An unusual type of mitochondrial DNA inheritance in the blue mussel Mytilus.

In animals, mitochondrial DNA (mtDNA) inheritance is predominantly maternal. In a few cases incidental transmission of paternal mtDNA was observed and estimated to account for only 10(-4)-10(-3) of an individual's mtDNA content. In contrast, biparental inheritance is common in mussels of the genus Mytilus. Here we present direct evidence that sex and mtDNA inheritance are coupled in Mytilus. Females inherit mtDNA only from their mother, but they transmit it to both daughters and sons. Males inherit mtDNA from both parents, but they transmit to sons only the mtDNA they inherited from their father. In pair matings, this mtDNA inheritance pattern is associated with a strong sex-ratio bias. These findings establish a newly discovered type of cytoplasmic DNA transmission. We also present evidence that the phenomenon breaks down in interspecific hybrids. IMAGES:

在动物中，线粒体DNA (mitochondrial DNA)的遗传模式以母系遗传为主。在少数案例中，曾观察到父系mtDNA的零星传递，据估算其仅占个体mtDNA总量的10^-4至10^-3。与之相反，双亲遗传在贻贝属（Mytilus）贝类中较为常见。本研究提供直接证据，证明贻贝属生物的性别与mtDNA遗传存在耦合关联。雌性个体仅从母亲处继承mtDNA，但可将其传递给女儿与儿子。雄性个体从双亲处均继承mtDNA，但仅能将其从父亲处获得的mtDNA传递给子代雄性。在成对交配实验中，这种mtDNA遗传模式与显著的性别比例偏倚相关联。上述研究发现确立了一种全新的细胞质DNA传递类型。本研究同时提供证据表明，该遗传现象在种间杂种中会失效。图像：