School of Biological Sciences, University of Adelaide, Adelaide, SA 5005, Australia.
School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TU, UK.
Biol Lett. 2021 Sep;17(9):20210342. doi: 10.1098/rsbl.2021.0342. Epub 2021 Sep 1.
Transposable elements (TEs) are self-replicating genetic sequences and are often described as important 'drivers of evolution'. This driving force is because TEs promote genomic novelty by enabling rearrangement, and through exaptation as coding and regulatory elements. However, most TE insertions potentially lead to neutral or harmful outcomes, therefore host genomes have evolved machinery to suppress TE expansion. Through horizontal transposon transfer (HTT) TEs can colonize new genomes, and since new hosts may not be able to regulate subsequent replication, these TEs may proliferate rapidly. Here, we describe HTT of the DNA transposon into sea kraits (), and its subsequent explosive expansion within genomes. This HTT occurred following the divergence of from terrestrial Australian elapids approximately 15-25 Mya. This has resulted in numerous insertions into introns and regulatory regions, with some insertions into exons which appear to have altered UTRs or added sequence to coding exons. has rapidly expanded to make up 8-12% of spp. genomes; this is the fastest known expansion of TEs in amniotes following HTT. Genomic changes caused by this rapid expansion may have contributed to adaptation to the amphibious-marine habitat.
转座元件 (TEs) 是自我复制的遗传序列，通常被描述为重要的“进化驱动因素”。这种驱动力是因为 TEs 通过促进重排，并通过作为编码和调节元件的适应性进化来推动基因组的新颖性。然而，大多数 TE 插入物可能导致中性或有害的结果，因此宿主基因组已经进化出抑制 TE 扩张的机制。通过水平转座子转移 (HTT)，TEs 可以殖民新的基因组，并且由于新宿主可能无法调节随后的复制，这些 TEs 可能会迅速增殖。在这里，我们描述了 DNA 转座子进入海蛇（）的 HTT，以及其随后在 基因组内的爆炸性扩张。这种 HTT 发生在 从陆地澳大利亚蛇类分化大约 15-25 Mya 之后。这导致了大量插入到内含子和调节区域，有些插入到外显子中，似乎改变了 UTR 或向编码外显子添加了序列。 已经迅速扩张，占 spp. 基因组的 8-12%；这是已知在 HTT 后在羊膜动物中 TE 最快的扩张。这种快速扩张引起的基因组变化可能有助于适应两栖-海洋生境。
