THE FATE OF PATERNAL MITOCHONDRIAL-DNA IN DEVELOPING FEMALE MUSSELS, MYTILUS-EDULIS - IMPLICATIONS FOR THE MECHANISM OF DOUBLY UNIPARENTAL INHERITANCE OF MITOCHONDRIAL-DNA

Species of the marine mussel family Mytilidae have two types of mitoch ondrial DNA: one that is transmitted from the mother to both female an d male offspring (the F type) and one that is transmitted from the fat her to sons only (the M type). By using pair matings that produce only female offspring or a mixture of female and male offspring and a pair of oligonucleotide primers I:hat amplify part of the COIII gene of th e M but not die F mitochondrial genome, we demonstrate that both male and female embryos receive M mtDNA through the sperm and that within 2 4 hr after fertilization the M mtDNA is eliminated or is drastically r educed in female embryos but maintained in male embryos. These observa tions are important for understanding the relationship between mtDNA t ransmission and sex determination in species with doubly uniparental i nheritance of mitochondrial DNA.