甲基胞嘧啶

迄今为止，不少人认为5-甲基胞嘧啶的存在可能是基因突变的热点。然而，事实上5-甲基胞嘧啶作为一种稀有碱基，本来就是许多真核生物DNA的正常组分。

5-methylcytosine ( m5C ) as a rare base exists in eucaryotic genomes , it is a normal constituent of many eucaryotic DNA , whose existence is a character of eucaryotic DNA .

胞嘧啶和甲基胞嘧啶回收率分别为99.6%及103.3%，RSD为3.7%（日内）及5.2%（日间）。

Recoveries of this method achieved to 99 . 6 % for cytosine and to 103.3 % for methylcytosine , and RSD 's found were 3 . 7 % ( intra-day ) and 5 . 2 % ( inter-days ) .

新发现的位置核苷酸，叫做强甲基胞嘧啶，位于动物细胞内，提示着有新的基因表达调控机制。

The discovery of a previously unknown nucleotide , called hydroxymethylcytosine , inside animal cells suggests a new mechanism for regulating gene expression .

目的：设计并合成含非甲基化胞嘧啶和鸟嘌呤二核苷酸的寡聚脱氧核糖核苷酸（CpG-ODN），以期筛选出对新生儿脐血单个核细胞免疫刺激作用较强的CpG-ODN；

Objective : Design and synthesize the oligodeoxynucleotides containing unm-ethylated CpG dinucleotides ( CpG-ODN ) to screen out the optimal CpG-ODN that could markedly enhance the immune function of cord blood mononuclear cells in health newborns .

含有非甲基化胞嘧啶鸟嘌呤二核苷酸序列的寡脱氧核苷酸不直接抑制病毒感染细胞，而是通过刺激免疫系统来起作用。

CpG ODN plays its anti-HSV role not by the direct suppression of the virus-infected cells but through the stimulation of immune system .

方法将基因组DNA变性成为单链，用亚硫酸氢盐修饰单链DNA，所有未甲基化的胞嘧啶被转变为尿嘧啶，而甲基化的胞嘧啶则不变。

Methods Target DNA was denatured by NaoH , then single strands DNA was modified by sodium bisulfite . All unmethylated , but not methylated cytosines were converted to uracil .

植物远缘杂交可以引起广泛的表观遗传变异，如：基因沉默、核仁显性、转座子激活、DNA甲基化变异等，而DNA甲基化尤其是胞嘧啶甲基化是表观遗传的主要调控机制之一。

Distant hybridization of plants can cause a wide range of apparent genetic variability , such as : gene silencing , nucleolar dominance , transposon activation , DNA methylation variations and so on , and DNA methylation , in particular cytosine methylation is one of the main epigenetic control mechanisms .

DNA甲基化（DNAMethylation）是目前已知的唯一天然的DNA共价修饰方式，由DNA转移酶催化，将S-腺苷甲硫氨酸上的甲基转移到胞嘧啶嘌呤环的第五位碳原子上。

DNA methylation is the only known covalent modification of DNA molecule . It is accomplished by transfer of the methyl group from S-adenosyl methionine to 5 position of the purine ring of cytosine .