Repeated horizontal transfer of a DNA transposon in mammals and other tetrapods
Repeated horizontal transfer of a DNA transposon in mammals and other tetrapods
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DOI：
10.1073/pnas.0806548105
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发表时间：
2008-11-04
影响因子：
11.1
通讯作者：
Feschotte, Cedric
中科院分区：
文献类型：
--
作者：
Pace, John K., II;Gilbert, Clement;Feschotte, Cedric
水平转移（HT）是原核生物物种进化的核心。自私的和移动的遗传元件，如质粒，转座子，是原核生物中HT的主要载体。在多细胞真核生物中，HT的流行和进化意义仍不清楚。在这里，我们确定了一组DNA转座子家族称为空间入侵者（或SPIN），其共有序列在其整个长度（2.9 kb）的基因组中的一致性接近96%，包括啮齿类（大鼠/小鼠），小棕蝠（原猴纲灵长类动物），小棕蝠（laurasiatherian），tenrec（非洲兽），负鼠（有袋动物）和两种非哺乳动物四足动物（变色蜥蜴和非洲爪蛙）。相比之下，SPIN元件在序列数据库中代表的其他物种中检测不到，包括其他19种具有全基因组组装草图的哺乳动物。这种不规则的分布，加上差异很大的四足动物中SPIN身份的极端水平，以及对这些元素总体缺乏选择性约束，与垂直遗传不相容，但强烈表明存在多次水平引入。我们表明，这些生殖细胞浸润可能发生在同一个进化时间（15-46百万年），并产生了任何物种谱系中有史以来最大的DNA转座子活性爆发（tenrec中每个单倍体基因组近100，000个SPIN拷贝）。这一过程还导致了一个新的基因的出现在小鼠谱系衍生自SPIN转座酶。总之，DNA转座子的HT对多种哺乳动物和四足动物物种的基因组的形成和多样化做出了重大贡献。
Horizontal transfer (HT) is central to the evolution of prokaryotic species. Selfish and mobile genetic elements, such as phages, plasmids, and transposons, are the primary vehicles for HT among prokaryotes. In multicellular eukaryotes, the prevalence and evolutionary significance of HT remain unclear. Here, we identified a set of DNA transposon families dubbed SPACE INVADERS (or SPIN) whose consensus sequences are approximate to 96% identical over their entire length (2.9 kb) in the genomes of murine rodents (rat/mouse), bushbaby (prosimian primate), little brown bat (laurasiatherian), tenrec (afrotherian), opossum (marsupial), and two non-mammalian tetrapods (anole lizard and African clawed frog). In contrast, SPIN elements were undetectable in other species represented in the sequence databases, including 19 other mammals with draft whole-genome assemblies. This patchy distribution, coupled with the extreme level of SPIN identity in widely divergent tetrapods and the overall lack of selective constraint acting on these elements, is incompatible with vertical inheritance, but strongly indicative of multiple horizontal introductions. We show that these germline infiltrations likely occurred around the same evolutionary time (15-46 mya) and spawned some of the largest bursts of DNA transposon activity ever recorded in any species lineage (nearly 100,000 SPIN copies per haploid genome in tenrec). The process also led to the emergence of a new gene in the murine lineage derived from a SPIN transposase. In summary, HT of DNA transposons has contributed significantly to shaping and diversifying the genomes of multiple mammalian and tetrapod species.