我国海域两种大型水母的分子鉴定

MOLECULAR IDENTIFICATION OF TWO MACRO-JELLYFISH IN CHINA

采用通用引物-PCR扩增法,测定了辽宁营口海蜇成体的部分16S基因序列578bp、部分COI基因序列633bp,以及黄海海域沙海蜇成体部分COI基因序列645bp、部分16S基因序列479bp。结果表明,海蜇个体间的16S序列只有一个变异位点,其余序列完全一致;COI序列共有4个变异位点,碱基之间只存在转换,没有颠换、插入或缺失的位点。沙海蜇个体间的COI序列碱基组成完全一致,16S序列碱基组成也完全一致。从辽宁盘锦和山东胶州所取的水母碟状体和稚水母的测序结果显示,COI序列与海蜇成体的差异为0.5%—0.6%,与沙海蜇成体的差异为18.9%—19.4%;16S序列与海蜇成体的差异为0.0%—0.2%,与沙海蜇成体的差异为13.1%—13.3%。以上结果表明,水母碟状体和稚水母都为海蜇而非沙海蜇。结合GenBank中已有的其它水母类COI基因同源序列信息,构建分子系统发育树。结果显示:轮环水母亚目(Kolpophorae)和指环水母亚目(Daktyliophorae)以及有肩板族(Scapulatae)和无肩板族(Inscapulatae)的分类划分,与传统分类一致。从分子水平上证明,在黄海海域采集的沙海蜇和在日本采集的越前水母的差异只处于种内水平,两者应为同物异名。

Rhopilema esculentum and Stomolophus meleagris are two common macro-jellyfishes in the Bohai Sea and the Yellow Sea, China. The partial sequences of COI （633bp, 645bp） and 16S （578bp, 479bp） genes were determined from adults of the two species. Only one variant locus in 16S sequence was revealed, while four variant loci were shown in R. esculentum. In S. meleagris, the partial COl gene showed coherent sequences among individuals, the same as that of the partial 16S gene. For ephyra and young jellyfish, the COI sequence differences in R. esculentum was 0.5%--0.6%; and 18.9%--19.4% in S. meleagris; the 16S sequence differences in R. esculentum was 0.0%--0.2%; and 13.1%--13.3% in S. rneleagris. The results show that the samples of ephyra and young jellyfish were actually R. esculentum. The homologous sequences of other jellyfishes were collected from GenBank to construct a molecular phylogeny tree. The relationship of four suborders agreed with the traditional taxonomy. The analyses on the COl gene sequence show that S. meleagris and Nemopilema nomurai should be the same species. Barcode used in this study would provide important references for the species identification, young jellyfish classification, and phylogeny.