The pathogenicity on legumes of Cucumber mosaic virus was determined by 243 nucleotides on 2a polymerase gene of viral RNA2

We had isolated and identified two Cucumber mosaic virus (CMV) isolates, the CMV red bean (CMV-RB) isolate and the CMV pea (CMV-P1) isolate. CMV-RB induces necrotic local lesions on inoculated leaves of broad bean, pea, cowpea and bean, and could not infect these hosts systemically. However, CMV-P1 was able to infect these legumes systemically. To study the difference of pathogenicity on the legumes induced by these two CMV isolates, the full-length infectious cDNA clones of CMV-Fny, which induced similar symptoms as CMV-RB in the four legumes, were used. The 243 nucleotides fragment, which encodes highly conserved GDD amino acid motif on 2a replicase gene of CMV-Fny RNA2, was replaced with that of CMV-P1. The constructed chimeric virus FP could infect these legumes systemically. The exchange of this region changes the virus symptoms on the legumes, indicating that this 243 nucleotides fragment has major effect on pathogenicity of CMV on the legumes.     

Coat protein gene and 3′ non-coding region of tobacco mosaic virus and tomato mosaic virus are associated with viral pathogenesis in Nicotiana tabacum

The camellia isolate of tomato mosaic virus (ToMV-TL) can induce local necrotic lesions on the inoculated leaves in Nicotiana tabacum, whereas the broad bean isolate of tobacco mosaic virus (TMV-B) produces the mosaic symptom on systemic leaves. To examine viral determinant for differential infection phenotype in N. tabacum, the coat protein gene and the 3′ non-coding region of TMV was replaced with that of ToMV, the chimeric virus induced similar local necrotic lesions to that induced by ToMV. The results indicate that the coat protein gene and the 3′ non-coding region of TMV and ToMV influence the virus-induced pathogenesis in N. tabacum.     

Generation of transgenic wheat resistant to wheat yellow mosaic virus and identification of gene silence induced by virus infection

The plasmid containing the promoter Act1, the coat protein (cp) gene of wheat yellow mosaic virus (WYMV) and the selectable bar gene, was delivered via particle bombardment, directly into immature embryos of a wheat cultivars. PCR and PCR-RFLP were employed to screen the existence of the cp gene in T0 and T1 generations. Seeds from the positive T1 plants were sowed in fields heavily contaminated with WYMV to detect their resistance. In field trial of virus infection, one of the transgenic wheat lines, P8-T2, exhibited highly disease-resistance. Western blot and RT-PCR analysis showed that the expression level of cp gene in the resistant transgenic line was reduced greatly compared to those susceptible to WYMV infection. This provided evidence to presume that the resistance obtained by the transgenic wheat line was stimulated by the mechanism of the virus induced gene silencing.     

苜蓿花叶病毒复制酶基因全长cDNA植物表达载体的构建

将苜蓿花叶病毒中国分离株（Alfalfa mosaic virus Chinese isolate，AlMV-Ch）的复制酶P2亚基（90KD蛋白）基因的全长cDNA构建到植物表达载体pROK Ⅱ中，得到重组植物表达载体pAlMV-FL．     

六安地区高粱花叶病毒P3基因的克隆和序列测定

从六安产甘蔗病叶中提取总RNA,逆转录获得甘蔗花叶病毒(Sorghun mosaic virus,SrMV)基因组cDNA。设计P3基因特异引物,通过PCR扩增P3基因,并将P3基因cDNA克隆、测序。     

Cloning and expression of the Chinese wheat mosaic virus RNA2 coat protein readthrough and 19 ku cysteinerich domains and localization of these proteins

The 5′-terminal (RTn) and 3′-terminal (RTc) halves of the coat protein readthrough domain and the 19 ku cysteine-rich protein of Chinese wheat mosaic virus (CWMV) were amplified by RT-PCR, cloned and expressed in E. coli. Antisera and monoclonal antibodies against these proteins were prepared by immunising these purified proteins to mice. Detection of RTn, RTc and 19 ku proteins in CWMV infected wheat sap and leaf tissue indicated that the RTn and RTc proteins were distributed on the surface of virus particles whereas the 19 ku protein was in the cytoplasm of the infected wheat cells.     

Increased viral pathogenicity after insertion of a 28S ribosomal RNA sequence into the haemagglutinin gene of an influenza virus

The haemagglutinin glycoprotein HA of influenza viruses is responsible for the attachment of the virus to neuraminic acid-containing receptors at the cell surface and subsequent penetration by triggering fusion of the viral envelope with cellular membranes. To express full activity of the newly synthesized precursor, HA has to be modified by post-translational proteolytic cleavage into the polypeptides HA1 and HA2 by cellular enzymes. If proteases suitable for cleavage are not present in the host cell, the resulting virus particles are non-infectious. During adaptation of the apathogenic influenza virus A/turkey/Oregon/71 to chicken embryo cells, which are not permissive for HA cleavage, we obtained an infectious virus variant with increased pathogenicity. Sequence analysis revealed that during adaptation 54 nucleotides were inserted into the HA gene; their sequence corresponds to a region of the 28S ribosomal RNA. This insertion is probably responsible for increased cleavability of HA, as well as for infectivity and pathogenicity of the adapted virus.     

Establishment of a coupled expression system mediated by modified T7 RNA polymerase gene

A coupled expression system for plants wasmerase gene was modified by addition of the coding sequenceof nuclear location signal from SV40 large T antigen. Plantexpression vector pBBT7 was constructed with the modifiedT7 RNA polymerase gene under the control of CaMV35Spromoter. Another expression vector pBTG contained cas-sette of gusA controlled by T7 promoter. The two vectorswere co-transformed into tobacco via the Agrobecte-rium-mediated method. Results of GUS activity indicatedthat the co-transformed plant with pBBT7 and pBTGshowed a high level of GUS activity. The results demon-strated that the coupled expression system of T7 polymeraseand T7 promoter was workable in plants.     

Nucleotide sequence of RNA2 and polyprotein processing sites of a Chinese isolate of broad bean wilt virus 2

RNA2 of broad bean wilt virus 2 (BBWV2) isolate B935 is composed of 3601 nucleotide (nt) residues, exclusive of the polyadenylate at the 3' end. Only one of the six possible reading frames has a long open reading frame, which extends from nt 231 to nt 3428 in the polarity of encapsidated RNA, and encodes a polyprotein of 119 kD. The N-terminus of the large coat protein (LCP) is located at 599 nt and the small coat protein (SCP) at 197 nl from the C-terminus of the 119 kD protein, which suggests that the coat proteins are released from the polyprotein by cleavages of a glulamine-glycine (Q-G) and a glutamine-alanine (Q-A) bond respectively. The sequence comparison of B935 with fabaviruses shows that B935 has very high sequence homology with other BBWV2 isolates and with patchoul' mild mosaic virus, but has lower homology with BBWV1 isolates. B935 has a similar genomic organization, but a low sequence homology to RNA2 molecules of comoviruses and nepoviruses.     

Modification of a viral satellite DNA-based gene silencing vector and its application to leaf or flower color change in Petunia hybrida

Gene silencing conserved in plants and animals is mediated by mechanisms that involve sequence- specific RNA degradation[1,2]. Gene silencing has been proven to play an important role in the study of gene function. Recently, a procedure known as virus ind…     

Effects of metal ions and heat shock on the expression of a metallothionein-like gene htMT2 in Helianthus tuberosus

The expression of htMT2 in tissues of Helianthus tuberosus treated with metal ions and heat shock is studied by Northern blot hybridization. The results indicate that htMT2 is not expressed in roots. The expression in leaves and stems can be reduced by Cu2+ and induced by low concentration of Zn2+. However, the expression of htMT2 can be suppressed by Zn2+ when its concentrations are above 500 μmol/L. The effects of Ca2+ on the expression of htMT2 in leaves are similar to that of Zn2+. But Ca2+ induces the expression of htMT2 in stems. The expression levels of htMT2 in various tissues are not significantly affected by heat shock. The results above demonstrate that the expression of htMT2 can be regulated by metal ions and confirm that htMT2 is a new metallothionein-like gene.     

三江黄牛Bola-DRB3基因第二外显子的PCR-RFLP多态性研究

用PCR-RFLP方法,对三江黄牛和黑白花奶牛的MHCⅡ类基因座位Bola-DRB3基因第2外显子的遗传样性进行了研究.结果表明:①三江黄牛HaeIII酶切出现3种基因型,即SS、RS、RR,由S和R两个基因控制,RR为优势基因型,R为优势基因;RsaI酶切出现4种基因型,即XX、XM、LM、MM,由X、M和L三个复等位基因控制,LM为优势基因型,M为优势基因;两种内切酶在三江黄牛Bola-DRB3基因的第二个外显子上有150、202、65、180等酶切位点,且4个位点的碱基存在多态性,表现为多碱基突变;经χ2适合性检验,HaeIII和RsaI酶切位点的χ2值分别为7.0802、14.1358,差异显著(p<0.05),说明三江黄牛Bola-DRB3基因第2外显子的4个酶切位点的碱基突变未达到Hardy-Weinberg平衡状态,存在选择、基因突变、近交、遗传漂变等因素的影响.②黑白花奶牛HaeIII酶切出现4种基因型,即JJ、KI、IJ、KJ,由J、K和I三个复等位基因控制,JJ为优势基因型,J为优势基因;RsaI酶切出现3种基因型,即LL、MM、LM,由L和M两个基因控制,LM为优势基因型,M为优势基因;HaeIII和RsaI两种内切酶在黑白花奶牛中也有多个酶切位点,在150、48、65、202位上有碱基多态性,表现为多碱基突变;经χ2适合性检验,RsaI酶切位点的χ2值为3.456,差异不显著(p>0.05),处于Hardy-Weinberg平衡状态;HaeIII酶切位点的χ2值为18.4211,差异显著(p<0.05),未达到Hardy-Weinberg平衡状态.③用两种酶在三江黄牛中共检测到7种基因型,且与黑白花奶牛在酶切位点上具有较多的差异,说明三江黄牛具有丰富的遗传多样性;这一结果与张成忠、赖松家等从血液蛋白、染色体、mtDNA等水平上的研究结果一致,也同三江黄牛的育成历史和所处生态条件一致.综上所述,三江黄牛具有丰富的遗传多样性,今后应加强对三江黄牛遗传多态性以及起源、演化和分类的研究,为这一畜种资源的进一步开发利用和保护提供理论基础.     

VIGS技术初步鉴定RgMLO6和RlMLO7基因对白粉病的负调控功能

为了探讨蔷薇科植物MLO基因在抗白粉病中的作用,研究应用病毒诱导的基因沉默技术(virus induced gene silencing,VIGS)抑制了大花香水月季RgMLO6基因和长尖叶蔷薇RlMLO7基因的表达,随后接种白粉菌对这2个基因进行抗性鉴定. 研究发现在VIGS载体转化植株叶片20 d后,RgMLO6和RlMLO7基因的相对表达量显著下降了80%～90%,沉默效果明显. 分别对2个基因沉默后的嫩叶进行白粉病抗性鉴定,大花香水月季和长尖叶蔷薇的抗性水平较对照组均提高. 显微镜观察白粉菌接种2个基因沉默后植株叶片中菌丝体的生长情况,整体表现出沉默植株叶表皮细胞上的白粉菌生长较对照组生长缓慢. 结果表明RgMLO6与RlMLO7基因对蔷薇科植物的白粉病有负向调控作用.     

The study on the immune response induced by expressing recombinant plasmid of dengue virus type 2 NS3 protein

The PSV·NS3, an expressing recombinant plasmid of dengue virus type 2 NS3 protein, was injected directly into the quadriceps of Balb/C mice to explore whether it could inducing immune response. The splenic T cell subsets of two groups was analysed by flow cytometry. It was found that the percentage of CD4⁺ and CD8⁺ T cells of experimental group were significantly higher than those of the control group. The titer of IgG antibody was as high as 1∶5 120 in experimental group, but it couldn’t be detected in control group by ELISA. The western blot further proved that the IgG antibody was specific for NS3 protein. Those results Suggested that inoculation Balb/C mice with PSV·NS3 could inducing immune response, and the NS3 protein might be used as the candidate protein of DNA vaccine of dengue virus. Foundation item: Supported by Foundation of American Chinese Medicine Biography, LI Xiang-qun(1963−), male, M.D, Research direction: molecular and clinical virology.     

首例t（8;20）易位的M2—ANLL白血病重组位点的初步研究

对临床上确认为Ｍ２－ＡＮＬＬ的病例，首先进行骨髓细胞染色体的核型分析，经Ｇ显带和Ｒ显色确定为ｔ（８；２０）（ｑ２２；ｐ２３）易位，是一种新的变异型，为进行分子生物学研究，分别设计引物，反转录扩增检测ＥＴＯ基因ｃＤＮＡ ３‘０端顺序和ＥＴＯ融合转录物检测为阴性，从分子水平上排除了经典的ｔ（８，２１）易位的可能性。说明了该病例为ｔ（８；２０）易位，ＥＴＯ基因受累的新变异型白血病。     

CTAB对血红蛋白仿过氧化物酶催化活性的影响

本文研究了表面活性剂介质存在下,血红蛋白作为过氧化物模拟酶,以邻苯二酚供氢体底物的催化特性和反应条件,并探讨了表面活性剂对酶催化反应的影响及可能机理,稳态速率法测定了米氏常数（Km）、米氏速率（Vm）及反应级数等动力学参数。试验表明本体系在阳离子表面活性剂CTAB存在和pH10.3的条件下形成的产物在258nm处有最大的吸收峰。     

板钛矿和锐钛矿TiO2对水热合成Bi4Ti3O12微结构的影响

分别以板钛矿和锐钛矿型的TiO2为先驱物水热合成钛酸铋亚微米棒.由X射线衍射、选区电子衍射以及Raman光谱的测量结果可知,合成的产品为Bi4Ti3O12. 源自板钛矿和锐钛矿的Bi4Ti3O12,其结构表现出明显的差异.在同样的条件下,Bi插入锐钛矿TiO2的量多于其插入板钛矿TiO2的量,从而导致部分X射线衍射峰向高角度方向稍微移动.保留下来的短Ti-O键限制了b-Bi4Ti3O12亚微米棒沿[010]方向生长,使得b-Bi4Ti3O12亚微米棒长度不均.