猪肌细胞生成素基因对部分生长性状的影响

采用PCR-SSCP方法对长白猪、大白猪、杜洛克猪、山西黑猪和马身猪的肌细胞生成素（Myogenin，简称MyoG）基因进行单核苷酸多态性检测，并分析MyoG基因对猪的初生重、断奶重、6月龄重和背膘厚的影响。根据猪MyoG基因的DNA序列设计10对引物，发现In2-3引物扩增的片段有多态性。统计结果发现，3种基因型（AA、AB、BB）在各品种中的分布不一致。χ^2独立性检验表明，基因型频率在外来猪种（长白猪、大白猪、杜洛克猪）与地方猪种（山西黑猪、马身猪）间存在显著差异（P〈0．05）。固定效应模型分析结果表明，初生重和背膘厚基因型间差异显著（P〈0．05），而断奶重和6月龄重基因型间差异不显著（P〉0．05）。最小二乘分析结果表明，BB基因型与其他两种基因型比较有较小的初生重，同AA和AB型比较差异极显著（P〈0．01），3种基因型在初生重的大小排列顺序为AA〉AB〉BB；AA基因型与其他两种基因型比较有较小的背膘厚，同AB和BB型比较差异极显著（P〈0．01），3种基因型在背膘厚的大小排列顺序为AA〈AB〈BB。因此，推测基因型对个体的初生重和胴体瘦肉率存在一定的影响，选择带有A等位基因的个体有望提高个体的初生重和胴体的瘦肉率。

Effects of the MyoG Gene on the Partial Growth Traits in Pigs

Single-nucleotide polymorphisms of the MyoG gene were tested using PCR-SSCP in different pig breeds including Landrace, Large White, Duroc, Shanxi Black, and Mashen pigs, and the effects of the MyoG gene on the birth weight, the weaning weight, the 6-month body weight, and the backfat thickness were also analyzed. On the basis of the published sequence of the porcine MyoG gene, ten pairs of primers were designed, and one polymorphism was found in the PCR product amplified with In2-3primers. The results showed that: (1) the Landrace, the Large White, and the Duroc breeds differ significantly (P＜0.05) in genotype distribution from the Shanxi Black and the Mashen breeds; (2) On the basis of the fixed effect model, significant differences were found in the birth weight and the backfat thickness among the different MyoG genotypes, whereas no significant differences existed in the weaning weight and the 6-month body weight; (3) Using least square analysis, it was seen that individuals of the BB genotype had significantly less (P＜0.01) birth weight than those of the AA and AB genotypes, with the order being AA＞AB＞BB; the pigs of the AA genotype had significantly lower (P＜0.01) backfat thickness than those of the AB and BB genotypes,with the order being AA ＜AB＜BB. These results suggest that the genotype has significant effects on the individual birth weight and the backfat thickness, and that the selection of the A allele is favored with regard to the birth weight and the backfat thickness.