Propagation of Transient Ca2+ Increase in Sea Urchin Eggs upon Fertilization and Its Regulation by Microinjecting EGTA Solution
| Autor: | Yukihisa Hamaguchi, Tatsuma Mohri |
|---|---|
| Rok vydání: | 1991 |
| Předmět: |
Cytoplasm
Microinjections genetic structures Fura-2 Physiology Video Recording chemistry.chemical_element Inositol 1 4 5-Trisphosphate Calcium Fluorescence chemistry.chemical_compound Human fertilization biology.animal Botany Animals Egtazic Acid Molecular Biology Sea urchin Ion transporter Ovum Microscopy biology Oocyte activation Cell Biology General Medicine EGTA chemistry Sperm entry Fertilization Sea Urchins Biophysics Female |
| Zdroj: | Cell Structure and Function. 16:157-165 |
| ISSN: | 1347-3700 0386-7196 |
| DOI: | 10.1247/csf.16.157 |
| Popis: | Upon fertilization, the concentration of intracellular Ca2+ (Cai) in sea urchin eggs increased up to 3 microM when measured with fura-2, a fluorescent Ca indicator and the increase in Cai traversed from the sperm entry point as a wave over the entire egg at the mean propagation velocities of 5.0 microns/sec in C. japonicus egg and 5.3 microns/sec in H. pulcherrimus egg. However, the velocity was not uniform; i.e., it was rapid in the vicinity of the sperm entry point and the opposite point, but slow in the central region of the egg. Microinjecting a Ca-EGTA buffer and an IP3 solution into the C. japonicus egg induced the transient Cai increase more rapidly than that upon fertilization, due perhaps to the diffusion of the injectates. In order to investigate Ca2+ release during Cai increase upon fertilization, EGTA solutions were microinjected into unfertilized or fertilizing eggs. Microinjecting 100 mM EGTA (final concentration of 1 mM) not only suppressed the transient Cai increase, but also reduced the increased Cai rapidly, and never induced egg activation after insemination, whereas 10 mM EGTA (final concentration of 0.1 mM) did not significantly affect the Cai increase or the activation. Ca2+ released upon fertilization was estimated to be 150-170 microM in the egg cytoplasm from the amount of microinjected EGTA and fura-2. It was concluded that although more than 150 microM of Ca2+ was released intracellularly upon fertilization, Cai increased to only a few microM because most of the released Ca2+ was sequestered by intracellular Ca2+ binding substances. |
| Databáze: | OpenAIRE |
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