Comparative genomics of bdelloid rotifers: evaluating the effects of asexuality and desiccation tolerance on genome evolution
Comparative genomics of bdelloid rotifers: evaluating the effects of asexuality and desiccation tolerance on genome evolution
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蛭形轮虫的比较基因组学：评估无性和耐干燥性对基因组进化的影响
DOI：
10.1101/226720
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发表时间：
2017
期刊：
影响因子：
--
通讯作者：
Nowell R
中科院分区：
文献类型：
--
作者：
Nowell R
蛭形轮虫是一种微小的无脊椎动物，已经存在了数百万年，显然没有性别或减数分裂。它们生活在全球各种临时和永久的淡水栖息地，许多物种对干燥具有极强的耐受性。蜈蚣类为更好地理解性别和重组的进化提供了机会，但之前的工作强调干燥是导致这一组中几个不寻常的基因组特征的原因。在这里，我们评估了无性繁殖和脱水耐受性对基因组进化的相对影响，通过比较三个蜈蚣物种的全基因组序列：Adineta ricciae(耐脱水)、Rotaria macrura和Rotaria Magacalcarata(两者都不耐脱水)与迄今为止唯一公布的蜈蚣基因组，Adineta van a(也耐脱水)的全基因组序列进行了比较。我们发现，四倍体在所有四种瓢虫物种中都是保守的，但在专性水生轮虫基因组中的同源差异性很低，完全在专性二倍体动物的等位基因之间观察到的范围内。此外，我们还发现了同源区域INA。水稻在很大程度上是共线的，并不形成回文重复，这在已发表的A中被观察到。迷走神经组件。这些发现与目前人们对干燥作用在形成瓢虫基因组中的作用的理解相反，并表明被解释为长期无丝分裂进化的基因组证据的各种特征并不适用于所有瓢虫物种，即使在同一属内也是如此。最后，我们证实了以前的发现，即在干燥和非干燥的蜈蚣物种中都存在高水平的水平转移的非后生动物基因，并表明这是蜈蚣类在相关动物门中的一个独特特征。然而，在蜈蚣体内以及与其他耐脱水动物的比较中，脱水在水平转移中的所谓作用再次受到质疑。
Bdelloid rotifers are microscopic invertebrates that have existed for millions of years apparently without sex or meiosis. They inhabit a variety of temporary and permanent freshwater habitats globally, and many species are remarkably tolerant of desiccation. Bdelloids offer an opportunity to better understand the evolution of sex and recombination, but previous work has emphasized desiccation as the cause of several unusual genomic features in this group. Here, we evaluate the relative effects of asexuality and desiccation tolerance on genome evolution by comparing whole genome sequences for three bdelloid species:Adineta ricciae(desiccation tolerant),Rotaria macruraandRotaria magnacalcarata(both desiccation intolerant) to the only published bdelloid genome to date, that ofAdineta vaga(also desiccation tolerant). We find that tetraploidy is conserved among all four bdelloid species, but homologous divergence in obligately aquaticRotariagenomes is low, well within the range observed between alleles in obligately sexual, diploid animals. In addition, we find that homologous regions inA. ricciaeare largely collinear and do not form palindromic repeats as observed in the publishedA. vagaassembly. These findings are contrary to current understanding of the role of desiccation in shaping the bdelloid genome, and indicate that various features interpreted as genomic evidence for long-term ameiotic evolution are not general to all bdelloid species, even within the same genus. Finally, we substantiate previous findings of high levels of horizontally transferred non-metazoan genes encoded in both desiccating and non-desiccating bdelloid species, and show that this is a unique feature of bdelloids among related animal phyla. Comparisons within bdelloids and to other desiccation-tolerant animals, however, again call into question the purported role of desiccation in horizontal transfer.
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