Untersuchungen zur Bedeutung der intrazellulären Ca$^{2+}$ -Konzentrationen für die Chemotaxis von Seeigel- und Seestern-Spermien

Van, Qui

Dissertation / PhD Thesis/Book

Untersuchungen zur Bedeutung der intrazellulären Ca$^{2+}$ -Konzentrationen für die Chemotaxis von Seeigel- und Seestern-Spermien

Van, Q. (Corresponding author)FZJ*

2005
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag Jülich

Jülich : Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag, Berichte des Forschungszentrums Jülich 4190, VIII, 112 p. (2005) = Köln, Univ., Diss., 2005

Please use a persistent id in citations: http://hdl.handle.net/2128/476

Report No.: Juel-4190

Abstract: The events that occur during chemotaxis of sperm are only partly known. As an essential step toward determining the underlying mechanism, we developed a sensitive laser-stroboscopic technique that allows the recording of changes in intracellular Ca$^{2+}$-concentration in swimming sperm of the sea urchin Arbacia punctulata and starfish Asterias amurensis. Stimulation of the sea urchin Arbacia punctulata by the themoattractant or by intracellular cGMP evokes Ca$^{2+}$ spikes in the flagellum. These Ca$^{2+}$ spikes control the swiming behaviour of sperm. A Ca$^{2+}$ spike elicits a turn in the trajectory followed by a period of straight swimming (‘turn-andrun’). The train of Ca$^{2+}$ spikes gives rise to repetitive loop-like movements. When sperm swim in a concentration gradient of the attractant, the Ca$^{2+}$ spikes and the stimulus function are synchronized, suggesting that precise timing of Ca$^{2+}$ spikes controls navigation. We identified the peptide asterosap as a chemotactic factor of the starfish Asterias amurensis. The similarities in first, the cGMP-induced Ca$^{2+}$ spikes in the flagellum, second, the motor response and third the swimming behavior of sperm from starfish and sea urchin imply that the signaling pathway of chemotaxis has been conserved in species, which diverged almost 500 million years ago. A cGMP-gated ion channel (CNG-channel), which might be involved in hyperpolarisation or Ca$^{2+}$ entry, could not yet be identified in Arbacia punctulata. Voltage-sensitive Ca$^{2+}$- channels, which are only said to have a function in the acrosome reaction, however, seem to play a more important role for the Ca$^{2+}$ entry during sperm chemotaxis.

Note: Record converted from VDB: 12.11.2012
Note: Köln, Univ., Diss., 2005

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