Amazing stuff!
What a great movie Ben Hur (1959) was! Do not cross the Rubicon! 😊
"Within minutes of fertilization, the egg of a fruit fly becomes a scene from the battle of the sexes. The egg attacks and destroys the cellular “power plants,” or mitochondria, from the sperm that had fertilized it, so that only its own mitochondria remain. These findings from a new ... study ... might provide insights into advanced fertilization treatments and shed light on a long-standing mystery: How and why do we inherit all of our mitochondria from our mothers?
Paternal mitochondria vanish soon after fertilization in virtually all species, from sexually reproducing plants through fungi and insects to mammals, including humans. One theory for this holds that paternal mitochondria are simply diluted by the vastly more abundant maternal ones, but another suggests that they are actively eliminated by the egg.
About a decade ago ... provided crucial evidence in favor of the active elimination theory. The new study, led by PhD student Sharon Ben-Hur, reveals the molecular details of this elimination, showing that the egg launches a deliberate, targeted attack on the sperm’s mitochondria. ..."
From the abstract:
"Mitochondria are maternally inherited, but the mechanisms underlying paternal mitochondrial elimination after fertilization are far less clear. Using Drosophila, we show that special egg-derived multivesicular body vesicles promote paternal mitochondrial elimination by activating an LC3-associated phagocytosis-like pathway, a cellular defense pathway commonly employed against invading microbes. Upon fertilization, these egg-derived vesicles form extended vesicular sheaths around the sperm flagellum, promoting degradation of the sperm mitochondrial derivative and plasma membrane. LC3-associated phagocytosis cascade of events, including recruitment of a Rubicon-based class III PI(3)K complex to the flagellum vesicular sheaths, its activation, and consequent recruitment of Atg8/LC3, are all required for paternal mitochondrial elimination. Finally, lysosomes fuse with strings of large vesicles derived from the flagellum vesicular sheaths and contain degrading fragments of the paternal mitochondrial derivative. Given reports showing that in some mammals, the paternal mitochondria are also decorated with Atg8/LC3 and surrounded by multivesicular bodies upon fertilization, our findings suggest that a similar pathway also mediates paternal mitochondrial elimination in other flagellated sperm-producing organisms."
Fig. 1: Rubicon is required for PME after fertilization.
Dr. Sharon Ben-Hur (lead researcher)
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