基于分子马达生物传感器技术的副溶血性弧菌分子分型方法的初步研究

[目的]建立基于分子马达技术的简便快速的分子分型方法,对携带和非携带毒力基因的副溶血性弧菌进行快速分类.[方法]以F0F1-ATPase为核心构建分子马达,以副溶血性弧菌毒力基因tdh、trh和种特异性基因tlh、toxR为靶基因设计4个探针.通过生物素-亲和素系统将探针与分子马达连接构建F0F1-ATPase分子马达生物传感器,对10株副溶血性弧菌分离株进行分类,并与PCR-电泳-凝胶成像结果进行比较;同时对生物传感器的检测灵敏度和特异性进行研究.[结果]10株试验菌株中10株tdh阳性,0株trh阳性,而10株菌都携带tlh和toxR,与PCR-电泳-凝胶成像结果一致;分子马达生物传感器的最低检测限为1 pg/反应体系,且能够对副溶血性弧菌特异性识别,PCR-电泳-凝胶成像方法的最低检测限为10 pg/PCR反应体系.[结论]建立了基于分子马达的分子分型方法,能够对副溶血性弧菌的致病性进行快速诊断,检测灵敏度比PCR-电泳-凝胶成像方法高了10倍,而且特异性非常高.该方法简便、快速、省时、省力,适用于地方疾控部门和口岸检疫部门的基层实验室开展副溶血性弧菌监测和流行病学溯源工作.     

一种免疫生物传感器对单核细胞增生李斯特菌快速检测方法的初步研究

应用F0F1-ATP酶旋转分子马达和免疫技术相结合,建立免疫生物传感器快速检测技术。首先pH变化敏感荧光物质F1300标记到色素体(chrom atophore)的内表面,然后在F0F1-ATP酶上连接β亚基抗体-生物素-链亲和素-生物素-单核细胞增生李斯特菌多抗复合体,得到可以捕获单核细胞增生李斯特菌的免疫生物传感器。传感器上负载菌量不同,酶活性不同,酶活变化以pH敏感的荧光探针来感应,最后通过荧光扫描仪检测不同菌量负载下的荧光信号。结果表明,该方法对单核细胞增生李斯特菌标准菌株(ATCC 15313)的检测时间为4.5 h,检出浓度为100 CFU/孔。     

SARS冠状病毒实时荧光RT-PCR定量检测

为建立一种快速、准确、特异的SARS病毒RNA定量检测方法,根据复合探针荧光定量分析原理,对SARS病毒核酸进行实时荧光定量RT-PCR检测.借助计算机辅助,对SARS病毒基因靶序列以及检测引物和探针进行了优化筛选;利用体外转录SARS病毒RNA靶序列,对RT-PCR反应的镁离子浓度参数进行了优化;比较Trizol法、磁珠法、Qiagen法、煮沸法等4种方法提取RNA的检测效果,建立了样本处理方法;通过对构建的体外转录靶序列模型的检测,对本方法的灵敏度、特异性、定量线性关系、精确度等进行了评价,并通过对42例临床标本的检测对本方法的检测效果进行了评估. 通过克隆SARS病毒核酸靶序列并进行体外转录,获得了长度约1.2 kb的体外转录RNA靶序列;经优化,荧光RT-PCR反应液中的Mg²⁺浓度以4.0 mmol/L为最好;RNA提取方法采用磁珠法效果较好;本方法的检测灵敏度最低可达5个拷贝的体外转录RNA分子,特异性100%,C_t值的CV值小于5%.对临床确诊的42份SARS病人血清和漱口水标本的检测结果表明,该方法的检出率为79%,与荧光抗体检测法的符合率为70%.上述结果表明,该方法建立的荧光定量RT-PCR技术能够快速准确、特异、敏感地对SARS病毒核酸进行定量分析,为临床SARS冠状病毒RNA的检测提供了新的,更为有效的检测方法.     

F0F1-ATPase分子马达技术对单核细胞增生李斯特菌检测的研究

利用载色体chromatophore上的F₀F₁-ATPase分子马达生物传感器,建立了应用在食品检测中快速检测方法。首先从嗜热菌中提取载色体后,标记荧光探针F-DHPE,合成生物素化单增李氏菌prfA探针,在已标记F-DHPE的载色体ATP合酶的ε亚基上连接ε亚基抗体-生物素-链霉亲和素-生物素-prfA探针,将待测单核细胞增生李斯特菌标准菌株和阴性对照分别与此生物传感器结合,通过环境H+量测定ATP产生量,进而对单核细胞增生李斯特菌DNA进行检测。结果表明,chro prfA(连接在载色体chro上的prfA探针)的浓度在0.052 mg/mL,单核细胞增生李斯特菌DNA浓度在40 ng/mL为最适检测条件。通过传统检测方法及PCR检测方法对照,本方法具有良好的检测符合性。     

逆转录环介导等温核酸扩增技术(RT-LAMP)在H5N1禽流感病毒基因检测中的应用

建立一种便捷、灵敏的检测方法,即逆转录环介导等温核酸扩增技术(RT-LAMP)用于H5N1亚型禽流感病毒基因检测.该技术使用特异对应于靶序列中8个基因区段的6条特异引物,在等温条件下进行核酸扩增反应.对51份实验感染动物及病毒培养标本的H5N1亚型禽流感病毒的HA、NA基因区进行了RT-LAMP检测,并以SYBR Green Ⅰ为反应指示剂进行了逆转录环介导等温核酸扩增技术,对该反应进行实时监控,经对扩增产物做内切酶验证和测序分析,证明RT-LAMP技术的特异性;同时,用10倍系列稀释的RNA样品对该检测方法的灵敏度进行了测试.结果显示:利用RT-LAMP技术成功检测到H5N1禽流感病毒的HA、NA基因区,且RT-LAMP与Real-time PCR结果呈现很好的一致性.此方法的灵敏度可达到能检测10个拷贝RNA分子水平.因此,RT-LAMP技术应用于H5N1亚型禽流感病毒的快速检测是一种可行的方法.     

滚环复制技术的建立及在RNA病毒基因检测中的初步应用

滚环复制是噬菌体繁殖所采取的一种基因复制方式,这种方式可使单链的环形分子在聚合酶和引物的作用下进行体外自我扩增。本文中用可特异性连接环化的寡核苷酸链作为探针,分别进行了1份细胞培养的禽流感病毒H5N1亚型样品、1份细胞培养的SARS病毒样品和4份丙型肝炎病毒阳性血清样品的检测。检测原理是探针与靶序列杂交后便可在T4DNA连接酶的作用下形成滚环复制中的环化单链分子,该分子在同温下可被特异性引物滚动复制和支链扩增。本文还利用按禽流感病毒NA1基因区序列合成的模拟DNA分子对该检测方法的灵敏度进行了测试。结果显示：利用固相RCA技术成功检测到三种RNA病毒的基因,该方法的灵敏度可达到能检测10^3拷贝模式DNA分子的水平。与传统的PCR方法敏感性的比较尚待进一步研究。     

检测粪便中GGⅡ型诺如病毒Real-time RT-PCR方法的建立

诺如病毒是世界急性胃肠炎的重要病原之一。为加强其控制,通过序列比对设计出针对GGⅡ型诺如病毒保守序列的特异性引物与探针,建立了TaqMan Real-time RT-PCR方法。结果显示,此方法对诺如病毒核酸检测高度特异,与轮状病毒、腺病毒、甲型肝炎病毒等无交叉反应,最低检出限可达102拷贝,线性范围为109~102拷贝,标准曲线的相关系数为-1.00。针对标准品质粒检测的批内实验变异系数为0.28%~1.63%(n=6)、批间实验为0.28%~1.05%(n=3),对同一样品分6次进行RNA提取和逆转录,其变异系数为3.88%。对212份临床腹泻标本分别用常规RT-PCR和本文建立的TaqMan Real-time PCR进行检测,发现后者检出率略高于前者。这些结果提示此研究建立的诺如病毒的TaqMan Real-time RT-PCR检测方法可用于临床腹泻粪便标本的检测。     

生物传感器

生物传感器 (biosensor)是由固定化生物物质与适当的化学信号换能器件组成的生物电化学分析系统 ,具有特异识别生物分子的能力 ,并能检测生物分子与分析物之间的相互作用 ,用于微量物质的检测。1　生物传感器的优点生物传感器与传统的化学传感器和离线分析技术(如 HPLC或质谱 )相比 ,具有许多不可比拟的优势 ,如高度特异性 ,灵敏度高 ,稳定性好 ,成本低廉 ,体积小 ,能在复杂的体系中进行快速在线的连续检测。一般不需要样品的预处理 ,样品用量少 ,响应快 ,固定化敏感材料可反复多次使用 ,成本远低于大型分析仪器 ,易于推广普及。2　生物传…     

Real-time TaqMan RT-PCR快速检测犬瘟热病毒方法的研究

按照犬瘟热(CDV)N基因序列,设计合成了特异性引物和探针,经各反应条件的优化,建立了Real-time荧光定量RT-PCR技术,对细胞培养物、肝脏、肺脏、脑、脾脏、淋巴结以及鼻腔拭子等组织病料中的CDV进行了特异性检测和敏感性试验。同时,利用建立的Real-time荧光定量RT-PCR方法与常规RT-PCR以及韩国BIOINDIST生产的BIT RAPID CDV检测试剂盒对57份临床样品进行了检测。结果:用20pmol/mL的引物浓度各1uL和20pmol/mL的探针浓度0．3uL,获得的荧光信号最强,曲线平滑。敏感性高,可检测到1．24×10—3ng/uL的病毒RNA;特异性强,与NDV、AIV、NiPV等RNA病毒不发生交叉反应。试验重复性的变异系数(CV)分别为2．3%、2．5%和4．2%;与常规RT-PCR和BIOINDIST生产的BIT RAPID CDV检测试剂盒相比较,该方法具有快速、特异、敏感、可定量,并可同时检测大量样品等优点。     

膜芯片检测A组轮状病毒的初步研究

建立表面带正电荷的尼龙膜为基片的基因芯片,采用RT-semi-nested PCR方法,对A组轮状病毒RNA实现高度扩增,并通过5'端带地高辛标记的上游引物实现扩增产物的标记.通过同膜芯片上探针的杂交和免疫显色,实现对A组轮状病毒的检测.结果表明,膜芯片对探针的固定效果、杂交吸脱和检测结果可靠,空白对照和阴性对照均为阴性,探针均显示为阳性信号,并且信号强弱与探针浓度关系不大,而主要与探针本身同互补链的结合相关.以上结果说明已经初步建立了快速检测A组轮状病毒的膜基因芯片检测技术.     

A Unique Protease Cleavage Site Predicted in the Spike Protein of the Novel Pneumonia Coronavirus (2019-nCoV) Potentially Related to Viral Transmissibility

正Dear Editor,In December 2019, a novel human coronavirus caused an epidemic of severe pneumonia(Coronavirus Disease 2019,COVID-19) in Wuhan, Hubei, China(Wu et al. 2020; Zhu et al. 2020). So far, this virus has spread to all areas of China and even to other countries. The epidemic has caused 67,102 confirmed infections with 1526 fatal cases     

Curcuminoids as inhibitors of thioredoxin reductase: A receptor based pharmacophore study with distance mapping of the active site

Curcumin is the yellow pigment of turmeric that interacts irreversibly forming an adduct with thioredoxin reductase (TrxR), an enzyme responsible for redox control of cell and defence against oxidative stress. Docking at both the active sites of TrxR was performed to compare the potency of three naturally occurring curcuminoids, namely curcumin, demethoxy curcumin and bis-demethoxy curcumin. Results show that active sites of TrxR occur at the junction of E and F chains. Volume and area of both cavities is predicted. It has been concluded by distance mapping of the most active conformations that Se atom of catalytic residue SeCYS498, is at a distance of 3.56 from C13 of demethoxy curcumin at the E chain active site, whereas C13 carbon atom forms adduct with Se atom of SeCys 498. We report that at least one methoxy group in curcuminoids is necessary for interation with catalytic residues of thioredoxin. Pharmacophore of both active sites of the TrxR receptor for curcumin and demethoxy curcumin molecules has been drawn and proposed for design and synthesis of most probable potent antiproliferative synthetic drugs.     

Comparative morphology of the carpel in the Liliaceae: Hewardieae, Petrosavieae, and Tricyrteae

The young pistils in the melanthioid tribes, Hewardieae, Petrosavieae and Tricyrteae, are uniformly tricarpellate and syncarpous. They lack raphide idioblasts. All are multiovulate, with bitegmic ovules. The Petrosavieae are marked by the presence of septal glands and incomplete syncarpy. Tepals and stamens adhere to the ovary in the Hewardieae and the Petrosavieae but not in the Tricyrteae. Two vascular bundles occur in the stamens of the Hewartlieae and Tricyrtis latifolia. Ventral bundles in the upper part of the ovary of the Hewardieae are continuous with compound septal bundles and placental bundles in the lower part. Putative ventral bundles occur in the alternate position in the Tricyrteae and putative placental bundles in the opposite. position in the Petrosavieae. The dichtomously branched stigma in each carpel of the Tricyrteae is supplied by a bifurcated dorsal bundle.     

Selection with two alleles and complete dominance

For a plant selection model with frequency-independent viabilities, fertilities and selfing rates, it is shown that apart from global fixation, for certain parameter combinations a protected polymorphism and facultative fixation (either allele may become fixed according to initial frequencies) may both occur. Facultative fixation requires different selling rates for the dominant and recessive type. Protection of the polymorphism requires resource allocation for male and female function. In this connection the problem of purely genetically caused population extinction is discussed.
For general frequency dependence and regular segregation, the chances for establishment of a completely recessive gene are compared to those of a completely dominant gene. It is proven that the process of establishment of the recessive gene, despite a fitness advantage, may be considerably endangered by drift effects if random mating prevails. The recessive gene may reach the same effectivity in establishment as a dominant gene, only if the recessive homozygote mates exclusively with its own type during the period of establishment.     

Composition and diversity of bird communities in Swedish farmland–forest mosaic landscapes

CapsuleThe amount of forest (at local and landscape scales) and occurrence of residual habitats at the local scale are shown to be the major factors influencing bird community composition in farmland–forest landscapes in central Sweden.

Aims To investigate the importance of local habitat and landscape structure for breeding birds in farmland–forest landscapes in central Sweden.

Methods Breeding birds were censused at 292 points. A detailed habitat mapping was made within 300 m of the points. Within a 300–600 m radius only two major habitats (forests and arable fields) were identified.

Results Cluster analyses of bird communities identified three site types that also differed in habitat composition: (i) partially forested sites in forested landscapes; (ii) heterogeneous sites with residual habitats in mosaic landscapes; and (iii) field-dominated farmland sites in open landscapes. A total of 19 of 25 farmland bird species (restricted to farmland or using both farmland and forest) had the highest abundance in farmland sites with mosaics of forest and farmland, while only six farmland species had the highest abundance in field-dominated sites. The bird community changed from being dominated by farmland species to being dominated by forest species (common in forest landscapes without farmland) at small proportions (10–20%) of forest at the local scale. A major difference in habitat composition between heterogeneous and field-dominated sites was the occurrence of different residual habitats (e.g. shrubby areas and seminatural grasslands). These habitats seemed to influence bird community composition more than land-use, despite covering <10% of the area. Seminatural grasslands were important for bird community composition and species-richness, but grazing seemed to be less important. Among different land-use types, cereal crops were the least preferred fields. Set-asides with tall vegetation and short rotation coppices were positively associated with species-richness of farmland birds.

Conclusion In general, the composition of the landscape was important for bird community composition, although amount and distribution of forests, occurrence of residual habitats and land-use of fields at the local scale had the strongest influence on bird community composition. The possible implications of these patterns for managing farmland–forest landscapes are discussed.     

Chemical constituents from the fruits of Rhus typhina L. and their chemotaxonomic significance

This work describes the isolation and characterization of twenty-nine compounds from the fruits of Rhus typhina L., including eleven flavonoids (1–11), eleven phenols (12–22), two pentacyclic triterpenes (23–24), two organic acids (25–26), one lumichrome (27), one courmarin (28) and one pyrimidine (29) on the basis of their spectroscopic data. Compounds apigenin (1), daidzein (4), orobol (5), 3′, 5, 5′, 7-tetrahydroxyflavanone (6), naringenin (7), butein (8), (-)-catechin (9), quercetin-3-O-α-L-(3″-O-galloyl)-rhamnoside (11), 2-hydroxybenzoic acid (13), 4-hydroxybenzaldehyde (14), vanillin (15), methyl 3,4-dihydroxybenzoate (16), 3,5-dihydroxybenzamide (18), tyrosol (19), caffeic acid (20), 3-(2,4,6-trihydroxyphenyl)-1-(4-hydroxyphenyl)-propan-1-one (21), phlorizin (22), friedelin (23), oleanolic acid (24), 4,4-dimethyl-heptanedioic acid (25), anthranilic acid (26), lumichrome (27), scoparone (28) and uracil (29) have not been recorded before in this plant. This is the first report on the occurrence of compounds 4–7, 9, 11, 13–14, 16, 18–21, 25–29 from the genus Rhus. Moreover, the chemotaxonomic significance of these isolated compounds was also summarized.