Localized accumulation of cytosolic calcium near the fused sperm is associated with the calcium- and voltage-dependent block of sperm entry in the sea urchin egg
| Autor: | Pedro I. Ivonnet, Tatsuma Mohri, David H. McCulloh |
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| Rok vydání: | 2016 |
| Předmět: |
Male
endocrine system chemistry.chemical_element Calcium Membrane Fusion Calcium in biology Membrane Potentials Cytosol biology.animal Genetics Animals Calcium Signaling Sea urchin reproductive and urinary physiology Ovum Membrane potential Sperm-Ovum Interactions biology urogenital system Cell Membrane Lipid bilayer fusion Cell Biology Anatomy Sperm Resting potential Spermatozoa Cell biology chemistry Sperm entry Fertilization Sea Urchins embryonic structures Female Calcium Channels Developmental Biology |
| Zdroj: | Molecular reproduction and development. 84(10) |
| ISSN: | 1098-2795 |
| Popis: | Sperm-egg interaction depolarizes the egg membrane, allowing the sperm to enter; however, if the egg membrane is not allowed to depolarize from its resting potential (e.g. by voltage-clamp), the sperm will not enter. Previous studies demonstrated that sperm entry into sea urchin eggs that are voltage-clamped at negative membrane potentials is regulated both by the egg's membrane potential and a voltage-dependent influx of calcium into the egg. In these cases, electrical or cytoplasmic continuity (sperm-egg membrane fusion) occurs at negative membrane potentials, but subsequent loss of cytoplasmic continuity results in failure of sperm entry (unfusion). The work presented herein examined where, in relation to the sperm, and when, in relation to the sperm-induced electrophysiological events, the egg's calcium influx occurs, and how these events relate to success or failed sperm entry. When sperm entered the egg, elevation of intracellular calcium concentration ([Ca2+]i) began near the fused sperm on average 5.9 sec after sperm-egg membrane fusion. Conversely, when sperm failed to enter the egg, [Ca2+]i elevated near the site of sperm-egg fusion on average 0.7 sec after sperm-egg membrane fusion, which is significantly earlier than in eggs for which sperm entered. Therefore, the accumulation of calcium near the site of sperm-egg fusion is spatially and temporally consistent with the mechanism that may be responsible for loss of cytoplasmic continuity and failure of sperm entry. This article is protected by copyright. All rights reserved |
| Databáze: | OpenAIRE |
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