Biscotti Maria Assunta, Gerdol Marco, Canapa Adriana, Forconi Mariko, Olmo Ettore, Pallavicini Alberto, Barucca Marco, Schartl Manfred
Dipartimento di Scienze della Vita e dell'Ambiente, Università Politecnica delle Marche, Via Brecce Bianche, 60131, Ancona, Italy.
Dipartimento di Scienze della Vita, Università di Trieste, Via Licio Giorgeri 5, 34127, Trieste, Italy.
Sci Rep. 2016 Feb 24;6:21571. doi: 10.1038/srep21571.
Lungfish and coelacanths are the only living sarcopterygian fish. The phylogenetic relationship of lungfish to the last common ancestor of tetrapods and their close morphological similarity to their fossil ancestors make this species uniquely interesting. However their genome size, the largest among vertebrates, is hampering the generation of a whole genome sequence. To provide a partial solution to the problem, a high-coverage lungfish reference transcriptome was generated and assembled. The present findings indicate that lungfish, not coelacanths, are the closest relatives to land-adapted vertebrates. Whereas protein-coding genes evolve at a very slow rate, possibly reflecting a "living fossil" status, transposable elements appear to be active and show high diversity, suggesting a role for them in the remarkable expansion of the lungfish genome. Analyses of single genes and gene families documented changes connected to the water to land transition and demonstrated the value of the lungfish reference transcriptome for comparative studies of vertebrate evolution.
肺鱼和腔棘鱼是现存仅有的肉鳍鱼类。肺鱼与四足动物的最后一个共同祖先之间的系统发育关系，以及它们与化石祖先相似的形态特征，使得这个物种极具吸引力。然而，它们的基因组大小是脊椎动物中最大的，这阻碍了全基因组序列的生成。为了部分解决这个问题，我们生成并组装了一个高覆盖度的肺鱼参考转录组。目前的研究结果表明，与腔棘鱼相比，肺鱼是与适应陆地生活的脊椎动物关系最密切的亲属。虽然蛋白质编码基因的进化速度非常缓慢，这可能反映了它们 “活化石” 的状态，但转座元件似乎很活跃且具有高度多样性，这表明它们在肺鱼基因组的显著扩张中发挥了作用。对单个基因和基因家族的分析记录了与从水生到陆生转变相关的变化，并证明了肺鱼参考转录组在脊椎动物进化比较研究中的价值。
