Lin C S, Sun Y L, Liu C Y, Yang P C, Chang L C, Cheng I C, Mao S J, Huang M C
Cardiovascular Research Center, Department of Comparative Medicine, Pig Research Institute Taiwan, P.O. Box 23, Chunan 350, Miaoli, Taiwan.
Gene. 1999 Aug 5;236(1):107-14. doi: 10.1016/s0378-1119(99)00247-4.
The complete nucleotide sequence of the pig (Sus scrofa) mitochondrial genome, containing 16613bp, is presented in this report. The genome is not a specific length because of the presence of the variable numbers of tandem repeats, 5'-CGTGCGTACA in the displacement loop (D-loop). Genes responsible for 12S and 16S rRNAs, 22 tRNAs, and 13 protein-coding regions are found. The genome carries very few intergenic nucleotides with several instances of overlap between protein-coding or tRNA genes, except in the D-loop region. For evaluating the possible evolutionary relationships between Artiodactyla and Cetacea, the nucleotide substitutions and amino acid sequences of 13 protein-coding genes were aligned by pairwise comparisons of the pig, cow, and fin whale. By comparing these sequences, we suggest that there is a closer relationship between the pig and cow than that between either of these species and fin whale. In addition, the accumulation of transversions and gaps in pig 12S and 16S rRNA genes was compared with that in other eutherian species, including cow, fin whale, human, horse, and harbor seal. The results also reveal a close phylogenetic relationship between pig and cow, as compared to fin whale and others. Thus, according to the sequence differences of mitochondrial rRNA genes in eutherian species, the evolutionary separation of pig and cow occurred about 53-60 million years ago.
本报告展示了猪（野猪）线粒体基因组的完整核苷酸序列，其长度为16613bp。由于在置换环（D环）中存在可变数量的串联重复序列5'-CGTGCGTACA，该基因组长度并非固定。已发现负责12S和16S rRNA、22种tRNA以及13个蛋白质编码区域的基因。除D环区域外，该基因组携带的基因间核苷酸极少，蛋白质编码基因或tRNA基因之间存在多处重叠。为评估偶蹄目和鲸目之间可能的进化关系，通过对猪、牛和长须鲸进行两两比较，对齐了13个蛋白质编码基因的核苷酸替换和氨基酸序列。通过比较这些序列，我们认为猪和牛之间的关系比它们与长须鲸之间的关系更为密切。此外，还将猪12S和16S rRNA基因中颠换和缺口的积累情况与其他真兽类物种（包括牛、长须鲸、人类、马和斑海豹）进行了比较。结果还表明，与长须鲸和其他物种相比，猪和牛之间存在密切的系统发育关系。因此，根据真兽类物种线粒体rRNA基因的序列差异，猪和牛在大约5300万至6000万年前发生了进化分离。
