Hur Jae H, Van Doninck Karine, Mandigo Morgan L, Meselson Matthew
Department of Molecular and Cellular Biology, Harvard University, USA.
Mol Biol Evol. 2009 Feb;26(2):375-83. doi: 10.1093/molbev/msn260. Epub 2008 Nov 7.
Rotifers of Class Bdelloidea are abundant freshwater invertebrates known for their remarkable ability to survive desiccation and their lack of males and meiosis. Sequencing and annotation of approximately 50-kb regions containing the four hsp82 heat shock genes of the bdelloid Philodina roseola, each located on a separate chromosome, have suggested that its genome is that of a degenerate tetraploid. In order to determine whether a similar structure exists in a bdelloid distantly related to P. roseola and if degenerate tetraploidy was established before the two species separated, we sequenced regions containing the hsp82 genes of a bdelloid belonging to a different family, Adineta vaga, and the histone gene clusters of P. roseola and A. vaga. Our findings are entirely consistent with degenerate tetraploidy and show that it was established before the two bdelloid families diverged and therefore probably before the bdelloid radiation.
蛭形轮虫纲的轮虫是丰富的淡水无脊椎动物，以其卓越的抗干燥生存能力以及缺乏雄性和减数分裂而闻名。对包含玫瑰旋轮虫（Philodina roseola）四个hsp82热休克基因的约50千碱基区域进行测序和注释，每个基因位于一条单独的染色体上，这表明其基因组是一个退化的四倍体。为了确定在与玫瑰旋轮虫远缘相关的蛭形轮虫中是否存在类似结构，以及退化四倍体是否在这两个物种分离之前就已形成，我们对属于不同科的蛭形轮虫—— vagans的hsp82基因区域以及玫瑰旋轮虫和vagans的组蛋白基因簇进行了测序。我们的发现与退化四倍体完全一致，并表明它在两个蛭形轮虫科分化之前就已形成，因此可能在蛭形轮虫辐射之前就已形成。
