Simpson Alastair G B, Stevens Jamie R, Lukes Julius
Canadian Institute for Advanced Research and Department of Biology, Dalhousie University, Halifax, Canada, B3H 4J1.
Trends Parasitol. 2006 Apr;22(4):168-74. doi: 10.1016/j.pt.2006.02.006. Epub 2006 Feb 28.
Five years ago, little was known about kinetoplastid evolution. Recent improvements in the taxon sampling for nuclear rRNA genes and several protein markers have transformed this understanding. Parasitism evolved at least four times in kinetoplastids. Obligate parasitic trypanosomatids are a relatively 'derived' group within kinetoplastids; their closest relative is likely to be the free-living Bodo saltans, and the ancestral trypanosomatids were probably parasites of insects. Although subject to recent controversy, trypanosomes (genus Trypanosoma) probably constitute a monophyletic group. Several unusual features of trypanosomatid genomes (e.g. trans-splicing, mitochondrial RNA editing and intron poverty) are common in kinetoplastids and pre-date the adoption of parasitism. The framework of relationships is becoming robust enough for real comparative approaches to be used to understand kinetoplastid biology.
五年前，人们对动质体的进化了解甚少。最近在核rRNA基因和几种蛋白质标记的分类群采样方面的改进改变了这种认识。寄生现象在动质体中至少进化了四次。专性寄生的锥虫是动质体中一个相对“衍生”的类群；它们最亲近的亲属可能是自由生活的波豆虫，而祖先锥虫可能是昆虫的寄生虫。尽管最近存在争议，但锥虫（锥虫属）可能构成一个单系类群。锥虫基因组的几个不寻常特征（如反式剪接、线粒体RNA编辑和内含子缺乏）在动质体中很常见，且早于寄生现象的出现。关系框架已经足够稳固，可以采用真正的比较方法来理解动质体生物学。
