Paternal mtDNA transmission
"[2][3][4] In testing 172 sheep, "The Mitochondrial DNA from three lambs in two half-sib families were found to show paternal inheritance.
In 1999 it was reported that paternal sperm mitochondria (containing mtDNA) are marked with ubiquitin to select them for later destruction inside the embryo.
Over the last 5 years, there has been considerable debate as to whether there is recombination in human mitochondrial DNA (mtDNA) (for references, see Piganeau and Eyre-Walker, 2004).
In a recent paper, Kraytsberg et al (2004) take this observation one step further, and claim to show that there has been recombination between the maternal and paternal mtDNA in this individual.
[11]Some sources state that so little paternal mtDNA is transmitted as to be negligible ("At most, one presumes it must be less than 1 in 1000, since there are 100 000 mitochondria in the human egg and only 100 in the sperm (Satoh and Kuroiwa, 1991).
[15] According to the study's abstract: In vertebrates, inheritance of mitochondria is thought to be predominantly maternal, and mitochondrial DNA analysis has become a standard taxonomic tool.
In accordance with the prevailing view of strict maternal inheritance, many sources assert that during fertilization, the sperm tail, with its mitochondria, gets excluded from the embryo.
The "missing mitochondria" story seems to have survived—and proliferated—unchallenged in a time of contention between hypotheses of human origins, because it supports the "African Eve" model of recent radiation of Homo sapiens out of Africa.The mixing of maternal and paternal mtDNA was thought to have been found in chimpanzees in 1999[16] and in humans in 1999[17] and 2018.
This last finding is significant, as biparental mtDNA was observed in subsequent generations in three different families leading to the conclusion that, although the maternal transmission dogma remains strong, there is evidence that paternal transmission does exist and there is probably a mechanism which, if elucidated, can be a new tool in the reproductive field (e.g. avoiding mitochondrial replacement therapy, and just using this mechanism so that the offspring inherit the paternal mitochondria).
