Peptide-induced hyperactivation-like vigorous flagellar movement in starfish sperm

Kogiku Shiba, Tomoko Tagata, Junko Ohmuro, Yoshihiro Mogami, Midori Matsumoto, Motonori Hoshi, Shoji A. Baba

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)


Asterosap, a sperm-activating peptide (SAP) from the starfish egg jelly coat, is diffusible and controls a cGMP-signalling pathway in starfish sperm in the same manner as resact, a potent chemoattracting SAP in sea urchins. This fact suggests that asterosap may serve as a chemoattractant like resact at concentrations with appropriate gradients. Since asterosap is one of three egg jelly components, which in concert induce the acrosome reaction, it is still worthwhile to evaluate how asterosap modulates sperm motility prior to this reaction. We analysed the flagellar movement of sperm of the starfish Aphelasterias japonica in artificial seawater (ASW) containing the asterosap isoform P15 at 1 μmol l-1. We found that sperm swim straighter with more symmetrical flagellar movement in P15 than in ASW, but without any significant difference in the flagellar beat frequency and the swimming velocity. The flagellar movement is, however, dramatically different between sperm firmly attached to the solid surface by the head in P15 and those attached in ASW: in P15 the flagellum bends to a greater extent, with higher curvature and with higher shear angle up to a right angle to the flagellar wave axis, and beats at an increased frequency. The vigorous flagellar movement of sperm, which can be activated when sperm are placed in high-load circumstances just as entering into a jelly layer, may increase propulsive forces and hydrodynamic resistances, allowing sperm to undergo the acrosome reaction as effectively as possible.

Original languageEnglish
Pages (from-to)23-32
Number of pages10
Issue number1
Publication statusPublished - 2006 Feb 1


  • Acrosome reaction
  • Aphelasterias japonica
  • Asterosap
  • Flagella
  • Starfish sperm

ASJC Scopus subject areas

  • Developmental Biology
  • Cell Biology


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