中华鲟野生群体及迁地群体的MHCⅠa基因遗传多样性变异研究

Study on the Genetic Variation of MHCⅠa Gene in Wild Population and Ex-situ Captive Breeding Population of Acipenser sinensis

利用特异性引物MHCⅠf和MHCⅠr,分别从30尾野生中华鲟(Acipenser sinensis)、30尾中华鲟子一代和30尾中华鲟子二代的基因组DNA中扩增MHCⅠa基因的多肽结合位点(PBR)片段,扩增产物长度为127 bp。中华鲟野生群体30个样品265个有效克隆中共检测出50条特异序列(单倍型),中华鲟子一代群体30个样品的278个有效克隆中共检测出66条特异序列(单倍型),中华鲟子二代群体30个样品的257个克隆中检测出64条特异序列(单倍型)。单倍型Acsi-UAB*0101在3个群体中所占的百分比最高,分别为58.1%、38.8%和60.7%。单倍型分布及群体内遗传多样性参数分析表明,中华鲟子一代群体的MHC基因遗传多样性最丰富,野生中华鲟群体的MHCⅠa基因遗传多样性较低。中华鲟野生群体非同义替代与同义替代比率为1.33,分析表明正向选择可能是中华鲟MHCⅠa多态性的主要因素。该研究结果提供了中华鲟从野生群体到子二代群体MHCⅠa基因的部分遗传信息和遗传变异规律,为中华鲟全人工种群优化和繁殖管理提供理论依据。

The peptide binding region（PBR） of MHCⅠa gene was amplified from 90 individuals which were sampled from wild population,first filial generation progenies and second filial generation progenies of captive Chinese sturgeon（Acipenser sinensis）,with a primer pair of MHCⅠf and MHCⅠr.Sequence analysis showed that the amplified fragments were 127 bp in length.50 unique sequences（haplotypes） were detected in 265 valid cloning from 30 individual of wild population,66 haplotypes were detected in 278 valid cloning from 30 samples of filial generation progenies,and 64 haplotypes were detected in 257 valid clones from 30 samples of second filial generation progenies.The proportions of the haplotype Acsi-UAB ＊0101were highest among the three groups,with 58.1%,38.8% and 60.7%,respectively.Distribution of haplotypes and parameter analysis of genetic diversity within population showed that the MHC Ia gene of first filial generation progenies had the most abundant genetic diversity,while wild population had the lowest genetic diversity.The rates of non-synonymous substitution（dn） were 1.36 times higher than the rate of synonymous substitution（ds） in the MHCⅠ in wild populations,showing that positive selection may be a major factor of MHCⅠa polymorphism.The present result provide part of the genetic information and general pattern of genetic variation of MHC Ⅰ a gene from wild populations to second filial generation progenies of Chinese sturgeon,providing a theoretical basis for artificial population optimization and reproductive management of Chinese sturgeon.