甲基化作用

Technologies for determining methylation patterns in cancer cells, Methyl Light and COBRA, both of which were based on the deamination of methylated cytosines—which converts these cytosines to uracil residues—and identification of the converted sequence by analytical methods.

在上世纪80年代期间，研究的主要方法是PCR和克隆，两者都不涉及甲基化内容，因此很快就被弃用了。90年代，Laird开发了两类技术去检测肿瘤细胞中的甲基化模式，MethylLight和COBRA，两者都是以甲基化胞嘧啶的脱氨作用（将胞嘧啶转化为尿嘧啶残基）以及通过分析方法鉴定修改的序列为基础。

The types of histone methyltransferases, the relationship between methylation of Lysine 9 of H3 and the formation of heterochromatin, gene regulation in euchromatin, and that with DNA methylation, were mainly introduced.

主要阐述了组蛋白甲基转移酶的类型，组蛋白H3中第9位赖氨酸甲基化与异染色质的形成、常染色体中基因表达的调控，以及与DNA甲基化之间的关系，说明了组蛋白甲基化与组蛋白乙酰化、磷酸化的相互关系，指出组蛋白甲基化对维持细胞各种状态的平衡起到极其重要的作用。

Objectives To detect the methylation of P15(superscript INK4B) gene in patients with myelodysplastic syndromes and to investigate the demethylating effects of decitabine and arsenic trioxide (As2O3). Methods The bone marron mononuclear cells from 14 MDS patients were collected.

目的 检测骨髓增生异常综合征患者P15(上标 INK4B)基因甲基化状况；探讨5-氮杂－2'-脱氧胞嘧啶和三氧化二砷(As2O3)对MDS患者细胞的去甲基化作用。

Objective To investigate the inhibition of tumor cell lines' growth and the demethylation of p16 gene by a component of natural drug, CDP.

目的 探讨中药成分CDP对肿瘤细胞系的生长抑制作用及其对抑癌基因P16启动子区CpG岛的去甲基化作用。

Although the biological significance of DNA methylation has been recognized to some extent, the mechanisms of DNA methylation regulation and of the establishment of tissue-specific DNA methylation pattern in somatic cells are still unclear, since the knowledge of the enzymes responsible for de novo DNA methylation and demethylation of DNA is very limited and up to now only two functional DNA methyltransferases in mammals have been cloned.

目前，虽然对DNA甲基化的作用已有一定认识，但DNA甲基化的调节以及发育过程中组织特异的DNA甲基化谱的建立机制还不清楚。问题主要在于对催化重新甲基化和去甲基化反应的酶的了解很少。至今仅克隆出两种有功能的哺乳动物DNA甲基转移酶。

The hypermethylation of 5 CpG in promoter region serves as a mechanism of the inactivation of RASSF1A gene. This mechanism has been widely confirmed in multiple tumorgenesis including prostate carcinoma cell line DU145. Object Our study is to disclose the epigenic mechanism of the carcinogenesis of prostate cancer. Including: 1. We use demethylation agents in combination with chemotherapeutic drugs, to disclose whether demethylation agents can enhance the anticancer effect of chemotherapeutic drugs. 2. to study whether demethylation drugs can affect the methylation level of RASSF1A gene in.

目的 本研究旨在探讨前列腺癌的表遗传学发生发展机制，包括： 1、甲基化抑制剂与多种化疗药物联合应用，探讨二者间的协同作用，增强化疗药物疗效； 2、体外应用甲基化抑制剂对前列腺癌细胞DU145的RASSF1A基因甲基化水平的影响； 3、体外应用甲基化抑制剂对前列腺癌细胞DU145的RASSF1A基因及蛋白表达的影响，以期为进一步深入探索通过改变抑癌基因的甲基化而为前列腺癌发生机制和基因治疗提供有意义的数据和理论依据。

RESULTS: APC promoter 1A was methylated in NCI-H460 cells, and unmethylated in NCI-H446 and SPC-A1 cells. Hypermethylation was detected in all 5 CpG islands (687, 707, 714, 719, 726) of APC promoter 1A in NCI-H460 cells. The expression of APC in NCI-H460 cells was decreased by 26.04% of that in NCI-H446 cells and by 32.36% of that in SPCA1 cells. After treatment of 1, 5, 10, 15μmol/L 5-aza-dC, the expression of APC promoter 1A in NCI-H460 cells was enhanced by 4.59, 5.78, 9.58, 5.98 folds, respectively.

结果：SPC-A1和NCI-H446细胞APC甲基化阴性，NCI-H460细胞APC甲基化阳性；甲基化芯片检测Ncl-H460细胞在APC启动子1A 5个CpG位点均存在甲基化(687、707、714、719、726)，SPC-A1和NCI-H446甲基化阴性，荧光定量结果NCI-H460的APC转录较SPC-A1和NCI-H446有明显的下降，仅为二者平均的30.04%；经5-aza-dC脱甲基化作用后，NCI-H460细胞的APC表达增加了约5~10倍，其中10μmol/L浓度作用下，APC表达增加最多。

Methods After treated with a specific demethylating agent,Aza and acetylating agent, TSA, the status of 5'CpC island methylation of ING1b gene in HT29 human colon cancer cell line was analyzed using methylation specific polymerase chain reaction,and the level of histone acetylation was analyzed by chromatin immunoprecipitation,and reverse transcription polymerase chain reactionwas used to examine ING1b mRNA expression.

应用特异性DNA甲基转移酶抑制剂5-氮-2'-脱氧胞苷（5-Aza-2'-dc，以下简称Aza）及组蛋白去乙酰化酶抑制剂曲古抑菌素A作用人结肠癌细胞株HT29后，用甲基化特异性PCR检测该ING1b基因核心启动子区域CpG岛甲基化情况，用染色质免疫沉淀检测其乙酰化组蛋白绑定的DNA情况，并用逆转录聚合酶链反应检测ING1bmRNA表达。

On the discussion about mechanism of mutation of methylating, we explored thermodynamics and dynamic properties on base pairs, investigating the proton transfer on base pairs.

从甲基化对嘌呤碱基电荷的影响，到甲基化引起碱基配对的改变造成碱基配对的诱变等都作了较为详细的探讨；在对甲基化诱变的探讨中，我们进行了热力学和动力学方面的研究，同时对碱基之间的质子迁移的难易程度也作了探讨；并在充分考虑水分子存在的情况下研究了甲基化对碱基之间的氢键作用和堆积作用的影响。

The influences of environmental factors on the abiotic methylation were studied. The biggest production of methylmercury was found after 2 days of incubation in presence of FA. The rate of production of methylmercury depends upon temperature. In presence of FA from sediment, the biggest production of methylmercury was found under 40℃. In presence of FA from soil, production rate increases with temperature. The biggest production of methylmercury was found when solution pH was 2 and 4 in presence of FA from sediment and soil, respectively. Increase in concentrations of inorganic mercury and FA solution causes an increase in the production of methylmercury. Under irradiation with ultraviolet ray, blacklight lamp as well as natural light, methylation is stimulated, especial for irradiation of ultraviolet light.

环境条件对汞甲基化作用的影响研究得出，在底泥和土壤FA体系中甲基汞产量均在反应2天后达到最大值；在底泥FA体系中汞的甲基化在反应温度为40℃时产量最大，而在土壤FA体系中，甲基汞产量在10～60℃之间随反应温度升高而增加；底泥和土壤FA体系中汞的甲基化分别在pH值为2和4时最大；甲基汞产量均随无机汞浓度和腐殖质浓度的增加而增加；紫外线、黑光灯和自然光照射都可促进甲基汞的生成，紫外线的作用尤其明显。

This one mode pays close attention to network credence foundation of the businessman very much.

这一模式非常关注商人的网络信用基础。

Cell morphology of bacterial ghost of Pasteurella multocida was observed by scanning electron microscopy and inactivation ratio was estimated by CFU analysi.

扫描电镜观察多杀性巴氏杆菌细菌幽灵和菌落形成单位评价遗传灭活率。