The mitochondrial genome of the screamer louse Bothriometopus (Phthiraptera: Ischnocera):: Effects of extensive gene rearrangements on the evolution of the genome
The mitochondrial genome of the screamer louse Bothriometopus (Phthiraptera: Ischnocera):: Effects of extensive gene rearrangements on the evolution of the genome
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DOI：
10.1007/s00239-007-9042-8
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发表时间：
2007-11-01
影响因子：
3.9
通讯作者：
Whiting, Michael F.
中科院分区：
文献类型：
--
作者：
Cameron, Stephen L.;Johnson, Kevin P.;Whiting, Michael F.
线粒体(Mt)基因组重排一般是从这一现象本身出发进行研究的，主要集中在它们的系统发育分布和致病机制上。重排通过影响替代、转录和信使核糖核酸的加工而具有额外的意义。虱子是研究重排与这些因素之间的相互作用的理想群体，因为这一群体内的重排速率较高。对尖叫虱的整个mt基因组进行了测序，并与之前测序的虱子基因组进行了比较。Mt基因组长15,564个碱基，呈环状，所有基因都编码在同一条链上。这种基因排列与其他虱子物种和祖先昆虫都有根本的不同。核苷酸组成是A+T偏向的，但没有偏斜，这可能是由于复制方向逆转或转录效应造成的。博氏木霉同时具有tRNA复制和协同进化，这是以前没有观察到的。在13个编码蛋白质的基因中，有11个具有3‘末端茎环结构，这可能允许在没有tRNA侧翼的情况下进行mRNA处理，从而促进基因重排。有五个候选控制区能够形成茎环结构。其中两种在结构上与其他昆虫物种的控制区比其他虱子的控制区更相似。对白纹伊蚊的分析表明，虱子mt基因组除了被广泛重排外，还在核苷酸组成偏向、tRNA进化、蛋白质编码基因结构和可能的信号位点(如控制区)等方面与大多数昆虫物种有显著差异。这可能是基因重排的原因或结果。
Mitochondrial (mt) genome rearrangement has generally been studied with respect to the phenomenon itself, focusing on their phylogenetic distribution and causal mechanisms. Rearrangements have additional significance through effects on substitution, transcription, and mRNA processing. Lice are an ideal group in which to study the interactions between rearrangements and these factors due to the heightened rearrangement rate within this group. The entire mt genome of the screamer louse Bothriometopus was sequenced and compared to previously sequenced louse genomes. The mt genome is 15,564 bp, circular, and all genes are encoded on the same strand. The gene arrangement differs radically from both other louse species and the ancestral insect. Nucleotide composition is A+T biased, but there is no skew which may be due to reversal of replication direction or a transcriptional effect. Bothriometopus has both tRNA duplication and concerted evolution which has not been observed previously. Eleven of the 13 protein-coding genes have 3' end stem-loop structures which may allow mRNA processing without flanking tRNAs and so facilitate gene rearrangements. There are five candidate control regions capable of forming stem-loop structures. Two are structurally more similar to the control regions of other insect species than those of other lice. Analyses of Bothriometopus demonstrate that louse mt genomes, in addition to being extensively rearranged, differ significantly from most insect species in nucleotide composition biases, tRNA evolution, protein-coding gene structures and putative signaling sites such as the control region. These may be either a cause or a consequence of gene rearrangements.