【摘要】 利用PCR-SSCP技术分析了352只藏绵羊免疫球蛋白Aα重链恒定区基因(immunoglobulin constant heavyα-chain gene,IGHA)DNA片段的多态性。结果显示:藏绵羊IGHA基因存在多态性,共有6种基因型(分别命名为AA、BB、CC、AB、AC和BC),由3个等位基因控制(分别命名为A、B、C),克隆测序表明它们主要表现在长度(A长度为321bp,B、C长度都为315bp)和多个单核苷酸差异上;藏绵羊以基因型BC为主(基因型频率为0.534);不同基因型与5种可辨析的胃肠道线虫粪便虫卵计数(faecal egg counts,FEC)关联分析表明,CC基因型蔵绵羊对于类圆线虫(Strongyloides sp.)和夏伯特线虫(Chabertia sp.)具有相对较低的每克粪便中的虫卵数(eggs per gram,EPG)(P<0.05),说明CC基因型具有较高的抗这2种线虫感染的能力,为优势基因型,可以初步将之作为藏绵羊分子标记辅助育种的标记之一。更多还原

【Abstract】 Tibetan sheep is the local variety which adapts to the special geographical environment and climate conditions in the Tibetan Plateau for long-term evolution,and has strong resistance to disease.In order to understand the molecular mechanism of disease resistance in Tibetan sheep,three hundred and fifty-two Tibetan sheep were used for PCR-SSCP test to investigate whether allelic variants of immunoglobulin constant heavyα-chain gene(IGHA)are present in Tibetan sheep.The results showed that there were six genotypes(AA,BB,CC,AB,AC and BC)controlled by three alles(A,B and C)in Tibetan sheep.After cloning and sequencing,three different nucleotide sequences of IGHA gene,a sequence of 321bp(allele A)and two sequences of 315bp(allele B and C)were identified,and the three sequences also showed many nucleic acid differences,and BC was the main genotype with 0.534 genotype frequency.Further analysis for the association between the FECs of the five gastrointestinal nematodes and genotypes revealed that the sheep of CC genotype had lower eggs per gram(EPG)in Strongyloides sp.and Chabertiasp.(P<0.05).It is suggested that the sheep of CC genotype had the higher resistance to the two nematodes and was the superior genotype.Therefore,it might be one of molecular assisted breeding markers.更多还原