Effects of antibodies against tubulin on the movement of reactivated sea urchin sperm flagella.

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Abstract
Antibodies binding to sea urchin [Strongylocentrotus purpuratus] flagellar outer-doublet tubulin were isolated from rabbit sera by tubulin-affinity chromatography employing electrophoretically purified tubulin as the immobilized substrate. This procedure provides induced antitubulin antibody from immune sera and spontaneous antitubulin antibody from preimmune sera. These antitubulins were characterized in terms of their specificity, ability to bind to sea urchin axonemes and effects on the motility of reactivated spermatozoa. Induced antitubulin antibody specifically reduced the bend angle and symmetry of the movement of demembranated reactivated spermatozoa without affecting the beat frequency. At identical concentrations, spontaneous antitubulin had no effect on motility. Affinity-purified induced antitubulins from 3 other rabbits all gave specific bend-angle inhibition; their corresponding spontaneous antitubulins had no effect on flagellar movement. The effects of antitubulin on microtubule sliding were examined by observing the sliding disintegration of elastase-digested axonemes induced by MgATP2-. Affinity-purified induced antitubulin antibody, in quantities sufficient to completely paralyze reactivated flagella, did not inhibit microtubule sliding. The amplitude-inhibiting effect of induced antitubulin on reactivated spermatozoa may be caused by action on a mechanism responsible for controlling flagellar bending rather than by interference with the active sliding process. This is the 1st report of an antitubulin antibody having an inhibitory activity on microtubule-associated movement.