甲基化作用

Tetrachloroterephthalic acid was prepared by chlorinating terephthalic acid, oleumsolvent and iodine catalyst. Tetrachloroterephthalic acid was acylated by sulphurous oxychloride in the presence of DMF to form tetrachloroterephthaloyl chloride. The acyl chloride product was fluorinated by potassium fluoride and esterified by methanol to synthesize dimethyl tetrafluoroterephthalate. The ester was reduced with potassium borohydride and lithium chloride to give tetrafluoroterephthalyl alcohol. The above product was bromated in the hydrobromic acid to obtain 4-bromomethyl-2,3,5,6-tetrafluoro-benzene methanol. 4-Methyl-2,3,5,-6-tetrafluorobenzene ethanol was obtained by reducing the bromide with magnesium. In the exist of DCC and DMAP, tefluthrin was got by the condensation reaction between 4-methyl-2,3,5,6-tetrafluoro-benzene methanol and-(1RS,3RS)- 3-(2- chloro-3,3,3-trifluoro-1-propenyl)-2,2-dimethyl cycolpropanecar-boxylate acid.

对苯二甲酸与氯气在碘存在下以发烟硫酸为溶剂进行氯化制备四氯对苯二甲酸；再以DMF为催化剂与二氯亚砜反应生成四氯对苯二甲酰氯；以氟化钾为氟化剂，环丁砜为溶剂置换氟化，再与甲醇酯化得到四氟对苯二甲酸甲酯；以KBH4-LiCl为还原剂二甲醚为溶剂反应制得四氟对苯二甲基苄醇；以氯苯为溶剂在溴化氢溶液中溴化得到溴化产物；在乙醇溶液中经镁粉还原得到4-甲基-2，3，5，6-四氟苄醇；甲基苄醇与功夫酸在催化剂二环己基碳二亚胺和4-二甲氨基吡啶作用下缩合得到七氟菊酯，总收率达43.6%。

The result of immobilization showed that hydrophile membranes were more advantageous than hydrophobe ones to act as immobilization carrier. Crosslinking organophosphorus hydrolase by glutaraldehyde on polyethersulfone membrane is a simple and practical immobilization method. An appropriate amount of bovine serum albumin and crosslinker is necessary to get a good result of immobilization. In the biodegradation of methyl-parathion through enzyme membrane reactor, the effect of immobilized enzyme amount, flow rate of peristaltic pump, pH of the feed, and the methyl-parathion concentration on biodegradation rate was studied. It was shown that the biodegradation rate increased with immobilized enzyme amount and substrate concentration. Biodegradation rate didn't increase when the folw rate of the peristaltic pump was larger than 7 ml/min.

然后，研究固定化酶降解甲基对硫磷，从不同材料的膜载体固定有机磷水解酶的比较中，发现亲水膜比疏水膜适合作固定化酶载体；在此基础上，将有机磷水解酶固定在聚醚砜微滤膜上，并制成酶膜生物反应器，用于降解甲基对硫磷；戊二醛化学交联法固定时，酶液与10%牛血清白蛋白溶液的比例在3：1~2：1，与交联剂的比例在7：2~7：4范围内，固定化效果较好，并发现牛血清白蛋白和膜载体有降低酶活损失的作用；将固定化的酶膜装于酶膜反应器降解甲基对硫磷，实验结果表明：反应器的降解速率与固定化酶量呈正比，也随底物浓度的增加而加快，当流速低时，降解速率随流速增大而加快，到7ml/min以上时，降解速率不随流速脑黾佣洌到獾淖畹团ǘ任？

DNA methylation on CpGs constitutes an epigenetic mark generally correlated with transcriptionally silent condensed chromatin.

DNA序列中CpGs结构的甲基化对表观遗传的调节具有显著作用，它可以使染色体转录沉默。

One role of DNA methylation is to turn off repetitive genes, such as transposable elements that can move or spread throughout a genome and disrupt other gene functions if left unchecked.

DNA甲基化的一个作用就是关闭一些重复的基因，例如一些在不加抑制的情况下能转移或者延伸到基因组的其他地方去阻断基因的转座子。

This implies that DNA methylation of promoter exon 1_7 may not underly the mechanism of GR up-regulation in GLP-1 -programmed rats.5 Hippocampal expression of GLP-1R and NGFI-A mRNAHippocampal GLP-1R (p =.009) and NGFI-A (p =.001) gene mRNA expression were significantly up-regulated in GP group as compared to VP group.Taken together, neonatal intramuscular injection of plasmid DNA encoding GLP-1 affects behavior and hippocampal GR expression in adolescent rats.

提示GR exon 1_7启动子区域DNA甲基化可能不参与GLP-1导致的GR转录上调。6海马GLP-1R和NGFI-A mRNA表达GP组大鼠GLP-lR(P=。009)和NGFI-A(P=。001)表达均显著高于VP组，表明肌肉注射GLP-1可能通过作用于其海马受体提高NGFI-A表达，进而调控GR表达。

Structural comparison shows that this loop selectively competes with the unmethylated strand of the DNA duplex for binding to FTO, suggesting that it has an important role in FTO selection against double-stranded nucleic acids.

结构比较表明，该循环选择性地与DNA双链的结合FTO导电甲基化链竞争，表明它具有在FTO导电选择对双链核酸的重要作用。

The recombinant plasmid DNA of PrM-E gene but not unmethylated CpG was capable of inducting antibodies against D2-43 virus.

我国登革2型病毒PrM-E基因重组质粒DNA具有一定的免疫原性。在本实验条件下，含非甲基化细菌性CpG的pUC19质粒DNA，对PrM-E基因的DNA免疫效果没有促进作用。

Methylated trivalent metabolites that are potent cytotoxins, genotoxins and enzyme inhibitors may contribute to the in vivo therapeutic effect of iAs〓.

甲基化的三价砷代谢产物具有更强的细胞毒性，基因毒性和对酶活性的抑制，并可能对As〓O〓在体内的治疗起了一定的作用。

DNA methylation is a kind of ordinary pheonemena in eukaryote.

DNA甲基化是高等真核生物中经常发生的现象，这种表观遗传学改变常发生在基因的启动子区域，并且不改变DNA序列和遗传密码，具有可逆性，在基因转录调控中发挥重要作用。

The results suggest hypermethylated and silenced p15 gene could be reexpressed by synergy of CdR and SB.

结果提示CdR和SB可诱导甲基化失活的白血病细胞p15基因重新表达，二者有明显的协同作用。

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。