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1.
《农业科学学报》2017,(3)
Plum pox virus(PPV)causes sharka-the most serious viral disease of stone fruit trees.PPV is wide spread in Europe and Mediterranean Basin,its incidence has been further approved in Asia and both Americas.Nine PPV strains have been recognized until now(PPV-D,PPV-M,PPV-Rec,PPV-EA,PPV-C,PPV-T,PPV-W,PPV-CR,and PPV-An),forming molecularly distinct entities,however,only partially differentiable by their biological or epidemiological properties.The most strict virus-host linkages under natural conditions have been detected for strains naturally infecting cherries(PPV-C and PPV-CR).However,although less stringent but still clear host preference is observed also for three epidemiologically most important strains(PPV-D/plum/apricot,PPV-M/peach,and PPV-Rec/plum).So far no genetic marker has been mapped in the PPV genome,which responsibility for the host specificity/preference could be explicitly demonstrated.In this review,we focus on the host preference of three major PPV strains as evidenced by analysis of an extensive dataset of PPV isolates of Slovak and world-wide origin.Together,we discuss several performed relevant experiments and further possible research procedures aimed to better understand the genetic determinants and mechanisms of the host preference of this potyvirus. 相似文献
2.
Correll DL 《Science (New York, N.Y.)》1966,151(3712):819-821
"Polyphosphate" and fragments isolated from acid hydrolysis of polyphosphate have an infrared absorption band at 1400 cm(-1), which is characteristic of imidodiphosphate linkages. Complete hydrolysis of purified "polyphosphate" releases 1 to 2 moles of phosphate per mole of ammonia. The polymer must contain subunits which are cyclic and which contain both imidodiphosphate linkages and phosphate anhydride linkages. 相似文献
3.
以单层聚对苯乙炔（PPV）薄膜发光二极管为例，研究其薄膜中的电场分布，探讨其电场分布对载流子注入、输运和复合的影响，研究结果有助于揭示其发光机理，为提高发光效率提供了有益的启示。 相似文献
4.
Stamenkovic VR Fowler B Mun BS Wang G Ross PN Lucas CA Marković NM 《Science (New York, N.Y.)》2007,315(5811):493-497
The slow rate of the oxygen reduction reaction (ORR) in the polymer electrolyte membrane fuel cell (PEMFC) is the main limitation for automotive applications. We demonstrated that the Pt3Ni(111) surface is 10-fold more active for the ORR than the corresponding Pt(111) surface and 90-fold more active than the current state-of-the-art Pt/C catalysts for PEMFC. The Pt3Ni(111) surface has an unusual electronic structure (d-band center position) and arrangement of surface atoms in the near-surface region. Under operating conditions relevant to fuel cells, its near-surface layer exhibits a highly structured compositional oscillation in the outermost and third layers, which are Pt-rich, and in the second atomic layer, which is Ni-rich. The weak interaction between the Pt surface atoms and nonreactive oxygenated species increases the number of active sites for O2 adsorption. 相似文献
5.
Strukelj M Papadimitrakopoulos F Miller TM Rothberg LJ 《Science (New York, N.Y.)》1995,267(5206):1969-1972
Operating lifetime is the main problem that complicates the use of polymeric light-emitting diodes (LEDs). A class of electron transport (ET) polymers [poly(aryl acrylate) and poly(aryl ether)s] is reported in which moieties with high electron affinities are covalently attached to stable polymer backbones. Devices based on poly(p-phenylenevinylene) (PPV) prepared with these materials exhibited a 30-fold improvement in stability and, in one case, dramatically lower (10 volts versus about 30 volts) operating voltage relative to those having conventional ET layers. The current-carrying capacity of indium tin oxide-PPV-polymeric ET layer-aluminum LEDs was also increased by a factor of 30. These improvements lead to an enhancement in power efficiency of nearly an order of magnitude. Choosing polymers with high glass transition temperatures increases device lifetime. 相似文献
6.
本研究首次成功地建立了检测PPV抗原的间接斑点酶联免疫吸附试验(Dot—ELISA)标准化程序,在所确定的最适条件下,对纯化PPV抗原的最低检出量为2.5ng/dot,其敏感性为血凝试验(HA)的125倍,但稍低于银加强胶体金检测法(SECGA)。PPV阳性猪血清的特异性阻断试验及与猪瘟病毒,猪伪狂犬病病毒,猪巴氏杆菌的交叉反应试验证明,该方法对PPV抗原的检测具有特异性。以该方法检测PPV人工感染兔样本和自然感染猪样本,PPV抗原的阳性检出率分别为肾样本100％(17/17)、81.82％(9/11),肝样本100％(16/16)、56.52％(13/23)。20份随机样本的间接Dot—ELISA检测结果与病毒分离和鉴定结果相符。 试验证明间接Dot—ELISA对PPV感染的检测具有简单、快速、经济、敏感性高、特异性强、重复性好和便于推广应用等优点,适用于大批量抗原样本的检测,是PPV感染快速诊断和流行病学调查的有效方法。 相似文献
7.
Block copolymers consist of two or more chemically different polymers connected by covalent linkages. In solution, repulsion between the blocks leads to a variety of morphologies, which are thermodynamically driven. Polyferrocenyldimethylsilane block copolymers show an unusual propensity to forming cylindrical micelles in solution. We found that the micelle structure grows epitaxially through the addition of more polymer, producing micelles with a narrow size dispersity, in a process analogous to the growth of living polymer. By adding a different block copolymer, we could form co-micelles. We were also able to selectively functionalize different parts of the micelle. Potential applications for these materials include their use in lithographic etch resists, in redox-active templates, and as catalytically active metal nanoparticle precursors. 相似文献
8.
不同大豆蛋白对幼建鲤体蛋白质沉积的影响 总被引：6，自引：2，他引：4
研究了用大豆分离蛋白(SPI)和去皮豆粕蛋白(DSBM)两种蛋白源分别替代鱼粉的饲料对10～35g幼建鲤CyprinuscarpioVar.Jian体蛋白质沉积率的影响。结果表明:饲料中用大豆分离蛋白替代鱼粉蛋白水平对幼建鲤的蛋白质效率比(PER)和蛋白质沉积率(PPV)的影响极显著(P<0.01)或显著(P<0.05),随着用大豆分离蛋白替代鱼粉蛋白比例的增加,蛋白质效率比和蛋白质沉积率均极显著下降(P<0.01),当大豆分离蛋白替代鱼粉蛋白比例超过60%时,蛋白质沉积率极显著下降(P<0.01);饲料中用去皮豆粕蛋白替代鱼粉蛋白比例对幼建鲤的蛋白质效率比、蛋白质沉积率影响显著(P<0.05)或极显著(P<0.01),随着替代水平的增加,蛋白质沉积率极显著下降(P<0.01),蛋白质效率比显著下降(P<0.05),当用去皮豆粕替代鱼粉蛋白的比例达50%时,可以使幼建鲤的蛋白质沉积效率极显著降低(P<0.01),这说明用大豆分离蛋白和去皮豆粕两种大豆蛋白分别替代鱼粉蛋白后,均可以引起10～35g幼建鲤的蛋白质沉积效率下降;在蛋白质质量分数为33%的幼建鲤饲料中,用大豆分离蛋白和去皮豆粕蛋白替代鱼粉蛋白的适宜比例分别为40%和25%。 相似文献
9.
为了检验细胞因子IFN-γ与猪细小病毒VP2融合蛋白的免疫效力,通过重叠延伸PCR技术将IFN-γ与PPV的VP2基因融合到一起,利用杆状病毒表达系统构建了重组杆状病毒r Bac-VP2、r Bac-VP2-IFN-γ,并在小鼠上验证了免疫原性。猪细小病毒ELISA抗体和中和抗体检测结果显示,VP2-IFN-γ组明显高于VP2和PPV灭活苗组;淋巴细胞增殖试验结果表明,VP2-IFN-γ组淋巴细胞数明显高于不加IFN-γ组。上述结果表明IFN-γ可提高猪细小病毒亚单位疫苗体液和细胞免疫应答,为重组IFN-γ的猪细小病毒病亚单位疫苗开发提供理论依据。 相似文献
10.
【目的】建立一种能够快速、灵敏地检测猪细小病毒（PPV）的SYBR GreenⅠ实时荧光定量PCR方法。【方法】根据GenBank中的PPV VP2基因序列,设计并合成1对引物。通过常规PCR,扩增猪细小病毒VP2基因,并将其纯化的PCR产物克隆入pGEM-T Easy 载体中,构建重组质粒。对扩增程序中的荧光染料浓度、引物浓度和Mg2+浓度条件进行优化,建立最佳的荧光定量 PCR 反应体系和标准曲线。以阳性重组质粒为模板,建立SYBR GreenⅠ荧光定量PCR方法,对其灵敏性、特异性和重复性进行检验。应用建立的SYBR GreenⅠ荧光定量PCR方法,对临床60份疑似PPV病料进行检测,同时与血凝试验(HA)和常规PCR方法的检测效果进行比较。【结果】 在25 μL扩增体系中,Mg2+终浓度为4.5 mol/L、SYBR Green染料浓度为20 μmol/L、引物浓度为25 μmol/L时,本底反应最小、循环阈值最低、扩增效率最高。所建立的SYBR GreenⅠ实时荧光定量PCR方法能够特异、定量地检测猪细小病毒,灵敏度达20 TCID50/mL;在临床样品检测中,其检出率比常规PCR方法高13.3%。【结论】 成功建立了PPV SYBR GreenⅠ实时荧光定量PCR检测方法,为临床猪细小病毒的早期诊断及定量分析病毒的感染程度奠定了基础。 相似文献
11.
从一育肥猪早、中期生产状况差的猪场收集猪血清214份,采用猪细小病毒(PPV)特异性检测引物进行PCR检测,选取1份阳性血清接种猪睾丸细胞(ST)进行PPV分离、部分生物学特性研究,以及PPV部分基因序列分析。结果表明:在15、16、17、18、22周龄猪血清中均检测到PPV,检测阳性率分别为10%、40%、20%、15.4%、9%,而从2~14及24周龄的猪血清中没有检测到PPV;病毒分离和部分生物学特性研究结果表明,从血清中分离的PPV在ST细胞上传到第5代能够出现较稳定的细胞病变(CPE),病毒血凝效价为28;PPV部分基因序列与GenBank收录的PPV毒株序列同源性在98%以上,其中与2012年西北农林科技大学时乐[1]分离的YL毒株同源性高达99.1%。以上结果证实本研究分离到PPV,且说明PPV在采样猪场的保育后期和育肥前、中期猪血清中具有较高的阳性率。 相似文献
12.
Kim JY Lee K Coates NE Moses D Nguyen TQ Dante M Heeger AJ 《Science (New York, N.Y.)》2007,317(5835):222-225
Tandem solar cells, in which two solar cells with different absorption characteristics are linked to use a wider range of the solar spectrum, were fabricated with each layer processed from solution with the use of bulk heterojunction materials comprising semiconducting polymers and fullerene derivatives. A transparent titanium oxide (TiO(x)) layer separates and connects the front cell and the back cell. The TiO(x) layer serves as an electron transport and collecting layer for the first cell and as a stable foundation that enables the fabrication of the second cell to complete the tandem cell architecture. We use an inverted structure with the low band-gap polymer-fullerene composite as the charge-separating layer in the front cell and the high band-gap polymer composite as that in the back cell. Power-conversion efficiencies of more than 6% were achieved at illuminations of 200 milliwatts per square centimeter. 相似文献
13.
Brown HR 《Science (New York, N.Y.)》1994,263(5152):1411-1413
The interfacial shear stress that occurs when a network of a polymer that is highly mobile at the segment level (an elastomer) is slid over a smooth surface of an immobile (glassy) polymer has been measured. The glassy material is covered by a thin layer of end-attached chains of the mobile material. The experiment was designed so that there were no free chains at the interface; the slip occurred between network chains on the one side and rigid material plus end-attached mobile chains on the other side. Two main results were obtained. (i) The interfacial shear stress is strongly affected by the segment mobility of the materials on both sides of the slip plane, and considerably lower stress is observed when the materials on both sides of the interface are highly mobile. (ii) Very thin layers of tethered chains can increase the interfacial friction. Both results are relevant to the understanding of a number of practical situations that range from the operation of thin layers of lubricants, such as those found in magnetic storage devices, to the problem of wall slip and melt fracture in polymer processing. 相似文献
14.
根据GenBank公布的猪细小病毒VP2基因序列,利用Premierexpress软件设计并合成了1对引物和1条相应的TaqMan探针,从猪细小病毒感染的PK．15细胞中提取DNA,经PCR扩增VP2基因,纯化的PCR产物克隆入pGEM-TEasy载体中,构建重组质粒．转化大肠杆菌JM109,经PCR及测序鉴定后得到阳性重组质粒,作为荧光定量PCR标准品模板建立标准曲线．在25此扩增反应体系中,对探针浓度、引物浓度、镁离子浓度和退火温度进行优化,建立了最佳的荧光定量PCR反应体系和扩增程序．该方法能够特异、定量检测猪细小病毒,灵敏度达1．12TCID50／mL． 相似文献
15.
Porcine parvovirus (PPV) is one of the major agents causing swine reproductive failure. NS1protein is a non-structural protein of PPV and can be used as a reagent for differentiation of vaccinated ani-mals and infected ones. In present study, a recombinant plasmid pET28a/NS1 was constructed by cloning thecoding sequence for NS1 of PPV into pET28a, a bacterial expression vector. The NS1 protein was expressed inE. coli BL21 (DE3) after induced by IPTG and the recombinant fusion protein was purified with affinity chro-matography. Expression amount of NS1 protein was improved by optimizing the inducing parameters. The re-combinant NS1 protein is reactive to PPV positive sera in Western blot and ELISA test and therefore can beapplicable in differential diagnosis of PPV infections. 相似文献
16.
《农业科学学报》2019,18(10):2302-2310
Stone fruits are an important crop in most parts of the world and are heavily challenged by several viruses including Plum pox virus(PPV), Prune dwarf virus(PDV), Prunus necrotic ringspot virus(PNRSV), and Apple chlorotic leaf spot virus(ACLSV). We validated the PPV resistance in C5 plum plants(commercially known as Honey Sweet) grown in the Czech Republic for more than 16 years in a field trial experiment under natural environmental conditions. We quantified single(PPV-Rec) and mixed viruses(PPV-Rec+ACLSV, PPV-Rec+PDV and PPV-Rec+ACLSV+PDV) in C5 transgenic plums inoculated for the period 2016 to 2018. The accumulation of PPV-Rec was high(～5.43 E+05 copies) compared with that of ACLSV(～8.70 E+04 copies) in the inoculated graft of C5 transgenic plants. Leaves close to the inoculum sources showed a differential level of virus titre in single and mixed infections(～10 to ～5×10~2 copies). C5 plants with permanent virus pressure showed 10~3-to 10~5-fold fewer copies of viruses than those of the inoculated graft. We observed high accumulation of conserved mi RNAs such as mi R167, mi R69 and mi R396 in C5 plants co-infected with PPV, ACLSV and PDV that are associated with its resistance against viruses. Overall, i) C5 transgenic plums showed high resistance to PPV infection, and a low level(～32 copies) of PPV only accumulated in some grafted plants, ii) high accumulation of PPV was found in inoculated grafts in single PPV infection and mixed infections, iii) heterologous virus infection sustained by ACLSV or PDV did not suppress PPV resistance, and iv) high and low conserved micro RNAs accumulated in C5 plants. 相似文献
17.
猪细小病毒LAMP检测方法的建立 总被引：5，自引：0，他引：5
【目的】建立一种快速、敏感、特异的检测猪细小病毒(PPV)环介导等温扩增(LAMP)方法,为诊断猪细小病毒提供准确可靠工具。【方法】根据GenBank公布的PPV序列,在其保守序列区域设计了多套LAMP引物,利用LAMP Real Time Turbidimeter LA-320仪监测反应进程并筛选最佳引物、反应条件,建立了对PPV病毒DNA进行特异扩增的 LAMP检测方法,并可通过加入SYBR Green I肉眼判断结果。【结果】该方法在63℃恒温下作用45 min,PPV病毒DNA获得了高效率的特异性扩增;其检出限量为0.23 TCID50,敏感性高;在反应结束后加入SYBR Green I肉眼判断结果,与Real Time Turbidimeter LA-320仪监测结果一致。通过对20份临床样品的LAMP检测与免疫荧光鉴定、PCR方法比对,符合率均为20/20。【结论】本研究建立的PPV LAMP检测方法具有快速、特异、灵敏,操作简单、设备要求低的特点,适合用于临床PPV快速检测。 相似文献
18.
猪细小病毒N株免疫期测定 总被引：2，自引：1，他引：1
用PPV—N株制备成弱毒疫苗,在配种前1个月接种PPV HI抗体阴性的后备母猪,接种2周后检测PPV HI抗体均达到1：256以上。当怀孕到40d时用PPV强毒攻击,攻毒后40d剖杀的2头怀孕母猪其胎儿正常健活,胎儿心血未检测到PPV HI抗体,胎儿脏器未分离到病毒;自然分娩的2头母猪,其仔猪健活,未吃初乳仔猪PPV HI抗体阴性,仔猪脏器未分离到病毒;而强毒攻击的对照猪均出现不同程度的死胎,并从未吃初乳仔猪检测到PPV HI抗体和从死胎儿肺回收到病毒。按上述方法连续观察到第3胎（免疫后15个月）,证明免疫母猪怀孕到第3胎仍能抵抗PPV强毒攻击,说明PPV—N株对母猪的免疫期达1年以上。 相似文献
19.
猪细小病毒(PPV)SD1株NS1基因的克隆与原核表达 总被引：1，自引：0，他引：1
[目的]为建立猪细小病毒的快速诊断方法提供理论依据。[方法]根据GenBank上猪细小病毒基因组序列和原核表达质粒pET30a(+)多克隆位点序列设计1对引物,应用PCR技术扩增出猪细小病毒SD1株NS1基因全序列,对阳性重组质粒进行测序和同源性比较。构建原核表达重组质粒pET 30a/NS1,并在大肠杆菌中进行诱导表达。[结果]通过PCR扩增获得2 208 bp目的片段。所克隆NS1基因与已报道的PPV相应基因的核苷酸同源性为97.3%~99.4%,表明NS1基因具有高度保守性,但在偏3′端连续缺失12个碱基。所克隆的PPVNS1基因在原核细胞中成功表达,其表达产物主要以包涵体形式存在。[结论]SDS-PAGE检测结果表明PPVNS1蛋白的分子量为86 kD。 相似文献