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Enzymatic alteration of the ability of mouse egg plasma membrane to interact with sperm
1Department of Obstetrics and Gynecology, Medical College of Georgia, Augusta 30912.
Abstract:
The effect of a variety of proteolytic, glycosidic and lipid hydrolyzing enzymes on the ability of mouse egg plasma membrane to interact with sperm was evaluated in this study. Zona-free mouse eggs were exposed to enzymes at various concentrations, washed, and inseminated; the number of sperm attached to or having penetrated the egg plasma membrane was determined at 20 and 180 min post-insemination, respectively. The proteases trypsin and chymotrypsin caused concentration-dependent reductions in both sperm attachment and sperm penetration levels when eggs were incubated at enzyme concentrations ranging from 1- to 1000 micrograms/ml for 30 min prior to insemination. Time-course studies revealed significant inhibition of both sperm attachment and sperm penetration levels after treating zona-free eggs for 5 min at 1000 micrograms/ml of either trypsin or chymotrypsin. Several of the phospholipases tested, including phospholipases C, D, and A2, had no inhibitory effect on sperm penetration levels, with phospholipase C and A2 (100 micrograms/ml) causing inhibition of sperm attachment. Of the glycosidic enzymes evaluated, glucuronidase (1000 micrograms/ml) caused significant inhibition of sperm binding but not sperm penetration, and glucosidase, galactosidase, and neuraminidase had no effect on either sperm attachment or sperm penetration. These findings indicate that the ability of the mouse egg plasma membrane to fuse with sperm can be preferentially altered by treatment with proteases.
Insights
Protease enzymes like trypsin significantly reduced sperm interaction with mouse egg plasma membranes. This suggests proteases can alter the egg
Area of Science:
- Reproductive Biology
- Cell Biology
- Enzymology
Background:
- Sperm-egg plasma membrane interaction is crucial for fertilization.
- The molecular mechanisms governing sperm-egg fusion are not fully understood.
- Enzymatic modification of the egg plasma membrane may influence fertilization.
Purpose of the Study:
- To investigate the impact of various hydrolyzing enzymes on sperm-egg plasma membrane interaction in mice.
- To determine if specific enzyme classes can modulate sperm attachment and penetration.
Main Methods:
- Zona-free mouse eggs were treated with proteolytic, glycosidic, and lipid-hydrolyzing enzymes at varying concentrations.
- Enzyme-treated eggs were inseminated, and sperm attachment and penetration were quantified at 20 and 180 minutes post-insemination.
- Time-course and concentration-dependent studies were performed for key enzymes.
Main Results:
- Trypsin and chymotrypsin significantly reduced sperm attachment and penetration in a dose-dependent manner.
- Short incubation times (5 minutes) with high protease concentrations (1000 µg/ml) were sufficient to inhibit sperm interaction.
- Phospholipases C, D, and A2 showed no effect on sperm penetration, though phospholipase C and A2 inhibited attachment.
- Glucuronidase inhibited sperm binding but not penetration; other glycosidases had no effect.
Conclusions:
- Proteolytic enzymes, specifically trypsin and chymotrypsin, can effectively inhibit sperm-egg plasma membrane interaction.
- The findings suggest that proteins on the mouse egg plasma membrane play a critical role in sperm fusion.
- Enzymatic treatment offers a method to selectively alter sperm-egg interactions, providing insights into fertilization mechanisms.