剑尾鱼RW-H近交系20个微卫星位点的遗传结构

为了对水生实验动物剑尾鱼(Xiphophorus helleri)RW-H系近交15代的遗传结构进行研究,寻找该近交系的标志基因位点,选择20个在野生剑尾鱼群体具多态性的微卫星位点,对剑尾鱼RW-H系(红眼白体)30尾个体进行分析。结果表明,其中有17个位点为单态,有可能作为该近交系的标志基因位点;另外3个位点Msa012、Msa033和Msc036具有多态性,多态信息含量值分别为0.3047、0.3457和0.3648。通过Pop-gene 3.2软件分析得知全部基因位点的纯合率达到了95.83%,个体间平均遗传距离为0.0482(0.000 0~0.1625),遗传相似系数为0.9518(0.8500~1.0000),说明剑尾鱼RW-H系已经具有很高的近交程度。几个多态性位点的发现,可以指导近交选育,加快选育进度。本研究方法不仅检测出剑尾鱼RW-H系具较低的遗传多样性,而且可为中国建立分子水平的实验动物监测标准提供基础数据。

Genetic structure of 20 microsatellite loci in RW-H swordtail fish (Xiphophorus helleri) inbred strain

Swordtail fish(Xiphophorus helleri Heckel 1848) is a small scale tropic freshwater fish which belongs to Cyprindontiformes,Cyprinodontidae,Xiphophorus.It is suitable to be used as aquatic laboratory animal with the characters of short propagation period,strong reproductive capacity and easy breeding.Pearl River Fisheries Research Institute,Chinese Academy of Fishery Sciences,began to inbreed them as laboratory animal in 1987 and the swordtail fish RW-H(red eye and white body) inbred strain has reached 15th generation so far.Researches on its biological characters,diet and nutrition,disease and disease monitoring etc.indicate that swordtail fish is suitable for study on genetics,toxicology and bacteriology.But researches about genetic structure and genetic inspection of the inbred strain were limited.In order to further understand the genetic structure and find the special gene loci for genetic inspection,30 individuals of RW-H inbreeding swordtail fish were analyzed using polymorphism microsatellite loci.Among 20 microsatellite loci,17 microsatellite loci showed no polymorphism in the inbreeding swordtail fish and would be used as special gene loci for RW-H strain's genetic inspecting.The other 3 microsatellite loci,Msa012,Msa033 and Msc036 revealed polymorphism and can be used for directing further inbreeding.The PIC values of Msa012,Msa033 and Msc036 polymorphism loci were 0.3047,0.3457 and 0.3648 respectively.The results analyzed by Pop-gene 3.2 showed that the average rate of homozygote for 20 microsatellite loci was 95.83%,and the mean genetic distance index was 0.0482(0.0000-0.1625);the mean genetic similarity index was 0.9518(0.8500-1.0000).It suggested that the inbreeding degree of RW-H swordtail fish was quite high for 15 generations inbreeding.The results of this paper also provided the data for establishing the genetic monitoring standard of aquatic laboratory animal.