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001-es BibID:	BIBFORM043635
Első szerző:	Izumi, Hiroko
Cím:	Membrane Hyperpolarization by Sperm-Activating and -Attracting Factor Increases cAMP Level and Activates Sperm Motility in the Ascidian Ciona intestinalis / Hiroko Izumi, Teréz Márián, Kazuo Inaba, Yoshitaka Oka, Masaaki Morisawa
Dátum:	1999
ISSN:	0012-1606
Megjegyzések:	In the ascidian Ciona intestinalis (and C. savignyi), sperm-activating and -attracting factor (SAAF) is released from the egg at fertilization and stimulates both Ca(2+) influx and a transient increase in cAMP level of the sperm, leading to the activation of sperm motility (M. Yoshida et al., 1994, Dev. Growth Differ. 36, 589-595). In this paper we show in C. intestinalis that valinomycin, a potassium-selective ionophore, as well as SAAF, activated sperm motility, and this activation was suppressed by extracellular high K(+). Membrane potential measurements showed that both SAAF and valinomycin increase K(+) permeability of sperm and induce membrane hyperpolarization, the amplitude of which depends on the external K(+) concentration. The membrane potential and intracellular K(+) concentration of Ciona sperm without SAAF were estimated to be about -50 mV and 560 +/- 40 mM, respectively. After treatment with SAAF or valinomycin the membrane potential became almost equal to the equilibrium potential of K(+) (-100 mV), and the cAMP level increased in artificial seawater. A potent voltage-dependent K(+) channel blocker, MCD peptide, at the concentration of 10 microM blocked SAAF-induced hyperpolarization of the cells, increase in cAMP, and sperm motility. These results suggest that membrane hyperpolarization produced by the opening of K(+) channels elevates cAMP synthesis and leads to the activation of sperm motility in Ciona.
Tárgyszavak:	Természettudományok Biológiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:	Developmental Biology. - 213 : 2 (1999), p. 246-256. -
További szerzők:	Márián Teréz (1950-) (radiobiológus) Inaba, Kazuo Oka, Yoshitaka Morisawa, Masaaki
Internet cím:	Szerző által megadott URL DOI Intézményi repozitóriumban (DEA) tárolt változat
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001-es BibID:	BIBFORM038939
Első szerző:	Krasznai Zoltán (biofizikus)
Cím:	Membrane hyperpolarization removes inactivation of Ca2+ channels, leading to Ca2+ influx and subsequent initiation of sperm motility in the common carp / Krasznai, Z., Marian, T., Izumi, H., Damjanovich, S., Balkay, L., Tron, L., Morisawa, M.
Dátum:	2000
Megjegyzések:	Change of osmolality surrounding spawned sperm from isotonic to hypotonic causes the initiation of sperm motility in the common carp. Here we show that membrane-permeable cAMP does not initiate motility of carp sperm that is quiescent in isotonic solution, and that motility of the demembranated sperm can be reactivated without cAMP. Furthermore, the cAMP level does not change during the initiation of sperm motility, and inhibitors of protein kinase do not affect sperm motility, suggesting that no cAMP-dependent system is necessary for the regulation of sperm motility. Sperm motility could not be initiated in Ca(2+)-free hypoosmotic solutions, and significant increase in the intracellular Ca(2+) level was observed by a Ca-sensitive fluorescence dye during hypoosmolality-induced active motion period. The demembranated sperm cells were fully reactivated in the solutions containing 10(-7) to 10(-5) M Ca(2+). Ca(2+) channel blockers such as verapamil and omega-conotoxin reversibly inhibited the initiation of sperm motility, suggesting that Ca(2+) influx is the prerequisite for the initiation of carp sperm motility. Motility of intact sperm was completely blocked; however, that of the demembranated sperm was not inhibited by the calmodulin inhibitor W7, suggesting that the calmodulin bound close to the plasma membrane participated in the initiation of sperm motility. Flow cytometric membrane potential measurements and spectrophotometric measurements by using fluorescence dyes showed transient membrane hyperpolarization on hypoosmolality-induced motility. This article discusses the role of membrane hyperpolarization on removal of inactivation of Ca(2+) channels, leading to Ca(2+) influx at the initiation of carp sperm motility.
Tárgyszavak:	Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:	Proceedings of the National Academy of Sciences of the United States of America. - 97 : 5 (2000), p. 2052-2057. -
További szerzők:	Márián Teréz (1950-) (radiobiológus) Izumi, Hiroko Damjanovich Sándor (1936-2017) (biofizikus) Balkay László (1963-) (biofizikus) Trón Lajos (1941-) (biofizikus) Morisawa, Masaaki
Internet cím:	Intézményi repozitóriumban (DEA) tárolt változat
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