The signal flow and motor response controling chemotaxis of sea urchin sperm.
The signalling pathway and the behavioural strategy underlying chemotaxis of sperm are poorly understood. We have studied the cellular events and motor responses that mediate chemotaxis of sperm from the sea urchin Arbacia punctulata. Here we show that resact, a chemoattractant peptide, initiates a rapid and transient rise in the concentration of cyclic GMP, followed by a transient influx of Ca2+. The binding of a single resact molecule elicits a Ca2+ response, and 50-100 bound molecules saturate the response. The ability to register single molecules is reminiscent of the single-photon sensitivity of rod photoreceptors. Both resact and cyclic nucleotides cause a turn or brief tumbling in the swimming path of sperm. We conclude that a cGMP-mediated increase in the Ca2+ concentration induces the primary motor response of sperm to the chemoattractant.
Kaupp
U Benjamin
UB
Institut für Biologische Informationsverarbeitung, Forschungszentrum Jülich, 52425 Jülich, Germany. a.eckert@fz-juelich.de
Solzin
Johannes
J
Hildebrand
Eilo
E
Brown
Joel E
JE
Helbig
Annika
A
Hagen
Volker
V
Beyermann
Michael
M
Pampaloni
Francesco
F
Weyand
Ingo
I
D000818:Animals; D002118:Calcium / Q000378:metabolism; D002633:Chemotaxis / Q000502:physiology*; D000242:Cyclic AMP / Q000031:analogs & derivatives / Q000378:metabolism; D006152:Cyclic GMP / Q000031:analogs & derivatives / Q000378:metabolism; D004527:Egg Proteins / Q000378:metabolism*; D006162:Guanylate Cyclase; D008297:Male; D015394:Molecular Structure; D011485:Protein Binding; D011956:Receptors, Cell Surface / Q000378:metabolism*; D012617:Sea Urchins / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology*; D013081:Sperm Motility; D013094:Spermatozoa / Q000166:cytology / Q000378:metabolism / Q000502:physiology*
D004527:Egg Proteins; D011956:Receptors, Cell Surface; D000242:Cyclic AMP; D006162:Guanylate Cyclase; C048639:resact protein, sea urchin; D006152:Cyclic GMP; D002118:Calcium