改变乙型肝炎病毒核心抗原基因3′端序列对其在原核细胞中表达的影响

乙型肝炎病毒(HBV)的核心抗原基因(C基因)编码185个氨基酸残基,在原核细胞或痘苗病毒系统中能表达并装配成27nm大小的核心抗原(HBcAg)多聚体颗粒。已证实HBV C基因3′端编码近40个氨基酸的碱基序列,不是表达形成HBcAg颗粒所必需的。用外源基因替换这部分序列,已表达出表面带有外源基因产物的杂合颗粒,它具有很好的免疫原性,成为新型的基因工程多决定簇颗粒载体疫苗。但我们的实验中发现,用另外的外源基因替换3′端序列能显著影响HBV C基因在大肠杆菌中的表达,不同组成的外源基因其影响程度有所不同。     

Duplications of the X chromosome in males: evidence that most parts of the X chromosome can be active in two copies

Summary We have analysed two duplications of the X chromosome in male patients using chromosome replication and DNA methylation patterns as determinants of the functional status of the duplicated segments. In both cases, the large duplicated regions, Xq12-q22 and Xq26.3-qter, were not inactivated. A review of previously reported male cases revealed that these duplications were also not subject to inactivation. Taken together, the examined duplications cover almost the entire X chromosome except the pericentromeric region and Xq25–26. Thus, most regions of the X chromosome can be present in two functional copies without lethal consequences.     

一种新病毒——兔出血症病毒的鉴定初报

从我国新发生的一种家兔急性败血性传染病死兔内脏抽提物中,观察到典型的病毒粒子,回归兔可引起典型发病,再从病死兔内脏回收到同样病毒,证明该病系病毒性传染病,暂定名为“兔病毒性出血症”,病原暂定为“兔出血症病毒”。经初步鉴定,认为本病毒可能是一种首次发现的新病毒,属双股RNA病毒。但从病毒大小和核酸节段看,又不同于呼肠病毒科。最终归属正在进一步研究。     

百日咳杆菌去内毒素及保护性抗原的纯化

内毒素(Endotoxin,简称ET)是百日咳全菌苗(Bordetellapertussis vaccine)产生副作用的主要毒素之一,且不易除去。现有的分离方法,如蔗糖密度梯度离心法,较繁琐,成本高。本文采用Sepha-cryl S-300凝胶层折法可以简便有效的去除大部分内毒素。初步毒素试验结果表明:已达到日本生物制品规格的要求。两种保护性抗原FHA和LPF-HA也得到进一步分离纯化,为今后研制高效的百日咳组分菌苗提供了实验条件。     

大豆下胚轴线粒体产生超氧物自由基的效率

大豆下胚轴线粒体在呼吸基质存在下,显著地增加了肾上腺素氧化速率,这种氧化速率能为外源SOD抑制,表明线粒体呼吸时产生分子氧的单电子还原成O_2(?)。亚线粒体颗粒产生O_2(?)的效率略高于线粒体。大豆下胚轴线粒体吸链内O_2(?)的产生为NADH所支持并与交替途径无关。表明分子氧单电子还原的部位可能是NADH-黄素蛋白和UbQ-Cyt.B。     

Effect of lysosomotropic amines on the secretory pathway and on the recycling of the asialoglycoprotein receptor in human hepatoma cells

We studied the intracellular transport of secretory and membrane proteins in the human hepatoma cell line HepG-2 infected with vesicular stomatitis virus. Cells were pulse-labeled in the presence of [35S]methionine and chased in the presence of the lysosomotropic agent primaquine. At a concentration of 0.3 mM primaquine effectively inhibited the secretion of albumin and, to a lesser extent, that of orosomucoid and transferrin. The drug also prevented the budding of virus particles at the cell surface. The intracellular transport to the Golgi complex of the membrane protein VSV-G was not affected by primaquine as it acquires resistance to endo-beta-N-acetylglucosaminidase H at the same rate as in control cells. Addition of primaquine at various times after the initiation of the chase period indicates that the effect of primaquine occurs just before secretion. In confirmation of the biochemical data, immunocytochemical localization of albumin in cells treated with NH4Cl demonstrated that albumin accumulated in vesicles at the trans side of the Golgi complex. The effect of primaquine on secretion was also compared with its effect on receptor recycling. The dose-response characteristics of the effect of primaquine on receptor recycling are identical to those of the effects on protein secretion and virus budding. These results indicate that both processes involve the same transport mechanism, and/or that they occur via at least one identical intracellular compartment.     

Crassulacean Acid Metabolism and Crassulacean Acid Metabolism Modifications in Peperomia camptotricha

Peperomia camptotricha, a tropical epiphyte from Mexico, shows variable forms of Crassulacean acid metabolism (CAM). Young leaves exhibit CAM-cycling, while mature leaves show an intermediate type of metabolism, between CAM and CAM-cycling, having approximately the same amount of nighttime gas exchange as daytime. Metabolism of young leaves appears independent of daylength, but mature leaves have a tendency toward more CAM-like metabolism under short days (8 hours). Large differences in the physical appearance of plants were found between those grown under short daylengths and those grown under long daylengths (14 hours). Some anatomical differences were also detected in the leaves. Water stress caused a switch to CAM in young and mature leaves, and as water stress increased, they shifted to CAM-idling.