Mammalian fertilization involves membrane events-adhesion,fusion,sperm engulfment,membrane block to polyspermy-whose causes remain largely unknown.Recently,specific oscillations of the sperm in contact with the egg we...Mammalian fertilization involves membrane events-adhesion,fusion,sperm engulfment,membrane block to polyspermy-whose causes remain largely unknown.Recently,specific oscillations of the sperm in contact with the egg were shown to be necessary for fusion.Using a microfluidic chip to impose the venue for the encounter of two gametes allowed real-time observation of the membrane remodelling occurring at the sperm/egg interface.The spatiotemporal mapping of egg CD9 revealed that this protein concentrates at the egg/sperm interface as a result of sperm oscillations,until a CDg-rich platform is nucleated on which fusion immediately takes place.Within 2-5 min after fusion,most of the CD9 leaves the egg for the external aqueous medium.Then an egg membrane wave engulfs the sperm head in^25 min.These results show that sperm oscillations initiate the CD9 recruitment that causes gamete fusion after which CD9 and associated proteins leave the membrane in a process likely to contribute to block polyspermy.They highlight that the gamete fusion story in mammals is an unexpected interplay between mechanical constraints and proteins.展开更多
文摘Mammalian fertilization involves membrane events-adhesion,fusion,sperm engulfment,membrane block to polyspermy-whose causes remain largely unknown.Recently,specific oscillations of the sperm in contact with the egg were shown to be necessary for fusion.Using a microfluidic chip to impose the venue for the encounter of two gametes allowed real-time observation of the membrane remodelling occurring at the sperm/egg interface.The spatiotemporal mapping of egg CD9 revealed that this protein concentrates at the egg/sperm interface as a result of sperm oscillations,until a CDg-rich platform is nucleated on which fusion immediately takes place.Within 2-5 min after fusion,most of the CD9 leaves the egg for the external aqueous medium.Then an egg membrane wave engulfs the sperm head in^25 min.These results show that sperm oscillations initiate the CD9 recruitment that causes gamete fusion after which CD9 and associated proteins leave the membrane in a process likely to contribute to block polyspermy.They highlight that the gamete fusion story in mammals is an unexpected interplay between mechanical constraints and proteins.
