摘要
通过聚合酶链式反应 (PCR)对中国华北型优良地方猪种莱芜猪及杜里猪、长白猪的卵泡刺激素 (FSH) β亚基基因结构区插入片段进行扩增 ,并对 0 .5kb扩增产物进行克隆和测序。序列分析表明 ,在已发表的猪FSHβ亚基基因全序列的 +80 9与 +810碱基之间 ,莱芜猪、杜里猪和长白猪分别存在一个长度为 2 75、2 77和 2 74bp的插入片段 ,插入片段末端的poly(A)分别为 17、19和 16个腺苷酸 ,均显著短于高产猪种太湖猪 (2 92bp和 32个腺苷酸 )。对FSHβ亚基基因插入片段进行BamHⅠ多态性分析 ,发现本研究所检测样品中不存在BamHⅠ多态性。插入片段中存在一个RNA聚合酶Ⅲ启动子及AluⅠ内切酶识别位点 ,所以该片段可能为Alu成分。因RNA聚合酶Ⅲ这种有功能的内部启动子能够转录相邻的染色体序列 ,该插入片段可能影响FSHβ亚基基因或其他基因的表达调控。把FSHβ亚基基因作为控制猪产仔数主效基因的候选基因与产仔数进行连锁分析 ,证明FSHβ基因座位在莱芜猪种中与控制猪产仔数的主效基因紧密连锁 ,优势基因AA纯合子比BB纯合子母猪平均每胎多产仔 1.2头。因不同品种猪插入序列的主要差异是末端的poly(A)长短不同 ,推测该插入片段末端的poly(A)结构亦可能影响猪的产仔数。
The inserted fragment of FSH β subunit gene in Laiwu pigs,an excellent local pig breed in North China,Duli pigs and Landrace pigs was amplified,cloned and sequenced. Sequence analysis showed that the length of the fragments inserted between +809bp and +810bp of the published sequences (D00621) were 275bp,277bp and 274bp in Laiwu,Duli and Landrace pigs,respectively. And the poly (A)s in these inserted fragments were 17,19 and 16 adenines,respectively. They were all shorter than those in Taihu pigs(292bp and 32 adenines,respectively)reported formerly. According to the RNA polymerase Ⅲ promoter structure and Alu Ⅰ restriction enzyme site in the inserted fragment,it should be regarded as an Alu element. FSH β subunit gene was considered as one candidate gene of pig litter size trait,while RNA polymerase Ⅲ promoter could promote the transcription of the neighboring chromosome sequence so as to control the expression of FSH β subunit gene or other genes. As a result,the major difference of the inserted fragment among different pig breeds was originated from the length of poly (A) end. So it was assumed that the poly (A) structure in the inserted fragment could influence the pig litter size. Because Laiwu pigs with genotype AA had 1.2 litter size more than those with genotype BB ,it could be concluded that FSH β subunit gene was related with pig litter size traits or linked with the genes of which,and the poly(A) structure in this Alu element played a critical role.
