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利用一对特异性引物MHC 2b-snp-sf和MHC 2b-snp-sr,从广东省3个不同罗非鱼养殖地区(以下分别称高要群体,茂名群体,惠州群体)采集的137尾尼罗罗非鱼(Oreochromis niloticus,GIFT strain)的个体基因组中扩增出长度为775~796 bp的片段。克隆后测序,序列分析结果显示:775~796 bp的核苷酸序列中共检测出62个简约信息位点,49个单碱基突变位点。112个多态位点中,增添/缺失位点34个,转换位点44个,颠换位点33个,另外一个位点既出现转换(C/T)又出现颠换(A/T)。137尾个体的751个阳性克隆的测序结果分析表明,751条序列分属于4个等位基因。其中,等位基因Orni-DAB*0101在3个群体中所占比例最高(85.2%)。等位基因的分布及群体内遗传多样性参数分析表明:高要、茂名群体遗传多样性较丰富,惠州群体遗传多样性较低。群体间的分化指数(FST值)、平均基因流(Nm)、分子方差分析(AMOVA)和平均K 2-P遗传距离均表明3个养殖群体间存在广泛的基因交流,未发生群体间的遗传分化。该研究结果提供了广东地区养殖尼罗罗非鱼MHCⅡB基因的部分遗传信息,为尼罗罗非鱼抗病品系的选育提供理论依据。
Using a pair of specific primers MHC 2b-snp-sf and MHC 2b-snp-sr, 137 tails collected from three different tilapia culture areas in Guangdong Province (hereinafter referred to as Gaoyao, Maoming and Huizhou populations) The length of 775 ~ 796 bp was amplified from the individual genome of Oreochromis niloticus (GIFT strain). Sequence analysis showed that 62 simple information sites and 49 single-base mutation sites were detected in the nucleotide sequence of 775-796 bp. Of the 112 polymorphic loci, 34 loci were added / deleted, 44 loci were translocated, 33 loci were translocated and the other locus was both C / T and A / T, . Analysis of sequencing results of 751 positive clones of 137 individuals showed that 751 sequences belonged to 4 alleles. Among them, the allele Orni-DAB * 0101 accounted for the highest proportion of the three populations (85.2%). The distribution of alleles and analysis of genetic diversity within populations showed that the genetic diversity of Gaoyao and Maoming populations was rich and the genetic diversity of Huizhou population was low. Differentiation index (FST), average gene flow (Nm), molecular variance analysis (AMOVA) and average K 2-P genetic distance among the three groups showed that there was a wide range of gene exchange among the three farmed groups without inter-population genetic Differentiation. The results provided some genetic information of MHCⅡB gene of farmed Nile tilapia in Guangdong region and provided theoretical basis for the breeding of the resistant strain of Nile tilapia.