Sperm Factor Initiates Capacitance and Conductance Changes in Mouse Eggs That Are More Similar to Fertilization Than IP3- or Ca2+-induced Changes
| Autor: | Sherwin C. Lee, Richard Nuccitelli, Rafael A. Fissore |
|---|---|
| Rok vydání: | 2001 |
| Předmět: |
Fura-2
Swine Inositol 1 4 5-Trisphosphate Biology patch clamp Capacitance Mice chemistry.chemical_compound Chlorides Animals endocytosis Patch clamp ionomycin Molecular Biology Protein Kinase C Sperm-Ovum Interactions Membrane potential Mice Inbred ICR Ionophores Electric Conductivity fura-2 Conductance Cell Biology Anatomy Sperm calcium imaging chemistry Fertilization Ionomycin Biophysics Calcium Female calcium channel exocytosis Intracellular Developmental Biology |
| Zdroj: | Developmental Biology. 232:127-148 |
| ISSN: | 0012-1606 |
| DOI: | 10.1006/dbio.2001.0155 |
| Popis: | We used patch clamp electrophysiology and concurrent imaging with the Ca(2+)-sensitive dye, fura-2, to study the temporal relationship between membrane capacitance and conductance and intracellular free Ca(2+) concentration ([Ca(2+)](i)) during mouse egg fertilization. We found an approximately 2 pF step increase in egg membrane capacitance and a minor increase in conductance with no change in [Ca(2+)](i) at sperm fusion. This was followed approximately 1 min later by a rise in [Ca(2+)](i) that led to larger changes in capacitance and conductance. The most common pattern for these later capacitance changes was an initial capacitance decrease, followed by a larger increase and eventual return to the approximate starting value. There was some variation in this pattern, and sub-microM peak [Ca(2+)](i) favored capacitance decrease, while higher [Ca(2+)](i) favored capacitance increase. The magnitude of accompanying conductance increases was variable and did not correlate well with peak [Ca(2+)](i). The intracellular introduction of porcine sperm factor reproduced the postfusion capacitance and conductance changes with a similar [Ca(2+)](i) dependence. Raising [Ca(2+)](i) by the intracellular introduction of IP(3) initiated fertilization-like capacitance changes, but the conductance changes were slower to activate. Capacitance decrease could be induced when [Ca(2+)](i) was increased modestly by activation of an endogenous Ca(2+) current, with little effect on resting conductance. These results suggest that net turnover of the mouse egg surface membrane is sensitive to [Ca(2+)](i) and that sperm and the active component of sperm factor may be doing more than initiating the IP(3)-mediated release of intracellular Ca(2+). |
| Databáze: | OpenAIRE |
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