Staton J L, Daehler L L, Brown W M
Department of Biology, University of Michigan, USA.
Mol Biol Evol. 1997 Aug;14(8):867-74. doi: 10.1093/oxfordjournals.molbev.a025828.
Numerous complete mitochondrial DNA sequences have been determined for species within two arthropod groups, insects and crustaceans, but there are none for a third, the chelicerates. Most mitochondrial gene arrangements reported for crustaceans and insect species are identical or nearly identical to that of Drosophila yakuba. Sequences across 36 of the gene boundaries in the mitochondrial DNA (mtDNA) of a representative chelicerate. Limulus polyphemus L., also reveal an arrangement like that of Drosophila yakuba. Only the position of the tRNA(LEU)(UUR) gene differs; in Limulus it is between the genes for tRNA(LEU)(CUN) and ND1. This positioning is also found in onychophorans, mollusks, and annelids, but not in insects and crustaceans, and indicates that tRNA(LEU)(CUN)-tRNA(LEU)(UUR)-ND1 was the ancestral gene arrangement for these groups, as suggested earlier. There are no differences in the relative arrangements of protein-coding and ribosomal RNA genes between Limulus and Drosophila, and none have been observed within arthropods. The high degree of similarity of mitochondrial gene arrangements within arthropods is striking, since some taxa last shared a common ancestor before the Cambrian, and contrasts with the extensive mtDNA rearrangements occasionally observed within some other metazoan phyla (e.g., mollusks and nematodes).
人们已经测定了节肢动物两个类群（昆虫和甲壳纲动物）中多个物种完整的线粒体DNA序列，但对于第三个类群——螯肢动物，却尚未有相关序列。报道的大多数甲壳纲动物和昆虫物种的线粒体基因排列与雅库布果蝇（Drosophila yakuba）的排列相同或几乎相同。一种具有代表性的螯肢动物——美洲鲎（Limulus polyphemus L.）的线粒体DNA（mtDNA）中36个基因边界的序列，也显示出一种与雅库布果蝇类似的排列。只有tRNA(LEU)(UUR)基因的位置不同；在美洲鲎中，它位于tRNA(LEU)(CUN)基因和ND1基因之间。这种定位在有爪动物、软体动物和环节动物中也能发现，但在昆虫和甲壳纲动物中则没有，这表明tRNA(LEU)(CUN)-tRNA(LEU)(UUR)-ND1是这些类群的祖先基因排列，正如之前所提出的那样。美洲鲎和果蝇之间蛋白质编码基因和核糖体RNA基因的相对排列没有差异，在节肢动物内部也未观察到差异。节肢动物中线粒体基因排列的高度相似性令人惊讶，因为一些分类单元在寒武纪之前就最后一次拥有共同祖先了，这与在其他一些后生动物门（如软体动物和线虫）中偶尔观察到的广泛的线粒体DNA重排形成了对比。
