A persistent mitochondrial deletion reduces fitness and sperm performance in heteroplasmic populations of <it>C. elegans</it>

• Main Authors: Chin Kara, Deshommes Cleonique, Gonzalez-Serricchio Aidyl S, Liau Wei-Siang, LaMunyon Craig W
• Format: Article
• Language: English
• Published: BMC 2007-03-01
• Series: BMC Genetics
• Online Access: http://www.biomedcentral.com/1471-2156/8/8

<p>Abstract</p> <p>Background</p> <p>Mitochondrial DNA (mtDNA) mutations are of increasing interest due to their involvement in aging, disease, fertility, and their role in the evolution of the mitochondrial genome. The presence of reactive oxygen species and the near lack of repair mechanisms cause mtDNA to mutate at a faster rate than nuclear DNA, and mtDNA deletions are not uncommon in the tissues of individuals, although germ-line mtDNA is largely lesion-free. Large-scale deletions in mtDNA may disrupt multiple genes, and curiously, some large-scale deletions persist over many generations in a heteroplasmic state. Here we examine the phenotypic effects of one such deletion, <it>uaDf5</it>, in <it>Caenorhabditis elegans </it>(<it>C. elegans</it>). Our study investigates the phenotypic effects of this 3 kbp deletion.</p> <p>Results</p> <p>The proportion of <it>uaDf5 </it>chromosomes in worms was highly heritable, although <it>uaDf5 </it>content varied from worm to worm and within tissues of individual worms. We also found an impact of the <it>uaDf5 </it>deletion on metabolism. The deletion significantly reduced egg laying rate, defecation rate, and lifespan. Examination of sperm bearing the <it>uaDf5 </it>deletion revealed that sperm crawled more slowly, both in <it>vitro </it>and <it>in vivo</it>.</p> <p>Conclusion</p> <p>Worms harboring <it>uaDf5 </it>are at a selective disadvantage compared to worms with wild-type mtDNA. These effects should lead to the rapid extinction of the deleted chromosome, but it persists indefinitely. We discuss both the implications of this phenomenon and the possible causes of a shortened lifespan for <it>uaDf5 </it>mutant worms.</p>