Molecular simulation of the preferential adsorption of CH4 and CO2 in middle-rank coal

The adsorption of the CO₂/CH₄ mixture in coal affects the CO₂-enhanced coalbed methane recovery project. To gain a better understanding of CH₄ and CO₂ interaction with middle-rank coal, we developed a molecular concept with support for the sorption of CH₄ and CO₂ on Ximing-8 coal (XM-8) (1.8% vitrinite reflectance). A XM-8 coal model was built by using molecular dynamic (MD) simulations. The molecular simulations were established by the Grand Canonical Monte Carlo and MD methods to study the effects of the temperature, pressure, and species bulk mole fraction on the pure component adsorption isotherms, isosteric heat and adsorption selectivity. It turns out that the CO₂ selectivity decreases as the pressure and its own bulk mole fraction increases, but it increases as temperature increases, and the selectivity values are not always greater than 1. The interactions between the small molecules and XM-8 were determined by using density functional theory. It was found that the interactions between the CO₂ and XM-8 surface is greater, particularly for the heteroatoms than CH₄. The adsorption selectivity and interaction were simultaneously used to reveal that the advantageously substituted range is high temperature, low pressure and a high content of heteroatoms.     

LncRNA FOXC2-AS1 protects cardiomyocytes from doxorubicin-induced cardiotoxicity through activation of WNT1-inducible signaling pathway protein-1

Doxorubicin (Dox) is an anthracycline antibiotic that has been used to treat different cancers. Dox-induced cardiotoxicity is common in clinical practice, while its mechanism is unknown. It has been proved that lncRNA FOXC2-AS1 may promote doxorubicin resistance and WNT1-inducible signaling pathway protein-1 (WISP1) blocks doxorubicin-induced cardiomyocyte death. Our study aimed to investigate the involvement of lncRNA FOXC2-AS1 and WISP1 in doxorubicin-induced cardiotoxicity and to explore their interactions. In our study we observed that FOXC2-AS1 and WISP1 mRNA were downregulated in heart tissues of mice with Dox-induced cardiotoxicity. FOXC2-AS1 and WISP1 mRNA expression were positively correlated in mice with Dox-induced cardiotoxicity but not in healthy mice. Overexpression of FOXC2-AS1 promoted to viability of mice cardiomyocytes under Dox treatment and also increased the expression level of WISP1. In contrast, WISP1 overexpression showed no significant effect on FOXC2-AS1. We therefore conclude that lncRNA FOXC2-AS1 may upregulate WISP1 to protect cardiomyocytes from doxorubicin-induced cardiotoxicity.     

海藻糖酶基因TRE2-like和TRE2在异色瓢虫羽化过程中的表达与功能

【目的】异色瓢虫Harmonia axyridis是一种重要的捕食性天敌昆虫,海藻糖在异色瓢虫的变态发育、羽化等整个生命过程都起着重要的作用。本研究以前期获得的类似膜结合型海藻糖酶(TRE2-like)与膜结合型海藻糖酶(TRE2)基因为基础,探讨在异色瓢虫羽化阶段这两个海藻糖酶的潜在功能,为阐明异色瓢虫从蛹发育到成虫时海藻糖代谢机制提供参考。【方法】根据TRE2-like和TRE2基因序列设计双链RNA(dsRNA)区域片段并合成对应的dsRNA,通过RNAi将其注射到异色瓢虫2日龄蛹中。采用实时荧光定量PCR(RT-qPCR)检测RNAi处理后羽化第1天的异色瓢虫成虫糖代谢相关基因的表达;同时采用蒽酮比色法、酶标法等分别测定RNAi处理后羽化第1天的异色瓢虫成虫主要糖类物质含量及TRE活性变化,并观察异色瓢虫羽化后的表型变化。【结果】结果表明,与对照组(dsGFP注射组)相比,异色瓢虫2日龄蛹被注射TRE2-like或TRE2 dsRNA后,其新羽化成虫体内TRE2-like和TRE2表达量均极显著下调,且少数个体出现了蜕皮与翅形成困难等畸形表型。可溶性海藻糖酶活性在注射dsTRE2-like后显著降低,膜结合型海藻糖酶活性在注射dsTRE2后显著降低;注射dsTRE2后糖原含量显著下降,注射dsTRE2-like后糖原和海藻糖含量显著下降,注射dsTRE2-like+dsTRE2后糖原和葡萄糖含量显著下降,且海藻糖含量极显著下降。注射dsTRE2-like, dsTRE2和dsTRE2-like+dsTRE2后可溶性海藻糖酶基因TRE1-1和TRE1-2表达下降或显著下降,而TRE1-5表达上升或显著上升,海藻糖合成酶(trealose-6-phosphate synthase, TPS)、糖原磷酸化酶(glycogen phosphorylase, GP)、糖原合成酶(glycogen synthase, GS)基因的表达均显著下调。【结论】TRE2-like和TRE2基因表达被抑制后,异色瓢虫海藻糖等代谢受到影响。研究结果为探究异色瓢虫体内膜结合型海藻糖酶的潜在功能和调控机制奠定了基础。     

甘肃东大山自然保护区岩羊生态行为的初步观察

2004年7月和8月,通过样线调查、野外直接跟踪观察和瞬间取样的方法,对东大山自然保护区岩羊(Pseudois nayaur)的种群结构和生态行为进行了初步研究。在观察到的720只岩羊中,719只组成了50个群,最大的群82只,最小的群2只,平均群大小(14.38±15.83)只(n=50)。雌雄性比为1∶0.63,成年雌体、亚成体和幼体之比是1∶0.4∶0.24。岩羊的昼间活动中,上午和下午各有一个瞬间觅食高峰,分别在6:30时和15:30时,中午有一段较长时间的休息期。通过对一个46只岩羊群连续12 d的野外跟踪观察,发现该岩羊群昼间的活动范围基本上在1.47 km2内。对152个自然死亡的雄性岩羊头骨的分析表明,东大山雄性岩羊的自然死亡年龄在7.5~11.5龄,其中9.5龄是其自然死亡的高峰。     

ToxR负调控副溶血弧菌中c-di-GMP的合成

副溶血弧菌(Vibrio parahaemolyticus)是世界范围内引起海产品相关食物中毒的主要致病菌,具有很强的生物膜形成能力。ToxR是一种膜结合调控蛋白,对副溶血弧菌生物膜形成具有一定的调控作用,但具体机制尚未见报道。c-di-GMP是一种普遍存在于细菌中重要的第二信使,参与调控细菌的多种生物学行为包括生物膜的形成。本文探究ToxR对副溶血弧菌中c-di-GMP代谢的调控作用。利用酶联免疫吸附法(enzyme linked immunosorbent assay,ELISA)测定副溶血弧菌野生株(wild-type,WT)和toxR突变株(ΔtoxR)中c-di-GMP水平的差异。挑选c-di-GMP代谢相关基因scrA、scrG和vpa0198为进一步研究的靶标,采用实时定量qPCR实验检测靶基因在WT和ΔtoxR中的转录水平差异;将靶基因调控区DNA序列克隆入pHRP309质粒中无启动子的β半乳糖苷酶基因上游,采用lacZ报告基因融合实验进一步研究ToxR对靶基因的转录调控关系;将重组质粒分别导入含有pBAD33或pBAD33-toxR的EC100lpir中,采用lacZ报告基因融合实验研究ToxR是否能在异体宿主中调控靶基因的表达;PCR扩增靶基因上游调控区DNA序列,并纯化His-ToxR蛋白,用凝胶阻滞实验(electrophoresis mobility shift assay,EMSA)研究His-ToxR与靶基因启动子区DNA序列是否具有结合作用。ELISA结果显示ΔtoxR中c-di-GMP含量显著性高于WT中的,说明ToxR抑制c-di-GMP的产生;实时定量qPCR结果表明WT中scrA、scrG和vpa0198的转录水平显著性高于ΔtoxR中的,表明ToxR抑制它们的转录;lacZ报告基因融合实验结果表明ToxR可抑制副溶血弧菌和EC100lpir中scrA、scrG和vpa0198的启动子区活性;EMSA实验显示His-ToxR能特异性地结合到scrA和scrG的上游调控区DNA序列上,而对vpa0198的上游调控区DNA序列无结合作用。综上所述,ToxR通过直接调控相关酶蛋白基因的转录来抑制副溶血弧菌内c-di-GMP的合成,从而有助于精确调控生物膜形成等细菌行为。     

利用CRISPR/Cas9系统检测果蝇细胞中组蛋白甲基化修饰对20E信号传导的调控

[目的]利用CRISPR/Cas9基因敲除系统在黑腹果蝇Drosophila melanogaster细胞中筛选并检测组蛋白甲基化修饰对蜕皮激素20-羟基蜕皮酮(20-hydroxyecdysone,20E)信号传导的调控.[方法]通过Flybase网站分析并总结黑腹果蝇组蛋白甲基转移酶及其修饰位点;将5个组蛋白甲基转...     

Binding of Cu2+ to S-adenosyl-L-homocysteine hydrolase

S-Adenosylhomocysteine (AdoHcy) hydrolase regulates biomethylation and homocysteine metabolism. It has been proposed to be a copper binding protein playing an important role in copper transport and distribution. In the present work, the kinetics of binding and releasing of copper ions was studied using fluorescence method. The dissociation constant for copper ions with AdoHcy hydrolase was determined by fluorescence quenching titration and activity titration methods using ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA), and glycine as competitive chelators. The experimental results showed that copper ions bind to AdoHcy hydrolase with a K(d) of approximately 10(-11) M. The association rate constant was determined to be 7 x 10(6) M(-1)s(-1). The releasing of copper ions from the enzyme was found to be biphasic with a k(1) of 2.8 x 10(-3) s(-1) and k(2) of 1.7x10(-5) s(-1). It is suggested that copper ions do not bind to the substrate binding sites because the addition of adenine substrate did not compete with the binding of copper to AdoHcy hydrolase. Interestingly, it was observed that EDTA could bind to AdoHcy hydrolase with a dissociation constant of K(1) = 8.0 x 10(-5) M and result in an increased affinity (K(d) = approximately 10(-17) M) of binding of copper ions to the enzyme.     

Characterization of a novel toxin-antitoxin module, VapBC, encoded by Leptospira interrogans chromosome

Comparative genomic analysis of the coding sequences (CDSs) of Leptospira interrogans revealed a pair of closely linked genes homologous to the vapBC loci of many other bacteria with respect to both deduced amino acid sequencesand operon organizations. Expression of single vapC gene in Escherichia coli resulted in inhibition of bacterial growth,whereas co-expression of vapBC restored the growth effectively. This phenotype is typical for three other character-ized toxin-antitoxin systems of bacteria, i.e., mazEF[1], reIBE[2] and chplK[3]. The VapC proteins of bacteria and a thermophilic archeae, Solfolobus tokodaii, form a structurally distinguished group of toxin different from the other known toxins of bacteria. Phylogenetic analysis of both toxins and antitoxins of all categories indicated that althought oxins were evolved from divergent sources and may or may not follow their speciation paths (as indicated by their 16s RNA seouences）, co-evolution with their antitoxins was obvious.     

Effect of cigarette smoke on fibroblast-mediated gel contraction is dependent on cell density

Cigarette smoke exposure has been associated with a variety of diseases, including emphysema. The current study evaluated the interaction of cell density and cigarette smoke extract (CSE) on fibroblast contraction of collagen gels. Protein levels of transforming growth factor (TGF)-beta1, fibronectin, PGE(2), and TGF-beta1 mRNA were quantified. Although both 5 and 10% CSE inhibited contraction by low-density fibroblasts (1 x 10(5) cell/ml), only 5% CSE augmented contraction in higher-density cultures (3-5 x 10(5) cells/ml). CSE also inhibited fibronectin and TGF-beta1 production in low-density cultures but stimulated fibronectin production in high-density cultures. Active TGF-beta1 was readily detectable only in higher-density cultures and was markedly augmented by 5% CSE. In contrast, although TGF-beta1 mRNA expression was inhibited in high-density cultures by 10% CSE, expression was increased in the presence of 5% CSE. These results suggest that CSE-induced inhibition of low-density fibroblast contraction is due to inhibition of fibronectin production, whereas CSE's stimulatory effect on high-density cells is the result of increased release of TGF-beta1. These effects may help explain the varied pathologies associated with exposure to cigarette smoke.