长江中游湖泊中黄颡鱼线粒体DNA的遗传变异

Variation in mitochondrial DNA of Pelteobagrus fulvidraco from three lakes in the Middle Yangtze River

运用mtDNAPCR RFLP技术对位于长江中游的洞庭湖、涨渡湖、长湖黄颡鱼(Pelteobagrusfulvidraco)自然群体的种群遗传结构进行比较分析。PCR技术扩增出黄颡鱼mtDNAND1/2基因,选用8种限制性内切酶对PCR产物进行酶切,3个群体的黄颡鱼共检出15种单倍型,单倍型间的遗传距离为0 20%～2 08%(0 8135%±0 4095%)。各不同群体的单倍型在系统树上有部分交叉,虽然不同群体在各单倍型中出现的频率有所不同,但每个群体都和其他群体存在共有的单倍型。尽管单倍型的分布或结构有所不同,但种群间的遗传距离不大,与通江型湖泊相比,两个阻隔型湖泊间的遗传距离更为接近。

Pelteobagrus fulvidraco Richardson is called Huangsang fish in China,belonging to Pelteobagrus (Bleeker),Bagridae,Siluriformes.It is one of the famous and excellent economical freshwater fishes in China.The Middle Reaches of the Yangtze River and the attached lakes are the major habitats of this species.During the recent three decades,the natural resources have been over developed year by year owing to reservoir construction,overfishing,environmental contamination,etc.Now the problem of protecting the gemplasm resources has been a priority.In this research,mtDNA-PCR technique was applied to make a comparative analysis on genetic structures of the natural populations of Huangsang fish from Dongting Lake ( a river-connecting lakelocated in Yueyang City of Hunan Province ),Zhangdu Lake and Changhu Lake (The latter two are located in Wuhan City and Jingzhou City of Hubei Province,respectively.They once connected with the River and are blocked lakes now) in the Middle Reaches of the Yangtze River .ND1 and ND2 genes on mitochondrial DNA were amplified from Huangsang fish by means of PCR technique .Eight restriction endonucleases that could recognize a sequence of 4 or 5 bases were chosen to conduct enzymatic cleavage of PCR products.Six enzymes were detected to be polymorphism.Fifteen haplotypes were detected from 42 individuals sampled from the three populations of Huangsang fish.Their degrees of polymorphism are higher than those of goldfish (Carassius auratus) and common carp (Cyprinus carpio) which are widely distributed in China,and of silver carp (Hypophthalmichthys molitrix),bighead carp (Arithtichthys nobilis),grass carp (Ctenopharyngodon idellus) and black carp (Mylopharyngodon piceus)which are distributed in the Middle and Lower Yangtze.The genetic distances between any two different haplotypes are from 0.20% to 2.08%(0.8135%±0.4151%).The haplotypes of the three different populations have partial chiasma in their phylogenetic tree.Although the occurrence of each haplotype in different populations might be different,each population has some common haplotypes with other populations.The π values that express the degrees of polymorphism within the populations are 0.2162% for Zhangdu population (ZH),0.2314% for Dongting population (DH) and 0.1961 for Changhu population (CH),respectively. According to the degrees of polymorphism and the distribution of haplotypes in each population,the net genetic distances between any two of the three populations could be found.The net genetic distance between DH and ZH is 0.3057%,between DH and CH is 0.2529,and between DT and CH is 0.2143%.In spite of different distributions and structures of haplotypes,the genetic distances between any two of the three populations are not large.In comparison with the genetic distance between DH and ZH or between DH and CH,the genetic distance between CH and ZH is closer.