1State Key Laboratory of Silkworm Genome Biology, The Key Sericultural Laboratory of Agricultural Ministry, Southwest University, Chongqing 400715, China.
DNA Res. 2013 Oct;20(5):471-84. doi: 10.1093/dnares/dst024. Epub 2013 Jun 14.
In this study, we developed a structure-based approach to identify Helitrons in four lepidopterans and systematically analysed Helitrons in the silkworm genome. We found that the content of Helitrons varied greatly among genomes. The silkworm genome harboured 67,555 Helitron-related sequences that could be classified into 21 families and accounted for ≈ 4.23% of the genome. Thirteen of the families were new. Three families were putatively autonomous and included the replication initiator motif and helicase domain. The silkworm Helitrons were widely and randomly distributed in the genome. Most Helitron families radiated within the past 2 million years and experienced a single burst of expansion. These Helitron families captured 3724 gene fragments and contributed to at least 1.4% of the silkworm full-length cDNAs, suggesting important roles of Helitrons in the evolution of the silkworm genes. In addition, we found that some new Helitrons were generated by combinations of other Helitrons. Overall, the results presented in this study provided insights into the generation and evolution of Helitron transposons and their contribution to transcripts.
在这项研究中，我们开发了一种基于结构的方法来鉴定四种鳞翅目昆虫中的转座子，并系统地分析了家蚕基因组中的转座子。我们发现，转座子的含量在不同基因组中差异很大。家蚕基因组中含有 67,555 个 Helitron 相关序列，可分为 21 个家族，约占基因组的 4.23%。其中 13 个家族是新的。三个家族被认为是自主的，包括复制起始子基序和解旋酶结构域。家蚕 Helitrons 广泛且随机地分布在基因组中。大多数 Helitron 家族在过去 200 万年中辐射进化，并经历了一次扩张爆发。这些 Helitron 家族捕获了 3724 个基因片段，至少贡献了家蚕全长 cDNA 的 1.4%，表明 Helitrons 在蚕基因的进化中发挥了重要作用。此外，我们发现一些新的 Helitrons 是由其他 Helitrons 组合产生的。总的来说，本研究的结果为 Helitron 转座子的产生和进化及其对转录本的贡献提供了新的认识。
