The Role of Muscarinic Acetylcholine Receptor M3 in Cardiovascular Diseases.

The muscarinic acetylcholine receptor M3 (M3-mAChR) is involved in various physiological and pathological processes. Owing to specific cardioprotective effects, M3-mAChR is an ideal diagnostic and therapeutic biomarker for cardiovascular diseases (CVDs). Growing evidence has linked M3-mAChR to the development of multiple CVDs, in which it plays a role in cardiac protection such as anti-arrhythmia, anti-hypertrophy, and anti-fibrosis. This review summarizes M3-mAChR's expression patterns, functions, and underlying mechanisms of action in CVDs, especially in ischemia/reperfusion injury, cardiac hypertrophy, and heart failure, opening up a new research direction for the treatment of CVDs.

Single-cell sequencing reveals the immune microenvironment landscape related to anti-PD-1 resistance in metastatic colorectal cancer with high microsatellite instability.

BACKGROUND: The objective response rate of microsatellite instability-high (MSI-H) metastatic colorectal cancer (mCRC) patients with first-line anti-programmed cell death protein-1 (PD-1) monotherapy is only 40-45%. Single-cell RNA sequencing (scRNA-seq) enables unbiased analysis of the full variety of cells comprising the tumor microenvironment. Thus, we used scRNA-seq to assess differences among microenvironment components between therapy-resistant and therapy-sensitive groups in MSI-H/mismatch repair-deficient (dMMR) mCRC. Resistance-related cell types and genes identified by this analysis were subsequently verified in clinical samples and mouse models to further reveal the molecular mechanism of anti-PD-1 resistance in MSI-H or dMMR mCRC. METHODS: The response of primary and metastatic lesions to first-line anti-PD-1 monotherapy was evaluated by radiology. Cells from primary lesions of patients with MSI-H/dMMR mCRC were analyzed using scRNA-seq. To identify the marker genes in each cluster, distinct cell clusters were identified and subjected to subcluster analysis. Then, a protein‒protein interaction network was constructed to identify key genes. Immunohistochemistry and immunofluorescence were applied to verify key genes and cell marker molecules in clinical samples. Immunohistochemistry, quantitative real-time PCR, and western blotting were performed to examine the expression of IL-1ß and MMP9. Moreover, quantitative analysis and sorting of myeloid-derived suppressor cells (MDSCs) and CD8+ T cells were performed using flow cytometry. RESULTS: Tumor responses in 23 patients with MSI-H/dMMR mCRC were evaluated by radiology. The objective response rate was 43.48%, and the disease control rate was 69.57%. ScRNA-seq analysis showed that, compared with the treatment-resistant group, the treatment-sensitive group accumulated more CD8+ T cells. Experiments with both clinical samples and mice indicated that infiltration of IL-1ß-driven MDSCs and inactivation of CD8+ T cells contribute to anti-PD-1 resistance in MSI-H/dMMR CRC. CONCLUSIONS: CD8+ T cells and IL-1ß were identified as the cell type and gene, respectively, with the highest correlation with anti-PD-1 resistance. Infiltration of IL-1ß-driven MDSCs was a significant factor in anti-PD-1 resistance in CRC. IL-1ß antagonists are expected to be developed as a new treatment for anti-PD-1 inhibitor resistance.

Dyadobacter diqingensis sp. nov., isolated from Baima snow mountain of Diqing Tibetan Autonomous Prefecture in Yunnan province, south-west China.

A Gram-negative, aerobic, nonmotile, rod-shaped and yellow-pigment-producing bacteria was isolated from Baima snow mountain of Diqing Tibetan Autonomous Prefecture in Yunnan province, south-west China and characterized using a polyphasic approach. The results of 16S rRNA gene sequence similarity analysis showed that strain YIM B04101T was closely related to the type strain of Dyadobacter koreensis DSM 19938T (97.81%) and Dyadobacter frigoris AR-3-8T (97.95%). The predominant respiratory quinone was menaquinone-7 (MK-7). The major polar lipid was phosphatidylethanolamine. The major fatty acids were summed feature 3 (C16:1ω7c/C16:1ω6c), C18:1ω9c and C16:0. The DNA G + C content was 43.5 mol%. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the strain YIM B04101T belonged to a cluster comprising species of the genus Dyadobacter. However, it differed from its closest relative, Dyadobacter koreensis KCTC 12537T and Dyadobacter frigoris AR-3-8T, in many physiological properties. Based on these phenotypic characteristics and phylogenetic distinctiveness, strain YIM B04101T is considered to be a novel species of the genus Dyadobacter, for which the name Dyadobacter diqingensis sp. nov. is proposed. The type strain is YIM B04101T (= CGMCC 1.19249T = CCTCC AB 2021270).

Levels, distribution characteristics, and sources of heavy metals in indoor dust in Shijiazhuang, China.

Heavy metals in indoor dust are associated with health risks in humans. However, in Shijiazhuang, a city in northern China with severe haze, no research has been published on this topic. To determine the content, distribution characteristics, and sources of heavy metals in indoor dust in the city of Shijiazhuang, indoor dust samples from 33 sampling points in the main urban area of Shijiazhuang were collected and tested. Concentrations of Cu, Ni, Cr, Zn, Cd, and Pb were 87.0, 35.1, 104.4, 568.0, 1.980, and 187.6 mg·kg-1, respectively; their levels have been discussed statistically in comparison with the reported values in other cities in China. The sources of heavy metals were analyzed using enrichment factor, correlation coefficient, and principal component analysis. The results showed that the levels of all six elements in indoor dust in Shijiazhuang exceeded the background values of soil in Hebei Province. Among these, Cd, Pb, and Zn were significantly enriched. The enrichment factors of Cu, Ni, and Cr were below 10, and their levels at different sampling points were similar, indicating their geogenic source. The corresponding pollution levels of Cd, Pb, and Zn were relatively high, and their levels at different points were significantly different and correlated, indicating that they were derived mainly from transportation. Additionally, the level of Zn was significantly affected by the indoor environment. Our findings provide a basis for conducting health risk assessments in the future.

A novel highly dispersed tetra-metal nano heterogeneous ozone catalyst derived from microbial adsorption and in situ pyrolysis.

In recent years, the pyrolysis of microbial biomasses that adsorb various metal ions has enabled the preparation of carbon-based polymetallic nanomaterials with excellent electrocatalytic and electrical energy storage properties. However, the preparation of ozone catalysts by this technique and the corresponding catalytic oxidation mechanism are still unclear. In this study, an Escherichia coli strain (BL21) was used for tetra-metal (Cu, Fe, Mn and Al) absorption and the obtained microbial biomass was pyrolyzed under the protection of a nitrogen flow at 700 °C and activated at 900 °C to prepare a microbial-char-based tetra-metal ozone catalyst (MCOC). This was used to degrade phenol and coking wastewater and exhibited a strong catalytic capability for coking wastewater, whose chemical oxygen demand removal efficiency of 70.86% is 16.7% higher than that of pure ozone and 14.67%, 7.21% and 3.58% higher than that of three commercial catalysts, respectively. It also improved the efficiency of ozonation for phenol by 33%. The MCOC was characterized by x-ray diffraction, x-ray photoelectron spectroscopy, scanning electron microscopy-energy-dispersive spectroscopy, transmission electron microscopy and other methods. The results demonstrated that the spherical metal nanoparticles had sizes ranging from 3 nm to 7 nm and that crystals of Fe2O3 and Fe3P were observed. The study showed that the MCOC promoted the production of more hydroxyl radicals and superoxides from ozone, which attack organics. The oxygen vacancies of the catalyst were also investigated. It was proved that the Lewis acid sites on the surface of metal oxides are the active centers of ozone decomposition. Therefore, this work provides a new method for the synthesis of multi-metal nanocomposites and expands the application of biosynthetic nanomaterials.

Observation of antiferromagnetic correlations in the Hubbard model with ultracold atoms.

Ultracold atoms in optical lattices have great potential to contribute to a better understanding of some of the most important issues in many-body physics, such as high-temperature superconductivity. The Hubbard model--a simplified representation of fermions moving on a periodic lattice--is thought to describe the essential details of copper oxide superconductivity. This model describes many of the features shared by the copper oxides, including an interaction-driven Mott insulating state and an antiferromagnetic (AFM) state. Optical lattices filled with a two-spin-component Fermi gas of ultracold atoms can faithfully realize the Hubbard model with readily tunable parameters, and thus provide a platform for the systematic exploration of its phase diagram. Realization of strongly correlated phases, however, has been hindered by the need to cool the atoms to temperatures as low as the magnetic exchange energy, and also by the lack of reliable thermometry. Here we demonstrate spin-sensitive Bragg scattering of light to measure AFM spin correlations in a realization of the three-dimensional Hubbard model at temperatures down to 1.4 times that of the AFM phase transition. This temperature regime is beyond the range of validity of a simple high-temperature series expansion, which brings our experiment close to the limit of the capabilities of current numerical techniques, particularly at metallic densities. We reach these low temperatures using a compensated optical lattice technique, in which the confinement of each lattice beam is compensated by a blue-detuned laser beam. The temperature of the atoms in the lattice is deduced by comparing the light scattering to determinant quantum Monte Carlo simulations and numerical linked-cluster expansion calculations. Further refinement of the compensated lattice may produce even lower temperatures which, along with light scattering thermometry, would open avenues for producing and characterizing other novel quantum states of matter, such as the pseudogap regime and correlated metallic states of the two-dimensional Hubbard model.

AllEnricher: a comprehensive gene set function enrichment tool for both model and non-model species.

BACKGROUND: Function genomic studies will generally result in lists of genes that may provide clues for exploring biological questions and discovering unanticipated functions, based on differential gene expression analysis, differential epigenomic analysis or co-expression network analysis. While tools have been developed to identify biological functions that are enriched in the genes sets, there remains a need for comprehensive tools that identify functional enrichment of genes for both model and non-model species from a different function classification perspective. RESULTS: We developed AllEnricher, a tool that calculates gene set function enrichment, with user-defined updatable libraries backing up for both model and non-model species as well as providing comprehensive functional interpretation from multiple dimensions, including GO, KEGG, Reactome, DO and DisGeNET. CONCLUSIONS: AllEnricher incorporates up to date information from different public resources and provides a comprehensive resolution for biologists to make sense out of specific gene sets, making it an advanced open-source tool for gene set function analysis.

A longitudinal study reveals the alterations of the Microtus fortis colonic microbiota during the natural resistance to Schistosoma japonicum infection.

The gut microbiota has been demonstrated to associate with protection against helminth infection and mediate via microbial effects on the host humoral immunity. As a non-permissive host of Schistosoma japonicum, the Microtus fortis provides an ideal animal model to be investigated, because of its natural self-healing capability. Although researches on the systemic immunological responses have revealed that the host immune system contributes a lot to the resistance, the role of gut microbiome remains unclear. In this study, we exposed the M. fortis to the S.japonicum infection, carried out a longitudinal research (uninfected control, infected for 7 days, 14 days, 21 days, and 31 days) on their colonic microbiota based on the 16S rRNA gene amplicon sequencing. The bacterial composition disclosed a disturbance-recovery alteration followed by the resistance to S. japonicum. The alpha diversity of colon microbiota was reduced after the infection, but it gradually recovered along with self-healing process. Further LEfSe analysis revealed that phyla shifted from Firmicutes to Bacteroidetes, which were mainly driven by an increase of Ruminococcaceae and a depletion of Muribaculaceae in the family level along the Control-Infection-Recovery (CIR) process. We identified a temporary blooming of Lactobacillaceae and Lactobacillus in the mid infection stage (D14). As a recognized probiotics repository, we speculate the increased abundance of Lactobacillaceae in M. fortis colonic microbiota might relate to the natural resistance to the schistosome. Besides, potential microbial functions were also significantly changed in the resistance process. These results demonstrate the remarkable alterations of reed vole colonic microbiota in both community structure and potential functions along with the resistance to S. japonicum infection. The identified microbial biomarkers might offer new ways for drug development to conquer human schistosomiasis.

Selective adsorption of palladium and platinum from secondary wastewater using Escherichia coli BL21 and Providencia vermicola.

It is important to recover precious metals from secondary wastewater because of their low crustal abundance. The selective adsorption of palladium (Pd) and platinum (Pt) ions from secondary wastewater, which contains a large amount aluminium and sodium ions, was investigated using Escherichia coli BL21 (BL21), genetically modified E. coli BL21 (EC20) and Providencia vermicola (P. V.). The results demonstrated that P.V., BL21 and EC20 cells took 95.9%, 88.2% and 97.5% of Pd ions, and 64.8%, 93.2% and 100% of Pt ions form industrial wastewater, respectively. All three bacterial biomass could be reused for Pd adsorption with a second adsorption efficiency of > 85%, specifically, the EC20 cells could absorb 93.8% of Pd ions from wastewater. SEM-EDS and XPS analyses confirmed the occurrence of Pd and Pt on the surface of wastewater-absorbed biomass. The shift in FTIR spectrum implied that functional groups, such as hydroxyl, amino, carboxyl and phosphate groups, were involved in wastewater adsorption.

Microbial synthesis of Pd-Pt alloy nanoparticles using Shewanella oneidensis MR-1 with enhanced catalytic activity for nitrophenol and azo dyes reduction.

Bimetallic nanoparticles (NPs) often exhibit improved catalytic performance due to the electronic and spatial structure changes. Herein, a novel green biosynthesis method for Pd-Pt alloy NPs using Shewanella oneidensis MR-1 was proposed. The morphology, size and crystal structure of Pd-Pt alloy NPs were studied by a suite of characterization techniques. Results showed Pd-Pt alloy NPs were successfully synthesized inside and outside the cell. The biosynthesized Pd-Pt alloy NPs were polycrystalline and face-centered-cubic structure with the particle size ranged from 3-40 nm. Furthermore, the catalytic experiment demonstrated that the Pd-Pt alloy NPs exhibited the highest performance for the catalytic reduction of nitrophenol and azo dyes compared with the as-synthesized Pd and Pt monometallic NPs. This enlarged catalytic activity resulted from the synergistic effect of Pd and Pt element. Thereby, this paper provided a simple biosynthesis method for producing bimetallic alloy nanocatalyst with superior activity for contaminant degradation.

Hexavalent chromium remediation based on the synergistic effect between chemoautotrophic bacteria and sulfide minerals.

Hexavalent chromium (Cr(VI)) is an environmental concern due to the carcinogenic and mutagenic effect on living organisms. Sulfide minerals based Cr(VI) reduction is an economical and efficient strategy for Cr(VI) remediation. In this study, Cr(VI) reduction through the synergistic effect between chemoautotrophic bacteria and sulfide mineral is systematically investigated. Sulfide minerals dissolution and Cr(VI) reduction performance highly depends on mineral acid soluble property. Cr(VI) reduction capacity of pyrrhotite, pyrite, marcasite and sphalerite was 50, 104, 104 and 44 mg/g (Cr(VI)/mineral) respectively in the biotic system. Acidithiobacillus ferrooxidans (A. ferrooxidans) significantly enhanced pyrite and marcasite based Cr(VI) reduction kinetic and capacity. Proton consumption, iron coprecipitation and the biological activity deficiency in the abiotic system significantly inhibited Cr(VI) reduction. Elemental sulfur and secondary iron mineral as the main composition of the passivation layer inhibited sustainable Cr(VI) reduction. A. ferrooxidans facilitated acid nonsoluble mineral dissolution and surface passivation layer removal, and promoted Cr(VI) reduction. Acid nonsoluble sulfide mineral disulfide bond rapture, S°/Sn2- oxidization, and Fe(III)/Cr(III) dissolution were accelerated by A. ferrooxidans, which facilitated Cr(VI) reduction reactive sites regeneration. Our study demonstrated that chemoautotrophic bacterial accelerated Cr(VI) reduction reaction through promoting acid nonsoluble sulfide mineral dissolution. This research is of environmental and practical significance to remediate redox sensitive contaminant based on the synergistic effect between sulfide minerals and chemoautotrophic A. ferrooxidans.

Enhancement of platinum biosorption by surface-displaying EC20 on Escherichia coli.

To increase the platinum adsorption capacity of Escherichia coli (E. coli) biomass, we fused EC20 protein to the E. coli cell surface using an InaKN-based display system, which is the N-terminal region of ice nucleation protein that can be employed as a cell surface display motif. The media and culture conditions were optimized for EC20 (a phytochelatin analogue with 20 repeating units of glutamate and cysteine) expression and Pt (IV) biosorption. Furthermore, the adsorption process was elucidated from aspect of adsorption kinetics and equilibrium, and the characterization of blank and Pt-loaded cells were analyzed using SEM, AFM, TEM, FT-IR and XPS. Our study demonstrated that E. coli strain, which had InaKN-EC20 protein expressed on the cell surface, showed a great enhancement in Pt (IV) adsorption under optimized condition when comparing with that of original E. coli strain. The SEM-EDX analysis revealed that the cellular morphology has been changed in Pt-loaded cells, and the weight percent of platinum in the surface of E.coli increased substantially after displaying EC20 protein. Furthermore, intracellular platinum accumulation was detected in Pt-loaded EC20 cells since a clear peak of platinum exhibited, implying that cytoplasmic EC20 protein might also contribute to platinum accumulation. FTIR analysis revealed that the predominant functional groups in platinum adsorption were amine, carboxyl and phosphate groups.

Synergistic effect between sulfide mineral and acidophilic bacteria significantly promoted Cr(VI) reduction.

Natural pyrite was an economical choice for efficient Cr(VI) remediation, while its deep utilization was inhibited due to the passivation effect. In this study, pyrite passivation/dissolution and active sites regeneration mechanism under the activity of acidophilic bacteria with different energy metabolism characteristic in Cr(VI) reduction have been investigated. The reduction capacity was in the order of Acidithiobacillus thiooxidans, Acidithiobacillus ferrooxidans(S), Acidithiobacillus ferrooxidans(Fe), Leptospirillum ferrooxidans and chemical control. The maximal reduction efficiency was achieved in A. thiooxidans system, which is 4.5 times higher than the L. ferrooxidans system. In chemical system, sulfur and Fe(III)/Cr(III)-oxyhydroxysulphate accumulation would result in pyrite passivation. A. thiooxidans attached on pyrite surface and exerted synergistic effect on pyrite corrosion coupled with Cr(VI). Sulfur oxidation promoted proton regeneration, pyrite lattice Fe(II) dissolution and active sites regeneration, which were beneficial to sustainable Cr(VI) reduction. Secondary iron mineral formation on pyrite was accelerated with the iron oxidation bacteria activity increasing. Excessive oxidation to surface sites Fe(II) and the accumulation of S0/Sn2- led to the passivation effect in L. ferrooxidans system. Cr(VI) acquired electron from Fe(II) and disulfide and resulted in the bond break between them. The combined effect of specific sulfur oxidizing bacteria activity and Cr(VI) oxidation efficient promoted pyrite dissolution and active sites regeneration. The interaction between acidophilic bacteria and pyrite significantly enhanced Cr(VI) reduction efficiency.

[Genetic Diversity and Cluster Analysis of Astragalus membranaceus in Gansu Province].

Objective: To investigate the genetic status of Astragalus membranaceuse resources in Gansu province. Methods: Using SSR molecular marker technology for collection of Astragalus membranaceuse resources for genetic diversity analysis and clustering analysis. Results: Nine SSR primers were used on PCR amplification of 57 samples in six main areas of Gansu province,PCR products molecular weighted between 100 ~ 500 bp,the polymorphic loci was 82,the polymorphism rate was 97. 56%,and the average polymorphism information content was 0. 438. At the species level,the number of alleles was 1. 976,the effective number of alleles was 1. 459,Nei' s genetic diversity was 0. 279,Shannon information index was 0. 431,the group of genetic diversity degree was 0. 248,the genetic differentiation among of population was 0. 117,the gene flow coefficient was 3. 775,and the genetic identity was 0. 896 ~ 0. 977. Conclusion: Astragalus membranaceuse resources of Gansu are relatively pure,and have abundant genetic diversity. The genetic variation mainly comes from the group of inside,the genes communication between populations is frequent,and the kinship between population is consistent with their geographic distance. In addition,the results of cluster analysis showed that the Core SSR primers can distinguish Astragalus and Hedysarum in the similarity of 0. 46,but Astragalus membranaceus var. mongholicus,Astragalus membranaceus and Astragalus tongolensis can't be distinguished.

[Astragali Radix and Hedysari Radix molecular identification of SSR primers screening and fingerprints code].

Leguminous related SSR primers were collected, core primers used for Astragali Radix and Hedysari Radix identification were screened and validated by using molecular marker techniques. 6 core primers were selected from 101 pairs of primers, the molecular weight of PCR products was 100-500 bp, which formed 7-12 electrophoresis bands with 55 amplified loci. The percentage of polymorphic loci was 100%, and the average polymorphism information content was 0.371. According to the results of cluster analysis, obtained core primer could completely distinguish 62 mixture samples of Astragali Radix and Hedysari Radix in similarity coefficient of 0.46. Core primers and the corresponding characteristics from gel electrophoresis were tagged. The results provide identification basis for Astragali Radix and Hedysari Radix.

Compressibility of a fermionic mott insulator of ultracold atoms.

We characterize the Mott insulating regime of a repulsively interacting Fermi gas of ultracold atoms in a three-dimensional optical lattice. We use in situ imaging to extract the central density of the gas and to determine its local compressibility. For intermediate to strong interactions, we observe the emergence of a plateau in the density as a function of atom number, and a reduction of the compressibility at a density of one atom per site, indicating the formation of a Mott insulator. Comparisons to state-of-the-art numerical simulations of the Hubbard model over a wide range of interactions reveal that the temperature of the gas is of the order of, or below, the tunneling energy scale. Our results hold great promise for the exploration of many-body phenomena with ultracold atoms, where the local compressibility can be a useful tool to detect signatures of different phases or phase boundaries at specific values of the filling.

Eif3ba regulates cranial neural crest development by modulating p53 in zebrafish.

Congenital diseases caused by abnormal development of the cranial neural crest usually present craniofacial malformations and heart defects while the precise mechanism is not fully understood. Here, we show that the zebrafish eif3ba mutant caused by pseudo-typed retrovirus insertion exhibited a similar phenotype due to the hypogenesis of cranial neural crest cells (NCCs). The derivatives of cranial NCCs, including the NCC-derived cell population of pharyngeal arches, craniofacial cartilage, pigment cells and the myocardium derived from cardiac NCCs, were affected in this mutant. The expression of several neural crest marker genes, including crestin, dlx2a and nrp2b, was specifically reduced in the cranial regions of the eif3ba mutant. Through fluorescence-tracing of the cranial NCC migration marker nrp2b, we observed reduced intensity of NCC-derived cells in the heart. In addition, p53 was markedly up-regulated in the eif3ba mutant embryos, which correlated with pronounced apoptosis in the cranial area as shown by TUNEL staining. These findings suggest a novel function of eif3ba during embryonic development and a novel level of regulation in the process of cranial NCC development, in addition to providing a potential animal model to mimic congenital diseases due to cranial NCC defects. Furthermore, we report the identification of a novel transgenic fish line Et(gata2a:EGFP)pku418 to trace the migration of cranial NCCs (including cardiac NCCs); this may serve as an invaluable tool for investigating the development and dynamics of cranial NCCs during zebrafish embryogenesis.

Cell proliferation and cell sheet detachment from the positively and negatively charged nanocomposite hydrogels.

The charged nanocomposite hydrogels (NC gels) were synthesized by copolymerization of positively or negatively chargeable monomer with N-isopropylacrylamide (NIPAm) in the aqueous suspension of hectorite clay. The ionic NC gels preserved the thermo-responsibility with the phase-transition temperature below 37°C. The L929 cell proliferation was sensitive to charge polarity and charge density. As compared to the PNIPAm NC gel, the cationic NC gels with <5 mol % of 2-(dimethylamino)ethyl methacrylate (DMAEMA) showed improved cell proliferation, whereas the cells grew slowly on the gels with negatively charged 2-acrylamido-2-methylpropane sulfonic acid (AMPSNa). By lowering temperature, rapid cell sheet detachment was observed from the surface of ionic NC gels with 1 mol % of ionizable monomers. However, lager amount of AMPSNa or DMAEMA did not support rapid cell sheet detachment, probably owing to the adverse swelling effects and/or enhanced electrostatic attraction.

Notch insensitive and self-healing PNIPAm-PAM-clay nanocomposite hydrogels.

In the present work, hydrophilic monomer acrylamide (AM) was copolymerized with N-isopropylacrylamide (NIPAm) in an aqueous hectorite clay suspension to prepare PNIPAm-PAM-clay nanocomposite hydrogels (NC gels). With increasing AM content, the elongation at break of the copolymerized NC gels increased but the strength as well as the hysteresis during the loading-unloading cycle decreased, showing faster relaxation due to the more hydrophilic copolymer chains with the AM segments. The elongation at break of the copolymerized NC gels was independent of the notch length and notch type, while the fracture energy was greatly increased to 3000-5000 J m(-2) from 700 J m(-2) for the pure PNIPAm NC gels. The copolymer chains resulted in this notch insensitivity by easily dispersing the stress concentration at the notch tip through disorientation of the copolymer chains and clay platelets. The copolymerized NC gels also exhibited excellent self-healing capability; the cut surfaces were connected together by simply keeping in contact for a period of time (about 4 days at 20 °C). This self-healing was accelerated by increasing the treatment temperature (about 4 h at 80 °C).

Metal resistance-related genes are differently expressed in response to copper and zinc ion in six Acidithiobacillus ferrooxidans strains.

Metal resistance of acidophilic bacteria is very significant during bioleaching of copper ores since high concentration of metal is harmful to the growth of microorganisms. The resistance levels of six Acidithiobacillus ferrooxidans strains to 0.15 M copper and 0.2 M zinc were investigated, and eight metal resistance-related genes (afe-0022, afe-0326, afe-0329, afe-1143, afe-0602, afe-0603, afe-0604, and afe-1788) were sequenced and analyzed. The transcriptional expression levels of eight possible metal tolerance genes in six A. ferrooxidans strains exposed to 0.15 M Cu(2+) and 0.2 M Zn(2+) were determined by real-time quantitative PCR (RT-qPCR), respectively. The copper resistance levels of six A. ferrooxidans strains declined followed by DY26, DX5, DY15, GD-B, GD-0, and YTW. The zinc tolerance levels of six A. ferrooxidans strains exposed to 0.2 M Zn(2+) from high to low were YTW > GD-B > DY26 > GD-0 > DX5 > DY15. Seven metal tolerance-related genes all presented in the genome of six strains, except afe-0604. The metal resistance-related genes showed different transcriptional expression patterns in six A. ferrooxidans strains. The expression of gene afe-0326 and afe-0022 in six A. ferrooxidans strains in response to 0.15 M Cu(2+) showed the same trend with the resistance levels. The expression levels of genes afe-0602, afe-0603, afe-0604, and afe-1788 in six strains response to 0.2 M Zn(2+) did not show a clear correlation between the zinc tolerance levels of six strains. According to the results of RT-qPCR and bioinformatics analysis, the proteins encoded by afe-0022, afe-0326, afe-0329, and afe-1143 were related to Cu(2+) transport of A. ferrooxidans strains.