Gladyshev Eugene A, Meselson Matthew, Arkhipova Irina R
Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA.
Gene. 2007 Apr 1;390(1-2):136-45. doi: 10.1016/j.gene.2006.09.025. Epub 2006 Oct 5.
Rotifers of class Bdelloidea, a group of aquatic invertebrates in which males and meiosis have never been documented, are also unusual in their lack of multicopy LINE-like and gypsy-like retrotransposons, groups inhabiting the genomes of nearly all other metazoans. Bdelloids do contain numerous DNA transposons, both intact and decayed, and domesticated Penelope-like retroelements Athena, concentrated at telomeric regions. Here we describe two LTR retrotransposons, each found at low copy number in a different bdelloid species, which define a clade different from previously known clades of LTR retrotransposons. Like bdelloid DNA transposons and Athena, these elements are found preferentially in telomeric regions. Unlike bdelloid DNA transposons, many of which are decayed, the newly described elements, named Vesta and Juno, inhabiting the genomes of Philodina roseola and Adineta vaga, respectively, appear to be intact and represent recent insertions, possibly from an exogenous source. We describe the retrovirus-like structure of the new elements, containing gag, pol, and env-like open reading frames, and discuss their possible origins, transmission, and behavior in bdelloid genomes.
蛭形轮虫纲的轮虫是一类水生无脊椎动物，从未有过雄性个体和减数分裂的记录，它们还与众不同地缺乏多拷贝的类LINE和类吉普赛逆转座子，而几乎所有其他后生动物的基因组中都有这些元件。蛭形轮虫确实含有大量完整的和已衰退的DNA转座子，以及集中在端粒区域的驯化的类佩内洛普逆转元件雅典娜。在这里，我们描述了两种LTR逆转座子，它们分别在不同的蛭形轮虫物种中以低拷贝数被发现，它们定义了一个与先前已知的LTR逆转座子进化枝不同的进化枝。与蛭形轮虫的DNA转座子和雅典娜一样，这些元件优先出现在端粒区域。与许多已衰退的蛭形轮虫DNA转座子不同，新描述的元件分别名为维斯塔和朱诺，它们分别存在于玫瑰旋轮虫和 vagans 艾氏轮虫的基因组中，似乎是完整的，代表了最近的插入，可能来自外源。我们描述了新元件的逆转录病毒样结构，包含gag、pol和env样开放阅读框，并讨论了它们在蛭形轮虫基因组中的可能起源、传播和行为。
