Transposable elements (TEs) are DNA sequences capable of transpositions within the genome and thus exerting a considerable influence on the genome functioning and structure and serving as a source of new genes. TE biodiversity studies in previously unexplored species are important for the fundamental understanding of the TE influence on eukaryotic genomes. TEs are classified into retrotransposons and DNA transposons. IS630/Tc1/mariner (ITm) superfamily of DNA transposons is one of the most diverse groups broadly represented among the eukaryotes. The study of 19 mollusk genomes revealed a new group of ITm superfamily elements, which we henceforth refer to as TLEWI. These TEs are characterized by the low copy number, the lack of terminal inverted repeats, the catalytic domain with DD36E signature and the presence of spliceosomal introns in transposase coding sequence. Their prevalence among the mollusks is limited to the class Bivalvia. Since TLEWI possess the features of domesticated TE and structures similar to the eukaryotic genes which are not typical for the DNA transposons, we consider the hypothesis of co-optation of TLEWI gene by the bivalves. The results of our study will fill the gap of knowledge about the prevalence, activity, and evolution of the ITm DNA transposons in multicellular genomes and will facilitate our understanding of the mechanisms of TE domestication by the host genome.

中文翻译：

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软体动物基因组中具有剪接体内含子的Tc1样元件。

可转座元件（TEs）是能够在基因组内进行转座的DNA序列，因此对基因组的功能和结构具有相当大的影响，并可以作为新基因的来源。对以前未开发物种的TE生物多样性研究对于从根本上了解TE对真核基因组的影响至关重要。TEs分为逆转座子和DNA转座子。DNA转座子的IS630 / Tc1 / mariner（ITm）超家族是真核生物中广泛代表的最多样化的群体之一。对19个软体动物基因组的研究揭示了一组新的ITm超家族元件，以下我们将其称为TLEWI。这些TE的特点是拷贝数低，末端无反向重复，具有DD36E签名的催化结构域和转座酶编码序列中存在剪接内含子。它们在软体动物中的流行仅限于双壳类。由于TLEWI具有驯化的TE的特征和类似于真核生物基因的结构，这对于DNA转座子而言并不常见，因此我们考虑了双壳类动物对TLEWI基因的选择性选择。我们的研究结果将填补关于多细胞基因组中ITm DNA转座子的发生率，活性和进化的知识空白，并将有助于我们了解宿主基因组驯化TE的机制。由于TLEWI具有驯化的TE的特征和类似于真核生物基因的结构，这对于DNA转座子而言并不常见，因此我们考虑了双壳类动物对TLEWI基因的选择性选择。我们的研究结果将填补关于多细胞基因组中ITm DNA转座子的发生率，活性和进化的知识空白，并将有助于我们了解宿主基因组驯化TE的机制。由于TLEWI具有驯化的TE的特征和类似于真核生物基因的结构，这对于DNA转座子而言并不常见，因此我们考虑了双壳类动物对TLEWI基因的选择性选择。我们的研究结果将填补关于多细胞基因组中ITm DNA转座子的发生率，活性和进化的知识空白，并将有助于我们了解宿主基因组驯化TE的机制。