【作者】 郭月英；

【导师】 靳烨；

【作者基本信息】 内蒙古农业大学 ， 农产品加工及贮藏， 2014， 博士

【摘要】 内蒙古大草原孕育了很多肉质鲜嫩的绵羊品种,巴美肉羊、苏尼特羊是其中杰出的代表。肉质是一个重要的经济指标,MyoG、Myf5、Myf6、CAST基因和MSTN基因被认为是影响肉质的重要的候选基因。实验分析了这些基因的表达量与肉质的相关性以及多态性对肉质的影响,实验结果将为巴美肉羊、苏尼特羊这些优良品种的选育、合理开发利用提供科学的理论依据。采用real-time PCR技术对不同月龄巴美肉羊(40只)、苏尼特羊(42只)中MyoG、 Myf5、Myf6、CAST和MSTN基因的表达规律、种间差异及基因表达量与肉质的相关性进行了研究。采用PCR-SSCP技术对101只巴美肉羊、107只苏尼特羊的钙蛋白酶抑制蛋白(calpastatin, CAST)基因进行了多态性分析,找到其突变位点,并对基因型与肉质的相关性进行了研究。测定的肉质指标包括嫩度、pH、色差、眼肌面积。结果发现：1.(1)巴美肉羊背最长肌中,Myf5基因表达量4、6月龄和12月龄的差异显著,12月龄>4月龄>6月龄；苏尼特羊背最长肌中,8月龄Myf5基因表达量显著高于5月龄；6、8月龄的苏尼特羊臂三头肌中Myf5基因的表达量显著高于背最长肌。(2)巴美肉羊臂三头肌中Myf6基因的表达量显著高于苏尼特羊。(3)苏尼特羊CAST基因在6、8、12月龄时,三个部位中的表达量均高于巴美肉羊;8月龄时,苏尼特羊臂三头肌中的CAST基因的表达量显著高于巴美肉羊。(4)①苏尼特羊6月龄背最长肌和股二头肌中的表达量显著高于巴美肉羊；苏尼特羊12月龄背最长肌中的表达量显著低于巴美肉羊。②巴美肉羊臂三头肌和股二头肌中MSTN在4月龄时表达量最高,背最长肌中MSTN基因的表达量一直升高;12月龄时,三个部位中MSTN的表达量基本相同。③苏尼特羊的三个测试部位中MSTN基因的表达规律相同,6月龄最高,12月龄降到最低,三个部位中臂三头肌的表达量最高。2.巴美肉羊和苏尼特羊6、8、12月龄的基因表达量与肉质相关性如下：(1)在苏尼特羊的在臂三头肌中,Myf5基因表达量与剪切力呈显著正相关。在苏尼特羊的臂三头肌中,Myf6基因表达量与pH2呈极显著负相关。在股二头肌中,Myf6基因表达量与pH2呈极显著负相关。(2)在巴美肉羊的股二头肌中,CAST基因表达量与剪切力呈显著正相关；苏尼特羊的背最长肌中CAST基因表达量与红度值呈显著负相关。(3)巴美肉羊背最长肌中的MSTN基因表达量与眼肌面积呈显著正相关与亮度值呈显著负相关。3.各个基因表达量的相关性如下：(1)巴美肉羊背最长肌中,MyoG与Myf6基因的表达量呈显著负相关关系。(2)在两个品种的所有测试部位中,Myf5与Myf6的表达量均为正相关关系,其中巴美肉羊臂三头肌中的Myf5和Myf6的表达量呈显著正相关。(3)Myf6与CAST基因在两个品种的三个测试部位中均表现为正相关性。(4)在苏尼特羊的三个部位中,各个基因表达量的相关性不显著。4.巴美肉羊、苏尼特羊基因分型发现：(1) CAST基因的第六外显子区存在三种基因型：AA、AB和AC型。巴美肉羊群体中多态信息含量为0.30；苏尼特羊群体中多态信息含量为0.28,均为中度多态。CAST基因第六外显子检测到2个突变位点,56bp处发生了A/G碱基替换,在184bp处出现了A/C碱基替换。5.CAST基因基因型与肉质的相关性研究中发现：6月龄巴美肉羊三各基因型的红度值存在显著性差异,AB型>AA型>AC型。更多还原

【Abstract】 Bamei and Sunit sheep in Inner Mongolia was famous for their super meat quality. Meat quality was an import ecnomic trait. MyoG, Myf5, Myf6, CAST and MSTN gene were impoetant candidate genes for meat quality. Correlation of the expression and Polymorphism with meat quality had been investigated. It may offer genetic theory for further development and utilization for Bamei and sunit sheep.Real-time PCR was used to investigate the expression of cadidate genes (MyoG, Myf5, Myf6, CAST, MSTN) in longissimus dorsi, triceps and biceps femoris in40Bamei and42sunit sheep of defferenet month age. The shear force, pH, colour, loin area were investigated after slaughter. The expression of the cadidate genes was detected. The correlation between the expression and meat quality traits were analyzed.The results show as follows:1.(1) The expression of Myf5of4,6month was significant difference with the expression of12month in longissimus dorsi in Bamei sheep, the order was12month>4month>6month. The expression of Myf5of8month in longissimus dorsi in Sunit sheep was highest and it was significant difference with the expression of5month. The expression of Myf5in6and8month in triceps in Bamei sheep was significant higher than in Sunit sheep.(2) The expression in triceps in Bamei sheep of12month was significant higher than in Sunit sheep.(3) The expression of CAST in Sunit sheep was higher than in Bamei sheep in three muscles of of6,8,12month. The expression of CAST of8month in triceps in Sunit sheep was significant higher than in Bamei sheep.(4) The expression of MSTN show as follows:①The expression of MSTN in longissimus dorsi and biceps femoris of6month in Sunit sheep was significent higher than in Bamei sheep. The expression of MSTN in longissimus dorsi of12month in Sunit sheep was significent lower than in Bamei sheep.②In Bamei sheep, the expression of MSTN in triceps and biceps femoris is highest of4month age, the expression of MSTN in iongissimus dorsi was increasing with the growth of month age. In three muscles investigated, the expression of MSTN was nearly same of12month age.③In Sunit sheep, there was a similar variation trend of the expression of MSTN in three musles investigated. It was highest of6month age and lowest of12month age.It was higer in triceps than in the other two muscles.2. The correlation between the expression and meat quality traits show as following: ①In Sunit sheep, the expression of Myf5in triceps had significant positive correlation with shear force (r=0.985, p=0.015), In Sunit sheep, the expression of Myf6in triceps had greatly signifieant negative correlation with pH2, in biceps femoris, it had significant negative correlation with pH2.②In Bamei sheep, the expression of CAST in biceps femoris had signifieant positive correlation with shear force.In Sunit sheep, in longissimus dorsi, it had signifieant negative correlation with red/green colours.③In Bamei sheep, the expression of MSTN in longissimus dorsi had signifieant positive correlation with loin area, it had signifieant negative correlation with lightness.3. The correlation between the cadidate genes:(1) In Bamei sheep, the expression of MyoG in longissimus dorsi had signifieant negative correlation with the expression of Myf6.(2) The expression of Myf5had positive correlation with the expression of Myf6in three muscles investigated in two breeds and in triceps in Bamei sheep, the positive correlation was signifcent.(3) The expression of Myf6had positive correlation with the expression of MSTN in three muscles investigated in two breeds.Polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) method was used to determine the polymorphism of exon6of CAST gene in101Bamei sheep and107Sunit sheep, the correlation between CAST gene and meat quality traits were analyzed. The result show as follows:4.There was two mutation have been found in the exon6of CAST gene (A56G, A184C) in the research.Three genotypes were identified as AA, AB and AC. Polymorphism information content was0.30in Bamei sheep. Polymorphism information content was0.28in Sunit sheep.5. The correlation between genotype and meat quality:In6-month Bamei sheep, there was significant difference of red/green colours (a*) in longissimus dorsi of three genotypes, red/green colours (a*) of AB genotype was better. In12-month Bamei sheep there was significant difference of lightness (L*) of three genotypes in both triceps and biceps femoris.更多还原