EXPOSURE OF PHOSPHATIDYLSERINE IN PARTHENOGENETICALLY ACTIVATED MOUSE EGGS

CURIA A; CUASNICÚ PS; COHEN DJ

San Juan

Jornada; XIII Jornadas Multidisiplinarias de la Sociedad Argentina de Biología (SAB); 2011

Phosphatidylserine (PS) is a phospholipid normally localized to the inner leaflet of the plasma membrane and it has been shown that its exposure is necessary for different cellular events. Recently, we have demonstrated that fertilization induces a transient exposure of PS in mouse eggs. In the present study we evaluated the exposure of PS in parthenogenetically activated mouse eggs. For this purpose, eggs were incubated with already known egg activators, and PS exposure was evaluated by incubation with  fluoresceinated-Anexin5 (ANX-5), that binds PS, and  microscopy.  The incubation with 10 mM SrCl2, 7% ethanol or 5 μM Ca2+ ionophore rendered a 94, 97 and 73% of activated eggs, respectively. Eggs activated by SrCl2 or ethanol showed a high percentage of ANX-5 labelling (96 and 90%, respectively) and a fluorescent pattern similar to that previously observed in fertilized eggs. By contrast, only 6% of ionophore-activated eggs showed ANX-5 labelling, evidencing the existence of differences between parthenogenetic activation methods. Interestingly, when previously ionophore- activated eggs were inseminated, the fertilized ones showed ANX-5 labeling, suggesting that PS exposure not only depends on the elevation of Ca2+. Taken together, these results indicate that the PS exposure observed in mouse eggs would occur as a result of egg activation.