Fertilization and elimination of the paternal mitochondrial genome

• Published in: Human reproduction (Oxford) Vol. 15; no. suppl-2; pp. 92 - 101
• Main Author: Cummins, J.M.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Oxford Oxford University Press 01.07.2000
• Subjects: Animals; Biological and medical sciences; DNA, Mitochondrial - genetics; Early stages. Segmentation. Gastrulation. Neurulation; embryogenesis; Embryology: invertebrates and vertebrates. Teratology; Extrachromosomal Inheritance - genetics; Female; fertilization; Fertilization - genetics; Fertilization - physiology; Fundamental and applied biological sciences. Psychology; Gene Transfer Techniques; Genome; Humans; Male; maternal inheritance; Mice; Mitochondria - genetics; mitochondrial DNA; mitochondrial transfer; Oocytes - physiology; Sex Determination Processes; Sperm-Ovum Interactions; Spermatozoa - physiology; Testis - physiology; Zygote - physiology; mitochondrial transfer; embryogenesis; fertilization; maternal inheritance; mitochondrial DNA; Embryonic development; Spermatozoa; Elimination; Mitochondrial DNA; Review; Germinal cell; Fecundation; Paternal origin; Vertebrata; Mitochondria; Mammalia; Inheritance(genetics); Genome
• ISSN: 0268-1161; 1460-2350
• DOI: 10.1093/humrep/15.suppl_2.92

With rare exceptions, mammalian mitochondria are inherited through the female. This probably serves to minimize lethal cytoplasmic gene competition and to prevent the inheritance of sperm mitochondrial DNA that has been subject to degradation by free radicals. In general, organisms are intolerant of mitochondrial heteroplasmy and, when this occurs in humans, it frequently presents as progressive and lethal bioenergetic or neurological disease. The mitochondria of spermatozoa are specifically destroyed by proteolysis in early embryonic development, in mice at the 4-to 8-cell transition. While there are concerns in human assisted reproduction that microinjection of abnormal or immature sperm cells could lead to lasting harm in the offspring through transmission of abnormal mitochondria, there is no clinical evidence to support this. There is more potential for harm through attempts to ‘rescue’ poor quality oocytes by cytoplasmic or nuclear transfer, as it is not currently possible to control the final fate of the donated mitochondria in relation to nuclear-mitochondrial interactions or the embryonic axes. Moreover, the balance between nuclear and mitochondrial genes and the role of cytoplasmic factors in epigenesis are still poorly understood. The future challenge for biologists is to comprehend the nature of the selective destruction of paternal mitochondria, as it appears to be a species-specific recognition phenomenon.