Distribution of Endophytic Bacteria in Alopecurus aequalis Sobol and Oxalis corniculata L. from Soils Contaminated by Polycyclic Aromatic Hydrocarbons

The distributions of endophytic bacteria in Alopecurus aequalis Sobol and Oxalis corniculata L. grown in soils contaminated with different levels of polycyclic aromatic hydrocarbons (PAHs) were investigated with polymerase chain reaction followed by denaturing gradient gel electrophoresis technology (PCR-DGGE) and cultivation methods. Twelve types of PAHs, at concentrations varying from 0.16 to 180 mg·kg⁻¹, were observed in the roots and shoots of the two plants. The total PAH concentrations in Alopecurus aequalis Sobol obtained from three different PAH-contaminated stations were 184, 197, and 304 mg·kg⁻¹, and the total PAH concentrations in Oxalis corniculata L. were 251, 346, and 600 mg·kg⁻¹, respectively. The PCR-DGGE results showed that the endophytic bacterial communities in the roots and shoots of the two plants were quite different, although most bacteria belonged to Firmicutes, Proteobacteria, Actinobacteria and Bacteroidetes. A total of 68 endophytic bacterial strains were isolated from different tissues of the two plants and classified into three phyla: Firmicutes, Proteobacteria and Bacteroidetes. In both plants, Bacillus spp. and Pseudomonas spp. were the dominant cultivable populations. With an increase in the PAH pollution level, the diversity and distribution of endophytic bacteria in the two plants changed correspondingly, and the number of cultivable endophytic bacterial strains decreased rapidly. Testing of the isolated endophytic bacteria for tolerance to each type of PAH showed that most isolates could grow well on Luria-Bertani media in the presence of different PAHs, and some isolates were able to grow rapidly on a mineral salt medium with a single PAH as the sole carbon and energy source, indicating that these strains may have the potential to degrade PAHs in plants. This research provides the first insight into the characteristics of endophytic bacterial populations under different PAH pollution levels and provides a species resource for the isolation of PAH-degrading endophytic bacteria.     

The Impacts of Dispositional Optimism and Psychological Resilience on the Subjective Well-Being of Burn Patients: A Structural Equation Modelling Analysis

Burn wounds are severely stressful events that can have a significant impact on the mental health of patients. However, the impact of burns on individuals with different personality traits can be different. The present study aimed to investigate the impact of dispositional optimism on the subjective well-being of burn patients, and mainly focused on the confirmation of the mediator role of psychological resilience. 410 burn patients from five general hospitals in Xi''an accomplished the revised Life Orientation Test, Connor-Davidson Resilience Scale, and Subjective Well-Being (SWB) scale. The results revealed that both dispositional optimism and psychological resilience were significantly correlated with SWB. Structural equation modelling indicated that psychological resilience partially mediated the relationship between dispositional optimism and SWB. The current findings extended prior reports and shed some light on how dispositional optimism influenced SWB. Limitations of the study were considered and suggestions for future studies were also discussed.     

The SNPs of Melanocortin 4 Receptor (MC4R) Associated with Body Weight in Beagle Dogs

Melanocortin 4 receptor (MC4R), which is associated with inherited human obesity, is involoved in food intake and body weight of mammals. To study the relationships between MC4R gene polymorphism and body weight in Beagle dogs, we detected and compared the nucleotide sequence of the whole coding region and 3′- and 5′- flanking regions of the dog MC4R gene (1214 bp). In 120 Beagle dogs, two SNPs (A420C, C895T) were identified and their relation with body weight was analyzed with RFLP-PCR method. The results showed that the SNP at A420C was significantly associated with canine body weight trait when it changed amino acid 101 of the MC4R protein from asparagine to threonine,while canine body weight variations were significant in female dogs when MC4R nonsense mutation at C895T. It suggested that the two SNPs might affect the MC4R gene’s function which was relative to body weight in Beagle dogs. Therefore, MC4R was a candidate gene for selecting different size dogs with the MC4R SNPs (A420C, C895T) being potentially valuable as a genetic marker.     

Insight into Glycoside Hydrolases for Debranched Xylan Degradation from Extremely Thermophilic Bacterium Caldicellulosiruptor lactoaceticus

Caldicellulosiruptor lactoaceticus 6A, an anaerobic and extremely thermophilic bacterium, uses natural xylan as carbon source. The encoded genes of C. lactoaceticus 6A for glycoside hydrolase (GH) provide a platform for xylan degradation. The GH family 10 xylanase (Xyn10A) and GH67 α-glucuronidase (Agu67A) from C. lactoaceticus 6A were heterologously expressed, purified and characterized. Both Xyn10A and Agu67A are predicted as intracellular enzymes as no signal peptides identified. Xyn10A and Agu67A had molecular weight of 47.0 kDa and 80.0 kDa respectively as determined by SDS-PAGE, while both appeared as homodimer when analyzed by gel filtration. Xyn10A displayed the highest activity at 80°C and pH 6.5, as 75°C and pH 6.5 for Agu67A. Xyn10A had good stability at 75°C, 80°C, and pH 4.5–8.5, respectively, and was sensitive to various metal ions and reagents. Xyn10A possessed hydrolytic activity towards xylo-oligosaccharides (XOs) and beechwood xylan. At optimum conditions, the specific activity of Xyn10A was 44.6 IU/mg with beechwood xylan as substrate, and liberated branched XOs, xylobiose, and xylose. Agu67A was active on branched XOs with methyl-glucuronic acids (MeGlcA) sub-chains, and primarily generated XOs equivalents and MeGlcA. The specific activity of Agu67A was 1.3 IU/mg with aldobiouronic acid as substrate. The synergistic action of Xyn10A and Agu67A was observed with MeGlcA branched XOs and xylan as substrates, both backbone and branched chain of substrates were degraded, and liberated xylose, xylobiose, and MeGlcA. The synergism of Xyn10A and Agu67A provided not only a thermophilic method for natural xylan degradation, but also insight into the mechanisms for xylan utilization of C. lactoaceticus.     

基于耦合协调度的黄土高原地区NDVI与降水关系的变异诊断

植被是地表生态系统的重要"指示器"，在能量交换、水循环、碳循环、生物地球化学循环和维持中发挥着重要作用，降水是影响植被变化的主要气候因子，研究两者之间的作用关系具有重要的意义和价值。利用Mann-Kendall趋势检验法和Hust指数分析了黄土高原地区归一化植被指数（NDVI）的变化趋势，使用相对发展率（RDR）指数和重心转移模型分析了NDVI变化的时空差异，并构建了基于耦合协调度理论和Pettitt检验方法的NDVI与降水关系的变异诊断方法，识别了黄土高原地区NDVI与降水关系的突变点，探讨了降水对NDVI变化的影响以及造成NDVI与降水关系变化的原因。结果表明：（1）黄土高原地区73.49%面积的NDVI在1998-2017年有呈现显著增加趋势（P<0.05），大部分地区NDVI在未来依旧呈现增加趋势；（2）黄土高原地区丘陵沟壑区与高原沟壑区的NDVI增加幅度大于黄土高原地区整体的增加幅度，而北部风沙区和农灌区以及黄土高原地区边界区域的NDVI增加滞后于区域整体变化；（3） NDVI与降水耦合协调程度逐年增强，两者关系在2006年发生显著突变（P<0.05）；（4） NDVI呈现显著增加区域降水明显高于不显著变化区域（P<0.05），降水对NDVI变化存在一定影响，在丘陵沟壑区、高原沟壑区北部和东部河谷及土石山区北部NDVI和降水存在显著正相关关系（P<0.05），然而黄土高原地区大部分区域的降水并不存在显著变化趋势（P>0.05），因此造成黄土高原地区NDVI与降水关系在2006年发生显著突变的主要原因应该是人类活动（P<0.05）。研究成果有助于进一步理解黄土高原植被变化与降水的相互作用，为黄土高原生态建设和水土流失治理提供一定的科学支撑。     

Inflammatory microenvironment of fibrotic liver promotes hepatocellular carcinoma growth,metastasis and sorafenib resistance through STAT3 activation

The pro-inflammatory and pro-fibrotic liver microenvironment facilitates hepatocarcinogenesis. However, the effects and mechanisms by which the hepatic fibroinflammatory microenvironment modulates intrahepatic hepatocellular carcinoma (HCC) progression and its response to systematic therapy remain largely unexplored. We established a syngeneic orthotopic HCC mouse model with a series of persistent liver injury induced by CCl₄ gavage, which mimic the dynamic effect of hepatic pathology microenvironment on intrahepatic HCC growth and metastasis. Non-invasive bioluminescence imaging was applied to follow tumour progression over time. The effect of the liver microenvironment modulated by hepatic injury on sorafenib resistance was investigated in vivo and in vitro. We found that the persistent liver injury facilitated HCC growth and metastasis, which was positively correlated with the degree of liver inflammation rather than the extent of liver fibrosis. The inflammatory cytokines in liver tissue were clearly increased after liver injury. The two indicated cytokines, tumour necrosis factor-α (TNF-α) and interleukin-6 (IL-6), both promoted intrahepatic HCC progression via STAT3 activation. In addition, the hepatic inflammatory microenvironment contributed to sorafenib resistance through the anti-apoptotic protein mediated by STAT3, and STAT3 inhibitor S3I-201 significantly improved sorafenib efficacy impaired by liver inflammation. Clinically, the increased inflammation of liver tissues was accompanied with the up-regulated STAT3 activation in HCC. Above all, we concluded that the hepatic inflammatory microenvironment promotes intrahepatic HCC growth, metastasis and sorafenib resistance through activation of STAT3.     

Genome-wide Screen for Modulation of Hepatic Apolipoprotein A-I (ApoA-I) Secretion

Control of plasma cholesterol levels is a major therapeutic strategy for management of coronary artery disease (CAD). Although reducing LDL cholesterol (LDL-c) levels decreases morbidity and mortality, this therapeutic intervention only translates into a 25–40% reduction in cardiovascular events. Epidemiological studies have shown that a high LDL-c level is not the only risk factor for CAD; low HDL cholesterol (HDL-c) is an independent risk factor for CAD. Apolipoprotein A-I (ApoA-I) is the major protein component of HDL-c that mediates reverse cholesterol transport from tissues to the liver for excretion. Therefore, increasing ApoA-I levels is an attractive strategy for HDL-c elevation. Using genome-wide siRNA screening, targets that regulate hepatocyte ApoA-I secretion were identified through transfection of 21,789 siRNAs into hepatocytes whereby cell supernatants were assayed for ApoA-I. Approximately 800 genes were identified and triaged using a convergence of information, including genetic associations with HDL-c levels, tissue-specific gene expression, druggability assessments, and pathway analysis. Fifty-nine genes were selected for reconfirmation; 40 genes were confirmed. Here we describe the siRNA screening strategy, assay implementation and validation, data triaging, and example genes of interest. The genes of interest include known and novel genes encoding secreted enzymes, proteases, G-protein-coupled receptors, metabolic enzymes, ion transporters, and proteins of unknown function. Repression of farnesyltransferase (FNTA) by siRNA and the enzyme inhibitor manumycin A caused elevation of ApoA-I secretion from hepatocytes and from transgenic mice expressing hApoA-I and cholesterol ester transfer protein transgenes. In total, this work underscores the power of functional genetic assessment to identify new therapeutic targets.     

New data on the Paederus biacutus species group from mainland China (Coleoptera,Staphylinidae, Paederinae)

Paederus jianyueae Peng & Li, sp. n. (Zhejiang: Qingliangfeng) is described and illustrated. Additional records of P. biacutus Li, Zhou & Solodovnikov, 2014 and P. parvidenticulatus Li, Zhou & Solodovnikov, 2014 are reported.     

Phosphorylation and ubiquitination of dynamin-related proteins (AtDRP3A/3B) synergically regulate mitochondrial proliferation during mitosis

The balance between mitochondrial fission and fusion is disrupted during mitosis, but the mechanism governing this phenomenon in plant cells remains enigmatic. Here, we used mitochondrial matrix‐localized Kaede protein (mt‐Kaede) to analyze the dynamics of mitochondrial fission in BY‐2 suspension cells. Analysis of the photoactivatable fluorescence of mt‐Kaede suggested that the fission process is dominant during mitosis. This finding was confirmed by an electron microscopic analysis of the size distribution of mitochondria in BY‐2 suspension cells at various stages. Cellular proteins interacting with Myc‐tagged dynamin‐related protein 3A/3B (AtDRP3A and AtDRP3B) were immunoprecipitated with anti‐Myc antibody‐conjugated beads and subsequently identified by microcapillary liquid chromatography–quadrupole time‐of‐flight mass spectrometry (CapLC Q‐TOF) MS/MS. The identified proteins were broadly associated with cytoskeletal (microtubular), phosphorylation, or ubiquitination functions. Mitotic phosphorylation of AtDRP3A/AtDRP3B and mitochondrial fission at metaphase were inhibited by treatment of the cells with a CdkB/cyclin B inhibitor or a serine/threonine protein kinase inhibitor. The fate of AtDRP3A/3B during the cell cycle was followed by time‐lapse imaging of the fluorescence of Dendra2‐tagged AtDRP3A/3B after green‐to‐red photoconversion; this experiment showed that AtDRP3A/3B is partially degraded during interphase. Additionally, we found that microtubules are involved in mitochondrial fission during mitosis, and that mitochondria movement to daughter cell was limited as early as metaphase. Taken together, these findings suggest that mitotic phosphorylation of AtDRP3A/3B promotes mitochondrial fission during plant cell mitosis, and that AtDRP3A/3B is partially degraded at interphase, providing mechanistic insight into the mitochondrial morphological changes associated with cell‐cycle transitions in BY‐2 suspension cells.