JERUSALEM, July 16 (Xinhua) -- Israeli scientists have discovered why most species, including humans, animals, and plants, inherit all their cellular powerhouse mitochondria from their mothers, the Weizmann Institute of Science said on Monday.
In a new study published in Nature Communications, the researchers investigated the phenomenon of paternal mitochondria disappearing shortly after fertilization.
Using fruit fly experiments, the team observed that immediately after fertilization, the egg initiates a targeted assault on the sperm's mitochondria, ensuring only its own mitochondria persist.
This discovery not only sheds light on the longstanding mystery of maternal mitochondrial inheritance but also holds promise for advancements in fertility treatments.
These include in vitro fertilization and mitochondrial replacement therapies, which involve substituting a mother's mitochondria, potentially harboring harmful mutations, with those from a donor egg.
During their study, the researchers observed vesicle clusters enveloping the sperm's tail upon penetration into the egg. These clusters form a protective sheath that facilitates the breakdown of the sperm's mitochondrial structure into smaller components.
Furthermore, the researchers uncovered that the egg employs an innate immune pathway to dismantle paternal mitochondria, treating them as intrusive entities. This aligns with the hypothesis that mitochondria, originally bacterial invaders, co-evolved with host cells to offer mutual benefits.
The urgency with which the egg breaks down paternal mitochondria underscores its potentially harmful contents for fetal development. At the same time, these mitochondria also contain molecules beneficial for fetal growth, prompting their breakdown and potential utilization. ■
