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Effect of Extracellular Ca 2+ and Ca 2+ ‐Antagonists on the Movement and Chemoorientation of Male Gametes of Ectocarpus siliculosus (Phaeophyceae)
Author(s) -
Maier I.,
Calenberg M.
Publication year - 1994
Publication title -
botanica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.871
H-Index - 87
eISSN - 1438-8677
pISSN - 0932-8629
DOI - 10.1111/j.1438-8677.1994.tb00820.x
Subject(s) - chemokinesis , sex pheromone , flagellum , pheromone , extracellular , motility , sea urchin , chemotaxis , biology , sperm , chemistry , biophysics , microbiology and biotechnology , stereochemistry , biochemistry , botany , gene , receptor
Chemoorientation in male gametes of Ectocarpus siliculosus in response to sexual pheromones is effected by two distinct mechanisms, chemokinesis and chemoklinotaxis. These are characterized by a strongly asymmetric bending pattern of the anteriorly‐directed flagellum and transient unilateral bending of the hind flagellum, respectively. Removal of extracellular Ca 2+ showed that normal flagellar movement and chemokinesis require millimolar concentrations of Ca 2+ in the medium. The response to pheromones is strongly inhibited by La 3+ , whereas the Ca 2+ ‐channel drugs, verapamil and nifedipine, have only little effect. Nifedipine nethertheless effectively inhibited accumulation at pheromone sources. These results are interpreted as an indication for the involvement of two pharmacologically distinct Ca 2+ ‐channels in chemokinesis and chemoklinotaxis. The calmodulin‐antagonist, trifluoperazine, induces, at low concentrations, the same flagellar response in chemokinesis as the pheromone, the mechanism of action remaining unknown.