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Published June 1985 | Published
Journal Article Open

Modulation of the asymmetry of sea urchin sperm flagellar bending by calmodulin

Abstract

Sea urchin spermatozoa demembranated with Triton X-100 in the presence of EGTA, termed potentially asymmetric, generate asymmetric bending waves in reactivation solutions containing EGTA. After they are converted to the potentially symmetric condition by extraction with Triton and millimolar Ca++, they generate symmetric bending waves in reactivation solutions containing EGTA. In the presence of EGTA, their asymmetry can be restored by addition of brain calmodulin or the concentrated supernatant obtained from extraction with Triton and millimolar Ca++. These extracts contain calmodulin, as assayed by gel electrophoresis, radioimmunoassay, activation of brain phosphodiesterase, and Ca++-dependent binding of asymmetry-restoring activity to a trifluorophenothiazine-affinity resin. Conversion to the potentially symmetric condition can also be achieved with trifluoperazine substituted for Triton during the exposure to millimolar Ca++, which suggests that the calmodulin-binding activity of Triton is important for this conversion. These observations suggest that the conversion to the potentially symmetric condition is the result of removal of some of the axonemal calmodulin and provide additional evidence for axonemal calmodulin as a mediator of the effect of Ca++ on the asymmetry of flagellar bending.

Additional Information

© 1985 by The Rockefeller University Press. Received for publication 10 December 1984, and in revised form 25 February 1985. The contributions of Adam Doyle, Larry Jones, and Hisaho Sonodo to this work by their digitizing all of the flagellar images are gratefully acknowledged. We also thank Dr. G.A. Orr for valuable suggestions. This work has been funded by National Institutes of Health grant GM 18711.

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August 22, 2023
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