Quantitation of the male and female types of mitochondrial DNA in a blue mussel, Mytilus galloprovincialis , using real‐time polymerase chain reaction assay

The system termed doubly uniparental inheritance (DUI) of mitochondrial transmission to progeny has been reported in Mytilus . Under DUI, it has been thought that males have both paternally (M type) and maternally (F type) transmitted mitochondrial DNA (mtDNA), and females have only F type. However, the presence of M type in females has been reported. To clarify the ratio of M type to F type mtDNA in female and male tissues to further our understanding of mitochondrial transmission, we developed a procedure to measure the copy numbers of the two types of mtDNA in Mytilus galloprovincialis using a real‐time polymerase chain reaction assay. The following results were obtained by this method. In females, the copy numbers of M type mtDNA detected in adductor muscle, gonad and eggs were approximately 10 000‐fold lower than those of F type. In males, F type dominated in adductor muscle, as in the female tissue. However, copy numbers of M type mtDNA were approximately 1000‐fold higher than those of F type in gonad and 100 000‐fold higher than those of F type in sperm. We examined the quantity relationship between the two types of mtDNA and the transmission mechanism of mtDNA in M. galloprovincialis .