我国十省(市)十字花科蔬菜芜菁花叶病毒(TuMV)株系分化研究 Ⅰ.用Green氏方法划分株系

Provvidenti,R.(1980)和Green,S.K.(1985)先后用同一套鉴别寄主谱,研究了美国和我国台湾省的TuMV株系分化情况。本文用Green的方法,对由十省(市)7,982份病样中筛选出的19个TuMV主流分离物,在同一条件下进行了鉴定。结果表明,属于C_1株系的有黑_3分离物;属于C_4株系的有京_2、京_3、冀_2、宁_1(南京)、粤_1和川_1共6个分离物;属于C_5株系的有黑_1、辽_1、京_1、冀_1、沪_1、鲁_1、鲁_2共7个分离物。未检出C_2和C_3株系。黑_2、沪_2、宁_2和秦_1(陕西)共4个性状相近的分离物和冀_3分离物尚不能按Green的标准归类,暂分别定为C_(3-2)和C_6株系。此外,对Green氏方法应用于我国十字花科蔬菜TuMV株系分化研究中存在的问题作了讨论。     

Mitogens and hepatocyte growth control in vivo and in vitro

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An env gene derived from a primary human immunodeficiency virus type 1 isolate confers high in vivo replicative capacity to a chimeric simian/human immunodeficiency virus in rhesus monkeys.

To explore the roles played by specific human immunodeficiency virus type 1 (HIV-1) genes in determining the in vivo replicative capacity of AIDS viruses, we have examined the replication kinetics and virus-specific immune responses in rhesus monkeys following infection with two chimeric simian/human immunodeficiency viruses (SHIVs). These viruses were composed of simian immunodeficiency virus SIVmac239 expressing HIV-1 env and the associated auxiliary HIV-1 genes tat, vpu, and rep. Virus replication was assessed during primary infection of rhesus monkeys by measuring plasma SIVmac p27 levels and by quantifying virus replication in lymph nodes using in situ hybridization. SHIV-HXBc2, which expresses the HIV-1 env of a T-cell-tropic, laboratory-adapted strain of HIV-1 (HXBc2), replicated well in rhesus monkey peripheral blood leukocytes (PBL) in vitro but replicated only to low levels when inoculated in rhesus monkeys. In contrast, SHIV-89.6 was constructed with the HIV-1 env gene of a T-cell- and macrophage-tropic clone of a patient isolate of HIV-1 (89.6). This virus replicated to a lower level in monkey PBL in vitro but replicated to a higher degree in monkeys during primary infection. Moreover, monkeys infected with SHIV-89.6 developed an inversion in the PBL CD4/CD8 ratio coincident with the clearance of primary viremia. The differences in the in vivo consequences of infection by these two SHIVs could not be explained by differences in the immune responses elicited by these viruses, since infected animals had comparable type-specific neutralizing antibody titers, proliferative responses to recombinant HIV-1 gp120, and virus-specific cytolytic effector T-cell responses. With the demonstration that a chimeric SHIV can replicate to high levels during primary infection in rhesus monkeys, this model can now be used to define genetic determinants of HIV-1 pathogenicity.     

Protease-induced infectivity of hepatitis B virus for a human hepatoblastoma cell line.

The human hepatoblastoma cell line HepG2 produces and secretes hepatitis B virus (HBV) after transfection of cloned HBV DNA. Intact virions do not infect these cells, although they attach to the surface of the HepG2 cell through binding sites in the pre-S1 domain. Entry of enveloped virions into the cell often requires proteolytic cleavage of a viral surface protein that is involved in fusion between the cell membrane and the viral envelope. Recently, we observed pre-S-independent, nonspecific binding between hepatitis B surface (HBs) particles and HepG2 cells after treatment of HBs antigen particles with V8 protease, which cleaves next to a putative fusion sequence. Chymotrypsin removed this fusion sequence and did not induce binding. In this study, we postulate that lack of a suitable fusion-activating protease was the reason why the HepG2 cells were not susceptible to HBV. To test this hypothesis, virions were partially purified from the plasma of HBV carriers and treated with either staphylococcal V8 or porcine chymotrypsin protease. Protease-digested virus lost reactivity with pre-S2-specific antibody but remained morphologically intact as determined by electron microscopy. After separation from the proteases, virions were incubated with HepG2 cells at pH 5.5. Cultures inoculated with either intact or chymotrypsin-digested virus did not contain detectable levels of intracellular HBV DNA at any time following infection. However, in cultures inoculated with V8-digested virions, HBV-specific products, including covalently closed circular DNA, viral RNA, and viral pre-S2 antigen, could be detected in a time-dependent manner following infection. Immunofluorescence analysis revealed that 10 to 30% of the infected HepG2 cells produced HBV antigen. Persistent secretion of virus by the infected HepG2 cells lasted at least 14 days and was maintained during several reseeding steps. The results show that V8-digested HBV can productively infect tissue cultures of HepG2 cells. It is suggested that proteolysis-dependent exposure of a fusion domain within the envelope protein of HBV is necessary during natural infection.     

Factors regulating baculovirus late and very late gene expression in transient-expression assays.

Eighteen genes of Autographa californica nuclear polyhedrosis virus are necessary and sufficient to transactivate expression from the late vp39 promoter in transient-expression assays in SF-21 cells. These 18 genes, known as late expression factor genes (lefs), are also required to transactivate the very late promoter of the polyhedrin gene, polh, but expression from this promoter is relatively weak compared with expression from the vp39 promoter. To further define the factors required for late and very late promoter expression, we first determined that the eighteen lefs were also required for expression from two other major baculovirus promoters: the late basic 6.9-kDa protein gene, p6.9, and the very late 10-kDa protein gene, p10. We next examined the effect of the very late expression factor 1 gene (vlf-1), a gene previously identified by analysis of a temperature-sensitive mutant, in the transient expression assay and found that vlf-1 specifically transactivated the two very late promoters but not the two late promoters. We then surveyed the Autographa californica nuclear polyhedrosis virus genome for additional genes which might specifically regulate very late gene expression; no additional vlf genes were detected, suggesting that VLF-1 is the primary regulator of very late gene expression. Finally, we found that the relative contribution of the antiapoptosis gene p35, which behaves as a lef in these transient-expression assays, depended on the nature of the other viral genes provided in the cotransfection mixtures, suggesting that other viral genes also contribute to the ability of the virus to block apoptosis.     

白背飞虱种群动态关联分析及预测模型的研究

根据灰色系统关联分析的基本原理,提出了白背飞虱种群动态的加权关联度预测法。衢县早稻后期白背飞虱发生量与历年6月25～30日平均百丛虫量X_1（t）、同期若虫比例X_2（t）、迟熟品种比例X_3（t）、6月下旬水分积分指数X_4（t）和平均气温X_5（t）等因素的关联序为：X_2（t）＞X_1（t）＞X_3（t）＞X_5（t）＞X_4（t）。据此建立的加权关联度预测模型,经12年资料回测和试报验证,结果令人满意。     

中国单头螨属一新种(蜱螨亚纲：叶螨科)

中国单头螨属一新种（蜱螨亚纲：叶螨科）谭瑞成,鲁素玲（湖南省林业科学研究所长沙４１０００４）（新疆石河子农学院新疆８３２００３）单头螨属ＡｐｌｏｎｏｂｉａＷＯｍｅｒｓｌｅｙ,１９４０前足体背毛３对,后半体背毛１０对,全部或部分背毛着生在明显结节Ｌ,背...     

龙胆属的系统发育分析

本文运用支序分类的原理和方法,对龙胆科龙胆属的属下等级进行了重新归类和系统发育分析。龙胆属是一个单系群,以3项近裔共性为归类依据。性状分析作了性状同源性分析和性状极性分析。性状极化主要以外类群比较、性状相关性及染色体资料为依据,其它方法,如生物重演律原则、地理递进原则以及孢粉形态等也被结合使用。分析结果,双蝴蝶属和蔓龙胆属被选择为外类群,71个性状被选择作为建立数据矩阵的基本资料。使用PAUP程序对矩阵进行了运算,得到4个最简约的谱系分支图,它们均具一致性系数0.637,支序长度为160步,f-比值范围为0.179～0.189,其中具最低f-比值的图被选作为类群归类和讨论亲缘关系的基础。在支序图上龙胆属归为15个组;其中5个组又划分为系,共包括23个系,其余组为单型组,故共有33个属下类群。一个严格的一致性谱系分支图总结了所有的一致点,从而支持了支序分析的结果。     

Inheritance of stomatal conductance in cotton (Gossypium barbadense)

Stomatal conductance in improved Pima cotton cultivars (Gossypium barbadense) has been previously shown to be positively associated with heat resistance and yield potential. In the present study we determined the mode of inheritance of stomatal conductance in crosses of six G. barbadense parents varying in origin, degree of agronomic development and stomatal conductance. Parents included a primitive tropical cotton (B368), two obsolete cultivars (St Vincent V135, Pima 32), one modern commercial line (Pima S-6) and two elite genotypes of the Pima germplasm (P70, P73). These lines showed distinct differences in stomatal conductance, under greenhouse and field conditions. The primitive B368 had the lowest conductance, and the elite lines the highest. Generation means analysis was used to quantify genetic effects in the crosses P70 × St Vincent V135, Pima S-6 × B368, Pima S-6 × Pima 32, P73 × Pima 32 and P73 × Pima S-6. Best-fit models of the inheritance of stomatal conductance varied in complexity from a simple additive-dominance model in the cross P70 × St. Vincent V135 to models displaying digenic epistatic interactions in the remaining crosses. Significant additive mean effects for stomatal conductance were detected in all crosses. Dominance mean effects were significant in the crosses P73 × Pima 32 and P73 × Pima S-6. Broadsense heritability estimates of stomatal conductance were relatively low (0.16–0.44) in all crosses except Pima S-6 × B368 (0.74). Results also show that the mode of inheritance of stomatal conductance is multigenic, and may have maternal as well as nuclear components. Recouping higher stomatal conductance levels from genetically wider crosses appears feasible and could proceed at a moderate rate. Fixing higher levels of stomatal conductance in populations from crosses of elite germplasm may be more difficult because of the presence of dominant mean effects and digenic epistatic interactions.