To explore the molecular genetic variation and provide experimental data for conducting further molecular breeding program, the DNA polymorphism of exon 1 and 5' flanking region of MyoG gene in cattle (Luxi and Bohai),yak and water buffalo were analyzed by use of PCR-SSCP and DNA directly sequencing.The results showed that SSCP polymorphisms exist in Luxi and water buffalo populations.Sequencing results demonstrated that no nucleotide mutation was detected in both Bohai cattle and yak samples,whose nucleotide sequences were consistent with the published data from GenBank.However,one transversion site (g.48G→C) in exon 1 of MyoG was found in Luxi cattle samples,which led to three genotypes of GG, GC and CC, and the allele frequencies of G and C were 0.743 7 and 0.266 4 respectively.Six mutation sites were found in water buffaloes.A transversion site g.-5 A→T led to two genotypes of AA and AT, and the allele frequencies of A and T were 0.825 0 and 0.175 0 respectively.The other five mutation sites were detected in exon 1 ,the transversion g.201T→G created a species special restriction enzymes site for water buffalo.All the mutants occurred in the third base of triplet codon with synonymous displacements.The deducted amino acid sequences of the four populations were completely identical.The g.48 G→C of MyoG gene exonl in Luxi cattle maybe a potential SNP marker correlated with the animal growth traits.%采用PCR-SSCP结合DNA直接测序技术,分析黄牛(鲁西牛、渤海黑牛)、牦牛和水牛肌细胞生成素基因(MyoG)外显子1和5′侧翼部分序列的DNA多态性,旨在揭示中国3个主要家养牛种的群体遗传变异并为开展分子育种提供试验依据.结果表明,鲁西牛和水牛群体存在SSCP多态性.序列分析结果显示,渤海黑牛和牦牛MyoG外显子1和5′侧翼部分序列与GenBank相应序列完全一致.鲁西牛在外显子1发生g.48 G→C颠换,由此形成GG、GC和CC 3种基因型,G、C等位基因频率分别为0.743 7、0.266 4;水牛分化明显,发生6处突变,位于g.-5 A→T颠换导致形成AA和AT 2种基因型,A、T等位基因的频率分别为0.825 0、0.175 0;另外5处突变发生在外显子1序列中,其中g.210 T→C颠换是水牛特异性的限制性酶切位点.所有突变均发生在三联体密码子的第3位,且均为同义替代.编码氨基酸在4个牛群体间完全一致.推测鲁西牛MyoG基因外显子1的g.48 G→C突变可能是一个与生长发育性状存在一定相关性的潜在SNP位点.
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