【作者】 陈勇；

【导师】 雒秋江；

【作者基本信息】 新疆农业大学 ， 草业科学， 2009， 博士

【摘要】 绵羊的繁殖性能受到基因、年龄、季节和营养等的影响,其中基因是影响绵羊多胎性状的一个重要因素。绵羊多胎性状由多个基因控制,在这多个基因中可能存在一个主基因,并且不同的绵羊品种,控制多胎性状的主基因可能是不同的。本研究采用候选基因法对BMPR-IB基因的A746G突变、BMP15基因的FecXG和FecXL位点、GDF9基因的外显子1和外显子2、PRLR基因的内含子9和外显子10、ESR基因的外显子1以及IGF-I基因的5`-侧翼区在小尾寒羊、中国美利奴(新疆型)多胎品系、中国美利奴(新疆型)肉用品系、中国美利奴(新疆型)体大品系、中国美利奴(新疆型)、德国肉用美利奴、萨福克以及陶赛特8个品种(品系)中约330例的多态性及其与平均窝产羔数间的关系进行了研究。研究结果表明:(1)采用PCR-RFLP技术除在小尾寒羊中检测到BMPR-IB A746G突变外,同时在中国美利奴(新疆型)多胎品系、肉用品系以及萨福克中存在该突变。但只有在小尾寒羊群中B等位基因为优势基因。BB基因型小尾寒羊平均窝产羔数比B+基因型和++基因型多0.97只和1.89只(P<0.01),B+基因型母羊平均窝产羔数比++基因型多0.92只(P<0.01)。B等位基因与小尾寒羊的多羔性有关,可应用于小尾寒羊多羔个体的选育工作。但在中国美利奴(多胎)品系中,BMPR-IB A746G突变可能不是影响其繁殖性能的主基因。(2)在小尾寒羊等8个品种(品系)中未发现BMP15 FecXG多态性;但在FecXL所在区域发现一个G1047A突变,该突变与FecXL(G962A)不同,不影响编码氨基酸,是在BMP15中新发现的一个突变,该突变也不影响小尾寒羊等7个品种(品系)的产羔数。(3)在小尾寒羊等8个品种(品系)GDF9基因外显子1编码区未发现多态性。在GDF9外显子2发现G4突变,该突变不影响小尾寒羊等7个品种(品系)的平均产羔数。(4)在绵羊PRLR内含子9的第259bp处,存在一个C→T,在小尾寒羊,BB基因的平均产羔数分别较AA和AB基因型提高0.81和0.87只(P<0.05);在PRLR外显子10的第304bp处存在一个G→A突变,该突变导致PRLR第387位氨基酸残基由Glu突变为Lys。该突变使中国美利奴(新疆型)多胎品系中AB基因型的平均产羔数较AA基因型和BB基因型增加0.58和0.80只(P<0.05)。在PRLR外显子10第571bp、585bp和606bp处分别存在G→A、C→G和C→T突变;其中前2处突变分别导致PRLR的第476位氨基酸由Ala突变为Thr;第480位氨基酸由Ser突变为Arg。其中Ala476Thr突变导致小尾寒羊的AB基因型的平均窝产羔数显著高于AA基因型的窝产羔数,增加0.8只(P<0.05)。(5)采用2对PCR引物对绵羊ESR外显子1进行PCR-SSCP分析,在该分析区域未发现多态性。(6)在绵羊IGF-I 5`端侧翼区,即外显子1起始密码子ATG上游-651bp和-649bp处分别发生了G→C和G→A的突变。在小尾寒羊AA基因型和AB基因型的产羔数较BB基因型高1.2和1.45只(P<0.05)。在中国美利奴(新疆型)多胎品系中,AB基因型有增加产羔数的趋势,AB基因型较AA基因型的产羔数高0.67只(P=0.077)。其它品种不同基因型的产羔数之间无显著差异。本研究结果提示:绵羊多羔个体的选择有品种差异,应根据不同品种(系)各自的多羔基因型进行选择。小尾寒羊多羔个体可选择BMPR-IB基因A746G位点的BB基因型,中国美利奴(新疆型)多胎品系多羔个体可选择PRLR基因外显子10 G304A的AB基因型。控制其它绵羊品种多羔性的主基因还需要进一步研究。更多还原

【Abstract】 The prolificacy of sheep was affected by many factors, such as genetic, age, season, nutrition, and so on. Genetic was the most important one. In some instances, the differences in ovulation rate have been attributed to the action of a single or a closely-linked group of genes. Mutations in these genes may change litter size of sheep. In the present research, the polymorphism of A746G of bone morphogenetic protein receptor IB (BMPR-IB), FecXG and FecXL locus of bone morphogenetic protein 15 (BMP15), exon 1 and exon 2 of growth differentiation factor 9 (GDF9), intron 9 and exon 10 of prolactin receptor (PRLR), exon 1 of estrogen receptor (ESR) and the 5` flanking region of insulin-like growth factor-I (IGF-I) gene in 330 sheep of eight breeds or strains, which including Small Tail Han (STH), Poll Dorset (PD), Suffolk (S) Germany Mutton Merino (GMM) and Chinese Merino (Xinjiang type) (including Prolific strain (PS), Meat strain (MS) and Large Frame strain (LFS) ), were detected and the relationship between genotypes and average litter size were analyzed. The results showed that (1) the A746G mutation in BMPR-IB gene was found not only in STH but also in PS, MS and S. Whereas B allele of the A746G mutation was the dominant gene only in STH population. The average litter size of BB genotype was 1.89 and 0.97 greater than those with genotype + + and B+, and B+ was more than 0.92 compare to that of ++ in Han sheep (P<0.01). But the different was not observed in PS. The results indicated that there was a significant positive correlation between B allele and prolificacy in STH, which could be used for the selection the prolificacy individual of STH. However, there was no correlation between B allele and litter size in other breeds or strains. (2) The polymorphism of FecXG locus of BMP15 was not detected in these 8 pupolations. A novel mutation, G1047A, was found in FecXL locus. However the new-found mutation did not affect the coding amino acid of sheep BMP15. There was no correlation between genotypes and average litter size of this locus. (3) The polymorphism in exon 1 of GDF9 was not found by PCR-SSCP in the 8 breeds/strains, but the known G4 mutation in the exon 2 of GDF9 gene was detected in these breeds/strains. However, further analysis displayed that the correlation between genotypes and litter size did not exist. (4) A C→T at No.259bp in PRLR intron 9 was found. The average litter size of BB genotype of this mutation was 0.81 and 0.87 more than that with AA and AB genotype in STH (P<0.05). In addition, four mutations, including G→A, G→A, C→G, and C→T, at No.304, 571, 585 and 606bp in PRLR exon 10 were found, respectively. Among these mutations, 304G→A, 571G→A and 585C→G leaded Glu changed to Lys at 378, Ala to Thr at 476, Ser to Arg at 480 in sheep PRLR, respectively. For the 304G→A, the average litter size of AB genotype was 0.58 and 0.80 greater than those with AA and BB genotype in PS population (P<0.05). In STH, the average litter size of the AB was 0.80 greater than that of AA genotype of 571G→A mutation. (5) Single nucleotide polymorphisms of exon 1 of ESR gene were detected by PCR-SSCP. No polymorphism was detected in the amplified region in the eight sheep breeds/strains. (6) PCR-SSCP analysis and DNA sequencing of the 5’flanking region of IGF-I revealed that there were two mutations, G→C and G→A, located at -651bp and -649bp upstream of initiator ATG. In STH, the average litter size of the AA and AB was 1.2 and 1.45 greater than that of BB genotype (P<0.05). In PS strain, the mutation has the tendency to increase the litter size. The average litter size of AB genotype was 0.67 greater than that of AA genotype in PS (P=0.077). In other population, the difference was not detected.These results suggested that species differences must be considered for prolificacy individual selection. For genetic selection, respective prolificacy genotype should be based on, such as BB genotype of A746G mutation in BMPR-IB gene for STH, AB genotype of G304A mutation in PRLR exon 10 for PS. For other sheep breeds or strains, the major genes controlling prolificacy require further study.更多还原