转基因小鼠和基因突变小鼠微卫星不稳定性分析

目的探讨微卫星在转基因和基因突变小鼠中的变化,为基因修饰和遗传突变动物的遗传检测和表型分析提供理论依据和技术手段。方法根据文献报道,从GenBank中选取198个等位基因数量多、富含多态性的微卫星位点,以野生型动物为对照,对6种近交系遗传背景的转基因小鼠和5种自然基因突变的近交系小鼠进行微卫星多态性检测,选用1.5%琼脂糖凝胶电泳和STR扫描技术,比较分析微卫星不稳定性。结果共有40个微卫星位点在转基因和基因突变小鼠中表现出多态性。在基因突变小鼠中,微卫星不稳定性有55.6%(10/18)是由纯合变为杂合(Ⅰ型),有3个位点(16.6%,3/18)是纯合突变(Ⅱ型),有5个位点同时存在2种类型的突变。但是在转基因动物中,大多数的微卫星多态性为Ⅰ型突变(87.5%,28/32),只有2个位点(6.2%,2/32)是Ⅱ型突变。另外有2个位点同时存在2种类型的突变。结论基因修饰或基因突变可引起小鼠相关微卫星发生不稳定性,而且某些微卫星位点对基因改变敏感性较高。

Analysis of microsatellite instability in transgenic mice and spontaneously mutated inbred mice

Objective To detect and analyze the microsatellite instability （MSI） in transgenic （Tg） mice and spontaneously mutated （SM） inbred mice. Methods According to the literature reports, we selected 198 microsatellite loci from 19 autosomes and X chromosomes of mice from GenBank. These loci are rich in polymorphic sites in mice. Then comparative analysis of microsatellite DNA polymorphism in mouse strains 6 Tg and 5 SM and in wild-type control mice was conducted with PCR amplification. The analysis of microsatellite DNA polymorphism was performed using 1.5% agarose gel electrophoresis and STR scanning. Results We found 40 microsatellite loci showing MSI after the genetic modification compared with that in the wild type control mice. In the spontaneously mutated mice, 55.6% （10/18） changed from homozygous to heterozygous （type Ⅰ） , whereas three loci （16.6%） of these mice experienced homozygous mutations （type Ⅱ）. Five loci （27.8%） had both types of mutations. In the Tg animals, however, most of the CMP genotypes （87.5% , 28/32） were changed from homozygous to heterozygous mutations （type Ⅰ） , whereas only two loci （6. 2% ） of the mice had homozygous mutations （type Ⅱ）. Moreover, two loci harbored both types of mutations. Conclusion Gene-modification or mutation may result in microsatellite instability in mice. Some microsatellite loci are more sensitive to gene modification.