Böhne Astrid, Brunet Frédéric, Galiana-Arnoux Delphine, Schultheis Christina, Volff Jean-Nicolas
Institut de Génomique Fonctionnelle de Lyon, Université de Lyon, France.
Chromosome Res. 2008;16(1):203-15. doi: 10.1007/s10577-007-1202-6.
Comparative genomics has revealed that major vertebrate lineages contain quantitatively and qualitatively different populations of retrotransposable elements and DNA transposons, with important differences also frequently observed between species of the same lineage. This is essentially due to (i) the differential evolution of ancestral families of transposable elements, with evolutionary scenarios ranging from complete extinction to massive invasion; (ii) the lineage-specific introduction of transposable elements by infection and horizontal transfer, as exemplified by endogenous retroviruses; and (iii) the lineage-specific emergence of new transposable elements, as particularly observed for non-coding retroelements called short interspersed elements (SINEs). During vertebrate evolution, transposable elements have repeatedly contributed regulatory and coding sequences to the host, leading to the emergence of new lineage-specific gene regulations and functions. In all vertebrate lineages, there is evidence of transposable element-mediated genomic rearrangements such as insertions, deletions, inversions and duplications potentially associated with or subsequent to speciation events. Taken together, these observations indicate that transposable elements are major drivers of genomic and biological diversity in vertebrates, with possible important roles in speciation and major evolutionary transitions.
比较基因组学研究表明，主要的脊椎动物谱系含有数量和质量上都不同的反转录转座元件和DNA转座子群体，而且在同一谱系的物种之间也经常观察到重要差异。这主要归因于：（i）转座元件祖先家族的差异进化，其进化情形从完全灭绝到大规模入侵不等；（ii）通过感染和水平转移进行的谱系特异性转座元件引入，以内源逆转录病毒为例；以及（iii）新转座元件的谱系特异性出现，在称为短散在元件（SINEs）的非编码反转录元件中尤为明显。在脊椎动物进化过程中，转座元件不断为宿主贡献调控序列和编码序列，导致新的谱系特异性基因调控和功能出现。在所有脊椎动物谱系中，都有证据表明存在转座元件介导的基因组重排，如插入、缺失、倒位和重复，这些重排可能与物种形成事件相关或发生在物种形成事件之后。综上所述，这些观察结果表明，转座元件是脊椎动物基因组和生物多样性的主要驱动因素，在物种形成和重大进化转变中可能发挥重要作用。
