Janke A, Feldmaier-Fuchs G, Thomas W K, von Haeseler A, Pääbo S
Zoologisches Institute, Universität München, Germany.
Genetics. 1994 May;137(1):243-56. doi: 10.1093/genetics/137.1.243.
The entire nucleotide sequence of the mitochondrial genome of the American opossum, Didelphis virginiana, was determined. Two major features distinguish this genome from those of other mammals. First, five tRNA genes around the origin of light strand replication are rearranged. Second, the anticodon of tRNA(Asp) is posttranscriptionally changed by an RNA editing process such that its coding capacity is altered. When the complete protein-coding region of the mitochondrial genome is used as an outgroup for placental mammals it can be shown that rodents represent an earlier branch among placental mammals than primates and artiodactyls and that artiodactyls share a common ancestor with carnivores. The overall rates of evolution of most of the mitochondrial genome of placentals are clock-like. Furthermore, the data indicate that the lineages leading to the mouse and rat may have diverged from each other as much as 35 million years ago.
已确定了美洲负鼠(弗吉尼亚负鼠)线粒体基因组的完整核苷酸序列。该基因组与其他哺乳动物的基因组有两个主要区别。第一,轻链复制起点周围的五个tRNA基因发生了重排。第二,tRNA(Asp)的反密码子在转录后通过RNA编辑过程发生改变,从而改变了其编码能力。当线粒体基因组的完整蛋白质编码区被用作胎盘哺乳动物的外类群时,可以表明啮齿动物在胎盘哺乳动物中代表的分支比灵长类动物和偶蹄目动物更早,并且偶蹄目动物与食肉动物有共同的祖先。胎盘哺乳动物线粒体基因组的大部分进化速率呈时钟状。此外,数据表明导致小鼠和大鼠的谱系可能在3500万年前就已彼此分化。