金皮猪肉质相关组织学特征与CAST基因HinfI多态性的关系研究

本实验选择具有优良肉质的本地金华猪与肉质较差的引进品种皮特兰猪杂交所产的金皮F2代为研究对象，利用PCR-RFLP的方法检测金皮F2代猪CAST基因型的频率，并以肌球蛋白重链（MHC）免疫组织化学、过碘酸希夫反应和苏木精-伊红等多种组织学方法，研究猪背腰最长肌的肌肉组织学特性，并对其进行图像分析，在此基础上采用SAS分析其相互关系。结果发现．PAS染色后肌纤维可区分为三种类型。PAS阴性（Ⅰ）、PAS反应强阳性（Ⅱ-a）和PAS反应强度中间型（Ⅱ-b）。利用肌球蛋白重链单克隆抗体MHCs和MHCf染色结果表明．金皮F2代杂交猪背腰最长肌MHCs阳性（慢肌）纤维的比例为7．62％，快肌纤维为92.38％。CAST基因的扩增产物具有524bp和632bp两个Hinfl多态性片段，定义等位基因为A（114＋192＋400＋632bp），B（114＋192＋400＋524bp）。AA、BB和AB基因型频率分别为0．1795、0．5897和0．2308，A和B的基因型频率分别为0．4743和0．5256。AA、BB和AB单型对眼肌面积．系水率、pH值、导电率等参数均无显著的影响。CAST基因的HinfI多态性对肌纤维的轴比有显著影响，AA单型有产生较多轴比较大（近似椭圆形）肌纤维的倾向．而BB则控制形成更多的轴比更小（近似于圆形）的肌纤维。具有AA单型的个体具有更多的肌间结缔组织．而具有BB单型的个体的肌间结缔组织较少．AB单型的个体介于两者之间。

THE HISTOLOGICAL CHARACTERISTICS OF LONGISSIMUS DORSI AND ITS CORRELATION WITH RESTRICTION FRAGMENTS POLYMORPHISM OF CALPASTATIN GENE IN F2 JINGHUA×PIETRAIN CROSSBRED PIGS.

In order to evaluate the genotype of CAST gene and its relationship with the muscle histology and other postmortem traits. 158 Jinpi F2 pigs were electrically stunned and exsanguinated. The blood and muscle samples were collected, and both postmortem and meat traits were recorded. PCR-RFLP, PAS and myosin heavy chain immunohistochemistry were employed to explore the relationship between the genotypes and the muscle histology. Based on the PAS reactivity, the muscle fibers can be divided into three types: I, II-a and II-b. Myosin heavy chain immunohistochemistry could differentiated the fibers into slow fibers and fast fibers, the ratio of slow fibers and fast fibers is about 7.62% and 92.38% respectively. The amplification products of the region between 6th and 7th exon of CAST gene were digested by HinfI and discriminated 2 polymorphic sites (524bp and 632bp) in endonuclease map. Only 3 genotypes (AA,AB and BB) was distinguished out. The frequency of AA, AB and BB is 0.1795, 0.5897 and 0.2308 respectively. The frequency of A and B is 0.4743 and 0.5256 respectively. Different genotypes had no statistical significant effect on area, water holding capacity, pH value, and conductivity of longissimus dorsi muscle. The results revealed that the genotypes had a significant effect on the aspect ratio of muscle and showed a negative correlation with the percentage of intramuscular connective tissue.