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罗氏沼虾(Macrobrachium rosenbergii)和日本沼虾(M.nipponense)已经在我国得到广泛的养殖,产生巨大的经济效益。祁连沼虾(M.qilianensis)是自然分布在我国甘肃省的土著虾种,因其外部形态符合沼虾属的特征,而被前人归入沼虾属。为了从分子生物学的角度理解罗氏沼虾、日本沼虾与祁连沼虾的遗传差异,为合理开发和利用沼虾资源提供理论基础,作者对这3种沼虾的线粒体COI基因序列进行研究。从甘肃、浙江等地分别采集这三种沼虾的样本各10尾,共30尾,其中祁连沼虾是野生样本,而罗氏沼虾和日本沼虾都是养殖样本。通过PCR方法扩增线粒体COI基因,并测序。通过比对,获得一致序列649bp。在30个样本中共检测到169个变异位点,占总变异的26.04%;共检测到7种单倍型。3种沼虾的核苷酸多态性分别为:罗氏沼虾0.411%、日本沼虾0.092%、祁连沼虾0.031%。野生的祁连沼虾遗传多样性远远低于养殖的罗氏沼虾和日本沼虾。三种沼虾单倍型之间的Kimura双参数遗传距离在19.87%～23.84%,三者之间的遗传距离较大,提示三者均为有效种。为进一步确定这三种沼虾在长臂虾科的分类地位,我们从NCBI数据库中下载了长臂虾科的其它种类的COI序列进行系统发生分析。用NJ法构建的分子系统树显示:日本沼虾和罗氏沼虾与沼虾属的其它种类聚成一枝,而祁连沼虾与同亚科的脊尾白虾(Exopalaemon carinicauda)和长角长臂虾(Palaemon debilis)较沼虾属另10种虾的遗传距离近,即祁连沼虾与白虾属及长臂虾属聚成另一枝。因此,COI序列的结果不支持祁连沼虾归入沼虾属。但其分类地位应该综合多方面证据重新进行分析确定。
Macrobrachium rosenbergii and M. nipponense have been extensively cultivated in our country, resulting in enormous economic benefits. M. qilianensis is an indigenous shrimp species distributed naturally in Gansu Province of our country, and was classified as a species belonging to the genus Macrobrachium due to its external appearance in line with the characteristics of the genus Macrobrachium. In order to understand the genetic differences between Macrobrachium rosenbergii, Macrobrachium rosenbergii and Macrobrachium rosenbergii and to provide theoretical basis for the rational exploitation and utilization of Macrobrachium shrimp resources from the molecular biology point of view, the authors studied the mitochondrial COI gene sequences of these three species of Macrobrachium . From Gansu, Zhejiang and other places were collected three samples of each of the 10 kinds of marsh shrimp, a total of 30, of which Qilian marsh is a wild sample, and Macrobrachium rosenbergii and marsh shrimp are cultured samples. The mitochondrial COI gene was amplified by PCR and sequenced. By alignment, a consensus sequence of 649 bp was obtained. A total of 169 polymorphic sites were detected in 30 samples, accounting for 26.04% of total variance. A total of 7 haplotypes were detected. The nucleotide polymorphisms of three species of Macrobrachium were 0.411% of Macrobrachium rosenbergii, 0.092% of Macrobrachium nipponense and 0.031% of Macrobrachium rosenbergii. The genetic diversity of wild Qilian marsh far below the breeding of Macrobrachium and Japanese marsh shrimp. The three genetic parameters of Kimura haplotypes were 19.87% ~ 23.84%. The three genetic distances were large, suggesting that all three were effective species. To further determine the taxonomic status of these three species of Macrobrachium in the Long-arm family Shrimp, we downloaded the COI sequences of the other species from the NCBI database for phylogenetic analysis. The molecular phylogenetic tree constructed by NJ method showed that Macrobrachium rosenbergii and Macrobrachium rosenbergii were clustered with other species of Macrobrachium, whereas Macrobrachium nipponense was associated with Exopalaemon carinicauda and long-horned long arm The genetic distance between Palaemon debilis and other 10 species of shrimp is close, that is to say, Macrobrachium rosenbergii and Porphyra shrimp belong to another species. Therefore, the result of COI sequence does not support the Macrobrachium marsh shrimp belong to genus. However, its taxonomic status should be re-analyzed and determined based on various evidences.