Fernández A I, Alves E, Fernández A, de Pedro E, López-García M A, Ovilo C, Rodríguez M C, Silió L
Departamento de Mejora Genética Animal, INIA, Ctra. de la Coruña km 7.5, 28040 Madrid, Spain.
J Anim Sci. 2008 Jun;86(6):1283-90. doi: 10.2527/jas.2007-0568. Epub 2008 Mar 14.
We carried out a study to investigate the associations between mitochondrial DNA polymorphisms and meat quality traits (intramuscular fat and protein content of the longissimus) in an Iberian porcine line named Torbiscal. The studied pigs (n = 319) belong to 9 maternal lineages and were previously assigned to 6 mitochondrial haplotypes (H1 to H6), based on Cytochrome b and Dloop sequences. Statistical analyses, following a bivariate mixed model, show a greater fat content and lower protein content in H3 haplotype carriers than H1, H2, H4, H5, and H6 haplotype carriers. The magnitudes of these differences are close to 1 g of fat and -0.5 g of protein per 100 g of muscle. To identify the causative mutation of these effects on intramuscular fat and protein contents, the complete mitochondrial DNA sequence of 6 individuals was determined, each one carrying a different mitochondrial haplotype. The alignments of these 6 complete mitochondrial sequences allowed identification of 32 substitutions and 2 indels. Two polymorphic positions were exclusively detected in H3 carriers: a synonymous transition 9104C > T in the gene-coding region of Cytochrome c oxidase subunit III and a substitution 715A > G in 12S rRNA. Genotyping results of a larger number of Torbiscal samples showed the exclusive presence of 9104T and 715G alleles in H3 carriers. The detected candidate substitutions are located in essential mitochondrial genes, and although they do not change the amino acid composition, we cannot disregard a potential change in the secondary structure of their corresponding mRNA. The usefulness of these polymorphisms as markers in selection programs requires validation of the consistency of these results in other Iberian pig lines.
我们开展了一项研究，以调查在一个名为托维斯卡尔（Torbiscal）的伊比利亚猪品系中，线粒体DNA多态性与肉质性状（背最长肌的肌内脂肪和蛋白质含量）之间的关联。所研究的猪（n = 319）属于9个母系谱系，此前根据细胞色素b和D环序列被分为6个线粒体单倍型（H1至H6）。采用双变量混合模型进行的统计分析表明，与H1、H2、H4、H5和H6单倍型携带者相比，H3单倍型携带者的脂肪含量更高，蛋白质含量更低。这些差异的幅度接近每100克肌肉中脂肪增加1克，蛋白质减少0.5克。为了确定这些对肌内脂肪和蛋白质含量产生影响的致病突变，我们测定了6头个体的完整线粒体DNA序列，每头个体携带不同的线粒体单倍型。这6条完整线粒体序列的比对使得能够鉴定出32个替换和2个插入/缺失。在H3携带者中仅检测到两个多态性位点：细胞色素c氧化酶亚基III基因编码区的同义转换9104C > T，以及12S rRNA中的替换715A > G。对更多托维斯卡尔样本的基因分型结果显示，H3携带者中仅存在9104T和715G等位基因。检测到的候选替换位于重要的线粒体基因中，尽管它们不会改变氨基酸组成，但我们不能忽视其相应mRNA二级结构的潜在变化。这些多态性作为选择计划中的标记的有用性需要在其他伊比利亚猪品系中验证这些结果的一致性。
