Mitochondrial genomes of Columbicola feather lice are highly fragmented, indicating repeated evolution of minicircle-type genomes in parasitic lice
Mitochondrial genomes of Columbicola feather lice are highly fragmented, indicating repeated evolution of minicircle-type genomes in parasitic lice
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DOI：
10.7717/peerj.8759
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发表时间：
2020-03-23
期刊：
影响因子：
2.7
通讯作者：
Cameron, Stephen L.
中科院分区：
文献类型：
--
作者：
Sweet, Andrew D.;Johnson, Kevin P.;Cameron, Stephen L.
大多数动物的线粒体基因组结构保守，只有一条染色体。然而，一些生物的线粒体基因分离在几条较小的圆形或线形染色体上。高度碎片化的圆形染色体(“微环”)在寄生虱子中尤其普遍，已知的16种寄生虱每个基因组有9至20个线粒体微环。所有这些物种都属于同一个Glade(哺乳动物虱子)，这表明严重分裂的单一来源。然而，其他研究表明，在一些禽类的羽虱中存在较小程度的碎片化(2-3条染色体/基因组)。在这项研究中，我们测试了羽虱属的四个物种的微小圆圈。利用全基因组鸟枪序列数据，我们应用了三种不同的生物信息学方法来组装炭疽菌线粒体基因组。我们通过从鸟枪测序读数中组装人马尾鱼的线粒体基因组进一步证实了这些方法，这是一个已知具有微环的物种。炭疽菌(Columicola Spp)基因组高度碎片化为15-17个微环，长度在1100-3100个碱基之间，每个微环有1-4个基因。随后对微环的注释表明，微环的tRNA排列在物种之间有很大差异。这些线粒体微环是第一个在完整的线粒体基因组中发现微环的羽虱(飞虱科)。结合最近对寄生虱的系统发育研究，我们的结果提供了强有力的证据，证明高度碎片化的线粒体基因组在生命树上是罕见的，在寄生虱中进化了多次。
Most animals have a conserved mitochondrial genome structure composed of a single chromosome. However, some organisms have their mitochondrial genes separated on several smaller circular or linear chromosomes. Highly fragmented circular chromosomes ("minicircles") are especially prevalent in parasitic lice (Insecta: Phthiraptera), with 16 species known to have between nine and 20 mitochondrial minicircles per genome. All of these species belong to the same Glade (mammalian lice), suggesting a single origin of drastic fragmentation. Nevertheless, other work indicates a lesser degree of fragmentation (2-3 chromosomes/genome) is present in some avian feather lice (Ischnocera: Philopteridae). In this study, we tested for minicircles in four species of the feather louse genus Columbicola (Philopteridae). Using whole genome shotgun sequence data, we applied three different bioinformatic approaches for assembling the Columbicola mitochondrial genome. We further confirmed these approaches by assembling the mitochondrial genome of Pediculus humanus from shotgun sequencing reads, a species known to have minicircles. Columbicola spp. genomes are highly fragmented into 15-17 minicircles between similar to 1,100 and similar to 3,100 bp in length, with 1-4 genes per minicircle. Subsequent annotation of the minicircles indicated that tRNA arrangements of minicircles varied substantially between species. These mitochondrial minicircles for species of Columbicola represent the first feather lice (Philopteridae) for which minicircles have been found in a full mitochondrial genome assembly. Combined with recent phylogenetic studies of parasitic lice, our results provide strong evidence that highly fragmented mitochondrial genomes, which are otherwise rare across the Tree of Life, evolved multiple times within parasitic lice.