奥尼罗非鱼杂交子代及亲本mtDNA D-loop基因序列的多态性

Polymorphism of the Mitochondrial DNA D-loop Gene Sequences of Oreochromis niloticus,O. aureus and Their Hybrids

利用PCR技术扩增奥利亚罗非鱼(Oreochromis aureus)、尼罗罗非鱼(O.niloticus)及其杂交子代(O.aureus♂×O.niloticus♀)3个群体mtDNA控制区全序列,分析其变异和遗传结构。结果显示:3个群体的mtDNA控制区序列长度多态性并不十分明显,全长921～933bp;3个群体间存在丰富的DNA序列多态性,共检测到138个变异位点(14.9%),44个个体具有44种单倍型(haplotype);3群体间的序列差异平均为4%,Tamura-Nei遗传距离平均为5.1%;采用NJ法和ME法构建的分子系统树中,奥利亚罗非鱼群体内所有的单倍型聚成一支,尼罗罗非鱼与其杂交子代的单倍型混杂在一起,聚成一支,表明杂交后代mtDNAD-loop表现为母系遗传。

The complete sequences of mitochondrial DNA control region in tilapia, Oreochromis aureus （OL）, O. niloticus （NL）and the hybrid of O. aureus ♂×O. niloticus♀（AN） were determined to analyze their sequence variation and genetic structure. The sequence length of the control region in individuals of tilapia was between 921bp and 933bp, which revealed that the length polymorphism of control region sequence in tilapia was not distinct, but high nucleotide content polymorphism was examined in the three populations. 138 loci （14.9%） were variable in mtDNA D-loop gene segments, and there were 44 haplotypes in 44 individuals. The average sequence divergence of conlrol region in three tilapia populations was 4%, and the Tamura-Nei distances was 5. 1%. In molecular phylogenetic tree constructed by NJ method and ME method, all the haplotypes of Oreochromis aureus samples clustered into one branch, while the haplotypes of Oreochromis niloticus and the hybrids samples intermixed together and clustered into another branch, which showed that mtDNA D-loop of the hybrids presented maternal inheritance.