Calmodulin during human sperm incorporation into hamster oocyte: an immunogold electron microscope study
A M Courtot1, J M Feinberg, D A Schoevaert
1Laboratoire de Biologie de la Reproduction et du Développement, CHU Bicétre, Kremlin-Bicêtre, France.
Molecular Reproduction and Development
|June 1, 1994
Summary
Calmodulin, a key protein, plays a crucial role in human fertilization. This study reveals its specific locations within sperm and its dynamic changes after sperm-egg fusion, suggesting involvement in fusion and calcium signaling.
Area of Science:
- Reproductive Biology
- Cell Biology
- Biochemistry
Background:
- Calmodulin is a calcium-binding protein involved in various cellular processes.
- Its precise role and localization during human fertilization remain incompletely understood.
Purpose of the Study:
- To investigate the ultrastructural localization and potential function of calmodulin during human fertilization.
- To examine calmodulin's distribution in sperm before and after fusion with a hamster oocyte.
Main Methods:
- Immunogold labeling of ultrathin sections of human sperm.
- Microscopic analysis of sperm before and after incorporation into hamster oocytes.
Main Results:
- Calmodulin was localized primarily in the subacrosomal and postacrosomal regions of human sperm heads.
- Postacrosomal calmodulin disappeared upon sperm head incorporation into the egg cytoplasm.
- Subacrosomal calmodulin remained detectable and did not co-localize with actin in the fertilization cone.
Conclusions:
- Calmodulin's unique localization and redistribution suggest a role in targeting from the acrosome to the postacrosome during spermatogenesis.
- The findings strongly implicate calmodulin in mediating sperm-egg fusion.
- Calmodulin is suggested to be involved in the initial calcium ion (Ca2+) pulse during fertilization.
Related Concept Videos
01:38Fertilization
During fertilization, an egg and sperm cell fuse to create a new diploid structure. In humans, the process occurs once the egg has been released from the ovary, and travels into the fallopian tubes. The process requires several key steps: 1) sperm present in the genital tract must locate the egg; 2) once there, sperm need to release enzymes to help them burrow through the protective zona pellucida of the egg; and 3) the membranes of a single sperm cell and egg must fuse, with the sperm...
01:16Calmodulin-dependent Signaling
Calmodulin (CaM) is a calcium-binding protein in eukaryotes that controls various calcium-regulated cellular processes. It has four calcium-binding sites that bind calcium to form the calcium-calmodulin ( Ca2+-CaM) complex. GPCR stimulation increases the calcium levels in the cells that bind to CaM and induces a conformational change.
The Ca2+-CaM complex does not have enzymatic activity by itself. Instead, the complex binds downstream target proteins, including membrane proteins or enzymes,...
The Ca2+-CaM complex does not have enzymatic activity by itself. Instead, the complex binds downstream target proteins, including membrane proteins or enzymes,...
01:20Immunogold Electron Microscopy
Immunoelectron microscopy utilizes immunogold labeling of endogenous proteins with specific antibodies to detect and localize these proteins in cells and tissues. The procedure provides insights into the distribution and quantification of protein under different stimulation conditions offering clues about their functions. Conjugating highly electron-dense gold particles with primary or secondary antibodies allow antigen detection on and within cells, with high resolution and specificity.