基于28S rDNA 的叩甲科分子系统发育关系研究

【目的】通过对叩甲科（Elateridae）昆虫核糖体28S rDNA基因片段序列进行比较,从分子水平研究叩甲科昆虫的系统发育关系,并和传统分类结果相比较,为我国叩甲科分类系统的论证和进一步修订奠定基础。【方法】将自测的我国9种（含两个地理种群）共10个叩甲科昆虫样品的28S rDNA基因片段序列与GenBank报道的32种叩甲科昆虫进行同一性比较,用DNAStar Lasergene v 7.1.0和MEGA4.0（NJ法、MP法和ME法）构建分子系统发育树。【结果】在获得的890 bp的序列中,保守位点477个,占全部位点的56.1％;简约位点291个,占全部位点的34.2％;G+C的平均含量为63.9％,明显高于A+T的平均含量,碱基组成偏向G和C;转换（transition）稍高于颠换（transversion）。遗传距离分析表明叩甲科昆虫各亚科内各种间遗传距离在0.000～0.130之间变动,明显小于各亚科之间的遗传距离。不同的系统发育树都支持叩甲科为一单系群,并将10个亚科聚为4个聚类簇:聚类簇Ⅰ为梳爪叩甲亚科（Melanotinae）＋叩甲亚科（Elaterinae）,聚类簇Ⅱ为槽缝叩甲亚科（Agrypninae）＋萤叩甲亚科（Pyrophorinae）＋单叶叩甲亚科（Conoderinae）,聚类簇Ⅲ为小叩甲亚科（Negastriinae）＋心盾叩甲亚科（Cardiophorinae）,聚类簇Ⅳ为齿胸叩甲亚科（Denticollinae）＋尖鞘叩甲亚科（Oxynopterinae）和异角叩甲亚科（Pityobiinae）。它们来源于2个支系,支系1包含聚类簇Ⅰ,支系2包含聚类簇Ⅱ、聚类簇Ⅲ和聚类簇Ⅳ,而Senodonia quadricollis总是单独作为一支与其他叩甲分开。【结论】本研究证实了过去基于成虫和幼虫形态为基础的分类系统的基本合理性,一是叩甲科为一单系类群;二是叩甲科可明显地分为4个簇群;三是心盾叩甲亚科（Cardiophorinae）为一单系类群,但其他许多亚科存在并系的情况,特别是Senodonia quadricollis的归属还需进一步论证。28S rDNA 序列分析是一种很好的研究叩甲科从种级到科级各类群间的系统发育关系的方法。     

翻译速率与蛋白质二级结构的关系

统计分析了人的 119种蛋白质和大肠杆菌的 92种蛋白质密码子翻译速率和蛋白质二级结构的关系。据m 密码子片段在不同二级结构中的频数分布 ,我们发现人和大肠杆菌中翻译速率与蛋白质二级结构之间有一定关系 :高翻译速率时倾向编码α螺旋、不倾向编码线团 (coil) ;低翻译速率时倾向编码线团、不倾向编码α螺旋 ;β折叠结构则随翻译速率表现出明显的振荡。同时 ,密码子的使用在不同片段内一般也是不均匀的 :在α螺旋片段内 ,结构尾部偏向使用高翻译速率密码子 ;中部倾向使用中翻译速率密码子 ;而头部使用的密码子翻译速率偏低。这样的倾向性不大可能归结为随机起伏的影响。     

原子力显微镜在生物领域中的应用

原子力显微镜(AFM)作为生物样品表面表征的有力工具,具有独特的优势.本文在介绍原子力显微镜基本原理的基础上,综述了原子力显微镜样品制备以及原子力显微镜形貌分析、力曲线以及动力学分析在生物领域中的应用.     

Classification analysis of dual nucleotides using dimension reduction

We introduce a new approach to investigate the dual nucleotides compositions of 11 Gram-positive and 12 Gram-negative eubacteria recently studied by Sorimachi and Okayasu. The approach firstly obtains a 16-dimension vector set of dual nucleotides by PN-curve from the complete genome of organism. Each vector of the set corresponds to a single gene of genome. Then we reduce the 16-dimension vector set to 2-dimension by principal components analysis (PCA). The reduction avoids possible loss of information averaging all 16-dimension vectors. Then we suggest a 2D graphical representation based on the 2-dimension vector to investigate the classification patters among different organisms.     

Mesenchymal stem cell-derived small extracellular vesicles in the treatment of human diseases:Progress and prospect

Mesenchymal stem cells(MSCs)are self-renewing,multipotent cells that could differentiate into multiple tissues.MSC-based therapy has become an attractive and promising strategy for treating human diseases through immune regulation and tissue repair.However,accumulating data have indicated that MSC-based therapeutic effects are mainly attributed to the properties of the MSC-sourced secretome,especially small extracellular vesicles(sEVs).sEVs are signaling vehicles in intercellular communication in normal or pathological conditions.sEVs contain natural contents,such as proteins,mRNA,and microRNAs,and transfer these functional contents to adjacent cells or distant cells through the circulatory system.MSC-sEVs have drawn much attention as attractive agents for treating multiple diseases.The properties of MSC-sEVs include stability in circulation,good biocompatibility,and low toxicity and immunogenicity.Moreover,emerging evidence has shown that MSC-sEVs have equal or even better treatment efficacies than MSCs in many kinds of disease.This review summarizes the current research efforts on the use of MSC-sEVs in the treatment of human diseases and the existing challenges in their application from lab to clinical practice that need to be considered.     

New method for global alignment of 2 DNA sequences by the tree data structure

We introduce a new approach to investigate problem of DNA sequence alignment. The method consists of three parts: (i) simple alignment algorithm, (ii) extension algorithm for largest common substring, (iii) graphical simple alignment tree (GSA tree). The approach firstly obtains a graphical representation of scores of DNA sequences by the scoring equation R₀*R−S₀*S−T₀*(a+bk). Then a GSA tree is constructed to facilitate solving the problem for global alignment of 2 DNA sequences. Finally we give several practical examples to illustrate the utility and practicality of the approach.     

Epoxyeicosatrienoic acids inhibit the activation of NLRP3 inflammasome in murine macrophages

Epoxyeicosatrienoic acids (EETs) derived from arachidonic acid exert anti-inflammation effects. We have reported that blocking the degradation of EETs with a soluble epoxide hydrolase (sEH) inhibitor protects mice from lipopolysaccharide (LPS)-induced acute lung injury (ALI). The underlying mechanisms remain essential questions. In this study, we investigated the effects of EETs on the activation of nucleotide-binding domain leucine-rich repeat-containing receptor, pyrin domain-containing-3 (NLRP3) inflammasome in murine macrophages. In an LPS-induced ALI murine model, we found that sEH inhibitor 1-trifluoromethoxyphenyl-3-(1-propionylpiperidin-4-yl), TPPU, profoundly attenuated the pathological injury and inhibited the activation of the NLRP3 inflammasome, characterized by the reduction of the protein expression of NLRP3, ASC, pro-caspase-1, interleukin precursor (pro-IL-1β), and IL-1β p17 in the lungs of LPS-treated mice. In vitro, primary peritoneal macrophages from C57BL/6 were primed with LPS and activated with exogenous adenosine triphosphate (ATP). TPPU treatment remarkably reduced the expression of NLRP3 inflammasome-related molecules and blocked the activation of NLRP3 inflammasome. Importantly, four EETs (5,6-EET, 8,9-EET, 11,12-EET, and 14,15-EET) inhibited the activation of NLRP3 inflammasome induced by LPS + ATP or LPS + nigericin in macrophages in various degree. While the inhibitory effect of 5,6-EET was the weakest. Mechanismly, EETs profoundly decreased the content of reactive oxygen species (ROS) and restored the calcium overload in macrophages receiving LPS + ATP stimulation. In conclusion, this study suggests that EETs inhibit the activation of the NLRP3 inflammasome by suppressing calcium overload and ROS production in macrophages, contributing to the therapeutic potency to ALI.     

单细胞转录组测序在药物成瘾研究中的应用

药物成瘾是复杂的中枢神经系统疾病，相关基础与临床研究均证实药物成瘾的神经机制及神经环路在成瘾行为形成的不同阶段逐渐发生改变。利用全基因组关联研究、全基因组测序、全外显子测序或高通量转录组测序等技术的组学研究对包括药物成瘾在内的精神疾病遗传的脆弱性进行了深入研究。上述单核苷酸多态性检测技术或测序技术主要预测疾病的遗传风险位点。然而，许多中枢神经系统疾病的发生与环境因素密切相关，而且在疾病发展的不同阶段，相关基因的表达存在脑区特异性的细胞异质性信息。因此，传统研究对发病机制的解释存在一定的局限性。单细胞转录组测序技术是针对单个细胞进行转录水平的测定，规避了传统测序对细胞群体平均转录水平检测的缺点，可以定量描述细胞异质性。近年来，单细胞转录测序技术在神经精神科学研究中的应用逐渐受到关注，本文总结了该技术在神经科学研究中的重要应用，并以药物成瘾为例，重点阐述说明其在中枢神经系统疾病中的应用价值。