Mitochondrial DNA in the bark weevils: size, structure and heteroplasmy.
Mitochondrial DNA in the bark weevils: size, structure and heteroplasmy.
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DOI：
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发表时间：
1989-12
期刊：
影响因子：
3.3
通讯作者：
T. M. Boyce;M. Zwick;C. Aquadro
中科院分区：
文献类型：
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作者：
T. M. Boyce;M. Zwick;C. Aquadro
高等动物的线粒体DNA已被描述为基因组结构和功能的极端效率的例子。当发现异常大的分子（大于20 kb）时，大多数都是作为物种内的罕见变体出现的，这表明这些变体很少出现，并且在进化过程中不会持续很长时间。与此相反，至少三种树皮象甲的所有个体都具有异常大的线粒体基因组（30-36 kb）。该分子的大尺寸归因于显着扩大的富含A + T的区域（9-13 kb）。在这个区域之外的基因内容和顺序似乎与在果蝇中发现的相同。一系列0.8-2.0-kb的重复序列出现在大的A + T富集区附近，并且可能在大尺寸以及前所未有的频率的尺寸变体异质性的产生中发挥作用。在所有三个物种（n = 219）的每一个象鼻虫采样表现出任何地方从两个到五个不同的大小类的mtDNA。这种大量的大小多态性通过两个物种形成事件结合丰富的大小变化的持久性表明，这些分子可能不会受到强大的选择小的整体尺寸和复制效率。这种变异模式与分子编码区基因内容和排列的保守性形成强烈对比。
Mitochondrial DNA of higher animals has been described as an example of extreme efficiency in genome structure and function. Where exceptionally large size molecules have been found (greater than 20 kb), most have occurred as rare variants within a species, suggesting that these variants arise infrequently and do not persist for long periods in evolutionary time. In contrast, all individuals of at least three species of bark weevil (Curculionidae: Pissodes) possess a mitochondrial genome of unusually large size (30-36 kb). The molecule owes its large size to a dramatically enlarged A + T-rich region (9-13 kb). Gene content and order outside of this region appear to be identical to that found in Drosophila. A series of 0.8-2.0-kb repeated sequences occur adjacent to the large A + T rich region and have perhaps played a role in the generation of the large size as well as an unprecedented frequency of size variant heteroplasmy. Every weevil sampled in all three species (n = 219) exhibits anywhere from two to five distinct size classes of mtDNA. The persistence of this large amount of size polymorphism through two speciation events combined with the abundant size variation within individuals suggests that these molecules may not be subject to strong selection for small overall size and efficiency of replication. This pattern of variation contrasts strongly with the conservation of gene content and arrangement in the coding region of the molecule.