Gemmell N J, Janke A, Western P S, Watson J M, Pääbo S, Graves J A
Department of Genetics and Human Variation, La Trobe University, Bundoora, Australia.
J Mol Evol. 1994 Aug;39(2):200-5. doi: 10.1007/BF00163808.
The vertebrate mitochondrial genome is highly conserved in size and gene content. Among the chordates there appears to be one basic gene arrangement, but rearrangements in the mitochondrial gene order of the avian lineages have indicated that the mitochondrial genome may be more variable than once thought. Different gene orders in marsupials and eutherian mammals leave the ancestral mammalian order in some doubt. We have investigated the mitochondrial gene order in the platypus (Ornithorhynchus anatinus), a representative of the third major group of mammals, to determine which mitochondrial gene arrangement is ancestral in mammals. We have found that the platypus mtDNA conforms to the basic chordate gene arrangement, common to fish, amphibians, and eutherian mammals, indicating that this arrangement was the original mammalian arrangement, and that the unusual rearrangements observed in the avians and marsupials are probably lineage-specific.
脊椎动物的线粒体基因组在大小和基因含量上高度保守。在脊索动物中，似乎存在一种基本的基因排列方式，但鸟类谱系中线粒体基因顺序的重排表明，线粒体基因组的变异性可能比人们曾经认为的更大。有袋类动物和真兽类哺乳动物中不同的基因顺序使得哺乳动物的祖先顺序存在一些疑问。我们研究了鸭嘴兽（Ornithorhynchus anatinus）的线粒体基因顺序，鸭嘴兽是哺乳动物第三大主要类群的代表，以确定哪种线粒体基因排列是哺乳动物的祖先排列。我们发现鸭嘴兽的线粒体DNA符合鱼类、两栖动物和真兽类哺乳动物共有的基本脊索动物基因排列方式，这表明这种排列方式是最初的哺乳动物排列方式，而在鸟类和有袋类动物中观察到的不寻常重排可能是特定谱系的。
