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Ionic mechanism of the fertilization potential of the marine worm, Urechis caupo (Echiura)
Microelectrode and tracer flux studies of the Urechis egg during fertilization have shown: (a) insemination causes a fertilization potential; the membrane potential rises from an initial level of -33 +/- 6 mV to a peak at +51 +/- 6 mV (n = 16), falls to a plateau of about +30 mV, then returns to the...
Formato: | Texto |
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Lenguaje: | English |
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The Rockefeller University Press
1979
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Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2215169/ https://www.ncbi.nlm.nih.gov/pubmed/571895 |
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collection | PubMed |
description | Microelectrode and tracer flux studies of the Urechis egg during fertilization have shown: (a) insemination causes a fertilization potential; the membrane potential rises from an initial level of -33 +/- 6 mV to a peak at +51 +/- 6 mV (n = 16), falls to a plateau of about +30 mV, then returns to the original resting potential 9 +/- 1 min (n - 10) later; (b) the fertilization potential results from an increase in Na+ permeability, which is amplified during the first 15 s by a Ca++ action potential; (c) the maximum amplitude of the fertilization potential, excluding the first 15 s, changes by 51 mV for a 10-fold change in external [Na+]; (d) in the 10 min period after insemination, both Na+ and Ca++ influxes increase relative to unfertilized egg values by factors of 17 +/- 7 (n = 6) and 34 +/- 14 (n = 4), respectively; the absolute magnitude of the Na+ influx is 16 +/- 6 times larger than that of Ca++; (e) in the absence of sperm these same electrical and ionic events are elicited by trypsin; thus, the ion channels responsible must preexist in the unfertilized egg membrane; (f) increased Na+ influx under conditions of experimentally induced polyspermy indicates that during normal monospermic fertilization, only a fraction of available Na+ channels are opened; we conclude that these channels are sperm- gated; (g) Ca++ influx at fertilization is primarily via the membrane potential-gated channel, because kinetics are appropriate, and influx depends on potential in solutions of varying [Na+], but is independent of number of sperm incorporations in normal sea water. |
format | Text |
id | pubmed-2215169 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 1979 |
publisher | The Rockefeller University Press |
record_format | MEDLINE/PubMed |
spelling | pubmed-22151692008-04-23 Ionic mechanism of the fertilization potential of the marine worm, Urechis caupo (Echiura) J Gen Physiol Articles Microelectrode and tracer flux studies of the Urechis egg during fertilization have shown: (a) insemination causes a fertilization potential; the membrane potential rises from an initial level of -33 +/- 6 mV to a peak at +51 +/- 6 mV (n = 16), falls to a plateau of about +30 mV, then returns to the original resting potential 9 +/- 1 min (n - 10) later; (b) the fertilization potential results from an increase in Na+ permeability, which is amplified during the first 15 s by a Ca++ action potential; (c) the maximum amplitude of the fertilization potential, excluding the first 15 s, changes by 51 mV for a 10-fold change in external [Na+]; (d) in the 10 min period after insemination, both Na+ and Ca++ influxes increase relative to unfertilized egg values by factors of 17 +/- 7 (n = 6) and 34 +/- 14 (n = 4), respectively; the absolute magnitude of the Na+ influx is 16 +/- 6 times larger than that of Ca++; (e) in the absence of sperm these same electrical and ionic events are elicited by trypsin; thus, the ion channels responsible must preexist in the unfertilized egg membrane; (f) increased Na+ influx under conditions of experimentally induced polyspermy indicates that during normal monospermic fertilization, only a fraction of available Na+ channels are opened; we conclude that these channels are sperm- gated; (g) Ca++ influx at fertilization is primarily via the membrane potential-gated channel, because kinetics are appropriate, and influx depends on potential in solutions of varying [Na+], but is independent of number of sperm incorporations in normal sea water. The Rockefeller University Press 1979-04-01 /pmc/articles/PMC2215169/ /pubmed/571895 Text en This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.rupress.org/terms). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 4.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/4.0/). |
spellingShingle | Articles Ionic mechanism of the fertilization potential of the marine worm, Urechis caupo (Echiura) |
title | Ionic mechanism of the fertilization potential of the marine worm, Urechis caupo (Echiura) |
title_full | Ionic mechanism of the fertilization potential of the marine worm, Urechis caupo (Echiura) |
title_fullStr | Ionic mechanism of the fertilization potential of the marine worm, Urechis caupo (Echiura) |
title_full_unstemmed | Ionic mechanism of the fertilization potential of the marine worm, Urechis caupo (Echiura) |
title_short | Ionic mechanism of the fertilization potential of the marine worm, Urechis caupo (Echiura) |
title_sort | ionic mechanism of the fertilization potential of the marine worm, urechis caupo (echiura) |
topic | Articles |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2215169/ https://www.ncbi.nlm.nih.gov/pubmed/571895 |