Related Experiment Videos
Motility and centrosomal organization during sea urchin and mouse fertilization
Abstract:
Motility and the behavior and inheritance of centrosomes are investigated during mouse and sea urchin fertilization. Sperm incorporation in sea urchins requires microfilament activity in both sperm and eggs as tested with Latrunculin A, a novel inhibitor of microfilament assembly. In contrast the mouse spermhead is incorporated in the presence of microfilament inhibitors indicating an absence of microfilament activity at this stage. Pronuclear apposition is arrested by microfilament inhibitors in fertilized mouse oocytes. The migrations of the sperm and egg nuclei during sea urchin fertilization are dependent on microtubules organized into a radial monastral array, the sperm aster. Microtubule activity is also required during pronuclear apposition in the mouse egg, but they are organized by numerous egg cytoplasmic sites. By the use of an autoimmune antibody to centrosomal material, centrosomes are detected in sea urchin sperm but not in unfertilized eggs. The sea urchin centrosome expands and duplicates during first interphase and condenses to form the mitotic poles during division. Remarkably mouse sperm do not appear to have the centrosomal antigen and instead centrosomes are found in the unfertilized oocyte. These results indicate that both microfilaments and microtubules are required for the successful completion of fertilization in both sea urchins and mice, but at different stages. Furthermore they demonstrate that centrosomes are contributed by the sperm during sea urchin fertilization, but they might be maternally inherited in mammals.
Insights
Fertilization in sea urchins and mice requires both microfilaments and microtubules, but their roles differ. Centrosomes are sperm-derived in sea urchins, contrasting with potential maternal inheritance in mice.
Area of Science:
- Cell Biology
- Developmental Biology
- Reproductive Biology
Background:
- Sperm and egg interactions are crucial for fertilization.
- The roles of cytoskeletal elements (microfilaments and microtubules) and centrosome inheritance in fertilization are not fully understood across different species.
- Mammalian fertilization mechanisms, particularly centrosome contribution, remain an area of active research.
Purpose of the Study:
- To investigate the roles of microfilaments and microtubules in sperm incorporation and pronuclear apposition during fertilization in sea urchins and mice.
- To examine the behavior and inheritance of centrosomes during fertilization in these species.
Main Methods:
- Utilized Latrunculin A, a microfilament assembly inhibitor, to test the requirement of microfilaments.
- Employed an autoimmune antibody against centrosomal material to detect and track centrosomes.
- Compared fertilization processes in sea urchins and mice at the molecular and cellular levels.
Main Results:
- Sperm incorporation in sea urchins requires microfilament activity, while mouse sperm incorporation occurs independently of microfilaments.
- Microfilament inhibitors arrested pronuclear apposition in mouse oocytes.
- Microtubules are essential for nuclear migrations in sea urchins (via sperm aster) and pronuclear apposition in mice (via egg cytoplasmic sites).
- Centrosomes were detected in sea urchin sperm but not unfertilized eggs, functioning in cell division.
- Mouse sperm lacked detectable centrosomal antigens; centrosomes were present in unfertilized oocytes.
Conclusions:
- Both microfilaments and microtubules are essential for fertilization in sea urchins and mice, but their specific functions and timing vary.
- Centrosomes are contributed by the sperm in sea urchins.
- Mammalian fertilization may involve maternal inheritance of centrosomes.