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ＭＡＰＯ诱发的ＣＨＯ细胞ＨＧＰＲＴ基因位点突变克隆ＤＮＡ，经ＥｃｏＲＩ和ＰｓｔＩ酶切消化后，用Ｓｏｕｔｈｅｒｎ印迹杂交法，与ＨＧＰＲＴ基因探针杂交。从杂交图谱可见，正常ＣＨＯ细胞基因组ＤＮＡ经ＰｓｔＩ酶切后杂交可显出６条杂交带，其中８３ｋｂ，７６ｋｂ，６０ｋｂ，和３２ｋｂ带为Ｘ染色体连锁的ＨＧＰＲＴ基因所有，分别代表外显子２，６８，４和３，其余两条带为假基因。而经ＥｃｏＲＩ酶切后，正常ＣＨＯ细胞基因组ＤＮＡ有１７５ｋｂ和１１３ｋｂ两条ＨＧＰＲＴ基因杂交带，分别代表了外显子６９和２４。而从ＭＡＰＯ所诱发的ＨＧＰＲＴ基因突变细胞杂交图谱可见，其主要改变是ＨＧＰＲＴ基因全部缺失或部分缺失，同时出现了新的杂交带。ＰｓｔＩ酶切的７个突变克隆均显出基因缺失或新的杂交带型，而ＥｃｏＲＩ酶切８个突变克隆中，有３个无ＨＧＰＲＴ基因改变。由此可见，ＭＡＰＯ诱发ＨＧＰＲＴ基因位点突变的分子机理主要是由于基因缺失或重排。
MAPO-induced CHO cell HGPRT gene mutation cloned DNA, digested with EcoRI and PstI digestion, Southern blotting hybridization, and HGPRT gene probe hybridization. From the hybridization map, we can see that there are 6 hybridized bands in normal CHO cells after digested with PstI, of which 83kb, 76kb, 60kb and 32kb are all X chromosome linked HGPRT genes , Representing exons 2,6 8, 4 and 3, respectively, and the remaining two bands are pseudogenes. However, after digestion with EcoRI, the genomic DNA of normal CHO cells have 17.5kb and 11.3kb two HGPRT gene hybridization bands, which respectively represent exons 6-9 and 2-4. The HGPRT gene mutation MAPK induced cell hybridization map shows that the main change is the HGPRT gene all deleted or partially deleted at the same time a new hybrid belt. Seven of the seven mutant clones that were digested with PstI showed either a deletion or a new hybridization band, whereas three of the eight mutant clones EcoRI digested without HGPRT. Thus, the molecular mechanism of MAPO-induced HGPRT gene mutation is mainly due to gene deletion or rearrangement.