Mechanisms of adaptive resistance in Phytobacter sp. X4 to antimony stress under anaerobic conditions.

Sb(III) oxidation by microorganisms plays a key role in the geochemical cycling of antimony and is effective for bioremediation. A previously discovered novel Sb(III)-oxidizing bacteria, Phytobacter sp. X4, was used to elucidate the response patterns of extracellular polypeptides (EPS), antioxidant system, electron transfer and functional genes to Sb(III) under anaerobic conditions. The toxicity of Sb(III) was mitigated by increasing Sb(III) oxidation capacity, and the EPS regulated the content of each component by sensing the concentration of Sb(III). High Sb(III) concentrations induced significant secretion of proteins and polysaccharides of EPS, and polysaccharides were more important. Functional groups including hydroxyl, carboxyl and amino groups on the cell surface adsorbed Sb(III) to block its entry. Hydroxyl radicals and hydrogen peroxide were involved in anaerobic Sb(III) oxidation, as revealed by changes in the antioxidant system and electron spin resonance (EPR) techniques. qPCR confirmed that proteins concerning nitrate and antimony transfer, antimony resistance and antioxidant system were regulated by Sb(III) concentration, and the synergistic cooperation of multiple proteins conferred high antimony resistance to X4. The adaptive antimony resistance mechanism of Phytobacter sp. X4 under anaerobic conditions was revealed, which also provides a reference value for bioremediation method of antimony contamination in anaerobic environment.

Extracellular proteins enhance Cupriavidus pauculus nickel tolerance and cell aggregate formation.

Heavy metal-resistant bacteria secrete extracellular proteins (e-PNs). However, the role of e-PNs in heavy metal resistance remains elusive. Here Fourier Transform Infrared Spectroscopy implied that N-H, C = O and NH2-R played a crucial role in the adsorption and resistance of Ni2+ in the model organism Cuprividus pauculus 1490 (C. pauculus). Proteinase K treatment reduced Ni2+ resistance of C. pauculus underlining the essential role of e-PNs. Further three-dimension excitation-emission matrix fluorescence spectroscopy analysis demonstrated that tryptophan proteins as part of the e-PNs increased significantly with Ni2+ treatment. Proteomic and quantitative real-time polymerase chain reaction data indicated that major changes were induced in the metabolism of C. pauculus in response to Ni2+. Among those lipopolysaccharide biosynthesis, general secretion pathways, Ni2+-affiliated transporters and multidrug efflux play an essential role in Ni2+ resistance. Altogether the results provide a conceptual model for comprehending how e-PNs contribute to bacterial resistance and adsorption of Ni2+.

Research on strain aging behavior of ultra-high strength dual-phase steel.

The bake hardening value is one of the vital strength indexes of dual-phase steel, representing the strengthening ability of materials after pre-strain and baking, playing an important role in vehicle safety and lightweight design. Studying and improving the strain aging mechanism of dual-phase steel helps one to understand the material characteristics and enhances its utilization value. However, the ultra-high strength dual-phase steel is often prone to fracture outside the gauge length of a tensile specimen of the bake hardening value test. No suitable theory explains the fundamental law of dislocation pinning during the saturation stage at present. This paper used FEA, DIC, SEM, TEM, internal friction, and metallographic methods to study the strain aging behavior of dual-phase steels under different pre-strain, bake time, and bake temperature conditions. The results show that the fracture outside the gauge length is related to factors such as the uneven distribution of pre-strain and the ultra-high upper yield strength. The rolling pin shape tensile specimen testing has successfully solved this testing problem. The measured results at the saturation stage of dislocation pinning are in good agreement with the fitting results of the dislocation pinning strengthen mechanism based on the probability event quantization assumption.

Microbial extracellular polymeric substances alleviate cadmium toxicity in rice (Oryza sativa L.) by regulating cadmium uptake, subcellular distribution and triggering the expression of stress-related genes.

Cadmium (Cd) accumulation in crops causes potential risks to human health. Microbial extracellular polymeric substances (EPS) are a complex mixture of biopolymers that can bind various heavy metals. The present work examined the alleviating effects of EPS on Cd toxicity in rice and its detoxification mechanism. The 100 µM Cd stress hampered the overall plant growth and development, damaged the ultrastructures of both leaf and root cells, and caused severe lipid peroxidation in rice plants. However, applying EPS at a concentration of 100 mg/L during Cd stress resulted in increased biomass, reduced Cd accumulation and transport, and minimized the oxidative damage. EPS application also enhanced Cd retention in the shoot cell walls and root vacuoles, and actively altered the expression of genes involved in cell wall formation, antioxidant defense systems, transcription factors, and hormone metabolism. These findings provide new insights into EPS-mediated mitigation of Cd stress in plants and help us to develop strategies to improve crop yield in Cd-contaminated soils in the future.

Exploring the dynamic of microbial community and metabolic function in food waste composting amended with traditional Chinese medicine residues.

The aim of this study was to explore the dynamic of microbial community and metabolic function in food waste composting amended with traditional Chinese medicine residues (TCMRs). Results suggested that TCMRs addition at up to 10% leads to a higher peak temperature (60.5 °C), germination index (GI) value (119.26%), and a greater reduction in total organic carbon (TOC) content (8.08%). 10% TCMRs significantly induced the fluctuation of bacterial community composition, as well as the fungal community in the thermophilic phase. The addition of 10% TCMRs enhanced the abundance of bacterial genera such as Acetobacter, Bacillus, and Brevundimonas, as well as fungal genera such as Chaetomium, Thermascus, and Coprinopsis, which accelerated lignocellulose degradation and humification degree. Conversely, the growth of Lactobacillus and Pseudomonas was inhibited by 10% TCMRs to weaken the acidic environment and reduce nitrogen loss. Metabolic function analysis revealed that 10% TCMRs promoted the metabolism of carbohydrate and amino acid, especially citrate cycle, glycolysis/gluconeogenesis, and cysteine and methionine metabolism. Redundancy analysis showed that the carbon to nitrogen (C/N) ratio was the most significant environmental factor influencing the dynamic of bacterial and fungal communities.

Effect of nickel (II) on the performance of anodic electroactive biofilms in bioelectrochemical systems.

The impact of nickel (Ni2+) on the performance of anodic electroactive biofilms (EABs) in the bioelectrochemical system (BES) was investigated in this study. Although it has been reported that Ni2+ influences microorganisms in a number of ways, it is unknown how its presence in the anode of a BES affects extracellular electron transfer (EET) of EABs, microbial viability, and the bacterial community. Results revealed that the addition of Ni2+ decreased power output from 673.24 ± 12.40 mW/m2 at 0 mg/L to 179.26 ± 9.05 mW/m2 at 80 mg/L. The metal and chemical oxygen demand removal efficiencies of the microbial fuel cells (MFCs) declined as Ni2+ concentration increased, which could be attributed to decreased microbial viability as revealed by SEM and CLSM. FTIR analysis revealed the involvement of various microbial biofilm functional groups, including hydroxyl, amides, methyl, amine, and carboxyl, in the uptake of Ni2+. The presence of Ni2+ on the anodic biofilms was confirmed by SEM-EDS and XPS analyses. CV demonstrated that the electron transfer performance of the anodic biofilms was negatively correlated with the various Ni2+ concentrations. EIS showed that the internal resistance of the MFCs increased with increasing Ni2+ concentration, resulting in a decrease in power output. High-throughput sequencing results revealed a decrease in Geobacter and an increase in Desulfovibrio in response to Ni2+ concentrations of 10, 20, 40, and 80 mg/L. Furthermore, the various Ni2+ concentrations decreased the expression of EET-related genes. The Ni2+-fed MFCs had a higher abundance of the nikR gene than the control group, which was important for Ni2+ resistance. This work advances our understanding of Ni2+ inhibition on EABs, as well as the concurrent removal of organic matter and Ni2+ from wastewater.

Longitudinal physiological and transcriptomic analyses reveal the short term and long term response of Synechocystis sp. PCC6803 to cadmium stress.

Due to the bioaccumulation and non-biodegradability of cadmium, Cd can pose a serious threat to ecosystem even at low concentration. Microalgae is widely distributed photosynthetic organisms in nature, which is a promising heavy metal remover and an effective industrial sewage cleaner. However, there are few detailed reports on the short-term and long-term molecular mechanisms of microalgae under Cd stress. In this study, the adsorption behavior (growth curve, Cd removal efficiency, scanning electron microscope, Fourier transform infrared spectroscopy, and dynamic change of extracellular polymeric substances), cytotoxicity (photosynthetic pigment, MDA, GSH, H2O2, O2-) and stress response mechanism of microalgae were discussed under EC50. RNA-seq detected 1413 DEGs in 4 treatment groups. These genes were related to ribosome, nitrogen metabolism, sulfur transporter, and photosynthesis, and which been proved to be Cd-responsive DEGs. WGCNA (weighted gene co-expression network analysis) revealed two main gene expression patterns, short-term stress (381 genes) and long-term stress (364 genes). The enrichment analysis of DEGs showed that the expression of genes involved in N metabolism, sulfur transporter, and aminoacyl-tRNA biosynthesis were significantly up-regulated. This provided raw material for the synthesis of the important component (cysteine) of metal chelate protein, resistant metalloprotein and transporter (ABC transporter) in the initial stage, which was also the short-term response mechanism. Cd adsorption of the first 15 min was primary dependent on membrane transporter and beforehand accumulated EPS. Simultaneously, the up-regulated glutathione S-transferase (GSTs) family proteins played a role in the initial resistance to exogenous Cd. The damaged photosynthetic system was repaired at the later stage, the expressions of glycolysis and gluconeogenesis were up-regulated, to meet the energy and substances of physiological metabolic activities. The study is the first to provide detailed short-term and long-term genomic information on microalgae responding to Cd stress. Meanwhile, the key genes in this study can be used as potential targets for algae-mediated genetic engineering.

Effects of Atrazine on Chernozem Microbial Communities Evaluated by Traditional Detection and Modern Sequencing Technology.

Atrazine is a long residual herbicide commonly used in maize fields. Although atrazine can effectively control weeds and improve crop yield, long-term application leads to continuous pollution in the agricultural ecological environment, especially in the soil ecosystem, and its impact on soil microorganisms is still not clear. Four methods were used in the experiment to clarify the effect of atrazine on the bacterial populations of cultivated soil layers of chernozem in a cold region in different periods: high-performance liquid chromatography (HPLC), colorimetry, microplate, and high-throughput sequencing. The level of residual atrazine in cold chernozem decreased from 4.645 to 0.077 mg/kg soil over time, and the residue gradually leached into deep soil and then decreased after accumulating to a maximum value. Atrazine significantly affected the activities of urease and polyphenol oxidase activity in the soil layers at different periods but had no significant effect on sucrase and phosphatase activity. Atrazine significantly reduced the diversity of microbial carbon source utilization and total activity in soil layers of 0-10 and 20-30 cm but only reduced the diversity of microbial carbon source utilization in the 10-20 cm layer. Atrazine had no significant effect on bacterial populations (10-12 phyla, 29-34 genera), but had a slight effect on the relative abundance of various groups. Atrazine significantly reduced the diversity of bacterial populations in cultivated soil layers of chernozem in a cold region, and the diversity of bacterial populations decreased with decreased residue. This lays a foundation for guiding the safe use of herbicides on farmland in Northeast China.

Biosorption behavior and mechanism of cadmium from aqueous solutions by Synechocystis sp. PCC6803.

Cyanobacteria are promising adsorbents that are widely used for heavy metal removal in aqueous solutions. However, the underlying adsorption mechanism of Synechocystis sp. PCC6803 is currently unclear. In this study, the adsorption behavior and mechanism of cadmium (Cd2+) were investigated. Batch biosorption experiments showed that the optimal adsorption conditions were pH 7.0, 30 °C, 15 min, and an initial ion concentration of 4.0 mg L-1. The adsorption process fitted well with the pseudo-second order kinetic model, mainly based on chemisorption. Complexation of Cd2+ with carboxyl, hydroxyl, carbonyl, and amido groups was demonstrated by Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) analyses. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy-dispersive X-ray spectrometry (EDX) analyses confirmed the presence of Cd2+ on the cyanobacterial cell surface and intracellularly. Cd2+ could lead to reactive oxygen species (ROS) accumulation and photosynthesis inhibition in cyanobacterial cells, and glutathione (GSH) played an important role in alleviating Cd2+ toxicity. Analyses of three-dimensional fluorescence spectroscopy (3D-EEM) and high performance anion exchange chromatography-pulsed amperometric detection (HPAEC-PAD) revealed the changes of the composition and content of EPS after Cd2+ adsorption, respectively. Real-time quantitative polymerase chain reaction (RT-qPCR) revealed the potential molecular regulatory mechanisms involved in Cd2+ biosorption. These results revealed the adsorption mechanism of Cd2+ by Synechocystis sp. PCC6803 and provided theoretical guidance for insight into the biosorption mechanisms of heavy metals by other strains.

Honokiol protects against epidural fibrosis by inhibiting fibroblast proliferation and extracellular matrix overproduction in rats post­laminectomy.

Epidural fibrosis (EF)­induced failed back surgery syndrome (FBSS) in patients post­laminectomy remains a medical challenge. Although the scarring mechanisms remain unclear, the majority of aetiological studies have reported fibroblast dysfunction. Honokiol, the major bioactive constituent of the magnolia tree, exerts a variety of pharmacological effects, including anti­proliferative and anti­fibrotic effects, on various cell types. The present study investigated whether honokiol attenuates EF progression. In vitro, it was found that honokiol inhibited excessive fibroblast proliferation induced by transforming growth factor­ß1 (TGF­ß1) and the synthesis of extracellular matrix (ECM) components, including fibronectin and type I collagen, in a dose­dependent manner. These effects were attributed to the ability of honokiol to suppress the activity of connective tissue growth factor (CTGF), which is indispensable for the progression of fibrosis. Mechanistically, honokiol attenuated the TGF­ß1­induced activation of the Smad2/3 and mitogen­activated protein kinase (MAPK) signalling pathways in fibroblasts. In vivo, honokiol reduced the proliferation of fibroblasts and the synthesis of ECM components, thus ameliorating EF in a rat model post­laminectomy. Taken together, these preclinical findings suggest that honokiol deserves further consideration as a candidate therapeutic agent for EF.

The roles of extracellular polymeric substances of Pandoraea sp. XY-2 in the removal of tetracycline.

In this study, the roles of extracellular polymeric substances (EPSs) excreted by Pandoraea sp. XY-2 in the removal of tetracycline (TC) were investigated. In the early stage, TC in the solution was mainly removed by the adsorption of EPSs, which accounted for 20% of TC. Thereafter, large amount of TC was transported into the intracellular and biodegraded. EPSs was extracted and the contents of polyprotein and polysaccharides reached their maximum values (30.84 mg/g and 11.15 mg/g) in the first four days. Fourier transform infrared spectroscopy analysis revealed that hydroxyl, methylidyne, methylene and amide I groups in EPSs participated in the adsorption of TC. Furthermore, three-dimensional excitation-emission matrix fluorescence spectroscopy analysis revealed that TC caused the quenching of EPSs fluorescent groups. The quenching mechanism was attributed to static quenching and protein-like substances in EPSs from Pandoraea sp. XY-2 dominated the TC adsorption process. Bioinformatic analysis of Pandoraea sp. XY-2 genome identified multiple genes involved in exopolysaccharide synthesis and EPSs formation. The insights gained in this study might provide a better understanding about the adsorption process of EPSs in tetracycline-contaminated environment.

Simple fluorescence-based detection of protein kinase A activity using a molecular beacon probe.

Protein kinase A was detected by quantifying the amount of ATP used after a protein kinase reaction. The ATP assay was performed using the T4 DNA ligase and a molecular beacon (MB). In the presence of ATP, DNA ligase catalyzed the ligation of short DNA. The ligation product then hybridized to MB, resulting in a fluorescence enhancement of the MB. This assay was capable of determining protein kinase A in the range of 12.5∼150 nM, with a detection limit of 1.25 nM. Furthermore, this assay could also be used to investigate the effect of genistein on protein kinase A. It was a universal, non-radioisotopic, and homogeneous method for assaying protein kinase A.

Expression of Critical Sulfur- and Iron-Oxidation Genes and the Community Dynamics During Bioleaching of Chalcopyrite Concentrate by Moderate Thermophiles.

Sulfate adenylyltransferase gene and 4Fe-4S ferredoxin gene are the key genes related to sulfur and iron oxidations during bioleaching system, respectively. In order to better understand the bioleaching and microorganism synergistic mechanism in chalcopyrite bioleaching by mixed culture of moderate thermophiles, expressions of the two energy metabolism genes and community dynamics of free and attached microorganisms were investigated. Specific primers were designed for real-time quantitative PCR to study the expression of these genes. Real-time PCR results showed that sulfate adenylyltransferase gene was more highly expressed in Sulfobacillus thermosulfidooxidans than that in Acidithiobacillus caldus, and expression of 4Fe-4S ferredoxin gene was higher in Ferroplasma thermophilum than that in S. thermosulfidooxidans and Leptospirillum ferriphilum. The results indicated that in the bioleaching system of chalcopyrite concentrate, sulfur and iron oxidations were mainly performed by S. thermosulfidooxidans and F. thermophilum, respectively. The community dynamics results revealed that S. thermosulfidooxidans took up the largest proportion during the whole period, followed by F. thermophilum, A. caldus, and L. ferriphilum. The CCA analysis showed that 4Fe-4S ferredoxin gene expression was mainly affected (positively correlated) by high pH and elevated concentration of ferrous ion, while no factor was observed to prominently influence the expression of sulfate adenylyltransferase gene.

Compounds from Dryopteris fragrans (L.) Schott with cytotoxic activity.

One new coumarin, dryofracoumarin A (1), and eight known compounds 2-9 were isolated from Dryopteris fragrans (L.) Schott. Their structures were established on the basis of extensive spectroscopic data analyses and comparison with reported spectroscopic data. The new compound 1 was determined to be 8-hydroxyl-4-isopropyl-7-methyl-6-methyl-2H-benzopyran-2-one. Two dimers, trans- and cis-3-(3,4-dimethoxyphen-yl)-4-[(E)-3,4-dimethoxystyryl]cyclohex-1-ene (compounds 8 and 9), were isolated from the Dryopteris genus for the first time. The other six were esculetin (2), isoscopoletin (3), methylphlorbutyrophenone (4), aspidinol (5), albicanol (6) and (E)-4-(3,4-dimethoxyphen-yl)but-3-en-1-ol (7). All compounds were evaluated for their cytotoxic effects by the MTT assay. Compounds 2, 3, 8 and 9 showed significantly cytotoxic effects against three cell lines (A549, MCF7 and HepG2), 1 and 5 against two cell lines (A549 and MCF7), and 6 against one cell line (MCF7). Their IC50 values ranged between 2.73 ± 0.86 µM and 24.14 ± 3.12 µM. These active compounds might be promising lead compounds for the treatment of cancer.

Huwentoxin-XVI, an analgesic, highly reversible mammalian N-type calcium channel antagonist from Chinese tarantula Ornithoctonus huwena.

N-type calcium channels play important roles in the control of neurotransmission release and transmission of pain signals to the central nervous system. Their selective inhibitors are believed to be potential drugs for treating chronic pain. In this study, a novel neurotoxin named Huwentoxin-XVI (HWTX-XVI) specific for N-type calcium channels was purified and characterized from the venom of Chinese tarantula Ornithoctonus huwena. HWTX-XVI is composed of 39 amino acid residues including six cysteines that constitute three disulfide bridges. HWTX-XVI could almost completely block the twitch response of rat vas deferens to low-frequency electrical stimulation. Electrophysiological assay indicated that HWTX-XVI specifically inhibited N-type calcium channels in rat dorsal root ganglion cells (IC50 ∼60 nM). The inhibitory effect of HWTX-XVI on N-type calcium channel currents was dose-dependent and similar to that of CTx-GVIA and CTx-MVIIA. However, the three peptides exhibited markedly different degrees of reversibility after block. The toxin had no effect on voltage-gated T-type calcium channels, potassium channels or sodium channels. Intraperitoneal injection of the toxin HWTX-XVI to rats elicited significant analgesic responses to formalin-induced inflammation pain. Toxin treatment also changed withdrawal latency in hot plate tests. Intriguingly, we found that intramuscular injection of the toxin reduced mechanical allodynia induced by incisional injury in Von Frey test. Thus, our findings suggest that the analgesic potency of HWTX-XVI and its greater reversibility could contribute to the design of a novel potential analgesic agent with high potency and low side effects.

Characterization of a new sesquiterpene and antifungal activities of chemical constituents from Dryopteris fragrans (L.) Schott.

One new sesquiterpene and six known compounds were isolated from Dryopteris fragrans (L.) Schot. They were identified as 3-O-ß-D-glucopyranosylalbicanol- 11-O-ß-D-glucopyranoside (1), dihydroconiferylalcohol (2), (E)-3-(4-hydroxyphenyl)acrylic acid (3), esculetin (4), 5,7-dihydroxy-2-hydroxymethylchromone (5), eriodictyol (6) and isoorientin (7) by UV, MS, 1D-NMR and 2D-NMR spectroscopy. The antifungal activities of the seven isolated compounds were screened. Compounds 2, 3, 4 and 5 showed obvious activities against Microsporum canis and Epidermophyton floccosum.

Fluorescence detection of adenosine triphosphate using smart probe.

A novel fluorescent probe for adenosine triphosphate (ATP) assay based on DNA ligation is proposed in this article. This approach uses a novel smart probe, T4 DNA ligase, and two short oligonucleotides. In the presence of ATP, the T4 DNA ligase catalyzes the ligation reaction and the ligation product restores the fluorescence of the smart probe. This method is very sensitive with a 0.5-nM limit of detection. Compared with current assay methods, the strategy is simpler, cheaper, and 40 times more sensitive.

Label-free highly sensitive detection of telomerase activity in cancer cell by chemiluminescence imaging.

We have developed a new methodology for label-free highly sensitive telomerase activity assay using chemiluminescence imaging. This method can detect the telomerase activity from as little as 10 cultured cancer cells without PCR. Furthermore, telomerase inhibition is shown, demonstrating the potential for screening of telomerase inhibitors as anticancer drug agents.

A new phenolic glycoside from the aerial parts of Dryopteris fragrans.

A new phenolic glycoside, 3,5-dimethyl-6-hydroxy-2-methoxy-4-O-D-glucopyranosyl-oxy-acetophenone (1), was isolated from the aerial parts of Dryopteris fragrans. The structure was elucidated on the basis of spectroscopic methods.

[Effects of long-term estrogen replacement treatment on the blood pressure and expression of IR and IRS-1 in myocardium].

OBJECTIVE: To determine the effects of long-term estrogen replacement treatment on blood pressure and expressions of insulin receptor (IR) and insulin receptor substrate-1 ( IRS-1) in myocardium. METHODS: Fifty female SD rats were randomly divided into 3 groups. And then sham ( n = 16), ovariectomy (OVX, n = 17), and estrogen replacement treatment group (OVX + E2, n = 17) were established. Systolic blood pressure of tail artery was determined by tail-cuff technique before the operation and on week 12 after the operation. The expressions of IR and IRS-1 were measured by RT-PCR in myocardium of SD rats. RESULTS: Blood pressure [ (118.75+/-2.77) mmHg] in OVX was significantly higher than that in the sham [ ( 103.86+/-1.84) mmHg, P < 0.05 ] and OVX + E2 [( 107.83+/-3.24) mmHg, P < 0.05 ] rats. Expression of IRS-1 in OVX group was significantly lower ( 1.2588+/-0.1045)than that in the sham(2.2089+/-0.0988, P <0.05) and OVX + E2 groups ( 1.9100+/-0.1230, P <0.05 ). However, there was no difference on blood pressure and expression of IRS-1 between sham and OVX + E2 groups (P > 0.05 ). The difference of IR expression has no statistical significance among the 3 groups. CONCLUSION: Long-term estrogen replacement treatment might protect cardiovascular system through decreasing the blood pressure and inducing the expression of IRS-1 in myocardium. However, plasma estrogen level doesn't significantly influence the IR expression.