应用微卫星DNA标记对Wistar和SD大鼠封闭群的遗传学研究

封闭群大鼠的遗传质量对其医学生物学实验结果有重要影响,但目前缺乏遗传检测方法和标准.本研究应用6个微卫星标记及其荧光标记一半自动基因分型技术,对北京和上海2家单位分别提供的Wistar和Spague-Darley(SD)大鼠封闭群进行了遗传检测和评估.6个微卫星位点均具有高度多态性,在两大鼠群体共发现等位基因36个,每位点等位基因数5-8个,其多态信息含量(PIC)从0.5892(D11Mgh3)到0.8019(D6Mit1),平均为0.688l.6个位点在Wistar和SD大鼠分别发现25和26个等位基因,其平均期望杂合度分别为O.6260和0.6249.两群体的各组遗传多样性指数间无显著差异.群体间的不同微卫星位点Fst范围0.046l到0.4363.平均为0.2069,表明其遗传分化程度较大;Nei(1972)遗传距离和Nei(1978)无偏遗传距离分别为1.2862和1.2726,表明了2群体之间较大的遗传差异:Hardy-Weinberg平衡检验表明Wistar大鼠在所有检测的6个位点均非常显著偏离Haraly-WeinJaerg平衡,SD大鼠在2个位点(D6Mit1和D11Mgh3)处于遗传平衡状态,且偏离位点均表现为杂合子缺陷.因此研究表明,Wistar和SD大鼠封闭群均具有较好的遗传多样性,且两群体之间有较大的遗传差异和分化程度,分别具有各自不同的遗传特征,偏离Hardy-Weinberg遗传平衡是其繁育过程中较多存在的问题.本研究结果将为两品系大鼠遗传检测方法和标准的建立提供基础资料和依据.

MICROSATELLITE ANALYSIS IN WISTAR AND SPAGUE DARLEY OUTBRED RATS

Genetic quality of outbred stock has an important effect for the experimental results by using those animals, but methods and standardization of genetic detection for outbred stock are absent. In the present study, 6 microsatellite markers were screened for Wistar from Beijing and Spague-Darley (SD) from Shanghai outbred rats by fluorescence-based semi-automated genotyping method. Good polymorphisms were detected on all the 6 microsatellite loci, with 36 alleles found in the 2 stocks, 5-8 alleles each locus, and the polymorphic information content (PIC) ranged from 0.5892 (D11Mgh3) to 0.8019 (D6Mit1), with an average of 0.6881. 25 and 26 alleles were detected in the 6 loci, and averages of unbiased expected heterozygosity were 0.6260 and 0.6249 in Wistar and SD outbred rats, respectively. No significant differences of genetic diversity index were tested between populations. The Fst per locus was varied from 0.0461 to 0.4363, and the average Fst of all loci was 0.2069, which implied large genetic differentiation between populations. Nei's (1972) genetic distance and Nei's (1978) unbiased genetic distance measures between the 2 stocks were 1.2862 and 1.2726, respectively, which indicated the distant genetic relationship and low genetic identity between them. All loci in Wistar and 4 of 6 loci in SD outbred rats showed significant deviations from Hardy-Weinberg equilibrium (HWE), and all deviations were caused by deficiency of heterozygous individuals. From the results, there is abundant genetic variation in Wistar and SD outbred rats. Large genetic differentiation existed between these two outbred stocks, and each possessed distinct genetic characteristic. Deviation from HWE seems a frequent problem in the 2 outbred stocks. This genetic research on outbred rats should assist in developing genetic monitoring methods and standardization of the outbred rats.