刀鲚和凤鲚的分子鉴定及其在仔鱼种类鉴定中的应用

MOLECULAR IDENTIFICATION OF COILIA ECTENES AND COILIA MYSTUS AND ITS APPLICATION ON LARVAL SPECIES

使用mtDNA Cyt b基因序列作为分子标记,基于400 bp左右的序列分析长颌鲚、短颌鲚及凤鲚成鱼的遗传关系。结果显示长颌鲚和短颌鲚间的遗传距离在0—0.5%之间;凤鲚与长颌鲚、短颌鲚的遗传距离分别在7.9%—8.9%和7.7%—8.6%之间。用Kimura双参数模型构建的NJ分子系统树显示,长颌鲚和短颌鲚不能形成彼此独立的分支,而是混合聚在一起形成一个分支;凤鲚则形成另一个分支。对长江口沿岸区域的鲚属仔鱼Cyt b基因片段序列分析发现,仔鱼个体之间的遗传距离为0—0.7%,仔鱼与长颌鲚、短颌鲚的遗传距离在0.1%—0.5%之间,而与凤鲚的遗传距离为8.3%—8.8%。在Kimura双参数模型构建的NJ分子系统树中,仔鱼与长颌鲚、短颌鲚聚为一类,而与凤鲚分开,表明分析的仔鱼样品不包括凤鲚个体。由于长江口一般没有短颌鲚分布,这些仔鱼应该都是长颌鲚。

Based on about 400 bp sequences,nucleotide sequences of Cytochrome（Cyt b） segments of mtDNA were analyzed for anadromous Coilia ectenes,freshwater resident C.ectenes and C.mystus in the Yangtze River,China,to develop a reference data for larval species identification of genus Coilia.The genetic distance ranged from 0 to 0.5% between the anadromous and freshwater resident C.ectenes,7.9% to 8.9% between C.mystus and the anadromous C.ectenes,and 7.7% to 8.6% between C.mystus and the freshwater resident C.ectenes.Neighbor-joining（NJ） molecular dendrogram using Kimura 2-parameter based on the sequences of Cyt b gene showed individuals of the anadromous and freshwater resident C.ectenes mixed into a cluster,and those of C.mystus forming another cluster.Thus,larvae of C.mystus could be distinguished from that of C.ectenes through Cyt b analysis.Nucleotide sequences of Cyt b of larvae of genus Coilia collected from the Yangtze Estuary were analyzed,and compared to the reference established above.Ge-netic distance ranged from 0.1% to 0.5% between the larvae and the anadromous and freshwater resident C.ectenes,and 8.3% to 8.8% between the larvae and C.mystus.NJ molecular dendrogram showed that all the larvae and the anadro-mous and freshwater resident C.ectenes clustered together,while individuals of C.mystus forming a separate cluster.Thus,the larvae were not of C.mystus.As there is no freshwater resident C.ectenes inhabiting in the Estuary,the larvae should be of the anadromous C.ectenes.