Equipe Ecologie Evolution Symbiose, Laboratoire Ecologie et Biologie des Interactions, UMR CNRS 7267, Université de Poitiers, 40 Avenue du Recteur Pineau, 86022, Poitiers Cedex, France,
J Mol Evol. 2013 Sep;77(3):107-18. doi: 10.1007/s00239-013-9587-7. Epub 2013 Sep 26.
Mitochondrial DNA (mtDNA) is usually depicted as a circular molecule, however, there is increasing evidence that linearization of mtDNA evolved independently many times in organisms such as fungi, unicellular eukaryotes, and animals. Recent observations in various models with linear mtDNA revealed the presence of conserved inverted repeats (IR) at both ends that, when they become single-stranded, may be able to fold on themselves to create telomeric-hairpins involved in genome architecture conversions. The atypical mtDNA of terrestrial isopods (Crustacea: Oniscidea) composed of linear monomers and circular dimers is an interesting model to study genome architecture conversions. Here, we present the mtDNA control region sequences of two species of the genus Armadillidium: A. vulgare and A. pelagicum. All features of arthropods mtDNA control regions are present (origin of replication, poly-T stretch, GA and TA-rich blocks and one variable domain), plus a conserved IR. This IR can potentially fold into a hairpin structure and is present in two different orientations among the A. vulgare populations: either in one sense or in its reverse complement. This polymorphism, also observed in a single individual (heteroplasmy), might be a signature of genome architecture conversions from linear to circular monomeric mtDNA via successive opening and closing of the molecules.
线粒体 DNA（mtDNA）通常被描绘为一个圆形分子，但越来越多的证据表明，在线粒体 DNA 的线性化在真菌、单细胞真核生物和动物等生物体中独立进化了多次。最近在具有线性 mtDNA 的各种模型中的观察结果表明，在两端都存在保守的反向重复（IR），当它们变成单链时，可能能够自身折叠形成参与基因组结构转换的端粒发夹。由线性单体和圆形二聚体组成的陆生等足目动物（甲壳纲：等足目）的非典型 mtDNA 是研究基因组结构转换的有趣模型。在这里，我们展示了两种 Armadillidium 属的物种的 mtDNA 控制区序列：A. vulgare 和 A. pelagicum。所有节肢动物 mtDNA 控制区的特征都存在（复制起点、多-T 延伸、GA 和 TA 丰富区和一个可变区），加上一个保守的 IR。这个 IR 可以潜在地折叠成一个发夹结构，并存在于 A. vulgare 种群中的两种不同取向：要么是正向，要么是反向互补。这种多态性也在单个个体（异质性）中观察到，可能是通过分子的连续打开和关闭从线性单体 mtDNA 到圆形单体 mtDNA 的基因组结构转换的特征。
