新城疫病毒M蛋白在病毒毒力和复制中的作用研究进展

M蛋白是新城疫病毒(Newcastle disease virus,NDV)基因组编码的一种非糖基化膜相关蛋白,主要位于病毒囊膜内表面,构成病毒囊膜与核衣壳连接的支架.研究表明,M蛋白是一种细胞核-细胞质穿梭蛋白,在抑制细胞基因转录和蛋白质合成以及协助病毒粒子组装和出芽方面发挥了重要作用.目前,国内外对NDV毒力和复制...     

Molecular phylogeny and species delimitation of Stachyuraceae: Advocating a herbarium specimen‐based phylogenomic approach in resolving species boundaries

Species concept and delimitation are fundamental to taxonomic and evolutionary studies. Both inadequate informative sites in the molecular data and limited taxon sampling have often led to poor phylogenetic resolution and incorrect species delineation. Recently, the whole chloroplast genome sequences from extensive herbarium specimen samples have been shown to be effective to amend the problem. Stachyuraceae are a small family consisting of only one genus Stachyurus of six to 16 species. However, species delimitation in Stachyurus has been highly controversial because of few and generally unstable morphological characters used for classification. In this study, we sampled 69 individuals of seven species (each with at least three individuals) covering the entire taxonomic diversity, geographic range, and morphological variation of Stachyurus from herbarium specimens for genome‐wide plastid gene sequencing to address species delineation in the genus. We obtained high‐quality DNAs from specimens using a recently developed DNA reconstruction technique. We first assembled four whole chloroplast genome sequences. Based on the chloroplast genome and one nuclear ribosomal DNA sequence of Stachyurus, we designed primers for multiplex polymerase chain reaction and high throughput sequencing of 44 plastid loci for species of Stachyurus. Data of these chloroplast DNA and nuclear ribosomal DNA internal transcribed spacer sequences were used for phylogenetic analyses. The phylogenetic results showed that the Japanese species Stachyurus praecox Siebold & Zucc. was sister to the rest in mainland China, which indicated a typical Sino‐Japanese distribution pattern. Based on diagnostic morphological characters, distinct distributional range, and monophyly of each clade, we redefined seven species for Stachyurus following an integrative species concept, and revised the taxonomy of the family based on previous reports and specimens, in particular the type specimens. Furthermore, our divergence time estimation results suggested that Stachyuraceae split from its sister group Crossosomataceae from the New World at ca. 54.29 Mya, but extant species of Stachyuraceae started their diversification only recently at ca. 6.85 Mya. Diversification time of Stachyurus in mainland China was estimated to be ca. 4.45 Mya. This research has provided an example of using the herbarium specimen‐based phylogenomic approach in resolving species boundaries in a taxonomically difficult genus.     

3D‐Printed Cathodes of LiMn1−xFexPO4 Nanocrystals Achieve Both Ultrahigh Rate and High Capacity for Advanced Lithium‐Ion Battery

A 3D‐printing technology and printed 3D lithium‐ion batteries (3D‐printed LIBs) based on LiMn_0.21Fe_0.79PO₄@C (LMFP) nanocrystal cathodes are developed to achieve both ultrahigh rate and high capacity. Coin cells with 3D‐printed cathodes show impressive electrochemical performance: a capacity of 108.45 mAh g^?1 at 100 C and a reversible capacity of 150.21 mAh g^?1 at 10 C after 1000 cycles. In combination with simulation using a pseudo 2D hidden Markov model and experimental data of 3D‐printed and traditional electrodes, for the first time deep insight into how to achieve the ultrahigh rate performance for a cathode with LMFP nanocrystals is obtained. It is estimated that the Li‐ion diffusion in LMFP nanocrystal is not the rate‐limitation step for the rate to 100 C, however, that the electrolyte diffusion factors, such as solution intrinsic diffusion coefficient, efficiency porosity, and electrode thickness, will dominate ultrahigh rate performance of the cathode. Furthermore, the calculations indicate that the above factors play important roles in the equivalent diffusion coefficient with the electrode beyond a certain thickness, which determines the whole kinetic process in LIBs. This fundamental study should provide helpful guidance for future design of LIBs with superior electrochemical performance.     

Molecular characterization of a Fus3/Kss1 type MAPK from Puccinia striiformis f. sp. tritici, PsMAPK1

Puccinia striiformis f. sp. tritici (Pst) is an obligate biotrophic fungus that causes the destructive wheat stripe rust disease worldwide. Due to the lack of reliable transformation and gene disruption method, knowledge about the function of Pst genes involved in pathogenesis is limited. Mitogen-activated protein kinase (MAPK) genes have been shown in a number of plant pathogenic fungi to play critical roles in regulating various infection processes. In the present study, we identified and characterized the first MAPK gene PsMAPK1 in Pst. Phylogenetic analysis indicated that PsMAPK1 is a YERK1 MAP kinase belonging to the Fus3/Kss1 class. Single nucleotide polymerphisms (SNPs) and insertion/deletion were detected in the coding region of PsMAPK1 among six Pst isolates. Real-time RT-PCR analyses revealed that PsMAPK1 expression was induced at early infection stages and peaked during haustorium formation. When expressed in Fusarium graminearum, PsMAPK1 partially rescued the map1 mutant in vegetative growth and pathogenicity. It also partially complemented the defects of the Magnaporthe oryzae pmk1 mutant in appressorium formation and plant infection. These results suggest that F. graminearum and M. oryzae can be used as surrogate systems for functional analysis of well-conserved Pst genes and PsMAPK1 may play a role in the regulation of plant penetration and infectious growth in Pst.     

川芎嗪对脑缺血/再灌注后所致肺损伤的影响

目的：观察川芎嗪对脑缺血／再灌注后肺损伤的影响。方法：采用Pulsinelli等的方法建立大鼠急性全脑缺血／再灌注模型。将Wistar大鼠随机分为三组,即：对照组（Control）、缺血／再灌注组（I／R）、川芎嗪＋缺血／再灌注组（TEP＋I／R）,分别测定各组肺功能（PaO2、PaCO2）,肺系数（LI％）、血浆和肺组织中与自由基有关物质的含量。结果：川芎嗪可有效改善脑缺血／再灌注后肺功能,减轻肺水肿,减少胞浆酶的漏出,增加自由基清除醇的活性,抑制组织脂质过氧化的发生。结论：川芎嗪对脑缺血／再灌注后肺损伤具有保护作用,其机制可能与其抗氧自由基和膜保护作用有关。     

商陆根部多糖的分离、纯化及其体外抗氧化活性

本研究从商陆根部提取分离出商陆多糖,并对该多糖含量进行测定及体外抗氧化活性研究。商陆根部经石油醚回流脱脂、热水抽提、脱色、乙醇沉淀等处理可从中提取出粗多糖。多糖经三氯乙酸脱蛋白纯化,再分别以考马斯亮蓝法和蒽酮-硫酸法测定其蛋白质含量和糖含量,并通过采用清除羟自由基和超氧自由基能力测定法、β-胡萝卜素-亚油酸法,以抗坏血酸(Vc)为对照,来分析粗多糖和纯多糖的体外抗氧化能力。采用水提法提取的粗多糖,含有10.69%的蛋白质和60.91%的多糖;纯化后的多糖糖含量达到91.04%。商陆粗多糖、纯多糖及Vc对羟自由基(·OH)清除率的IC50分别是1.26mg/mL、4.78mg/mL和0.224mg/mL;对超氧自由基(O2-·)清除率的IC50分别为1.91mg/mL、2.28mg/mL和0.123mg/mL;对β-胡萝卜素-亚油酸体系的抑制作用的IC50分别为0.471mg/mL、0.692mg/mL和0.379mg/mL。实验结果表明商陆多糖是一种较好的抗氧化剂,可作为潜在天然抗氧化剂应用于食品和医药工业中。     

新型产甲烷古菌研究进展

产甲烷古菌是一类能利用简单化合物产生甲烷气体的厌氧菌。近年来,随着测序技术的不断发展,科学家结合宏基因组学和其他技术先后发现了众多之前未被报道的新型产甲烷古菌。基因组分析等研究发现这几类新型产甲烷古菌具有独特的甲烷代谢通路以及广泛的生态分布,科学家推测它们在全球生态调节以及碳循环中可能起到了不可忽视的作用。然而,这些新型产甲烷古菌大部分尚未通过传统培养方法获得纯培养菌株,其确切的生理代谢机制和生态功能还有待深入研究。为了更加系统地了解这些新型产甲烷古菌,本文从它们的分类、系统发育地位、代谢机制、生态分布以及分离培养等方面进行了综述,并对新型产甲烷古菌未来的研究方向进行了展望。     

Catalpol protects dopaminergic neurons from LPS-induced neurotoxicity in mesencephalic neuron-glia cultures

Inflammation plays an important role in the pathogenesis of Parkinson's disease (PD). Microglia, the resident immune cells in the central nervous system, are pivotal in the inflammatory reaction. Activated microglia can induce expression of inducible nitric-oxide synthase (iNOS) and release significant amounts of nitric oxide (NO) and TNF-alpha, which can damage the dopaminergic neurons. Catalpol, an iridoid glycoside, contained richly in the roots of Rehmannia glutinosa, was found to be neuroprotective in gerbils subjected to transient global cerebral ischemia. But the effect of catalpol on inflammation-mediated neurodegeneration has not been examined. In this study, microglia in mesencephalic neuron-glia cultures were activated with lipopolysaccharide (LPS) and the aim of the study was to examine whether catalpol could protect dopaminergic neurons from LPS-induced neurotoxicity. The results showed that catalpol significantly reduced the release of reactive oxygen species (ROS), TNF-alpha and NO after LPS-induced microglial activation. Further, catalpol attenuated LPS-induced the expression of iNOS. As determined by immunocytochemical analysis, pretreatment by catalpol dose-dependently protected dopaminergic neurons against LPS-induced neurotoxicity. These results suggest that catalpol exerts its protective effect on dopaminergic neurons by inhibiting microglial activation and reducing the production of proinflammatory factors. Thus, catalpol may possess therapeutic potential against inflammation-related neurodegenerative diseases.