Tollis Marc, Boissinot Stéphane
Department of Biology; Queens College; The City University of New York; Flushing, NY USA; The Graduate Center; The City University of New York; New York, NY USA.
Mob Genet Elements. 2011 Jul;1(2):107-111. doi: 10.4161/mge.1.2.17733. Epub 2011 Jul 1.
The recent sequencing of the lizard genome provides a unique opportunity to examine the evolution of vertebrate genomes in a phylogenetic context. The lizard genome contains an extraordinary diversity of active transposable elements that far exceeds the diversity reported in extant mammals and birds. Retrotransposons and DNA transposons are represented by multiple active families, contributing to the very diverse repetitive landscape of the lizard. Surprisingly, ancient transposon copies are relatively rare suggesting that the transposon copy number is tightly controlled in lizard. This bias in favor of young copies results from the joint effect of purifying selection acting on novel insertions and a high rate of DNA loss. Recent analyses have revealed that the repetitive landscape of reptiles differ drastically from other extant amniotes by their diversity but also by the dynamics of amplification of their transposons. Thus, from the point of view of mobile elements, reptile genomes show more similarity to fish and amphibians than to other amniotes.
近期蜥蜴基因组的测序为在系统发育背景下研究脊椎动物基因组的进化提供了独特的机会。蜥蜴基因组包含异常多样的活跃转座元件，其多样性远远超过现存哺乳动物和鸟类中报道的多样性。逆转录转座子和DNA转座子由多个活跃家族代表，这造就了蜥蜴极为多样的重复序列景观。令人惊讶的是，古老的转座子拷贝相对较少，这表明蜥蜴中转座子拷贝数受到严格控制。这种偏向年轻拷贝的情况是由对新插入片段进行纯化选择的联合效应以及较高的DNA丢失率导致的。最近的分析表明，爬行动物的重复序列景观不仅在多样性上，而且在其转座子的扩增动态方面，都与其他现存羊膜动物有很大不同。因此，从可移动元件的角度来看，爬行动物基因组与鱼类和两栖动物的相似性高于与其他羊膜动物的相似性。
