侵染香蕉的黄瓜花叶病毒株系的血清学特征

香蕉花叶病三类不同症状,即断续条纹类（BS）、连续条纹类（CS）和斑驳类（MM）在田间广泛存在,经过血清学、生物学、核酸斑点杂交和反转录聚合酶链反应,已确定它们都由黄瓜花叶病毒（Cucumberm。。i。virus,CMV）所弓愧f’］。这三类症状分离物在鉴别寄主、粒子形态、粒子电泳相对迁移率以及在西葫芦（CI;curbitafor）和烟草（Nicotianatabacumcv．HV38）上增殖和运转动力学的特征也表现不同［’］。这些不同可能揭示了香蕉三类分离物分属不同的株系。血清学是鉴定和研究CMV株系间亲缘关系的重要依据。大量文献【’,‘1报道…     

决明组织培养的研究

以草决明无菌苗子叶为外植体,接种于７类诱导愈伤组织的培养基上：Ａ．ＭＳ＋２．０２,４－Ｄｍｇ／Ｌ（以下单位省略）＋０．３ＢＡ＋０．２ＮＡＡ．Ｂ．ＭＳ＋０．２２,４－Ｄ十０．２ＢＡ＋２．０ＮＡＡ．Ｃ．ＭＳ＋１．０２,４－Ｄ＋０．５ＢＡ＋０．２ＫＴ．Ｄ．ＭＳ＋０．７ＢＡ＋１．５ＮＡＡ＋０．１ＫＴ．Ｅ．ＭＳ＋１．５２,４－Ｄ＋０．７ＢＡ十０．２ＭＡＡ．Ｆ．ＭＳ＋０．４２．４－Ｄ＋１．０ＮＡＡ＋０．１ＫＴ．Ｇ．ＭＳＢ（ＭＳ的无机成份和Ｂ５有机成分）＋０．１５ＮＡＡ＋ＢＡ,ＫＴ和ＺＴ各０．５。８～１５天后分别有９０～９９．６％的子叶片被诱导出愈伤组织,并且Ｆ．与Ｃ．类培养基对诱导愈伤组织比较理想,放于Ｇ培养基上的愈伤组织有９．２～３０．２％的芽分化率。芽在生根培养基１／２ＭＳ＋０．２ＩＢＡ中、９８％生根,形成完整的再生植株。     

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。来自一患红（Ｓａｌｖｉａｓｐｌｅｎｄｅｎｓ）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果,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。     

中国南瓜曲叶双生病毒的生物学,血清学和分子杂交的研究

从广西南宁市的南瓜上分离到一株可经烟粉虱（Ｂｅｍｉｓｉａｔａｂａｃｉ）传播的南瓜曲病毒,它可侵染南瓜（Ｃｕｃｕｒｂｉｔａｍｏｓｃｈａｔａ）和西葫芦（Ｃ．ｐｅｐｏ）引致叶片卷曲和严重矮化的症状。ＥＬＩＳＡ测定表明,其病叶粗提液与非洲木薯花叶病毒（ＡＣＭＶ－Ｋ）单克隆抗体ＳＣＲ１８呈强阳性反应,与ＳＣＲ１１呈较弱的阳性反应,而与ＳＣＲ２３呈阴性反应;与印度木薯花叶病毒（ＩＣＭＶ）单克隆抗体ＳＣＲ５６和ＳＣＲ６６呈强阳性巨应,与ＳＣＲ６２呈弱阳性反应,但与ＳＣＲ５２呈阴性反应。分子杂交试验进一步证实中国南瓜曲叶病的病原是南瓜曲叶双生病毒。     

藏红花愈伤组织诱导及其细胞培养的研究

藏红花幼叶愈伤组织的诱导频率在ＭＳ,Ｂ５和Ｗｈｉｔｅ三种培养基上均高达９８％;幼叶和芽的诱导率差异不大,高达９９％;不同时期的叶片差异较大,以幼叶诱导为佳;球茎诱导率为近８０％;激素配比以２．４－Ｄ２．０ｍｇ／Ｌ,ＢＡＰ０．１～０．５ｍｌ／Ｌ为宜。在继代培养阶段,ＭＳ比Ｂ５和Ｗｈｉｔｅ更适合细胞的快速生长繁殖;并且以叶片的愈伤组织生长较快,芽次之,球茎最慢,适合于细胞生长的激素配比为ＮＡＡ２．０～３．０ｍｇ／Ｌ,ＢＡＰ０．５～１．０ｍｇ／Ｌ为宜。     

栝楼的快速繁殖及愈伤组织的诱导

本文对栝楼的快速繁殖及愈伤组织的诱导进行了初步研究。结果表明：含腋芽的栝楼外植体在ＭＳ＋６－ＢＡ１．０＋ＮＡＡ０．２上可以快速繁殖;茎切段、叶片切块及子叶切块在ＭＳ＋２,４－Ｄ１．０＋６－ＢＡ０．５上能够形成愈伤组织但以茎段形成愈伤组织的速度最快,质量最好;愈伤组织在ＭＳ＋６－ＢＡ１．０＋ＮＡＡＯ．１上分化成芽。     

侵染新疆甜菜的两种病毒分离物的研究

在新疆甜菜的根部和叶片分离到两个球状病毒分离物。从病毒形态、生物学及物化性质等研究结果证明这两个分离物实是一种病毒。病毒粒体力２０面体,直径约２８ｎｍ,回接到甜菜上产生环斑和沿脉线纹最后形成坏死斑。此外还侵染苋色藜,昆诺阿黎,番杏,菠菜等,引起局部坏死斑。在普通烟,心叶烟,菜豆,黄瓜,蕃茄上无症状侵染,病毒致死温度为７０℃,１０分钟。体外存括期１３天以上,冻干病叶７年后仍有侵染力。通过ＰＥＧ沉淀、差速离心、琼脂糖柱层析及蔗糖梯度离心,可得到较高浓度的纯化病毒,病毒的紫外吸收最低值在２４５ｎｍ,最高值在２６０ｎｍ。经ＳＤＳ－ＰＡＧＥ测定,病毒外壳蛋白的分子量为２．７×１０￣４道尔顿,病毒基因组核酸为三个组份,分子量分别为３．０８ｋｂ,１．２８ｋｂ和０．８５ｋｂ。在琼脂双扩散实验中,能与番茄黑环病毒（ＴＢＲＶ）抗血清产生较弱的沉淀线,与黄瓜花叶病毒（ＣＷＶ）、烟草环斑病毒（ＴＲＳＶ）、烟草坏死病毒（ＴＮＶ）、香石竹环斑病毒（ＣａＲＳＶ）的抗血清不发生反应。     

转基因烟草中Bt毒蛋白基因的表达行为

构建了高效植物表达载体ｐＢｉｎＭｏＢｃ,该载体携带超强表达复合启动子ＯＭ及Ω因子控制下的ＣｒｙＩＡ（ｃ）基因。采用根癌土壤杆菌（Ａｇｒｏｂａｃｔｅｒｕｍ ｔｕｍｅｆａｃｉｅｎｓ（Ｓｍｉｔｈ ｅｔ Ｔｏｗｎｓｅｎｄ）Ｃｏｎｎ）介导的方法转化烟草（Ｎｉｃｏｔｉａｎａ ｔａｂａｃｕｍ Ｌ．）,ＥＬＩＳＡ检测表明,大多数转基因烟草中ＣｒｙＩＡ（ｃ）基因表达量均超过０．１％,最高可达０．２５５％;转基因烟草     

pCMBS对完整红细胞膜阴离子通透性的影响

根据等渗ＮＨ４Ｃｌ溶血动力学,探讨了ｐＣＭＢＳ（对氯汞苯磺酸）对完整红细胞膜阴离子通透性的影响．０．０５ｍｍｏｌ／ＬｐＣＭＢＳ使阴离子通透系数Ｐｃｌ下降为对照的８６．５％;１．０ｍｍｏｌ／Ｌ以上浓度时Ｐｃｌ值反而变大。ｐＣＭＢＳ浓度高于０．３ｍｍｏｌ／Ｌ时,细胞悬浮液在１０ｓ之前光密度下降过快,偏离理论拟合方程且不受ＤＩＤＳ抑制．半胱氨酸对ｐＣＭＢＳ引起的效应有恢复作用。结果表明ｐＣＭＢＳ和股骨架蛋白上特殊－ＳＨ基相互作用,导致ｂａｎｄ３构象改变,致使改变膜时阴离子的通透性。     

豆科植物上分离的黄瓜花叶病毒（CMV）五个分离物的比较研究

从豌豆、扁豆、菜豆和赤豆分离到五个ＣＭＶ分离物,除寄主反应及核酸组分外,５个分离物在体外抗性、蚜虫传毒、提纯病毒粒体形态和稳定性、衣壳蛋白分子过和病毒粒体迁移率等方面无明显差异．在琼脂糖双扩散试验中五个分离物与ＣＭＶ抗血清形成的沉淀线相互融合,在Ａ蛋白双抗体夹心ＥＬＢＡ测定中,也无明显差异。根据在四种豆科植物上的症状反应,五个分离物可归为两个型：Ⅰ型在豌豆、蚕豆、菜豆和豇豆上产生局部枯斑症状;Ⅱ型在这四种植物上产生系统症状。五个分离物中,ＣＭＶＰ＿２含有五个枝酸组分,其它分离物为四个组分,即ＣＭＶＰ＿２可能含有卫星ＲＮＡ．     

应用PCR-SSCP技术快速检测我国水稻条纹病毒的分子变异

应用PCR SSCP技术快速检测我国水稻条纹病毒病害特异性蛋白 (SP)基因和外壳蛋白 (CP)基因的分子变异。结果发现我国水稻条纹病毒 7个分离物之间存在广泛的变异 ,其中 ,PJ分离物的SP基因和JD分离物的CP基因不能扩增出来 ,能扩增出的 6个分离物的CP基因变性电泳后带型各不相同 ,但SP基固表现出 5种带型 ,其中云南省的YL和BS分离物带型一样。     

应用PCR-SSCP技术快速检测我国水稻条纹病毒的分子变异

应用PCR-SSCP技术快速检测我国水稻条纹病毒病害特异性蛋白(SP)基因和外壳蛋白(CP)基因的分子变异。结果发现我国水稻条纹病毒7个分离物之间存在广泛的变异,其中,PJ分离物的SP基因和JD分离物的CP基因不能扩增出来,能扩增出的6个分离物的CP基因变性电泳后带型各不相同,但SP基固表现出5种带型,其中云南省的YL和BS分离物带型一样。     

侵染香蕉的黄瓜花叶病毒分离物衣壳蛋白的肽链分析

香蕉花叶病为华南香蕉生产的重要限制因素之一［‘1。特别是随着组培苗应用面积的扩大,发生越来越严重,一般地块发病率为20—40％,个别重病地块高达90％,损失严重。此病病原虽在1930年【’1就被鉴定为黄瓜花叶病毒（Cucumbermosaicvirus,CMV）,但至今对其研究不多。从有限的文献看,大多数作者【’·’嘟认为其病原为CMV的一个株系,即香蕉株系。但也有认为为二个株系［‘］、或三个株系的［’］。因此有关病原的调查鉴定就成为当前迫切需要解决的一个重要问题。1991～1993年我｛I’J在广东省广州市天河和黄埔区,以及顺德、番禹…     

脱氮除硫菌株的分离鉴定和功能确认

从长期稳定运行的脱氮除硫反应器污泥中,分离获得两株具有脱氮除硫功能的芽孢杆菌。经形态观察、生理试验和16SrDNA序列比对,将两菌株归入芽孢杆菌属,菌株CB归类于Bacillus pseudofirmus,菌株CS则与Bacillus hemicellulosilytus和Bacillus halodurans最为接近。以Biolog板检测,菌株CB的基质多样性不明显,菌株CS则可利用Biolog板中多种碳源。菌株CB和菌株CS都能以硝酸盐氧化硫化物,其中菌株CB对硝酸盐、硫化物的转化能力大于CS,菌株CB对硝酸盐的亲和力也大于菌株CS。     

URP‐based DNA Fingerprinting of Bipolaris sorokiniana Isolates Causing Spot Blotch of Wheat

Spot blotch, caused by the pathogen Bipolaris sorokiniana is an important disease of wheat and is responsible for large economic losses world wide. In this study, molecular variability in B. sorokiniana isolates collected from different regions of India was investigated using URP‐PCR technique. All the 40 isolates used in the study were pathogenic when tested on susceptible host, Agra local, although they varied in pathogenicity. Isolate BS‐49 was least virulent showing 4.5 infection index while BS‐75 was the most virulent with 63.4 infection index. The universal rice primers (URPs’) are primers which have been derived from DNA repeat sequences in the rice genome. Out of the 12 URP markers used in the study, 10 markers were effective in producing polymorphic fingerprint patterns from DNA of B. sorokiniana isolates. The analysis of entire fingerprint profile using unweighted pair group method with arithmetic averages (UPGMA) differentiated B. sorokiniana isolates obtained from different geographic regions. One isolate BS‐53 from northern hill zone was different from rest of the isolates showing less than 50% similarity. Broadly, three major clusters were obtained using UPGMA method. One cluster consisted of isolates from North western plain zone; second cluster having isolates from North eastern plain zone and third cluster consisted of isolates from Peninsular zone showing more than 75% genetic similarity among them. One of the markers, URP‐2F (5′GTGTGCGATCAGTTGCTGGG3′) amplified three monomorphic bands of 0.60, 0.80 and 0.90 kb size which could be used as specific markers for identification of B. sorokiniana. Further, based on URP‐PCR analysis, the grouping of the isolates according to the geographic origin was possible. This analysis also provided important information on the degree of genetic variability and relationship between the isolates of B. sorokiniana.     

Stability of the Encoding Plasmids and Surface Expression of CS6 Differs in Enterotoxigenic Escherichia coli (ETEC) Encoding Different Heat-Stable (ST) Enterotoxins (STh and STp)

Enterotoxigenic Escherichia coli (ETEC), one of the most common reasons of diarrhea among infants and children in developing countries, causes disease by expression of either or both of the enterotoxins heat-labile (LT) and heat-stable (ST; divided into human-type [STh] and porcine-type [STp] variants), and colonization factors (CFs) among which CS6 is one of the most prevalent ETEC CFs. In this study we show that ETEC isolates expressing CS6+STh have higher copy numbers of the cssABCD operon encoding CS6 than those expressing CS6+STp. Long term cultivation of up to ten over-night passages of ETEC isolates harboring CS6+STh (n = 10) or CS6+STp (n = 15) showed instability of phenotypic expression of CS6 in a majority of the CS6+STp isolates, whereas most of the CS6+STh isolates retained CS6 expression. The observed instability was a correlated with loss of genes cssA and cssD as examined by PCR. Mobilization of the CS6 plasmid from an unstable CS6+STp isolate into a laboratory E. coli strain resulted in loss of the plasmid after a single over-night passage whereas the plasmid from an CS6+STh strain was retained in the laboratory strain during 10 passages. A sequence comparison between the CS6 plasmids from a stable and an unstable ETEC isolate revealed that genes necessary for plasmid stabilization, for example pemI, pemK, stbA, stbB and parM, were not present in the unstable ETEC isolate. Our results indicate that stable retention of CS6 may in part be affected by the stability of the plasmid on which both CS6 and STp or STh are located.     

Prevalence of CS31A and F165 surface antigens in Escherichia coli isolates from animals in France, Canada and India

Bovine and porcine enterotoxigenic and non-enterotoxigenic Escherichia coli isolates from France, Canada, and India were characterized with respect to serogroup and production of fimbrial antigens CS31A and F165. Of 231 bovine isolates from the 3 countries, 20.5% produced CS31A alone, 17.7% produced F165 alone, and 17.3% produced both CS31A and F165. On the other hand, of 84 porcine isolates from Canada, 1.2% produced CS31A alone, 14.3% produced F165 alone, and no isolate produced both CS31A and F165. CS31A was found together with F5 (K99) in 7 of 16 bovine enterotoxigenic E. coli isolates of serogroups 08, 09, 020, and 023, but was not found in any of 20 F4 (K88)- or 5 F6 (987P)-positive porcine enterotoxigenic E. coli isolates. F165 was not found in enterotoxigenic E. coli. Among non-enterotoxigenic isolates, CS31A and F165 were mainly associated with serogroups 08, 09, 011, 015, 017, 023, 025, 078, 0101, 0115, 0117, 0141, and 0153.     

Isolation and characterization of cold-adapted strains producing beta-galactosidase

beta-Galactosidase is extensively employed in the manufacture of dairy products, including lactose-reduced milk. Here, we have isolated two gram-negative and rod-shaped coldadapted bacteria, BS 1 and HS 39. These strains were able to break down lactose at low temperatures. Although two isolates were found to grow well at 10 degrees , the BS 1 strain was unable to grow at 37 degrees . Another strain, HS-39, evidenced retarded growth at 37 degrees . The biochemical characteristics and the results of 16S rDNA sequencing identified the BS 1 isolate as Rahnella aquatilis, and showed that the HS 39 strain belonged to genus Buttiauxella. Whereas the R. aquatilis BS 1 strain generated maximal quantities of beta-galactosidase when incubated for 60 h at 10 degrees , Buttiauxella sp. HS-39 generated beta-galactosidase earlier, and at slightly lower levels, than R. aquatilis BS 1. The optimum temperature for beta-galactosidase was 30 degrees for R. aquatilis BS-1, and was 45 degrees for Buttiauxella sp. HS-39, thereby indicating that R. aquatilis BS-1 was able to generate a cold-adaptive enzyme. These two cold-adapted strains, and most notably the beta-galactosidase from each isolate, might prove useful in some biotechnological applications.