A thirty million year-old inherited heteroplasmy
Public Library of Science
© 2008 Doublet et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Due to essentially maternal inheritance and a bottleneck effect during early oogenesis, newly arising mitochondrial DNA (mtDNA) mutations segregate rapidly in metazoan female germlines. Consequently, heteroplasmy (i.e. the mixture of mtDNA genotypes within an organism) is generally resolved to homoplasmy within a few generations. Here, we report an exceptional transpecific heteroplasmy (predicting an alanine/valine alloacceptor tRNA change) that has been stably inherited in oniscid crustaceans for at least thirty million years. Our results suggest that this heteroplasmy is stably transmitted across generations because it occurs within mitochondria and therefore escapes the mtDNA bottleneck that usually erases heteroplasmy. Consistently, at least two oniscid species possess an atypical trimeric mitochondrial genome, which provides an adequate substrate for the emergence of a constitutive intra-mitochondrial heteroplasmy. Persistence of a mitochondrial polymorphism on such a deep evolutionary timescale suggests that balancing selection may be shaping mitochondrial sequence evolution in oniscid crustaceans.
This research was funded by the Centre National de la Recherche Scientifique (CNRS) and the French Ministère de l'Education Nationale, de l'Enseignement Supérieur et de la Recherche. VD was supported by a Ph.D. fellowship from Région Poitou-Charentes. RC was supported by a CNRS Young Investigator ATIP award. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Vol. 3, No. 8, Article no. e2938
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