环氧化酶-2基因启动子甲基化及表达与胃黏膜病变的关系

目的 探讨环氧化酶2(COX-2)基因启动子区甲基化水平和蛋白表达与胃黏膜病变的关系,并对其相关的影响因素进行研究.方法 以1201例患有不同胃黏膜病变的高危人群为研究对象,采用免疫组织化学方法榆测COX-2表达,用亚硫酸氢钠-变性高效液相色谱(DHPLC)对COX-2启动子甲基化率进行定量分析,采用13C尿素呼气实验(13C-UBT)对幽门螺旋杆菌(H priori)感染状况进行测定.结果 COX-2甲基化率中位数随胃黏膜病变的加重逐渐升高,在浅表性胃炎和慢性萎缩性胃炎(SG/CAG)、肠上皮化生(IM)及不确定性异型增生和异璎增生(Ind DYS/DYS)病变中分别为10.6%、11.8%、13.8%,各病变组之间差异有统计学意义(X2=8.312,P=0.016).分层分析显示,在H pylori感染阴性病例中,COX-2甲基化率仍随病变加重明显升高,在SG/CAG、IM、Ind DYS/DYS病变中其中位数分别为8.8%、10.6%、14.1%(X2=6.629,P=0.036).进一步分析发现,COX-2甲基化率随着COX-2表达强度的增强而降低,由COX-2弱阳性表达的13.3%降至强阳性表达的7.6%(X2=10.400,P=0.015).结论 COX-2启动子甲基化水平与胃黏膜病变程度及H pylori感染状况密切相关,并与COX-2表达强度呈负相关,说明COX-2启动子区异常甲基化可能在胃黏膜病变的演变过程中起重要作用.     

A nuclear mutant of Chlamydomonas that exhibits increased sensitivity to UV irradiation,reduced recombination of nuclear genes,and altered transmission of chloroplast genes

Summary Meiotic progeny of Chlamydomonas reinhardtii normally receive chloroplast genomes only from the mt ⁺ parent. However, exceptional zygotes, which transmit the chloroplast genomes of both parents or, more rarely, only those of the mt ^- parent, arise at a low frequency. Mutations at the mt ⁺-linked mat-3 locus were found previously to elevate the transmission of chloroplast genomes from the mt-parent, resulting in a much higher than normal frequency of exceptional zygotes. In this paper we demonstrate that an ultraviolet-sensitive nuclear mutation mapping at the uvsE1 locus, which is unlinked to mating type, also promotes chloroplast genome transmission from the mt ^- parent. This mutant, which was previously shown to reduce recombination of nuclear genes in meiosis, acts synergistically which the mat3-3 mutation to produce an extremely high frequency of exceptional zygotes. Through the use of restriction fragment length polymorphisms existing in the chloroplast genomes of C. reinhardtii and the interfertile strain C. smithii, we show that chloroplast DNA fragments from the mt ^- parent normally begin to disappear shortly after zygote formation. However, this process appears to be blocked totally in the absence of wild-type uvsE1 and mat-3 gene products. Our findings are consistent with the hypothesis that both gene products contribute to the mechanism responsible for uniparental inheritance of the chloroplast genome from the mt ⁺ parent.     

赖型钩体flaB2与VR1012中的CpG基序分析

目的：对问号赖型钩端螺旋体（赖型钩体）DNA疫苗[包括内鞭毛蛋白基因（flaB2)和质粒DNA表达载体（VR1012）]的CpG基序（CpG motifs)进行分析，为DNA疫苗免疫机制的阐明和提高DNA疫苗的效能奠定基础。方法：以flaB2与VR1012构建重组DNA的免疫原，对flaB2及VR1012全核苷酸序列进行计算机分析（分类、计数和定位）。结果：CpG的“C”的侧翼为两个嘌呤，“G”的侧翼为两个嘧啶，在flaB2中共3个，分别为GACGCT，GACGTC和GACGCC；在VR1012中共11个，分别为GACGTC1个，GACGCT2个，GACGCC1个，GACGTT1个，GGCGTT2个，GGCGCT2个，GGCGCC1个，AACGCT1个，其中特别重要的TGACGTCA4个和TAACGCCA有1个，位于5'端456－463；509－516；592－599；778－785和486－493；4个TGACGTCA和1个TAACGCCA均位于5'端且相对集中。结论：赖型钩体flaB2与VR1012构成的DNA疫苗含有TGACGTCA等CpG，这些基序又称免疫刺激序列，构成了DNA疫苗中的佐剂。     

Duchenne型肌营养不良症

作者综述了１０年来对Ｄｕｃｈｅｎｎｅ型肌营养不良症（ＤＭＤ）的研究概况。主要包括①ＤＭＤ的临床研究。②血清生化研究表明ＣＫ、ＬＤＨ、Ｍｂ是诊断ＤＭＤ病人和携带者的敏感指标。③心脏无创性检测和肌肉超微结构研究。④部分抗肌萎缩蛋白基因ＹＡＣ物理图谱，精细限制酶图谱和缺失热区的核苷酸顺序分析，首次发现内含子中ＡＴ富集区的同源顺序与ＤＭＤ断裂有关。⑤抗肌萎缩蛋白的缺失热区疏水肽段存在与否与ＤＭＤ发病密切相关。     

Antimutagenic activities of naturally occurring polyamines in Chinese hamster ovary cells in vitro

Spermine and spermidine, ubiquitous polyamines present in bacteria and animal cells, are also involved in cell growth. Since they interact with the double helix, they can stabilize the DNA molecule. Recent evidence of the antimutagenic and anticarcinogenic capacity of spermine has focused attention on the mechanism(s) by which such agents can protect cells from induced damages. In the present paper we show the ability of spermine and spermidine to decrease the level of sister chromatid exchanges induced in Chinese hamster ovary cells cultivated in vitro, by treating them with Psoralen + UVA irradiation (able to induce mainly monoadducts and DNA cross-links). Two different mechanisms of polyamine action can be invoked to explain the preservative activity of this class of agents.     

细胞色素P450调节剂对DNA加合物形成的影响

人羊膜上皮细胞ＦＬ系分别接触ａ－萘黄酮（０．６ｍｍｏｌ·Ｌ￣（－１））β－萘黄酮（２０ｐｍｏｌ·Ｌ￣（－１））２４ｈ后，再用苯并（ａ）芘［Ｂ（ａ）Ｐ，１０ｕｍｏｌ·Ｌ￣（－１）］处理２４ｈ，用３２Ｐ后标记技术测定以Ｂ（ａ）－ＤＮＡ加合物。结果发现，阳性对照组，ａ－萘黄酮预处理组及β－萘黄酮预处理组加合物的量分别为（加合物个数／１０’个核苷酸）：４．７±０．２（１００％），１．８±０．９（３８．３％），１６．０±２．２（３４０．１％）．该实验结果直接显示了纳胞色素Ｐ４５０调节剂对肿瘤发生影响的作用水平。亦为药物对致癌物代谢影响的研究提供了一种方法．     

Differential effects of luminol,nickel, and arsenite on the rejoining of ultraviolet light and alkylation-induced DNA breaks

When Chinese hamster ovary cells were treated with ultraviolet (UV) light or methyl methanesulfonate (MMS), a large number of DNA strand breaks could be detected by alkaline elution. These strand breaks gradually disappeared if the treated cells were allowed to recover in a drug-free medium. The presence of nickel or arsenite during the recovery incubation retarded the disappearance of UV-induced strand breaks, whereas the disappearance of MMS-induced strand breaks was retarded by the presence of arsenite or of luminol, a new inhibitor for poly(ADP-ribose) synthetase. Luminol, however, had no apparent effect on the repair of UV-induced DNA strand breaks, and nickel had no effect on the repair of MMS-induced DNA strand breaks. When UV- or MMS-treated cells were incubated in cytosine arabinofuranoside (AraC) plus hydroxyurea (HU), a large amount of low molecular weight DNA was detected by alkaline sucrose sedimentation. The molecular weight of these DNAs increased if the cells were further incubated in a drug-free medium. This rejoining of breaks in cells pretreated with UV plus AraC and HU was inhibited by nickel and by arsenite, but not by luminol. The rejoining of breaks in cells pretreated with MMS plus AraC and HU was inhibited by luminol and by arsenite, but not by nickel. These results suggest that different enzymes may be used in DNA resynthesis and/or ligation during the repairing of UV- and MMS-induced DNA strand breaks, and that nickel, luminol, and arsenite may have differential inhibitory effects on these enzymes. © 1994 Wiley-Liss, Inc.     

Fractionation of a chalone-containing preparation from Ehrlich's ascites tumor by high performance liquid chromatography

Department of Biology, Medico-Biological Faculty, and Applied Research Laboratory of Ecology, Toxicology, and Metabolism of Medicinal Preparations, attached to the Department of Biochemistry, Medico-Biological Faculty, N. I. Pirogov Second Moscow Medical Institute. Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 112, No. 10, pp. 418–419, October, 1991.     

Rapid and simple isolation of DNA from agarose gels

Summary We present a simple method for the isolation of DNA from agarose gels that is economic, fast, and independent of electrical equipment. DNA fragments of up to 6 kb can be easily extracted within 5 min using a disposable plastic syringe and filter paper. Total extraction of DNA fragments between 10 and 20 kb in size is achieved by concentrating the DNA flushed from the gel in a DNA-binding column.