Source identification and risk assessment of heavy metals in road dust of steel industrial city (Anshan), Liaoning,Northeast China

Abstract

The purpose of the study was to acquire the source and evaluate the risk posed by heavy metals in road dust of steel industrial city (Anshan), Liaoning, Northeast China. Potential ecological risk index (RI), pollution index (PI) and geo-accumulation index (Igeo) were applied to evaluate the heavy metal pollution level, and the carcinogenic risk (RI) and hazard index (HI) were calculated to estimate the human health risk. The geographic information system maps clearly reveal the hot spots of heavy metal spatial distribution. Principle component analysis (PCA) and cluster analysis (CA) classified heavy metals into three groups. The metal Zn and Pb originate from the traffic emission, while Cd, Cr, Fe, Mn, Ni and Sb primarily come from industrial activities. These two pathways were the major source of heavy metals pollution by positive matrix factorization (PMF). The Igeo and PI values of heavy metals were decreased in the following order: Cd?>?Sb?>?Zn?>?Fe?>?Pb?>?Cu?>?Cr?>?Sn?>?Mn?>?Ni. The RI index showed the heavy metals were moderate to very high potential ecological risk. The HI values for children and adults presented a decreasing order of Cr?>?Pb?>?Ni?>?Cu?>?Cd?>?Zn. The HI also predicted a possibility of non-carcinogenic risk for children living in urban areas in comparison with adults.     

Binding mechanism of maltol with catalase investigated by spectroscopy,molecular docking,and enzyme activity assay

Maltol is a flavor additive that is widely used in the daily diet of humans, and its biosafety attention is concomitantly increasing. Catalase (CAT) is an antioxidant enzyme to maintain homeostasis in the tissue's environment of human body and protect cells from oxidative damages. The adverse effects of maltol to CAT activity within mouse hepatocytes as well as the structural and functional changes of CAT on molecular level were investigated by multiple spectroscopy techniques, enzyme activity experiments, and molecular docking. Results suggested that when the maltol concentrations reached to 8 × 10^?5 mol L^?1, the viability of hepatocytes decreased to 93%, and CAT activity was stimulated by maltol to 111% than the control group after exposure for 24 hours. Changes in CAT activity on molecular level were consistent with those on cellular level. The fluorescence quenching of CAT by maltol was static with the forming of maltol‐CAT complex. Moreover, ultraviolet‐visible (UV‐visible) absorption, synchronous fluorescence, and circular dichroism (CD) spectra reflected that the presence of maltol caused conformational change of CAT and made the CAT molecule skeleton loose and increased α‐helix of CAT. Maltol mainly bound with CAT through hydrogen bond, and binding site that is near the heme ring in the enzyme activity center did not interact with its main amino acid residues. This study explores the combination between maltol and CAT, providing references for evaluating health damages caused by maltol.     

Expression profiles and potential roles of transfer RNA-derived small RNAs in atherosclerosis

Knowledge regarding the relationship between the molecular mechanisms underlying atherosclerosis (AS) and transfer RNA-derived small RNAs (tsRNAs) is limited. This study illustrated the expression profile of tsRNAs, thus exploring its roles in AS pathogenesis. Small RNA sequencing was performed with four atherosclerotic arterial and four healthy subject samples. Using bioinformatics, the protein-protein interaction network and cellular experiments were constructed to predict the enriched signalling pathways and regulatory roles of tsRNAs in AS. Of the total 315 tsRNAs identified to be dysregulated in the AS group, 131 and 184 were up-regulated and down-regulated, respectively. Interestingly, the pathway of the differentiated expression of tsRNAs in cell adhesion molecules (CAMs) was implicated to be closely associated with AS. Particularly, tRF-Gly-GCC might participate in AS pathogenesis via regulating cell adhesion, proliferation, migration and phenotypic transformation in HUVECs and VSMCs. In conclusion, tsRNAs might help understand the molecular mechanisms of AS better. tRF-Gly-GCC may be a promising target for suppressing abnormal vessels functions, suggesting a novel strategy for preventing the progression of atherosclerosis.     

βII spectrin (SPTBN1): biological function and clinical potential in cancer and other diseases

βII spectrin, the most common isoform of non-erythrocyte spectrin, is a cytoskeleton protein present in all nucleated cells. Interestingly, βII spectrin is essential for the development of various organs such as nerve, epithelium, inner ear, liver and heart. The functions of βII spectrin include not only establishing and maintaining the cell structure but also regulating a variety of cellular functions, such as cell apoptosis, cell adhesion, cell spreading and cell cycle regulation. Notably, βII spectrin dysfunction is associated with embryonic lethality and the DNA damage response. More recently, the detection of altered βII spectrin expression in tumors indicated that βII spectrin might be involved in the development and progression of cancer. Its mutations and disorders could result in developmental disabilities and various diseases. The versatile roles of βII spectrin in disease have been examined in an increasing number of studies; nonetheless, the exact mechanisms of βII spectrin are still poorly understood. Thus, we summarize the structural features and biological roles of βII spectrin and discuss its molecular mechanisms and functions in development, homeostasis, regeneration and differentiation. This review highlight the potential effects of βII spectrin dysfunction in cancer and other diseases, outstanding questions for the future investigation of therapeutic targets. The investigation of the regulatory mechanism of βII spectrin signal inactivation and recovery may bring hope for future therapy of related diseases.     

草地土壤有机质不同组分氮库对长期氮添加的响应

土壤氮库对生态系统的养分循环至关重要。目前多数研究主要关注氮沉降对土壤总氮的影响, 而对土壤不同有机质组分的氮库对氮沉降响应的研究较为缺乏。该研究基于内蒙古典型草地的长期多水平施氮(0、8、32、64 g·m^-2·a^-1)实验平台, 利用土壤密度分级方法, 探究氮添加处理13年后典型草地中两种土壤有机质组分(颗粒态有机质(POM), 矿质结合态有机质(MAOM))氮含量的变化及调控机制。结果显示: 土壤总碳含量、POM和MAOM的碳含量在施氮处理间均没有显著差异。土壤总氮含量则随着施氮水平增加呈显著增加的趋势, 同时施氮处理下POM的氮含量显著上升, 而MAOM的氮含量没有变化。进一步分析发现, 施氮促进植物地上生物量积累, 增加了凋落物量及其氮含量, 从而导致POM的氮含量增加。由于MAOM主要通过黏土矿物等吸附土壤中小分子有机质形成, 其氮含量受土壤中黏粒与粉粒含量影响, 而与氮添加水平无显著相关关系。该研究结果表明长期氮添加促进土壤氮库积累, 但增加的氮主要分布在稳定性较低的POM中, 受干扰后容易从生态系统中流失。为了更准确地评估和预测氮沉降对陆地生态系统的氮循环过程的影响, 应考虑土壤中不同有机质组分的差异响应。     

BAG3-dependent noncanonical autophagy induced by proteasome inhibition in HepG2 cells

Emerging lines of evidence have shown that blockade of ubiquitin-proteasome system (UPS) activates autophagy. The molecular players that regulate the relationship between them remain to be elucidated. Bcl-2 associated athanogene 3 (BAG3) is a member of the BAG co-chaperone family that regulates the ATPase activity of heat shock protein 70 (HSP70) chaperone family. Studies on BAG3 have demonstrated that it plays multiple roles in physiological and pathological processes, including antiapoptotic activity, signal transduction, regulatory role in virus infection, cell adhesion and migration. Recent studies have attracted much attention on its role in initiation of autophagy. The current study, for the first time, demonstrates that proteasome inhibitors elicit noncanonical autophagy, which was not suppressed by inhibitors of class III phosphatidylinositol 3-kinase (PtdIns3K) or shRNA against Beclin 1 (BECN1). In addition, we demonstrate that BAG3 is ascribed to activation of autophagy elicited by proteasome inhibitors and MAPK8/9/10 (also known as JNK1/2/3 respectively) activation is also implicated via upregulation of BAG3. Moreover, we found that noncanonical autophagy mediated by BAG3 suppresses responsiveness of HepG2 cells to proteasome inhibitors.     

Helicobacter pylori Cholesteryl α-Glucosides Contribute to Its Pathogenicity and Immune Response by Natural Killer T Cells

Approximately 10–15% of individuals infected with Helicobacter pylori will develop ulcer disease (gastric or duodenal ulcer), while most people infected with H. pylori will be asymptomatic. The majority of infected individuals remain asymptomatic partly due to the inhibition of synthesis of cholesteryl α-glucosides in H. pylori cell wall by α1,4-GlcNAc-capped mucin O-glycans, which are expressed in the deeper portion of gastric mucosa. However, it has not been determined how cholesteryl α-glucosyltransferase (αCgT), which forms cholesteryl α-glucosides, functions in the pathogenesis of H. pylori infection. Here, we show that the activity of αCgT from H. pylori clinical isolates is highly correlated with the degree of gastric atrophy. We investigated the role of cholesteryl α-glucosides in various aspects of the immune response. Phagocytosis and activation of dendritic cells were observed at similar degrees in the presence of wild-type H. pylori or variants harboring mutant forms of αCgT showing a range of enzymatic activity. However, cholesteryl α-glucosides were recognized by invariant natural killer T (iNKT) cells, eliciting an immune response in vitro and in vivo. Following inoculation of H. pylori harboring highly active αCgT into iNKT cell-deficient (Jα18^−/−) or wild-type mice, bacterial recovery significantly increased in Jα18^−/− compared to wild-type mice. Moreover, cytokine production characteristic of Th1 and Th2 cells dramatically decreased in Jα18^−/− compared to wild-type mice. These findings demonstrate that cholesteryl α-glucosides play critical roles in H. pylori-mediated gastric inflammation and precancerous atrophic gastritis.     

Study of PE and iPP orientations on the surface of carbon nanotubes by using molecular dynamic simulations

In this study, the early stage of interfacial crystallisation behaviour of low molecular weight polyethylene (PE) and isotactic polypropylene (iPP) oligomer on the surface of carbon nanotubes (CNTs) with different diameters, chiralities and topography structures was studied using MD simulations. We started to simulate the effect of CNTs chirality and diameter on PE molecular chain orientation, and then the effect of CNTs topography structure on PE and iPP molecular chain orientation was investigated. Finally, some experiments were carried out to prove the simulated results. Our study shows that for CNTs with a diameter comparable with the radius of gyration (R_g) of a polymer chain, an easy orientation of PE chains along CNTs axis is observed for all the systems of the CNTs with different chiralities due to a geometric confinement effect. For CNTs with a much larger diameter, multiple orientation of PE chains is induced on its surface due to the lattice matching between graphite lattice and PE molecular chains. In this case, the chirality of CNTs dominates the orientation of graphite lattice, which determines the orientation of PE chains arrangement on CNTs surface. More importantly, it was found that the groove structure formed by CNT bundles is very useful for the stabilisation of polymer chain, and thus facilitates the orientation of molecular chain along the long axis of CNTs. As a result, a novel nanohybrid shish–kebab (NHSK) structure with CNTs acting as central shish while polymer lamellae as kebab can be successfully obtained for both PE with zigzag conformation and iPP with helical conformation. This simulation result was well supported by the experimental observation. Our study could provide not only a deep understanding of the origin of the polymer chain orientation on CNTs surface but also the guidance for the preparation of polymer/CNTs nanocomposites with novel NHSK structure.