Journal of Molecular Evolution

, Volume 65, Issue 6, pp 651–659

Structure and Evolution of the Atypical Mitochondrial Genome of Armadillidium vulgare (Isopoda, Crustacea)

  • Isabelle Marcadé
  • Richard Cordaux
  • Vincent Doublet
  • Catherine Debenest
  • Didier Bouchon
  • Roland Raimond
Article

Abstract

The crustacean isopod Armadillidium vulgare is characterized by an unusual ∼42-kb-long mitochondrial genome consisting of two molecules co-occurring in mitochondria: a circular ∼28-kb dimer formed by two ∼14-kb monomers fused in opposite polarities and a linear ∼14-kb monomer. Here we determined the nucleotide sequence of the fundamental monomeric unit of A. vulgare mitochondrial genome, to gain new insight into its structure and evolution. Our results suggest that the junction zone between monomers of the dimer structure is located in or near the control region. Direct sequencing indicated that the nucleotide sequences of the different monomer units are virtually identical. This suggests that gene conversion and/or replication processes play an important role in shaping nucleotide sequence variation in this mitochondrial genome. The only heteroplasmic site we identified predicts an alloacceptor tRNA change from tRNAAla to tRNAVal. Therefore, in A. vulgare, tRNAAla and tRNAVal are found at the same locus in different monomers, ensuring that both tRNAs are present in mitochondria. The presence of this heteroplasmic site in all sequenced individuals suggests that the polymorphism is selectively maintained, probably because of the necessity of both tRNAs for maintaining proper mitochondrial functions. Thus, our results provide empirical evidence for the tRNA gene recruitment model of tRNA evolution. Moreover, interspecific comparisons showed that the A. vulgare mitochondrial gene order is highly derived compared to the putative ancestral arthropod type. By contrast, an overall high conservation of mitochondrial gene order is observed within crustacean isopods.

Keywords

Atypical mitochondrial genome Armadillidium vulgare Trimeric structure Linear monomer Gene conversion Heteroplasmy tRNA gene recruitment Gene rearrangements Isopod 

Copyright information

© Springer Science+Business Media, LLC 2007

Authors and Affiliations

  • Isabelle Marcadé
    • 1
  • Richard Cordaux
    • 1
  • Vincent Doublet
    • 1
  • Catherine Debenest
    • 1
  • Didier Bouchon
    • 1
  • Roland Raimond
    • 1
  1. 1.Laboratoire de Génétique et Biologie des Populations de Crustacés, UMR CNRS 6556Université de PoitiersPoitiersFrance

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