不同CMV分离物侵染寄主的超微结构变化

应用电镜观察了黄瓜花叶病毒CMV不同分离物侵染寄主的细胞 超微结构变化。来自一串红(Salvia splendens)的不含卫星RNA分离物M-22侵染心叶烟,病毒粒子散布于细胞质,在液泡中形成大片病毒粒子结晶,液泡膜边缘产生小泡结构,完整的病毒粒子穿过胞间连丝在细胞间运转,胞间连丝中央部分有扩张现象。自然感染三生烟的含坏死卫星RNA分离物8-S1侵染普通烟,病毒粒子分散于细胞质,在液泡中未观察到结晶体,叶绿体产生囊泡结构,部分病毒粒子处在叶绿体空泡中。田间寄主上受8-S1侵染的三生烟细胞质中分布着大量球形病毒粒子,叶绿体也产生含有病毒粒子的囊泡结构。表明含有卫星RNA和不含卫星RNA的CMV分离物引起的细胞病变特征存在差别,可能是CMV卫星RNA参与病理变化的依据之一。     

受番茄花叶病毒侵染后寄主的超微病变研究

电镜观察了番茄花叶病毒（ＴｏＭＶ）侵染不同寄主的细胞超微结构变化。在２５℃下ＴｏＭＶ侵染番茄（ＬｙｃｏｐｅｒｓｉｃｏｎｅｓｃｕｌｅｎｔｕｍＭｉｌｌ）后,病毒粒子在叶片的表皮,薄壁细胞,维管束组织的细胞质中形成大块结晶体和类结晶体,液泡膜处产生小泡结构,有多泡体和髓鞘样结构构伸入液泡中,在２５℃下ＴｏＭＶ侵染珊西烟（ｉｃｏｔｉａｎａｔａｌａｃｕｍＬ．ｃｖ．Ｘａｎｔｈｉｎｎ）后,除存在病毒结晶体和类结     

与蚕豆萎蔫病毒2号胞间运动和长距离转运相关的寄主细胞超微结构研究

电镜超微结构观察和免疫金标记显示:受蚕豆萎蔫病毒2号(Broad bean wilt virus 2,BBWV 2)中国分离物B935侵染的豌豆(Pisum sativum)和蚕豆(Vicia faba)叶细胞中膜结构增生,形成膜结构增生区,病毒以结晶体和管状体形式存在于细胞质中。在病变早期,叶肉细胞的胞间连丝处连接有小管结构,病毒样颗粒呈纵列排在小管中,穿越胞间连丝的小管能被BBWV 2的金标记抗体特异性标记。维管束组织的薄壁细胞、伴胞及转移细胞内存在膜增生区及病毒管状体,在筛管壁附近存在的病毒样颗粒能被BBWV 2金标记抗体特异性标记。实验结果表明BBWV 2胞间运动形式与豇豆花叶病毒(CPMV)相似,以完整粒子通过在胞间连丝处形成的小管结构穿越胞间连丝;细胞质中存在的直径160nm管状体只是一种病毒聚集体,与胞间运动无直接关系;该病毒在筛管中可能也是以完整粒子形式进行长距离转运的。     

侵染细胞质膜附近小泡的来源及其作用

箭舌豌豆根瘤幼龄侵染细胞的壁和质膜比较光滑,成熟侵染细胞与此不同,不仅细胞壁厚薄均,有较多的胞间连丝,而且质膜常常内陷形成各种突起,然后离质膜形成小泡。这些位于质膜附近的小泡体积较小,多呈圆形,既可单独存在,也可多个聚在一起。在向细胞中央移动中,有的小泡靠近细胞质膜,甚至与细菌周期融合,有的小泡不民附近的小液泡融合变为较大液泡,并常用降解程度不同的细菌位于其中,在衰老侵染细胞中,细胞壁附近有小泡,     

植物病毒在细胞间转运的机理探讨

植物病毒在寄主体内的移动包括细胞间转运和系统性转运两个部分。在这两个过程中,如何有效地利用和修饰胞间连丝,是病毒成功侵染的关键。病毒通过编码运动蛋白与寄主因子互作靶定于细胞质膜,然后通过一系列复杂机制修饰胞间连丝从而顺利完成细胞间转运。综述了植物病毒在细胞间转运过程中与寄主发生的一系列互作,着重阐述了病毒与胞间连丝之间互作的机制,旨在为相关研究工作提供参考。     

侵染香蕉的黄瓜花叶病毒株系的形态和生物学特征

对香蕉花叶病广东三个代表分离物的形态和生物学特征进行了较为全面的研究。在六种鉴别寄主上,斑驳类（ＭＭ）和断续条纹类（ＢＳ）分离物侵染较多的寄主种类诱导较为严重的症状,连续条纹类（ＣＳ）分离物侵染能力较弱。电镜观察表明：ＢＳ、ＣＳ和ＭＭ三个代表分离物的粒子呈球状、其粒子直径分别为２２．５、２４．３和２７ｎｍ,纯化的病毒粒子电泳相对迁移率分别为０．７２、０．５６和０．５１,在西葫芦上的增殖速度：不管在子叶或真叶,都是ＭＭ最快、ＢＳ次之、ＣＳ最慢。从西葫芦接种叶运转出接种叶的速度：ＭＭ和ＢＳ相似、ＣＳ明显较慢。在烟草上,三个分离物的运转速度和增殖速度以ＭＭ最快、ＢＳ次之、ＣＳ最慢;而且在烟草上随着接种后时间的延长,三个分离物除ＭＭ维持高浓度的时间较长外,ＢＳ和ＣＳ的都很短。在西葫芦和烟草上提纯产量,ＭＭ类最多、ＢＳ类次之、ＣＳ类最低。     

红豆草根瘤侵染细胞中液泡内含物的超微结构特征

用透射电镜研究了红豆草（Onobrychis viciifolia）根瘤侵染细胞中液泡内含物的超微结构特征。结果表明,早期发育侵染细胞的液泡中只含有少量的纤维状物质。随着细胞的发育,液泡不断变大,液泡中的纤维状物质和膜状物质越来越多。在中央液泡形成后,液泡中的纤维状物质逐渐减少,类细胞质、泡状和膜状物质明显增多,它们常由一层来自液泡膜的膜包围,其形状一般近似圆形或椭圆形。液泡内含物的大量出现可能与红豆草及其根瘤具有高度的抗旱件有关。     

葡萄扇叶病毒移动蛋白在寄主体内的动态检测和免疫金标记

利用葡萄扇叶病毒法国分离物F13(Grapenive fanleaf virus, GFLVF13)移动蛋白抗体对杭州分离物(GFLVH)移动蛋白进行Western blot,分析表明移动蛋白在接种GFLVH 3d后的苋色藜(Chenopodium amaranticolor)系统叶中就可检测到,随着时间推移,其积累量逐渐升高,接种16d后达到最高值。接种32d后的病叶已经枯黄,但移动蛋白积累量并没有减少。超薄切片电镜观察发现,在感染GFLVH的昆诺藜(C.quinoa)和苋色藜的叶肉组织薄壁细胞中,病毒粒子呈纵列整齐地排列在小管状结构中,在胞间连丝中也发现有管状结构。免疫金标记显示胶体金能定位在细胞质、细胞壁和胞间连丝上,在管状结构也发现有少量的金粒子。这些结果进一步说明了GFLV是通过管状结构实现细胞间移动的。     

抗病毒转基因植物

欧共体委员会(CEC)桥(Bridge)计划最近资助了一项题为植物病毒胞间移动与胞间连丝结构间关系的细胞生物学的项目。对在侵染周期中可使植物病毒进入健康细胞的病毒蛋白(细胞间移动蛋白)的研究对所涉及的病毒机制和正在探讨的植物结构都有所启发。在病毒侵染周期中细胞间移动蛋白由病毒基     

冬小麦(Triticum aetivum)进入寒冬过程中分蘗节细胞内酸性磷酸酶活性的超微结构定位

冬小麦分蘖节细胞内的酸性磷酸酶活性在麦苗秋季的活跃生长时期,主要定位于液泡膜内侧和液泡内含物周围,核内染色质上,以及细胞间隙周围的细胞壁表面和细胞间隙的内含物上,到寒冬时期,除保持以上各部位的活性外,突出的变化是在质膜上以及质膜和细胞壁分离的间隙内产生该酶的高活性。作者认为,这可能是对植物在寒冬中细胞内水流到细胞外结冰,避免细胞内结冰伤害的一种适应。图版说明图1—2,秋季生长时期(10月20日)的分蘖节细胞。酶活性主要定位于液泡膜上和液泡内含物的周围、染色质以及细胞间隙周围的细胞壁表面和细胞间隙的内含物上。图1,×11500。图2,×10400。V:液泡。Vm:液泡膜。CH:染色质。PL:质膜。N:核仁。Pd:胞间连丝。Is:细胞间隙。W:细胞壁。图3—4,寒冬中(12月9日)的分蘖节细胞。液泡内侧和液泡内含物表面表现酸性磷酸酶的高活性;特别是质膜和细胞壁之间也呈现大量的反应产物。图3,×14400。图4,×12200。图5,仲冬(1月10日)固定的材料。在质膜以及质膜和细胞壁分离的间隙内,突出地显示出酶的高活性反应。图5,×8900。     

Ultrastructural Alteration of Host Plants Infected with Tomato Mosaic Virus

The ultrastructural aheration of two host plants infected with tomato mosaic virus (ToMV) were studies with transmission electron microscopy. A large number of virus particles were found being accumulated in different cells such as epidermis, parenchyma cells and vascular bundle cells of Lycopersicon esculentum Mill. grown at 25℃ Crystalline inclusions and paracrystal inclusions composed of ToMV particles were observed in the cytoplasm or vacuoles. Some muhivesicular bodies and myeloid bodies protming into the vacuole and vires-specific vesicles associated with the tonoplast were also observed. The ultrastructuml alteration of Nicotiana tabacum L. tv. Xanthinn was similar to that in tomato infected by ToMV grown at 25 cE. In addition to the aggregate inclusions described above, some cytoplasmic angularly-layered aggregates and abnormal chloroplasts with small peripheral vesicles were observed in the parenchyma cells. The densely stained amorphous material was seen in the cytoplasm of N. tabacum L. cv. Xanthiun grown at 35℃. No X- body was observed in the cytoplasm of the ToMV infected tomato and tobacco grown at 25℃ or 35℃. The authors' results suggest a significant difference between the cytopathological effects of ToMV and tobacco mosaic virus (TMV). These characteristic difference may be useful in the virus diagnosis and identification virus infections in plants.     

A Novel Satellite RNA of Cucumber Mosaic Virus Induces Unique Line-pattern Mosaic Symptoms in Tobacco

The CMV(YW) isolate of cucumber mosaic virus (CMV) induced unique line‐pattern mosaic symptoms in systemically infected leaves of tobacco (Nicotiana tabacum cv. Ky57). By northern hybridization analysis using cDNA to CMV(Y) satellite RNA as a probe, it was confirmed that CMV(YW) contained a satellite RNA. which was designated sat‐YW RNA; this was 388 nucleotides in length and did not have either a conserved domain that induces necrosis in tomato or chlorosis in tobacco. CMV(YW) free of sat‐YW RNA. which was isolated by the single lesion isolation method using Chenopodium amaranticolor, did not induce the unique line‐pattern mosaic symptom. Furthermore, the sat‐YW RNA‐mediated line‐pattern mosaic symptom was also induced by in vitro transcribed infectious sat‐YW RNA in tobaccos infected with either CMV(YW) or CMV(Y) genomic RNA. These results clearly demonstrated that sat‐YW RNA induces the unique line‐pattern mosaic symptom on CMV‐infected tobaccos.     

用感染病毒细胞超微结构的差异区分RMV及TMV株系

通过透射电镜观察被长叶车前草花叶病毒(RMV)和烟草花叶病毒(TMV)不同株系感染的普通烟叶肉细胞的超微结构,发现两种病毒的粒子分布、内含体类型、被感染细胞超微结构的病变均存在差异.病毒粒子分布有成束、分散、环状、膜包被及角状成层或平行成层排列等类型,存在于细胞质及液泡中,但未见于细胞核、线粒体及叶绿体等细胞器中.内含体的X-小管形状有长杆状、短杆状及颗粒状,数量各异.细胞壁常引起增厚、结构松散及扭曲等变化.叶绿体聚集成堆或分布于细胞边缘,其数量、大小、形状及所含淀粉粒、嗜锇颗粒等存在差异,有些还有颗粒状物质积累.线粒体及内质网等在不同株系间也存在差异.本项研究表明,被感染细胞超微结构的差异可作为RMV和TMV株系区分的依据.     

Subcellular localization of the coat protein in tobacco cells infected by cucumber mosaic virus isolated from Catharanthus roseus

Electron microscopy and immunolabelling with antiserum specific to cucumber mosaic virus coat protein were used to examine tobacco leaf cells infected by cucumber mosaic virus isolated from Catharanthus roseus (CMV-Cr). Crystalline and amorphous inclusions in the vacuoles were the most obvious cytological modifications seen. Immunogold labelling indicated that the crystalline inclusion was made up of virus particles and amorphous inclusions contained coat protein. Rows of CMV-Cr particles were found between membranes of dictyosomes, but membranous bodies and tonoplast-associated vesicles were not evident. Virus particles and/or free coat protein were easily detected in the cytoplasm by immunolabelling. No gold labelling was found within nuclei, chloroplasts and mitochondria.     

Cucumber-mosaic-virus-associated RNA-5: XII. — Symptom-modulating effect is codetermined by the helper virus satellite replication support function

In tomato, the disease-modulating effects of a cucumber mosaic virus (CMV) satellite isolate from Belgium, here designated T-CARNA-5 (CARNA-5 = CMV-associated RNA-5), were found to be different depending on the supporting helper virus strain. With two CMV strains, T-CARNA-5 induced lethal necrosis, but with a third strain from Ixora spp. (CMV-Ix), aggravated stunting was observed. However, the primary structure of the T-CARNA-5 contained within virus isolated from tobacco or tomato infected with each of these three CMV strains, conformed to the conserved sequence profile of CARNA-5 isolates which are necrogenic in tomato. Dilution end-point bioassay of T-CARNA-5 established a direct cause-effect relationship between it and tomato necrosis or stunting, depending on the helper virus. Total nucleic acid extracts taken at different times from tomato plants infected with the above CMV strains and T- or S-CARNA-5 (used as non-necrogenic control) showed viral RNA, ssCARNA-5 and dsCARNA-5 to be present in significant amounts, but in sometimes dissimilar proportions depending on the combination; except in CMV-Ix/S-CARNA-5 infection where neither ss-nor dsCARNA-5 was found.The experiments established that CARNA-5 biological expression studies in CMV-infected tomato have to take into account the helper virus satellite replication support function, which may be a primary codeterminant of quantitative or qualitative differences in the symptom modulation observed.     

Cytopathology of satellite tobacco mosaic virus and its helper virus in tobacco

Ultrastructural responses of tobacco cells infected with a newly discovered satellite virus (STMV) that has an isometric morphology and is associated with rigid rodshaped tobacco mosaic virus (TMV) were studied in situ. In cells infected with TMV alone,TMV particles occurred as crystalline arrays in the cytoplasm and were usually associated with TMV-characteristic X bodies. In cells infected with both TMV and STMV, particles of STMV occurred only in cells that contained TMV particles, which suggests a correlation between the satellite and helper virus presence. However, the replication and/or accumulation sites of STMV appear to be independent from its helper virus. Unlike TMV particles, STMV particles were associated with several cytopathic structures such as granular inclusions, membranous vesicles of 50–80 nm, and myelin-like bodies which were all bounded by a single common membrane, No X bodies occurred in cells containing STMV particles, and the mitochondria possessed abnormal tubular structures containing flocculent material.     

Replication of cucumber mosaic virus satellite RNA in vitro by an RNA-dependent RNA polymerase from virus-infected tobacco.

An RNA-dependent RNA polymerase purified from tobacco infected with cucumber mosaic virus catalyzes the synthesis of (-) and (+) strands of the viral satellite RNA, CARNA 5, but fails to replicate the satellite RNA of peanut stunt virus (PSV). The enzyme replicates the genomic RNAs of the three principal cucumoviruses CMV, PSV and tomato aspermy virus (TAV) with varying efficiencies. The specificity with which CMV RdRp replicates different sequence-unrelated RNA templates suggests that the site of their recognition requires secondary or higher level structural organization.     

感染病毒的小麦全蚀菌的超微结构

将感染病毒的小麦全蚀菌山东烟台株培养 20天的菌体细胞,进行超微结构的研究。于电镜下观察到球状病毒颗粒,平均直径23—30nm,多是无规则松散的分布于胞质中;或紧密聚集于液泡、线粒体周围;或排列成线状;或7—8个颗粒排列成环状。病毒仅分布于细胞质中,细胞核、脂肪体内均未见病毒颗粒。病毒浓度在较老的菌体内有增加的趋势。全蚀菌的菌丝细胞壁有三层,外层电子致密内含纤维状物,内层电子较为透明,中层为一电子致密度很深的狭窄夹层。壁的厚度不均,外缘不规则;在菌丝体产生隔膜的早期阶段,于隔膜附近有1—3个外被膜结构的沃罗宁体 Woronin body,隔膜形成的后期,见电子致密物质沉积在核膜孔上,形成中的隔膜顶端为尖状突起向基部逐渐增宽略成金字塔形。     

十字花科蔬菜上黄瓜花叶病毒分离物的比较研究

对从杭州市郊青菜、萝卜、花椰菜上分离的6个CMV分离物进行了生物学、血清学及双链RNA比较研究。生物学测定结果表明,不同分离物在所测定的6种十字花科蔬菜上的致病力有差异。6种分离物颗粒形态、衣壳蛋白分子量和血清学方面无差异,且都属血清型Ⅰ。dsRNA分析结果表明,6个分离物的dsRNAl,2,3和4在PAGE中迁移率相似,但在1.5kb～0.4kb之间有多条量相对较少的条带,这些条带在不同分离物之间差异较大。6个分离物均含有卫星RNA。