远交系小鼠胚胎干细胞系的建立及嵌合鼠的获得

ＥＳ细胞（ＥｍｂｒｙｏｎｉｃＳｔｅｍＣｅｌｌｓ）是来源于小鼠早期胚胎的多潜能干细胞,它可以在体外大量培养。并以单细胞的形式注射到早期胚胎里,发育为嵌合体。到目前为止,通常使用的１２９小鼠品系是来源于近交系（ｉｎｂｒｅｄ）小鼠的胚胎．与之相比,远交系小鼠应当具有较强的生命力和抗病能力。曾有人报道过建成了远交系小鼠胚胎干细胞系,但是尚没有见到获得嵌合鼠的报道。有人甚至认为：由于不同品系小鼠所具有的遗传背景不同,有的小鼠不能建成ＥＳ细胞系。最近,本实验室在这方面做了有益的探索,成功地建成了远交系小鼠胚胎干细胞系,并在这里报导首例用远交系小鼠胚胎干细胞系培育成功嵌合体小鼠。采用源于Ｓｗｉｓｓ小鼠远交群的昆明（ＫＭ）品系小鼠囊胚建成了三个小鼠胚胎干细胞系（ＫＥ１．ＫＥ２．ＫＥ５）。核型正常率均达到７０％以上。自第八代起分批冻存,复苏后,培养至第１２代,消化成单细胞,通过囊胚显微注射,将其注射到６１５品系小鼠胚胎。在幸存的幼鼠中获得了一只来源于ＫＥ１细胞的嵌合鼠（Ｔａｂｌｅ１）．其毛色表现为受体鼠（６１５）的白色中嵌合有供体鼠（ＫＭ）的黑褐色（ＰｌａｔｅＩ－Ａ）．嵌合鼠与受体鼠的杂交后代鼠中仍然出现了受体鼠的毛色类型（     

Targeting foreign proteins to human immunodeficiency virus particles via fusion with Vpr and Vpx.

The human immunodeficiency virus type 1 (HIV-1) and HIV-2 Vpr and Vpx proteins are packaged into virions through virus type-specific interactions with the Gag polyprotein precursor. To examine whether HIV-1 Vpr (Vpr1) and HIV-2 Vpx (Vpx2) could be used to target foreign proteins to the HIV particle, their open reading frames were fused in frame with genes encoding the bacterial staphylococcal nuclease (SN), an enzymatically inactive mutant of SN (SN*), and chloramphenicol acetyltransferase (CAT). Transient expression in a T7-based vaccinia virus system demonstrated the synthesis of appropriately sized Vpr1-SN/SN* and Vpx2-SN/SN* fusion proteins which, when coexpressed with their cognate p55Gag protein, were efficiently incorporated into virus-like particles. Packaging of the fusion proteins was dependent on virus type-specific determinants, as previously seen with wild-type Vpr and Vpx proteins. Particle-associated Vpr1-SN and Vpx2-SN fusion proteins were enzymatically active, as determined by in vitro digestion of lambda phage DNA. To determine whether functional Vpr1 and Vpx2 fusion proteins could be targeted to HIV particles, the gene fusions were cloned into an HIV-2 long terminal repeat/Rev response element-regulated expression vector and cotransfected with wild-type HIV-1 and HIV-2 proviruses. Western blot (immunoblot) analysis of sucrose gradient-purified virions revealed that both Vpr1 and Vpx2 fusion proteins were efficiently packaged regardless of whether SN, SN*, or CAT was used as the C-terminal fusion partner. Moreover, the fusion proteins remained enzymatically active and were packaged in the presence of wild-type Vpr and Vpx proteins. Interestingly, virions also contained smaller proteins that reacted with antibodies specific for the accessory proteins as well as SN and CAT fusion partners. Since similar proteins were absent from Gag-derived virus-like particles and from virions propagated in the presence of an HIV protease inhibitor, they must represent cleavage products produced by the viral protease. Taken together, these results demonstrate that Vpr and Vpx can be used to target functional proteins, including potentially deleterious enzymes, to the human or simian immunodeficiency virus particle. These properties may be exploitable for studies of HIV particle assembly and maturation and for the development of novel antiviral strategies.     

phbB,phbC基因克隆,序列分析及植物表达载体的构建

利用聚合酶链式反应技术,从真养产碱杆菌Ａｌｃａｌｉｇｅｎｅｓ ｅｕｔｒｏｐｈｕｓ Ｈ１６染色体ＤＮＡ中的主增并克隆了调控聚－β－羧基丁酸生物合成的两个关键酶基因;依赖ＮＡＤＰＨ的乙酰乙酰ＣｏＡ还原酶基因和ＰＨＢ合成酶基因。限制性内切酶图谱和核苷酸序列分析证实了克隆结果,并表明所克隆的基因与国外报道的有很高的同源性。     

籼稻的抗冷性与亲本的关系

四个籼稻（Ｏｒｙｚａ ｓａｔｉｖａ Ｌ．）品种幼苗经１℃黑暗或光照２５０ μｍ ｏｌ·ｍ － ２·ｓ－ １处理后,抗冷的“桂山矮选３”比不抗冷的“青华６ 号”幼苗存活率高,其子代是以“桂山矮选３”为母本的比“青华６ 号”为母本的存活率较高。抽穗期剑叶经光照低温处理１２、２４ 和３６ ｈ 后,光合作用是“桂山矮选３”和以“桂山矮选３”为母本的子代比“青华６ 号”和以“青华６ 号”为母本的子代下降较少。呼吸作用是前者比后者在处理１２ ｈ 时有明显升高现象。荧光参数Ｆｖ／Ｆｏ和Ｆｖ／Ｆｍ比值在处理２４ ｈ 时前者比后者下降明显,但在常温下恢复则是前者比后者明显较快。自然低温（寒露风）对叶绿素荧光的影响亦有相似的规律。对水稻后代的抗冷性倾向于母本进行了讨论     

菜豆热激蛋白在生物膜上的定位

选用菜豆 Phaseolus vulgris L. 下胚轴 ,运用35S- Met标记放射自显影和二维电泳技术 ,研究热激蛋白 HSPs 的表达和在生物膜组分中的定位 .实验结果表明 ,盐溶蛋白中主要HSPs为 70 k D HSPs和小分子量 HSPs,而小分子量组 HSPs大量富集在质膜和液泡膜组分中 .     

棒状类细菌电击转化中多种条件对转化效率的影响

以质粒PXZl0145电击转化不同棒状类细菌菌株,研究了影响电击转化效率的诸个因素,在含4%甘氨酸的培养基中生长至对数前期的菌体最适用于电击转化,当以同源DNA进行电击转化时,1．μgDNA中转化效率最高可达到8×1O⁶转化子,但用异源DNA时,转化效率要比前者低10²～10³倍。     

复合酶制剂EA－2对鲤生长的影响

利用复合酶制剂ＥＡ－２在池溏中饲养鲤５０ｄ,实验组鲤尾增重率高于对照组１２．３—２７．５％,而饲料系数低于对照组１８．７６—１０．８９％。实验组鲤肝胰脏淀粉酶活力显著增加,而肝、胰脏蛋白酶活力显著降低,实验组鲤肠内蛋白酶活力和淀粉酶活力均显著增加。酶制剂对鲤肥满度、肝胰比、内脏比、肝胰脏和背部肌肉的生化成份均无显著影响。     

巴山松天然林生物量和生产力的研究

 经测定分析陕西南部28—37年生巴山松天然林的生物量和净初级生产量,结果表明,林分乔木层生物量为81.28t／ha,草本下木生物量为1.45t／ha,林分凋落物量为11.16t／ha;乔木层净初级生产量为6.94t／ha·yr,约45%分配到树叶。巴山松林的消光系数平均为0.33。在地上部生产结构方面,枝重主要集中在树冠中、下部,叶龄愈大,叶重在树冠下部的比例愈高。巴山松林木的根系总长度约99.4km／ha,其中细根占58%。     

Evidence forCis- andTrans-acting element coevolution of the 2-μm circle genome inSaccharomyces cerevisiae

Summary We compared the DNA sequence of the yeas 2-μm plasmidcis-actingSTB andtrans-actingREP1 partition loci of laboratory haploid and industrial amphiploid strains. Several industrial strains had a uniqueSTB sequence (type 1) sharing only 70% homology with laboratorySTB (type 2). Type 1 plasmids had a REP1 protein with 6–10% amino acid substitutions when compared to REP1 of type 2 plasmids. All 2-μm variants that shared a similarSTB consensus sequence exhibited a high degree ofREP1 nucleotide and amino acid sequence conservation. These observations suggest molecular coevolution oftrans-acting elements with cognate target DNA structure. Based on DNA sequencing and Southern hybridization analyses, we classified 2-μm variants into two main evolutionary lineages that differ atSTB as well asREP1 loci. The role of molecular coevolution in yeast intra- and interspecies plasmid evolution was discussed.     

溶液流动对等电溶菌酶晶体生长的影响

本文对等温自由生长和强制性溶液生长的等电溶菌酶的晶体形态进行了研究,发现这些形态变化与溶液相的流动密切相关,指出生物晶体生长停止是由于生长晶体周围的溶质贫乏造成的;通过某些手段减薄或消除这一溶质贫乏区,就可以保证晶体的持续生长。本文的研究对改善大尺寸晶体的生长提供了一条途径。