Bernardo Larissa Paim, Loreto Elgion L S
PPG Biodiversidade Animal, CCNE, Universidade Federal de Santa Maria, Santa Maria, Brazil.
Genetica. 2013 Dec;141(10-12):471-8. doi: 10.1007/s10709-013-9746-1. Epub 2013 Oct 25.
Transposable elements (TEs) are ubiquitous components of nearly all genomes studied. These elements are highly variable in copy number, molecular structure and transposition strategies. They can move within and between genomes, thus increasing their copy numbers and avoiding being eliminated by stochastic and deterministic processes. hobo is a class II element isolated from Drosophila melanogaster. Previous phylogenetic analyses have shown that the canonical hobo element from D. melanogaster has a sister group formed by sequences found in D. willistoni (called howilli2) and D. mojavensis (called homo1). In the present study, we investigated 36 Drosophilidae species for sequences similar to howilli2 and homo1 using degenerate primers. Additionally, in silico searches were performed in 21 available Drosophila genomes. The obtained sequences formed a monophyletic sister group with the canonical hobo element; we termed these sequences 'hobo-brothers' elements. These elements showed a patch distribution and incongruities with the TE and host species phylogenies, suggesting possible cases of horizontal transfer (HT). Species that possess hobo-brothers sequences are from the New World, mainly Neotropical areas. In addition, the estimated divergence of the sequences found showed that these elements are or were recently active; the large number of HT events observed suggests that these elements could be experiencing an expansion process in Neotropical genomes. A comparison of these results with the literature is discussed with regard to the importance of the time and location of horizontal transposon transfer events.
转座元件（TEs）是几乎所有已研究基因组中普遍存在的组成部分。这些元件在拷贝数、分子结构和转座策略方面高度可变。它们可以在基因组内部和之间移动，从而增加其拷贝数，并避免被随机和确定性过程消除。hobo是从黑腹果蝇中分离出的II类元件。先前的系统发育分析表明，来自黑腹果蝇的典型hobo元件有一个姐妹类群，由在威氏果蝇（称为howilli2）和莫哈韦果蝇（称为homo1）中发现的序列组成。在本研究中，我们使用简并引物对36种果蝇科物种进行了类似于howilli2和homo1序列的研究。此外，还在21个可用的果蝇基因组中进行了电子搜索。获得的序列与典型hobo元件形成了一个单系姐妹类群；我们将这些序列称为“hobo兄弟”元件。这些元件呈现出斑块状分布，并且与转座元件和宿主物种的系统发育不一致，表明可能存在水平转移（HT）的情况。拥有hobo兄弟序列的物种来自新大陆，主要是新热带地区。此外，所发现序列的估计分歧表明这些元件现在或最近是活跃的；观察到的大量水平转移事件表明这些元件可能正在新热带基因组中经历一个扩展过程。本文就水平转座子转移事件的时间和地点的重要性，对这些结果与文献进行了比较讨论。
