Related Experiment Videos
Phalloidin inhibits cortical granule exocytosis and ooplasmic segregation in loach eggs
V V Ivanenkov1, A A Minin, S G Ozerova
1N.K. Koltzov Institute of Developmental Biology, U.S.S.R. Academy of Sciences, Moscow.
Abstract:
Injections of phalloidin under the surface of loach eggs, followed by activation of the eggs in tap water, result in local inhibition of cortical granule (CG) exocytosis. Light and electron microscopy revealed that in the region where exocytosis is inhibited the thickness of the microfilamentous cortex (MC) separating CGs from the plasma membrane (PM) is increased significantly, and many CGs are detached and have moved away from the MC. Injections of phalloidin also inhibit ooplasmic segregation in fertilized eggs. The experiments suggest that in intact eggs the MC represents a physical barrier to CG exocytosis, and that interactions of the MC with the PM and CGs are crucial for the retention of CGs near the sites of fusion.
Insights
Phalloidin injections inhibit cortical granule exocytosis in loach eggs by thickening the microfilamentous cortex, which acts as a barrier. This disruption also affects ooplasmic segregation, highlighting the cortex
Area of Science:
- Developmental Biology
- Cell Biology
- Reproductive Biology
Background:
- Cortical granules (CGs) are essential for the cortical reaction in eggs, preventing polyspermy.
- The microfilamentous cortex (MC) plays a role in egg structure and cortical granule exocytosis.
- Understanding the MC's role is crucial for comprehending fertilization and early development.
Purpose of the Study:
- To investigate the role of the microfilamentous cortex (MC) in regulating cortical granule (CG) exocytosis in loach eggs.
- To determine the effect of phalloidin, a microfilament stabilizer, on CG exocytosis and ooplasmic segregation.
Main Methods:
- Microinjection of phalloidin into loach eggs.
- Activation of eggs in tap water.
- Light and electron microscopy to examine CG exocytosis and MC structure.
- Observation of ooplasmic segregation in fertilized eggs.
Main Results:
- Phalloidin injections locally inhibited CG exocytosis.
- Inhibition of exocytosis correlated with increased MC thickness and CG detachment from the MC.
- Phalloidin also inhibited ooplasmic segregation in fertilized eggs.
Conclusions:
- The MC acts as a physical barrier to CG exocytosis in intact loach eggs.
- Interactions between the MC, plasma membrane (PM), and CGs are critical for retaining CGs at fusion sites.
- Phalloidin disrupts MC structure, impacting both CG exocytosis and ooplasmic segregation.