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将正常ＨｅＬａＭＲ细胞用６０Ｃｏγ射线分别进行０～８．０Ｇｙ照射后，在含６巯基鸟嘌呤（６ＴＧ）的培养基中克隆和筛选ｈｐｒｔ基因突变细胞。细胞的突变频率与γ射线的照射剂量有关，共获得３个自然突变的细胞克隆和１８个γ射线诱导的突变细胞克隆，用８对ｈｐｒｔ寡核苷酸引物进行多聚酶链式反应（ＰＣＲ），从培养细胞提取ＤＮＡ中分别扩增ｈｐｒｔ基因的９个外显子片段，分析突变细胞的ｈｐｒｔ基因外显子突变情况。结果表明，在辐射致突的克隆中，约７７．８％（１４／１８）的ｈｐｒｔ基因突变为外显子缺失，其中２个突变是外显子全部缺失，而１２个是外显子部分缺失。另外，约有２２．２％（４／１８）的突变无明显的ＰＣＲ扩增变化，属于点突变，且突变程度与照射剂量有关。在３个自然突变克隆中，点突变和缺失突变的比例分别为６７％（２／３）和３３％（１／２），突变程度远远低于照射组。这对于估计辐射剂量和辐射远后效应观察，揭示辐射致突的分子机理提供了信息。
The normal HeLaMR cells were irradiated with 0 ~ 8.0Gy 60Coγ ray respectively, then the hprt gene mutant cells were cloned and screened in the medium containing 6TG. The frequency of cell mutation was related to the dose of γ-rays. Three naturally mutated cell clones and 18 γ-ray-induced mutant clones were obtained. Eight pairs of hprt oligonucleotide primers were used for polymerase chain reaction (PCR) Nine exons of hprt gene were amplified from the cultured cells and the exon mutation of hprt gene was analyzed. The results showed that about 77.8% (14/18) of the hprt genes were mutated to exon deletions in radiation-induced clones, of which 2 were all exon deleted and 12 were exon Missing. In addition, about 22.2% (4/18) of the mutations showed no significant changes in PCR amplification, belonging to point mutations, and the degree of mutation was related to irradiation dose. Among 3 natural mutant clones, the ratio of point mutation and deletion mutation were 67% (2/3) and 33% (1/2) respectively, and the mutation degree was much lower than that of the irradiation group. This provides information on the observation of the far-reaching effects of radiation dose and radiation, revealing the molecular mechanism of radiation-induced neurite outgrowth.