Protein Components of Bacteriophages λ and λ Virulent

Parallel studies have been made of the protein coats of the temperate bacteriophage λ and of a deletion mutant, λ virulent. A new method for preparing ghosts of both phages by the action of Cu⁺⁺ is described. Protein ghosts of both phages can be dissolved in citrate at pH values below 3, more rapidly in the presence of 8 m urea. Both phages yielded three apparently identical protein components which can be separated by thin-layer gel filtration and thin-layer gel electrophoresis. The protein of molecular weight 47,000 ± 1,500 represents about 55% of the protein of the ghosts and is therefore likely to be the subunit of the head. The other proteins of molecular weight 30,000 ± 1,500 and 16,000 ± 1,500 represent approximately 25% and 20% of the protein, respectively. Amino acid analyses of the ghosts from the two phages have been carried out and show no significant differences. The buoyant density of phage λ virulent is 0.016 g/ml less than that of λ. Since no differences have been found in the protein components of the two phages, this indicates that the virulent mutant contains approximately 16% less deoxyribonucleic acid than the temperate phage.     

Synthesis and antiplatelet, antiinflammatory, and antiallergic activities of 2-substituted 3-chloro-1,4-naphthoquinone derivatives

A series of 2-substituted 3-chloro-1,4-naphthoquinones was synthesized, and the antiplatelet, antiinflammatory, and antiallergic activities of these compounds were evaluated. The structure-activity relationships in this series were also examined. Most of the 2-alkyl/arylcarboxamido derivatives of 3-chloro-1,4-naphthoquinone showed potent activities with similar trends in each of the activities evaluated.     

Human liver aldehyde dehydrogenase in Chinese and Asiatic Indians: Gene deletion and its possible implications in alcohol metabolism

Two separate human liver aldehyde dehydrogenases exist which show differences in substrate specificity, cation inhibition or activation, and molecular weight. In this paper we report a common absence of enzyme 2 in Chinese which may be taken to indicate a gene deletion coding for this enzyme. The possible implication of this gene deletion among Chinese is discussed.     

Mitogenomes provide new insights of evolutionary history of Boreheptagyiini and Diamesini (Diptera: Chironomidae: Diamesinae)

Mitogenomes have been widely used for phylogenetic reconstruction of various Dipteran groups, but specifically for chironomid, they have not been carried out to resolve the relationships. Diamesinae (Diptera: Chironomidae) are important bioindicators for freshwater ecosystem monitoring, but its evolutionary history remains uncertain for lack of information. Here, coupled with one previously published and 30 new mitogenomes of Diamesinae, we carried out comparative mitogenomic analysis and phylogenetic analysis. Mitogenomes of Diamesinae were conserved in structure, and all genes arranged in the same order as the ancestral insect mitogenome. All protein‐coding genes in Diamesinae were under stronger purifying selection than those of other nonbiting midge species, which may exhibit signs of adaptation to life at cold living conditions. Phylogenetic analyses strongly supported the monophyly of Diamesinae, with Boreheptagyiini deeply nested within Diamesini. In addition, phylogenetic relationship of selected six genera was resolved, except Sympotthastia remained unstable. Our study revealed that the mitogenomes of Diamesinae are highly conserved, and they are practically useful for phylogenetic inference.     

北京永定河-海河干流河岸带植物的区系分析

探讨了北京永定河-海河干流河岸带植物区系特征。结果表明,河岸带植被中共有维管束植物37科100属134种,其中包括种子植物36科100属133种,蕨类植物1科1种。北京永定河-海河干流河岸带植物种类比较丰富,其中,在科的组成结构上,植物种类主要集中于少数几个大科如为禾本科和菊科,而多数科只有少数种或单种。在属的组成结构上,主要以单种属和小属为主。对其中种子植物的植物区系分布类型在种级水平上进行了分析,结果表明:河岸带共有4大类区系性质成分和16个地理成分类型,总体呈温带特性,各类温带分布类型67种,占河岸带植物总种数的50%。各河段河岸带植物区系结构存在差异:永定河山峡段与海河干流段区系结构比较相近,各结构在植物种所占比例上的排序为温带类世界类热带类亚洲类;而大部分长期干涸的永定河平原段,则温带类热带类世界类亚洲类。     

泛素化修饰与植物免疫应答

植物暴露在细菌、病毒和真菌等病原微生物环境中,病虫害是限制农作物产量和品质的主要因素,而植物病虫害的防治依赖于对植物抗病机制的深入认识。近年来的研究表明,蛋白质泛素化广泛地参与植物防御调节。蛋白质泛素化是真核生物中重要的翻译后修饰方式之一,在植物中,泛素化修饰在多种信号传导途径中发挥作用,如激素、光、糖应答,发育调节和病原菌防御信号途径等。综述了蛋白质泛素化修饰在植物免疫应答中的调控作用。     

马传染性贫血病毒基因非编码区LTR嵌合克隆的构建

在已有全长感染性克隆pLGFD3-8和pD70344的基础上,根据马传贫弱毒疫苗致弱过程中不同代次毒株LTR序列的分析,在LTR U3区选取特定的酶切位点对EIAV非编码区LTR基因进行了部分替换.将替换的全基因克隆转染驴胎皮肤细胞(FDD)并以驴白细胞(DL)传代,用逆转录酶活性检测、RT-PCR方法及Real-time RT-PCR验证其感染性.结果发现,其衍生病毒感染上述两种细胞均出现明显的细胞病变;细胞培养上清可检测到RT酶活性和RT-PCR阳性.电镜下可见大量典型的EIAV颗粒.pLGFD9-12嵌合克隆衍生病毒与其父本克隆衍生病毒pLGFD3-8具有相似的复制水平,pLGFD9-12嵌合克隆衍生病毒在DL细胞上复制水平略高于FDD细胞.此结果为进一步深入研究LTR对马传染性贫血病毒复制水平和毒力的影响奠定了基础.     

皖南尖吻蝮蛇毒出血毒素Ⅳ的纯化与初步鉴定

从皖南尖吻蝮蛇（Ａｇｋｉｓｔｒｏｄｏｎａｃｕｔｕｓ）毒液中经ＤＥＡＥ－Ｓｅｐｈａｒｏｓｅ和ＳｅｐｈａｃｒｙｌＳ－２００两步凝胶柱层析首次纯化出一种中分子量出血毒素（简称ＡａＨⅣ）．经ＳＤＳ－ＰＡＧＥ和等电聚焦凝胶电泳测定其分子量为４４ｋＤ,等电点为ｐＨ５．０．从５００ｍｇ粗毒中可获得２０ｍｇＡａＨⅣ纯品．ＡａＨⅣ有较强的出血活性,最小出血剂量（ＭＨＤ）为０．４μｇ．