Data from: Early replication dynamics of sex-linked mitochondrial DNAs in the doubly uniparental inheritance species Ruditapes philippinarum (Bivalvia Veneridae)

Mitochondrial homoplasmy, which is maintained by strictly maternal
inheritance and a series of bottlenecks, is thought to be an adaptive
condition for metazoans. Doubly uniparental inheritance (DUI) is a unique
mode of mitochondrial transmission found in bivalve species, in which two
distinct mitochondrial genome (mtDNA) lines are present, one inherited
through eggs (F) and one through sperm (M). During development, the two
lines segregate in a sex- and tissue-specific manner: females lose M
during embryogenesis, whereas males actively segregate it in the germ
line. These two pivotal events are still poorly characterized. Here we
investigated mtDNA replication dynamics during embryogenesis and
pre-adulthood of the venerid Ruditapes philippinarum using real-time
quantitative PCR. We found that both mtDNAs do not detectably replicate
during early embryogenesis, and that the M line might be lost from females
around 24 h of age. A rise in mtDNA copy number was observed before the
first reproductive season in both sexes, with the M mitochondrial genome
replicating more than the F in males, and we associate these boosts to the
early phase of gonad production. As evidence indicates that DUI relies on
the same molecular machine of mitochondrial maternal inheritance that is
common in most animals, our data are relevant not only to DUI but also to
shed light on how differential segregations of mtDNA variants, in the same
nuclear background, may be controlled during development.