5个品种(系)罗非鱼线粒体12S rRNA基因序列及其RFLP分析

Sequence Analysis and RFLP Analysis of 5 Varieties(Strains) of Tilapias Based on Partial Sequences of Mitochondrial 12S rRNA Gene

采用PCR产物直接测序法分别测定了尼罗罗非鱼(Oreochromis niloticus)埃及品系、美国品系和吉富品系以及奥利亚罗非鱼(O.aureus)、尼奥罗非鱼(尼罗罗非鱼♂×奥利亚罗非鱼♀)的线粒体12S rRNA基因部分序列,并结合从Genbank中下载的尼罗罗非鱼同源序列进行了序列比对分析。结果表明,3个尼罗罗非鱼品系与从Genbank中下载的尼罗罗非鱼的同源序列仅有1处碱基不同,奥利亚罗非鱼和以奥利亚罗非鱼为母本的尼奥罗非鱼之间也仅有1处碱基不同,但是3个尼罗罗非鱼品系以及从Genbank中下载的尼罗罗非鱼同源序列与奥利亚、尼奥罗非鱼相比对,则有14个位点不同,这个结果符合mtDNA母性遗传的特点,也说明12S rRNA在这5个罗非鱼品种(系)间是相当保守的,尼罗和奥利亚罗非鱼之间尚有一定的遗传多样性,但尼罗罗非鱼3品系的12S rRNA基因序列则几乎完全相同,可见mtDNA 12S rRNA基因不太适用于罗非鱼种内的遗传多样性分析。对得到的PCR产物进行限制性内切酶分析发现,mtDNA 12S rRNA上的BglⅡ酶切位点可作为鉴定尼罗罗非鱼和奥利亚罗非鱼及其正反交后代的有效分子标记。

The 12S rRNA sequences were amplified in 3 varieties(strains) (Egypt strain,America strain and Gift strain) of Nile tilapia(Oreochromis niloticus),Blue tilapia(O. aureus) and Blue-Gift tilapia(Blue tilapia♀×Gift♂) by PCR and directly sequenced.Combined with homologous Oreochromis niloticus 12S rRNA gene from Genbank,6 sequences were compared and analyzed.The results showed that there was only one site difference among 3 strains of Nile tilapias and homologous sequence from Genbank,and there was also one site difference between Blue tilapia and Blue-Gift tilapia.However,there were 14 variable sites between 3 strains of Nile tilapias and Blue tilapia.This comparison results was in accordance with the maternal inheritance characteristic of mtDNA.It also indicated that 12S rRNA was quite conserved in 5 varieties(strains) tilapias.There was still some genetic diversity between Nile and Blue tilapia,but the 12S rRNA sequences of 3 strains of Nile tilapias were almost identical,thereby the 12S rRNA sequence was not suitable for intra-species genetic diversity analysis in tilapias.PCR amplicons of 12S rRNA were digested by restriction endonucleases selected,the endonucleases BglⅡwas demonstrated to be reliable in Nile tilapia and Blue tilapia identification.