单管可视化环介导等温扩增技术快速检测恶性疟原虫

目的:建立一种基于环介导等温核酸扩增技术(Loop-mediated Isothermal Amplification,LAMP)的恶性疟原虫高灵敏可视化闭管检测方法。方法:针对恶性疟原虫核糖体DNA的序列保守区设计LAMP引物,通过优化LAMP体系中的Mg2+、甜菜碱浓度和反应温度等因素,建立环介导等温扩增法;并结合蜡封反应管对产物进行检测,检测结果可直接通过肉眼观察SYBR Green I荧光显色进行判定。结果:本方法可检测到70个拷贝/管的恶性疟原虫核酸片段,并具有高特异性,可区分检测常见的血液病毒。该法具有如下优点:1、整个反应恒温进行,无需热循环仪;2、闭管检测,极大降低了扩增产物交叉污染的风险;3、检测速度快,整个检测过程只需30 min。结论:该法的建立为恶性疟原虫的现场快速筛检提供了一种简便、高灵敏、高特异的工具。     

多重环介导核酸等温扩增技术检测血液中常见病原体

背景：血液安全性筛查是输血前必要检测项目。目前临床采用血清学检测技术,存在较长的检测窗口期,易产生假阴性检测结果,造成输血交叉感染。目的：建立多重环介导核酸等温扩增技术,实现在一管反应体系内同时检测四种病原体：乙肝病毒,丙肝病毒,艾滋病毒和梅毒螺旋体。方法：通过限制性酶切处理多重环介导核酸等温扩增产物,利用酶切产物的长度分析扩增产物的种类,从而分析待测样本中含有何种血液病原体。结果：检测164例临床样本,其检测结果可以通过琼脂糖电泳,聚丙烯酰胺凝胶电泳及芯片电泳分析,且均可实现对多重扩增产物的酶切片段进行区分和鉴别。结论：多重环介导核酸等温扩增技术可以同时单管检测多种待测血液病原体,可以为临床提高简单、快速、高灵敏和高特异的检测技术。     

鸭瘟病毒LAMP可视化检测方法的建立

目的:建立一种快速、简便、特异性高的鸭瘟病毒(DPV)环介导等温扩增(LAMP)检测方法。方法:根据Gen Bank中DPVUI6基因的保守序列设计一套特异性引物,并对反应条件进行优化,建立DPV的LAMP可视化检测方法。结果:建立的LAMP方法对其他鸭常见病原体无扩增反应;可通过肉眼观察颜色直接判定结果;敏感性可达0.1fg,是常规PCR方法的100倍;扩增反应只须在常规水浴锅中进行,可在1 h内完成。结论:建立的DPV LAMP方法简便、快速、灵敏、特异,可用于DPV感染的快速检测。     

核酸试纸条在检测转EPSPS基因作物中的应用

目的:建立快速、简便和特异的检测转EPSPS基因作物的方法。方法:针对转EPSPS基因作物外源基因cp4-EPSPS的8个区域,设计2对特异性引物和1对环引物,对反应体系中的MgSO4、内引物、环引物、甜菜碱、dNTP浓度和反应温度等条件分别进行优化,并用核酸试纸条对扩增产物进行检测,建立用于检测转EPSPS基因作物的环介导等温扩增方法(LAMP)。结果:用建立的LAMP方法检测转EPSPS基因作物时,在64℃恒温反应30 min,即可根据试纸条显色直接观察结果;该方法具有高度特异性,可检测到10个拷贝的EPSPS DNA。结论:LAMP方法可快速、灵敏、特异、经济地检测转EPSPS基因作物,在基层和实验室都具有良好的应用前景。     

环介导等温扩增技术的应用进展

环介导等温扩增(loop-mediated isothermal amplification,LAMP)是一种新式核酸扩增技术,它依靠一种具有链置换活性的DNA聚合酶与2对特殊设计的引物,在等温条件下即可高效快速地完成扩增反应。相较于传统扩增检测方法,LAMP技术具有特异性强、灵敏度高、操作简单快速等优点,更能在现场快速检测和基层应用中广泛推广,目前LAMP技术已广泛应用于植物病害检测、动物病害检测、食品安全检测等领域。基于此,简要介绍了LAMP技术的基本原理、反应产物的检测方法,重点阐述了LAMP技术的改进与发展,综述了近年来其在科研生产中的应用进展,并对其发展前景进行了展望,以期为LAMP技术的进一步发展提供合理的研究方向。     

LAMP快速检测对虾IHHNV的方法与应用

建立了一种检测对虾传染性皮下及造血组织坏死病毒(Infectious hypodermal and hematopoietic necrosis vi-rus,I HHNV)快速、灵敏的环介导等温扩增(Loop-mediated isothermal amplification,LAMP)方法。针对I HHNV非结构蛋白基因NS1序列的6个保守区域,利用Pri mer Explorer v4.0软件设计4条引物,建立了I HHNV环介导等温扩增快速检测方法,对反应温度和反应时间等参数进行了优化,并将建立的LAMP检测方法与常规PCR检测进行了比较分析。结果表明,LAMP最适反应在65℃恒温条件60min内完成,凝胶电泳呈现特征性梯型条带;反应体系中添加SYBR Green I荧光染料后,绿色的阳性结果很明显区别于橙色阴性结果。LAMP方法的最低检出限为100拷贝/μL,灵敏度较常规PCR高1000倍。用建立的LAMP方法对临床发病南美白对虾样品进行了检测,结果表明建立的LAMP方法适合于对虾I HHNV的现场快速检测。     

环介导等温扩增技术的研究进展

环介导等温扩增(loop-mediated isothermal amplification,LAMP)是一种新式核酸扩增技术,它依靠一种具有链置换活性的DNA聚合酶和2对特殊设计的引物,不需要反复的温度循环和昂贵的仪器设备,在等温条件下即可高效快速地完成扩增反应,目前已广泛应用于细菌、病毒、寄生虫等病原体的检测,及动物胚胎性别的鉴定。该文总结了LAMP技术的基本原理、相对于传统核酸检测技术的优点、产物的检测方法及其临床应用,最后指出LAMP目前存在的不足以及采取的相应措施,并对其发展前景进行了展望。     

不同加热方式对嗜肺军团菌环介导等温扩增检测法的影响

目的：研究不同的加热方式对嗜肺军团菌环介导等温扩增检测法的影响方法：用已知的13株嗜肺军团菌样本,采用空气浴、水浴和PCR仪同时进行环介导等温扩增,观察沉淀反应、荧光反应以及产物电泳结果。结果：水浴和PCR仪加热LAMP反应的沉淀产物较多,荧光反应较强,电泳检测结果较为明显。空气浴的3种检测结果均较弱。结论：采用水浴和PCR仪进行环介导等温扩增反应的效果较好,从仪器设备的成本及实验条件考虑,采用水浴是环介导等温扩增反应首选的加热方式。     

环介导等温扩增技术原理及其在检测诊断病原微生物中的应用

环介导等温扩增技术(loop-mediated isothermal amplification,LAMP)是近年来发展出来的一种核酸扩增技术.通过设计识别目的片段6个序列的4个特异引物,整个反应可以在恒温(60～65℃)条件下1 h内完成,由于采用4个引物,与传统的核酸扩增技术相比,它具有敏感、特异的特点;且产物中有大量的副产物--白色焦磷酸镁沉淀,扩增产物可通过肉眼观察或浊度计即可判定结果;反应不需要精密控温设备和高级复杂的分析仪器,对操作人员的熟练度和专业水平要求不高,因此该方法特别适合基层或者实验条件较差的试验室进行病原微生物的快速检测.就其原理及其在病原微生物的检测中的应用做一综述.     

不同加热方式对嗜肺军团菌环介导等温扩增检测法的影响

目的:研究不同的加热方式对嗜肺军团菌环介导等温扩增检测法的影响方法:用已知的13株嗜肺军团菌样本,采用空气浴、水浴和PCR仪同时进行环介导等温扩增,观察沉淀反应、荧光反应以及产物电泳结果。结果:水浴和PCR仪加热LAMP反应的沉淀产物较多,荧光反应较强,电泳检测结果较为明显。空气浴的3种检测结果均较弱。结论:采用水浴和PCR仪进行环介导等温扩增反应的效果较好,从仪器设备的成本及实验条件考虑,采用水浴是环介导等温扩增反应首选的加热方式。     

β-Myrcene,a Potent Attractant Component of Pine Wood for the Pine Wood Nematode,Bursaphelenchus xylophilus

A new convenient assay method for nematode attractants was developed. Using this method, the attracting activity of volatile components in a pine, Pinus densiflora, was examined for the pine wood nematode, Bur saphelenchus xylophilus, which causes serious damage to pine trees in Japan. Among the volatile components, β-myrcene showed the strongest attracting potency. This compound was assumed to play an important role in the transmigration of the nematode from the sawyer to the pine tree and for the movement of the nematode inside the pine wood.     

Transmission of Bursaphelenchus xylophilus between Monochamus alternatus and Monochamus saltuarius through interspecific mating behaviour

Cerambycid adults of the genus Monochamus transmit the pine wood nematode (Bursaphelenchus xylophilus [Steiner et Buhrer] Nickle), the causative agent of pine wilt disease. To confirm the transmission of B. xylophilus between vector species, nematode‐infected Monochamus alternatus Hope and nematode‐free Monochamus saltuarius (Gebler) adults were paired and their behaviour was observed for 107–220 min. In three pairs that exhibited mounting without copulation, nematode transmission occurred, whereas it was not found in another pair without mountings. The effect of nematode transmission between different vector species on the invasion biology of B. xylophilus is discussed.     

植物根际益生细菌代表性菌株贝莱斯芽孢杆菌FZB42对松材线虫的抑杀性

【目的】由松材线虫导致的松树萎蔫病是松树的毁灭性病害,也是我国最主要的林业病害之一。本研究测评了在农业上广泛使用的、我国微生物肥料行业主要菌种资源之一——贝莱斯芽孢杆菌,对松材线虫的潜在抑杀性能。【方法】选用贝莱斯芽孢杆菌的代表性菌株FZB42为材料,测定对不同条件下的菌液上清、不同菌株的菌液上清、细菌素plantazolicin的提取物以及菌体直接接触等方式,对松材线虫死亡率/存活率的影响,并构建FZB42生物膜合成缺损菌株,测定比较其对松材线虫存活率的影响。【结果】相比于Landy培养基,使用LB培养基得到的菌液上清,对松材线虫具有明显抑杀性,培养48h的菌液上清比培养24h的菌液上清抑杀性更强,同时,菌液上清的抑杀效能随浓度升高及处理时间增长而有所增加。其中,使用培养48h后收集的LB菌液上清处理48h,松材线虫死亡率可高达约50%。之前报道对秀丽隐杆线虫有杀线虫活性的细菌素plantazolicin,经不同突变株上清以及plantazolicin提取物测试,被证实对松材线虫无抑制作用。直接接触实验表明,尽管FZB42的生物膜形成作用会刺激松材线虫提高抗胁迫能力,但整体而言,菌体接触对松材线虫亦有明显抑杀效果。【结论】本研究通过严格细致的测试证明,贝莱斯芽孢杆菌FZB42对松材线虫具有抑杀性,该抑杀作用的分子基础和作用机理有待深入挖掘,但其与plantazolicin无关。作为安全性好、研究开发程度高的一类生防菌株,贝莱斯芽孢杆菌在防治松材线虫病方面的潜在价值值得关注。     

Water relations, xylem embolism and histological features of Pinus thunbergii inoculated with virulent or avirulent pine wood nematode, Bursaphelenchus xylophilus

The development process of pine wilt disease caused by Bursaphelenchusxylophilus (Steiner and Buhrer) Nickle, pine wood nematode,was studied ecophysiologically and histologically in relationto pathogenicity of B. xylophilus. Judging from the predawnxylem pressure potential of needles, the heat pulse velocity,and the soil water potential, the control Pinus thunbergii Parl.,used for the study, was not water-stressed. Virulent B. xylophilusisolate can kill non-waterstressed pines. In virulent B. xylophilusisolateinoculated pines, the predawn xylem pressure potentialof needles abruptly decreased when the colour of 1-year-oldneedles changed to brown and then the water conducting functionof the xylem was lost completely. Avirulent B. xylophilus isolatedoes not affect the needle colour and the xylem pressure potentialof pines. Avirulent B. xylophilus isolate-inoculated pines,however, responded to nematode invasion by decreasing hydraulicconductance of stem and root xylems. In addition, oleoresinexudation slightly decreased. The decreased hydraulic conductanceresults from embolism of tracheids caused by cavitation in thecentral part of the xylem. From histological observation, allof the parenchyma cells in virulent B. xylophilus isolateinoculatedpines died. In contrast, the parenchyma cells, degenerated inavirulent B. xylophilus isolateinoculated pines, were limitedin the embolized region of the xylem. The difference betweenthe response of pine to the virulent B. xylophilus isolate invasionand that to avirulent B. xylophilus isolate invasion indicatesthat nematode-induced death of pine relates to the death ofparenchyma cells, as well as the decrease in xylem hydraulicconductance. Key words: Embolism, hydraulic conductance, parenchyma cells, pathogenicity of pine wood nematode, pine wilt disease.     

On the Taxonomy and Morphology of the Pine Wood Nematode, Bursaphelenchus xylophilus (Steiner &Buhrer 1934) Nickle 1970

During the past 3 yr, nematologists in the United States have found specimens of Bursaphelenchus sp. in the wood of dead and dying pine trees. This nematode-host association resembles a similar interaction reported from Japan where pine trees are being killed by the pine wood nematode. This taxonomic research was conducted to determine if the Japanese pine wood nematode and similar populations in the United States are of the same species. Based upon typical morphological characters of original specimens of Bursaphelenchus xylophilus (Steiner and Buhrer 1934) Nickle 1970 that were rediscovered in the USDA Nematode Collection and genetic crosses among the Japanese and American nematode populations, it was concluded that they are all the same species, B. xylophilus.     

Secretome Analysis of the Pine Wood Nematode Bursaphelenchus xylophilus Reveals the Tangled Roots of Parasitism and Its Potential for Molecular Mimicry

Since it was first introduced into Asia from North America in the early 20^th century, the pine wood nematode Bursaphelenchus xylophilus has caused the devastating forest disease called pine wilt. The emerging pathogen spread to parts of Europe and has since been found as the causal agent of pine wilt disease in Portugal and Spain. In 2011, the entire genome sequence of B. xylophilus was determined, and it allowed us to perform a more detailed analysis of B. xylophilus parasitism. Here, we identified 1,515 proteins secreted by B. xylophilus using a highly sensitive proteomics method combined with the available genomic sequence. The catalogue of secreted proteins contained proteins involved in nutrient uptake, migration, and evasion from host defenses. A comparative functional analysis of the secretome profiles among parasitic nematodes revealed a marked expansion of secreted peptidases and peptidase inhibitors in B. xylophilus via gene duplication and horizontal gene transfer from fungi and bacteria. Furthermore, we showed that B. xylophilus secreted the potential host mimicry proteins that closely resemble the host pine’s proteins. These proteins could have been acquired by host–parasite co-evolution and might mimic the host defense systems in susceptible pine trees during infection. This study contributes to an understanding of their unique parasitism and its tangled roots, and provides new perspectives on the evolution of plant parasitism among nematodes.     

Cloning and characterization of an extracellular serine protease from the nematode-trapping fungus <Emphasis Type="Italic">Arthrobotrys conoides</Emphasis>

An extracellular serine protease (Ac1) with a molecular mass of 35 kDa was purified from the nematode-trapping fungus Arthrobotrys conoides. The optimum activity of Ac1 is at pH 7.0 and 53.2°C (over 20 min). Ac1 can degrade a broad range of substrates including casein, gelatin, bovine serum albumin, collagen, and nematode cuticles. Moreover, the enzyme can immobilize the free-living nematode Panagrellus redivivus and the pine wood nematode Bursaphelenchus xylophilus, indicating Ac1 may be involved in infection against nematodes. The encoding gene of Ac1 contains one intron of 60-bp and two exons encoding a polypeptide of 411 amino acid residues. The deduced polypeptide sequence of Ac1 showed a high degree of similarity to two previously reported serine proteases PII and Mlx from other nematode-trapping fungi (81% aa sequence identity). However, three proteases Ac1, Aoz1 and Mlx showed optimum temperatures at 53.2, 45 and 65°C, respectively. Compared to PII, Ac1 appears to have a significantly higher activity against gelatin, bovine serum albumin, and non-denatured collagen. Moreover, our bioassay experiments showed that Ac1 is more effective at immobilizing P. redivivus than B. xylophilus.