下司犬线粒体DNA的遗传多样性研究

Genetic Diversity of Mitochondrial DNA Sequences in Xiasi Dog

为调查下司犬种群的遗传资源,采用PCR扩增和测序方法获得10只下司犬线粒体D-loop序列,发现其D-loop 5’端高变区Ⅰ582bp碱基序列的A+T含量明显高于G+C含量,表现出强烈的反G偏倚。并于下司犬高变区Ⅰ序列检测到11个多态位点,构成7种单倍型,单倍型多样性为0.867,说明下司犬线粒体D-loop的单倍型类型丰富,但其高变区Ⅰ的核苷酸多样性(P i=0.005 19)和平均核苷酸差异(k=3.002)却提示,下司犬的遗传多样性较低。聚类分析结果显示,中国家犬有3个母系来源,下司犬起源于C ladeⅠ并与藏獒的亲缘关系最近,因此藏獒可用于对下司犬的选育和复壮。

To investigate the genetic resource of Xiasi dog, the mitochondrial D -loop sequences of 10 individuals were obtained by Polymerase Chain Reaction （PCR）. The hypervariable region I （582 bp） at the 5＇terminus of D - loop contained higher percentage of A ＋ T than C ＋ G due to anti - G bias, and seven haplotypes with abundant diversity （ Hd = 0. 867） were defined by a total of 11 polymorphic sites from Xiasi dog. The nucleotide diversity and average number of nucleotide differences were 0.005 19 and 3. 002, respectively, indicating the narrow genetic diversity in Xiasi dog population. The cluster analysis showed that Xiasi dog originated from Clade I, one of three maternal lines of China domestic dog. Furthermore, it demonstrated a close relationship with Tibetan Mastiff, which may be beneficial for breeding and rejuvenation of Xiasi dog population.