摘要
罗非鱼种间,尤其是尼罗罗非鱼与杂种尼奥罗非鱼之间,很难区分。本文对尼罗罗非鱼、奥利亚罗非鱼、莫桑比克罗非鱼和杂交种尼奥罗非鱼(尼罗罗非鱼♀×奥利亚罗非鱼♂)和红罗非鱼的核糖体DNA内部转录间隔子1(ITS1)序列及其两侧的18S和5.8S部分序列特征进行分析,以筛选种间鉴别标记。PCR扩增产物大小约700 bp,测序结果表明,(去除引物后)18S长146 bp,5.8S长66 bp,不同种类之间无差异;ITS1长383-483 bp,因种类不同而异,其GC含量大于AT含量,达到67.1%。序列比对分析结果表明,18S和5.8S片段高度保守,但各有3个变异位点可以把上述几个种和杂种相互区分开;18S序列上有一个UnbI限制性酶切位点,可作为尼罗和尼奥罗非鱼的鉴别标记。ITS1序列种间变异大,系统发育分析表明,所研究的5个种聚成2个类群,尼罗与尼奥罗非鱼为一组,莫桑比克-红罗非鱼-奥利亚罗非鱼为另一组。组内种间遗传距离较小,尼罗和尼奥罗非鱼的种间遗传距离为0.006;莫桑比克、奥利亚和红罗非鱼的种间遗传距离在0.007-0.009之间;两组罗非鱼之间的遗传距离较大,在0.030-0.035之间,表明罗非鱼ITS1序列多态性较高,适合于种类区分。结合部分18S和5.8S序列,细胞核rDNA具有鉴别罗非鱼及其杂种的潜力。
It＇s very difficult to distinguish different Oreochromis species from each other, especially between Nile （ Oreochromis niloticus） and Ni - ao （ O. niloticus♀ × O. aureus ♂） tilapias, based on their morphological characters. In order to obtain the species diagnostic markers, complete ITS1 and its flanked 18S and 5.8S partial sequences of ribosomal DNA of five tilapias were analyzed, including Nile tilapia, Blue tilapia （O. aureus）, Mozambique tilapia （O. mossamb/cus） hybrid tilapias of Ni -ao ti- lapia and Red tilapia （O. mossambicus x O. niloticus）. The PCR product was about 700 bp long, which contained 146 bp of 18S and 66 bp of 5.8S after excluding primers sequences. The full length of ITS1 ranged from 383 to 483 bp. The GC content of ITS1 （67. 1% ） was higher than AT content. Sequence variation analysis indicated that 18S and 5. 8S are highly conserved, each with only three variable sites, which can tell the tilapias from their hybrids. The UnbI restriction site was found in 18S and can be used to distinguish Nile from Ni - ao tilapia. ITS1 was highly variable with insertions or deletions. Phylogenetic analysis showed that the tilapias studied constitute two clades ： Clade I with Nile and Ni - ao tilapias, and Clade Ⅱ with Blue, Mozambique and Red tilapias. Among the five species, genetic distances were 0. 006 between Nile and Ni - ao tilapias in Clade I, 0. 007 - 0. 009 among Mozambique, bule and red tilapia in Clade II, and 0. 030 to 0. 035 between the two clades. This study indicated that com- plete ITS1 and its flanked 18S and 5.8S partial sequences of rDNA could be used as potential markers for identification of tilapia species and their hybrids.
出处
《福建水产》
2009年第1期25-30,共6页
Journal of Fujian Fisheries
基金
广州番禺区科技计划项目(2004-Z-61-1)
关键词
罗非鱼
细胞核rDNA
序列变异
种类鉴定
Oreochromis tilapias
Nuclear rDNA
Sequence variation
Species identification
