关键词: 拖网捕捞, 海洋生态系统, 食性指数, 品种组成指数

Abstract: By using PCR-SSCP, the single-nucleotide polymorphism of 3′ side of MyoG gene in pig breeds Landrace, Large White, Duroc, Shanxi Black and Mashen was tested, with the effects of the MyoG gene on the test pigs birth mass, weaning mass, 6-month body mass, and backfat thickness analyzed. On the basis of published sequence of 3′ side of pig MyoG gene, three pairs of primers were designed, and one polymorphism was found in the PCR product amplified with F1/R1 primers. The results showed that in the breeds Landrace, Large White and Duroc, allele B was the dominant gene and its frequency was 0.8807, 0.7256 and 0.8581, respectively, while in breeds Shanxi Black and Mashen, allele A was the dominant gene and its frequency was 0.9359 and 10000, respectively.Breeds Landrace, Large White and Duroc differed significantly (P<0.01) in their genotype frequencies from breeds Shanxi Black and Mashen. Based on the analysis with fixed effect model, significant differences among different MyoG genotypes were observed in birth mass (P<0.05), whereas no significant differences existed in weaning mass, 6-month body mass, and backfat thickness. Least square analysis indicated that the individuals of BB genotype had significantly higher (P<0.01) birth mass than those of AA and AB genotypes, with the sequence of BB>AB>AA. These results suggested that genotype had significant effects on the individual’s birth mass, and selecting the individuals with B allele could be favorable to the birth mass.

Key words: Trawl fishing, Marine ecosystem, Trophic index, Composition index