Actin in mating structures of Chlamydomonas eugametos gametes

The presence of actin in Chlamydomonas eugametos mating structures was studied using monoclonal anti-actin antibodies. Immunofluorescent labelling of mating gametes clearly stained their mating structures and this was confirmed at the electron microscope level by immunogold labelling of sections. Anti-actin labelling also strongly stained the flagella at the flagellar collar regions and weakly stained the rest of the flagella. Treatment of gametes with 6–8% ethanol induced mating structures which protruded as large 'balloons'. Balloons stained brilliantly with anti-actin antibodies and weakly with FITC-phalloidin, a fluorescent reagent that stains F-actin. Isolated mating structure balloons and flagella were analyzed using western blotting. A prominent 43 kDa band, co-migrating with actin in erythrocyte ghosts, reacted with anti-actin antibodies. The results indicate that actin is present in mating structures and flagella of both mating types of C, eugametos .