[The histological characteristics of longissimus dorsi and its correlation with restriction fragments polymorphism of calpastatin gene in f2 Jinghua x Pietrain crossbred pigs].

Abstract

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.