Kyriakou Eleni, Kravariti Lara, Vasilopoulos Themistoklis, Zouros Eleftherios, Rodakis George C
Department of Biochemistry and Molecular Biology, National and Kapodistrian University of Athens, Panepistimioupolis, 15701 Athens, Greece.
Department of Biology, University of Crete, 71409 Heraklion, Crete, Greece.
Gene. 2015 May 10;562(1):83-94. doi: 10.1016/j.gene.2015.02.047. Epub 2015 Feb 19.
Sea mussels (genus Mytilus) have two mitochondrial genomes in obligatory co-existence, one that is transmitted through the egg and the other through the sperm. The phenomenon, known as Doubly Uniparental Inheritance (DUI) of mitochondrial DNA (mtDNA), is presently known to occur in more than 40 molluscan bivalve species. Females and the somatic tissues of males contain mainly the maternal (F) genome. In contrast, the sperm contains only the paternal (M) genome. Through electrophoretic mobility shift assay (EMSA) experiments we have identified a sequence element in the control region (CR) of the M genome that acts as a binding site for the formation of a complex with a protein factor that occurs in the male gonad. An adenine tract upstream to the element is also essential for the formation of the complex. The reaction is highly specific. It does not occur with protein extracts from the female gonad or from a male or female somatic tissue. Further experiments showed that the interaction takes place in mitochondria surrounding the nucleus of the cells of male gonads, suggesting a distinct role of perinuclear mitochondria. We propose that at a certain point during spermatogenesis mitochondria are subject to degradation and that perinuclear mitochondria with the M mtDNA-protein complex are protected from this degradation with the result that mature spermatozoa contain only the paternal mitochondrial genome.
贻贝（紫贻贝属）有两个线粒体基因组，它们必然共存，一个通过卵子传递，另一个通过精子传递。这种现象被称为线粒体DNA（mtDNA）的双亲单亲遗传（DUI），目前已知在40多种软体双壳类物种中存在。雌性和雄性的体细胞组织主要包含母本（F）基因组。相比之下，精子只包含父本（M）基因组。通过电泳迁移率变动分析（EMSA实验），我们在M基因组的控制区（CR）中鉴定出一个序列元件，它作为一个结合位点，与雄性性腺中出现的一种蛋白质因子形成复合物。该元件上游的一个腺嘌呤序列对复合物的形成也至关重要。这种反应具有高度特异性。它不会在雌性性腺或雄性或雌性体细胞组织的蛋白质提取物中发生。进一步的实验表明，这种相互作用发生在雄性性腺细胞的细胞核周围的线粒体中，这表明核周线粒体具有独特的作用。我们提出，在精子发生过程中的某个时刻，线粒体容易受到降解，而带有M mtDNA-蛋白质复合物的核周线粒体受到保护，免受这种降解，结果成熟精子只包含父本线粒体基因组。
