators for the biorecovery of palladium as nanorods.

In nature, microbes use extracellular electron transfer (EET) to recover noble metals. Most attention has been paid to the biorecovery process occurring intracellularly and on the cell surface. In this work, we report that Pd nanorods could be biosynthesized by Enterobacter cloacae SgZ-5T in the extracellular space. This bacterium possesses both a direct EET pathway through membrane redox systems and an indirect EET pathway via the self-secreted electron carrier hydroquinone (HQ). When exposed to Pd(II), the bacteria adjusted their metabolic pathway and membrane-bound proteins to secrete riboflavin (RF). However, no HQ was detected in the supernatant in presence of Pd(II). No significant change was observed through metabolomic analysis regarding the abundance of HQ in presence of Pd(II) compared to Pd(II)-free supernatant. Similar results were also obtained through transcriptomic analysis of YqjG gene encoding glutathionyl-HQ reductase synthase. X-ray photoelectron spectroscopic evidence indicated that HQ may adsorb to the surface of Pd nanorods. Moreover, the gene encoding RF synthase (ribE) was up-regulated in the present of Pd(II), suggesting that this bioreduction process induced RF synthase, which had been shown in previous results. The UV-vis spectroscopy data demonstrated that the Pd(II) reduction rate was enhanced by 5%, 5.5% and 30% by the addition of 3.33 µM HQ, 3.33 µM RF and the both, respectively. All these results revealed that the bi-mediators secreted by bacteria were beneficial for biorecovery of Pd. This work is of significance for understanding metal biorecovery processes and natural biogeochemical processes.

Immunomodulatory effect of low molecular-weight seleno-aminopolysaccharide on immunosuppressive mice.

Low molecular-weight seleno-aminopolysaccharides (LSA) have been shown to possess a variety of biological activities in vitro. In the present study, we further investigated the immunomodulatory effect of LSA on immunosuppressive mice induced by cyclophosphamide (CPA) and its molecular mechanism. The results demonstrated that LSA could significantly increase spleen and thymus indices, proliferation of splenic lymphocyte, the secretion of cytokines (IL-2, IL-4, IL-10 and INF-γ) of serum and ileum, and secretory immunoglobulin A (sIgA) content of small intestine. LSA dramatically improved the gene expression levels of IL-2, IL-4, IL-10 and INF-γ in small intestine by real-time fluorescent quantitative reverse transcription-polymerase chain reaction (qRT-PCR). Furthermore, our data indicated that LSA could significantly increase the gene expression levels of IL-1ß and iNOS in RAW264.7 cells. LSA was further shown to remarkably promote inhibitor kappa Bα (IκBα) and nuclear factor-kappa B (NF-κB) p65 phosphorylation with western blot analysis. Taken together, these findings suggest that LSA has immunomodulatory activity on immunosuppressive mice and macrophage RAW264.7 cells, and its mechanism may be related to activation of NF-κB signaling pathway.

Facile Preparation of Metal-Organic Framework (MIL-125)/Chitosan Beads for Adsorption of Pb(II) from Aqueous Solutions.

In this study, novel composite titanium-based metal-organic framework (MOF) beads were synthesized from titanium based metal organic framework MIL-125 and chitosan (CS) and used to remove Pb(II) from wastewater. The MIL-125-CS beads were prepared by combining the titanium-based MIL-125 MOF and chitosan using a template-free solvothermal approach under ambient conditions. The surface and elemental properties of these beads were analyzed using scanning electron microscopy, Fourier transform infrared and X-ray photoelectron spectroscopies, as well as thermal gravimetric analysis. Moreover, a series of experiments designed to determine the influences of factors such as initial Pb(II) concentration, pH, reaction time and adsorption temperature was conducted. Notably, it was found that the adsorption of Pb(II) onto the MIL-125-CS beads reached equilibrium in 180 min to a level of 407.50 mg/g at ambient temperature. In addition, kinetic and equilibrium experiments provided data that were fit to the Langmuir isotherm model and pseudo-second-order kinetics. Furthermore, reusability tests showed that MIL-125-CS retained 85% of its Pb(II)-removal capacity after five reuse cycles. All in all, we believe that the developed MIL-125-CS beads are a promising adsorbent material for the remediation of environmental water polluted by heavy metal ions.

Protective effect of low molecular-weight seleno-aminopolysaccharides against H2O2-induecd oxidative stress in intestinal epithelial cells.

Organoselemium compounds possess strong antioxidant activity as well as protecting cells from DNA damage, mitochondrial injury, lipid peroxidation, protein denaturation and cell death. Herein, we used an in vitro oxidative model to further investigate the antioxidant effects of a novel organoselemium compound, low molecular-weight seleno-aminopolysaccharides (LSA) in intestinal porcine epithelial cells (IPEC-1), and the molecular mechanisms of these effects. Analysis by MTT assay showed that LSA could significantly increase the viability of IPEC-1 cells compared to cells exposed to H2O2. We found that the levels of different antioxidant enzymes could dramatically increase in LSA pretreatment group compared to H2O2 treatment group. Furthermore, LSA significantly increased the gene expression of antioxidant enzymes and phase 2 detoxifying enzymes in IPEC-1 cells, as measured by qRT-PCR. In addition, LSA up-regulated the expression level of intracellular transcription factor NF-E2-related factor 2 (Nrf2) and inhibited the level of kelch-like ECH-associated protein 1 (Keap1) with western blot analysis. Collectively, the present study suggested that LSA has the protective effect of IPEC-1 cells against H2O2-induecd oxidative stress, and its mechanism may be related to activation of Keap1/Nrf2 signaling pathway in intestinal epithelial cells.