Upholt W B, Dawid I B
Cell. 1977 Jul;11(3):571-83. doi: 10.1016/0092-8674(77)90075-7.
Mitochondrial DNA (mtDNA) from sheep and goat was compared by restriction endonuclease analysis and heteroduplex mapping in the electron microscope. The fragment patterns produced by endonuclease Hae III from three individual sheep and two goat mtDNAs all differed from each other. The three sheep mtDNAs had identical Eco RI and Hind III fragments, but the two goat mtDNA patterns differed from each other as well as from sheep mtDNA. We estimate that each sheep mtDNA differs from each other by 0.5-1% of its nucleotide sequences, the two goat mtDNAs by 1-2%, and there is a 6-11% sequence difference between sheep and goat mtDNAs. We have mapped the Eco RI and Hind III sites of goat and sheep mtDNA and determined the positions of the D loop, which marks the replication origin, relative to the restriction map. The D loops are at homologous positions on the mtDNAs from both species, but the goat D loop is only 75% as long as the sheep D loop. Regions with a high degree of sequence divergence occur at both ends of the D loop. We suggest that a duplication of about 150 base pairs has occurred in the region where the sheep and goat D loops differ in length. We discuss mtDNA evolution in terms of divergence of isolated "mitochondrial DNA clones."
通过限制性内切酶分析和电子显微镜下的异源双链体图谱对绵羊和山羊的线粒体DNA（mtDNA）进行了比较。来自三只个体绵羊和两只山羊mtDNA的Hae III内切酶产生的片段模式均彼此不同。三只绵羊的mtDNA具有相同的Eco RI和Hind III片段，但两只山羊的mtDNA模式彼此不同，也与绵羊的mtDNA不同。我们估计，每只绵羊的mtDNA彼此之间的核苷酸序列差异为0.5 - 1%，两只山羊的mtDNA之间为1 - 2%，绵羊和山羊的mtDNA之间存在6 - 11%的序列差异。我们绘制了山羊和绵羊mtDNA的Eco RI和Hind III位点图谱，并确定了标记复制起点的D环相对于限制性图谱的位置。D环在两个物种的mtDNA上处于同源位置，但山羊的D环比绵羊的D环短75%。D环两端出现了高度序列分歧的区域。我们认为，在绵羊和山羊D环长度不同的区域发生了约150个碱基对的重复。我们根据分离的“线粒体DNA克隆”的分歧来讨论mtDNA的进化。
