Hoelzel A R, Lopez J V, Dover G A, O'Brien S J
Laboratory of Viral Carcinogenesis, National Cancer Institute, Frederick, MD 21702.
J Mol Evol. 1994 Aug;39(2):191-9. doi: 10.1007/BF00163807.
We describe a repetitive DNA region at the 3' end of the mitochondrial DNA (mtDNA) control region and compare it in 21 carnivore species representing eight carnivore families. The sequence and organization of the repetitive motifs can differ extensively between arrays; however, all motifs appear to be derived from the core motif "ACGT." Sequence data and Southern blot analysis demonstrate extensive heteroplasmy. The general form of the array is similar between heteroplasmic variants within an individual and between individuals within a species (varying primarily in the length of the array, though two clones from the northern elephant seal are exceptional). Within certain families, notably ursids, the array structure is also similar between species. Similarity between species was not apparent in other carnivore families, such as the mustelids, suggesting rapid changes in the organization and sequence of some arrays. The pattern of change seen within and between species suggests that a dominant mechanism involved in the evolution of these arrays is DNA slippage. A comparative analysis shows that the motifs that are being reiterated or deleted vary within and between arrays, suggesting a varying rate of DNA turnover. We discuss the evolutionary implications of the observed patterns of variation and extreme levels of heteroplasmy.
我们描述了线粒体DNA（mtDNA）控制区3'端的一个重复DNA区域，并在代表8个食肉动物科的21种食肉动物中对其进行了比较。重复基序的序列和组织在不同阵列之间可能有很大差异；然而，所有基序似乎都源自核心基序“ACGT”。序列数据和Southern印迹分析表明存在广泛的异质性。在个体内的异质变体之间以及物种内的个体之间，阵列的一般形式相似（主要在阵列长度上有所不同，不过来自北象海豹的两个克隆是例外）。在某些科中，尤其是熊科，物种之间的阵列结构也相似。在其他食肉动物科，如鼬科中，物种之间的相似性并不明显，这表明一些阵列的组织和序列发生了快速变化。在物种内和物种间观察到的变化模式表明，这些阵列进化过程中涉及的一个主要机制是DNA滑动。一项比较分析表明，正在重复或缺失的基序在阵列内和阵列间有所不同，这表明DNA周转速率不同。我们讨论了观察到的变异模式和极端异质性水平的进化意义。
