黑龙江流域黑斑狗鱼遗传多样性的Cytb基因初探

Preliminary Study on Genetic Diversity of Esox reicherti in Amur River Basin Based on Cytochrome b Gene

[目的]了解黑龙江流域黑宽狗鱼不同地理群体的遗传多样性，为其种质资源的保护和开发提供分子的依据。[方法]从4尾来自黑龙江、17尾来自乌苏里江和5尾来自牡丹江的黑斑狗鱼中提取DNA，测定其线粒体DNA细胞色素b基因序列，采用Kirmra2-parameter模型计算各群体间和单倍型间的遗传距离；以白斑狗鱼为外类群，用邻接法构建系统发育树，构建单倍型的简约性网络图；根据单倍型多样性和核苷酸多态性等信息评估种群的遗传多样性。[结果]获得黑斑狗鱼细胞色素b（Cytb）基因1053bp序列，其中G含量最低，仅14．2％，A＋T含量（57．7％）高于G＋C含量（42．3％）；变异位点有8个，总变异率为0．76％，其中简约信息住点有3个；序列中无插入和缺失，转射颠换为7／1，26尾黑癍狗鱼中共有7个单倍型，单倍型多样性（H）较高（0．76308±0．00315），但核苷酸多态性（π）极低（0．00126）；3个地理群体黑斑狗鱼群体间遗传距离小（0．067％～0．143％）。[结论]黑龙江流域3个群体的26尾黑斑狗鱼属于同一个种群，其遗传多样性极为贫乏，种质资源亟需得到有效保护。

[Objective] The study aimed to understand the genetic diversity of different geographical populations of E. reicherti in Amur River basin. [Method] DNA was extracted from 26 fishes of E. reicherti sampled from Mudanjiang, Heilongjiang, and Wusuli River, partial sequences of mitochondrial Cytochrome b gene were sequenced and genetic distances among 3 geographic groups were computed with Kimura 2-parametre model. With E. downloaded from Genbank as outgroup, phylogenetic tree was constructed by neighbor-joining （NJ） method. [Result] 1 053 by Cyt b gene was determined, the content of A and T （57.7%） was higher than that of G and C （42.3% ） , and G content was the lowest by only 14.2%. There were 8 substituted nucleotide sites, of which 3 were parsimony-informative sites, and the mutation rate was 0.76% ,7 nucleotide substitution were nucleotide conversion, only 1 transversion, no insertion and nucleotide deletion.The ratio of transitional pairs versus transversional pairs was 7/1. 7 haplotypes were found in 26 samples, total haplotype diversity （H） is （0.763 08±0.00315）, but nucleotide polymorphism （sr） is only 0.（X）1 26. Genetic distance within and among 3 geographic groups of E. reicherti were in the range of 0.067% -0.143% . [Conclusion] The 3 geographic groups of E . reicheri in Amur River drainage might belong to the same population, and mitochondrial DNA diversity of E. reicherti was extremely poor, gennplasm resources of E. reicherti needed to be effectively protected.