Department of Genetics and Marine Biotechnology, Institute of Oceanology Polish Academy of Sciences, Sopot, Poland.
Sci Rep. 2020 Jul 9;10(1):11256. doi: 10.1038/s41598-020-67976-6.
Doubly uniparental inheritance (DUI) of mitochondrial DNA is a rare phenomenon occurring in some freshwater and marine bivalves and is usually characterized by the mitochondrial heteroplasmy of male individuals. Previous research on freshwater Unionida mussels showed that hermaphroditic species do not have DUI even if their closest gonochoristic counterparts do. No records showing DUI in a hermaphrodite have ever been reported. Here we show for the first time that the hermaphroditic mussel Semimytilus algosus (Mytilida), very likely has DUI, based on the complete sequences of both mitochondrial DNAs and the distribution of mtDNA types between male and female gonads. The two mitogenomes show considerable divergence (34.7%). The presumably paternal M type mitogenome dominated the male gonads of most studied mussels, while remaining at very low or undetectable levels in the female gonads of the same individuals. If indeed DUI can function in the context of simultaneous hermaphroditism, a change of paradigm regarding its involvement in sex determination is needed. It is apparently associated with gonadal differentiation rather than with sex determination in bivalves.
线粒体 DNA 的双重单亲遗传（DUI）是一种罕见的现象，发生在一些淡水和海洋双壳类动物中，通常表现为雄性个体的线粒体异质性。以前对淡水贻贝类的研究表明，雌雄同体的物种即使与其最接近的雌雄异体物种具有 DUI 现象，它们也没有 DUI。到目前为止，还没有关于雌雄同体中存在 DUI 的记录。在这里，我们首次表明，雌雄同体贻贝 Semimytilus algosus（贻贝目）很可能存在 DUI，这是基于两条线粒体 DNA 的完整序列以及 mtDNA 类型在雄性和雌性性腺之间的分布。这两个线粒体基因组显示出相当大的差异（34.7%）。推测的父系 M 型线粒体基因组在大多数研究贻贝的雄性性腺中占主导地位，而在同一个体的雌性性腺中则处于非常低或无法检测到的水平。如果 DUI 确实可以在同时存在雌雄同体的情况下发挥作用，那么就需要改变其在性别决定中的作用模式。它显然与性腺分化有关，而不是与双壳类动物的性别决定有关。
