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Genotyping Single Nucleotide Polymorphisms in the Mitochondrial Genome by Pyrosequencing
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Gene fragmentation: a key to mitochondrial genome evolution in Euglenozoa?

Pavel Flegontov1, Michael W Gray, Gertraud Burger

  • 1Biology Centre, Institute of Parasitology, Czech Academy of Sciences, and Faculty of Sciences, University of South Bohemia, 37005, České Budĕjovice, Czech Republic.

Current Genetics
|May 6, 2011
PubMed
Summary

Mitochondrial genomes in Euglenozoa microbes evolved complex structures through neutral evolution. Small gene fragments and RNA processing led to gene fragmentation, RNA editing, and trans-splicing, creating unique genetic systems.

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Area of Science:

  • * Molecular biology
  • * Evolutionary biology
  • * Microbiology

Background:

  • * Phylum Euglenozoa includes kinetoplastids, diplonemids, and euglenids, all eukaryotic microbes.
  • * Their mitochondrial (mt) genomes display highly divergent organization and expression.
  • * Gene fragmentation is a notable characteristic of euglenid and diplonemid mtDNAs.

Purpose of the Study:

  • * To explain the evolution of divergent mtDNA types in Euglenozoa.
  • * To understand the origins of RNA editing and trans-splicing in these organisms.
  • * To propose a model for the emergence of complex mitochondrial genetic systems.

Main Methods:

  • * Theoretical modeling based on evolutionary principles.
  • * Analysis of proposed molecular interactions and RNA processing.
  • * Application of the constructive neutral evolution paradigm.

Main Results:

  • * Small expressed gene fragments in the ancestral Euglenozoa mitochondrion initiated neutral evolution.
  • * Interactions between antisense and full-length transcripts, aided by RNA enzymes, facilitated RNA editing and trans-splicing.
  • * These processes allowed tolerance of mutations and further gene fragmentation, driving divergence.

Conclusions:

  • * Constructive neutral evolution explains the development of complex mitochondrial genomes in Euglenozoa.
  • * Initially neutral molecular interactions accumulated via genetic drift, leading to 'irremediable complexity'.
  • * This model accounts for the diverse mtDNA structures and RNA processing mechanisms observed in Euglenozoa.