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Calcium and flagellar response during the chemotaxis of bracken spermatozoids
Author(s) -
Brokaw C. J.
Publication year - 1974
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/jcp.1040830118
Subject(s) - bracken , calcium , chemotaxis , biophysics , biology , fern , ion , stimulus (psychology) , biochemistry , chemistry , microbiology and biotechnology , botany , psychology , receptor , organic chemistry , psychotherapist
The attraction of fern spermatozoids by secretions from the female reproductive structures, and by salts of malic acid, has long been known as a classic example of precise chemotactic orientation by motile cells. Spermatozoids of the bracken fern are attracted by the partially ionized form of malic acid, bimalate ion, and also by calcium ions. Both calcium and bimalate ions must be present for chemotactic response and for response to voltage gradients, Spermatozoids swimming up a bimalate concentration gradient swim in helical paths of abnormally small radius; if they accidentally swim down the concentration gradient the radii of their path helices become abnormally large. These observations suggest that changes in the direction of flagellar beating in response to the rate of change of bimalate ion concentration with time may be the basis for chemotactic orientation. A “coupled diffusion” hypothesis for chemo‐reception is presented, which postulates a membrane carrier which can only circulate freely in the membrane if it binds both bimalate and calcium ions. This hypothesis could explain time‐differentiation of the stimulus, the coupling of a specific stimulus — bimalate ions — to a general mediator of intracellular response — calcium ions — and the quantitative relationship between response of the spermatozoids and the chemical potential of “calcium bimalate.”