Department of Biology, Washington University in St Louis, St Louis, MO, USA.
Mob DNA. 2010 Mar 1;1(1):10. doi: 10.1186/1759-8753-1-10.
Sadhu elements are non-autonomous retroposons first recognized in Arabidopsis thaliana. There is a wide degree of divergence among different elements, suggesting that these sequences are ancient in origin. Here we report the results of several lines of investigation into the genomic organization and evolutionary history of this element family.
We present a classification scheme for Sadhu elements in A. thaliana, describing derivative elements related to the full-length elements we reported previously. We characterized Sadhu5 elements in a set of A. thaliana strains in order to trace the history of radiation in this subfamily. Sequences surrounding the target sites of different Sadhu insertions are consistent with mobilization by LINE retroelements. Finally, we identified Sadhu elements grouping into distinct subfamilies in two related species, Arabidopsis arenosa and Arabidopsis lyrata.
Our analyses suggest that the Sadhu retroelement family has undergone target primed reverse transcription-driven retrotransposition during the divergence of different A. thaliana strains. In addition, Sadhu elements can be found at moderate copy number in three distinct Arabidopsis species, indicating that the evolutionary history of these sequences can be traced back at least several millions of years.
Sadhu 元件是非自主逆转录转座子，最初在拟南芥中被识别。不同元件之间存在广泛的差异，表明这些序列起源于远古时期。在这里，我们报告了对该元件家族基因组组织和进化历史的几方面研究结果。
我们提出了拟南芥中 Sadhu 元件的分类方案，描述了与我们之前报道的全长元件相关的衍生元件。我们对一组拟南芥品系中的 Sadhu5 元件进行了特征描述，以追踪该亚家族辐射的历史。不同 Sadhu 插入靶位点周围的序列与 LINE 逆转录元件的转座一致。最后，我们在两个相关物种，拟南芥荒地和拟南芥斑叶种中鉴定出 Sadhu 元件分组成不同的亚家族。
我们的分析表明，Sadhu 逆转录元件家族在不同拟南芥品系的分化过程中经历了靶标引发的反转录驱动的逆转录转座。此外，Sadhu 元件在三个不同的拟南芥物种中以中等拷贝数存在，表明这些序列的进化历史可以追溯到至少几百万年前。
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