Marine Biology Research Division, Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA, USA.
J Evol Biol. 2010 Mar;23(3):528-38. doi: 10.1111/j.1420-9101.2009.01917.x. Epub 2010 Jan 7.
Organismal fitness requires functional integration of nuclear and mitochondrial genomes. Structural and regulatory elements coevolve within lineages and several studies have found that interpopulation hybridization disrupts mitonuclear interactions. Because mitochondrial RNA polymerase (mtRPOL) plays key roles in both mitochondrial DNA (mtDNA) replication and transcription, the interaction between mtRPOL and coevolved regulatory sites in the mtDNA may be central to mitonuclear integration. Here, we generate interpopulation hybrids between divergent populations of the copepod Tigriopus californicus to obtain lines having different combinations of mtRPOL and mtDNA. Lines were scored for mtDNA copy number and ATP6 (mtDNA) gene expression. We find that there is a genotype-dependent negative association between mitochondrial transcriptional response and mtDNA copy number. We argue that an observed increase in mtDNA copy number and reduced mtDNA transcription in hybrids reflects the regulatory role of mtRPOL; depending on the mitonuclear genotype, hybridization may disrupt the normal balance between transcription and replication of the mitochondrial genome.
生物体的适应性需要核基因组和线粒体基因组的功能整合。结构和调节元件在谱系内共同进化，有几项研究发现，种间杂交会破坏线粒体与核的相互作用。由于线粒体 RNA 聚合酶（mtRPOL）在线粒体 DNA（mtDNA）复制和转录中都起着关键作用，因此 mtRPOL 与 mtDNA 中共同进化的调节位点之间的相互作用可能是线粒体与核整合的核心。在这里，我们在加利福尼亚桡足类动物的两个不同种群之间产生了种间杂种，以获得具有不同 mtRPOL 和 mtDNA 组合的品系。对 mtDNA 拷贝数和 ATP6（mtDNA）基因表达进行了评分。我们发现线粒体转录反应与 mtDNA 拷贝数之间存在基因型依赖性的负相关。我们认为杂交种中 mtDNA 拷贝数的增加和 mtDNA 转录的减少反映了 mtRPOL 的调节作用；根据线粒体与核的基因型，杂交可能会破坏线粒体基因组转录和复制之间的正常平衡。
