de Paula, W.B., Agip, A.N., Missirlis, F., Ashworth, R., Vizcay-Barrena, G., Lucas, C.H., and Allen, J.F. (2013) Female and male gamete mitochondria are distinct and complementary in transcription, structure, and genome function. Genome biology and evolution. 5(10):1969-1977.
Respiratory electron transport in mitochondria is coupled to ATP synthesis while generating mutagenic oxygen free radicals.
Mitochondrial DNA mutation then accumulates with age, and may set a limit to the lifespan of individual, multicellular organisms.
Why is this mutation not inherited? Here we demonstrate that female gametes—oocytes—have unusually small and simple mitochondria
that are suppressed for DNA transcription, electron transport, and free radical production. By contrast, male gametes—sperm—and
somatic cells of both sexes transcribe mitochondrial genes for respiratory electron carriers and produce oxygen free radicals.
This germ-line division between mitochondria of sperm and egg is observed in both the vinegar fruitfly and the zebrafish—species
spanning a major evolutionary divide within the animal kingdom. We interpret these findings as an evidence that oocyte mitochondria
serve primarily as genetic templates, giving rise, irreversibly and in each new generation, to the familiar energy-transducing
mitochondria of somatic cells and male gametes. Suppressed mitochondrial metabolism in the female germ line may therefore
constitute a mechanism for increasing the fidelity of mitochondrial DNA inheritance.