Dissertation / PhD Thesis/Book

PreJuSER-32757

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Chemotaxis von Seeigel-Spermien: Kinetische Messungen intrazellulärer Botenstoffe

Solzin, J. (Corresponding author)FZJ*

2003
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag Jülich

Please use a persistent id in citations: http://hdl.handle.net/2128/2565

Report No.: Juel-4030

Abstract: The egg-petide resact induces a chemotactical response of sperm from sea urchin Arbacia punctulata. By bindig to a receptor-guanylylcyclase on the flagellar membrane resact activates a signaling-cascade. This leads to an increase in cGMP-/cAMP-concentration, Ca$^{2+}$- concentration an pH. The sequence and thereby the causal relations of the single physiological reactions were unkown before. In order to reveal the sequence of the signaling events I have established two methods which allowed time-resolved measurements (e.g. in millisecond time-scale) of the physiological reactions. The quenched-flow-method was used to detect the time-course of the cGMP-/cAMP-concentration. Therefore it was combined with cGMP-/cAMP-sensitive Radioimmunoassays. The stopped-flow-method was used to record the timecourse of the Ca$^{2+}$- or pH-sensitive fluorescence-indicators. Both methods enabled me to measure for the first time the sequence of the physiological reactions. The measurements showed, that resact induces a fast and high increase of the cGMP-concentration. The cGMP-concentration starts rising within the first 25 ms and reaches its half-maximal concentration within 200 ms. A cGMP-increase is already induced at picomolar resact-concentrations whereas a cAMP-increase is only induced by nanomolar resactconcentrations. Furthermore the cAMP-increase is slighter and slower compared to the cGMP-increase. Arround 250 ms after the stimulation with resact the Ca$^{2+}$-concentration increases. This Ca$^{2+}$- signal can be devided in an „early“ and a „late“ Ca$^{2+}$-signal. While the early Ca$^{2+}$-signal can be already triggered by single resact-molecules the late Ca$^{2+}$-signal is less sensitive to the eggpetide. The early Ca$^{2+}$-signal is either directly or through other signaling events triggered by cGMP. The cAMP-increase is – at least in the presence of the PDE-inhibitor IBMX – slower than the late Ca$^{2+}$-signal. Therby cAMP could only trigger the late Ca$^{2+}$-signal. In contrast to the late Ca$^{2+}$-signal the early Ca$^{2+}$-signal is induced at the same time as the resact-induced change of the swimming-behavior. Thus the early Ca$^{2+}$-signal represents the crucial reaction in the resact-induced signaling-cascade. Like the early Ca$^{2+}$-signal, the pH responds to resact-concentrations over more than 6 orders of magnitude. The delay of the pH-change is only at high resact-concentrations faster than the delay of the Ca$^{2+}$-signal. At low resact-concentrations the pH increases after the Ca$^{2+}$-concentration. Contrary to other publications, this results shows that the pH-increase does not trigger the Ca$^{2+}$-increase.

Note: Record converted from VDB: 12.11.2012
Note: Köln, Univ., Diss., 2003

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Contributing Institute(s):

1. Zelluläre Signalverarbeitung (IBI-1)

Research Program(s):

1. Neurowissenschaften (L01)

Appears in the scientific report 2003

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Database coverage:

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