The effect of myosin antibody on the division of starfish blastomeres

Abstract

Antiserum against starfish [Asterias amurensis] egg myosin was produced in rabbits. Antibody specificity to myosin was demonstrated by Ouchterlony''s immunodiffusion test and by immunoelectrophoresis in the presence of sodium dodecylsulfate (SDS). The latter technique showed that antibody bound to both H and L chains of egg myosin. The antibody reacted with starfish sperm myosin and starfish adult muscle myosin at both H and L chains. It did not react with bovine platelet myosin or rabbit skeletal muscle myosin in Ouchterlony''s test, but a weak reaction was observed in the presence of SDS between the antibody and these myosin H chains. Ca- and Mg-ATPase activities of egg myosin were not affected by the antibody, but it inhibited actin-activated ATPase activity of egg myosin. Microinjection of the antibody into blastomeres of starfish eggs at the 2-cell stage was carried out. Anti-egg myosin .gamma.-globulin inhibited the subsequent cleavages at amounts > 0.3 ng when injected at interphase. The inhibition was reduced when injection was carried out near the initiation of cleavage. At the onset of the 2nd cleavage the antibody was not inhibitory, but an appropriate amount inhibited the 3rd cleavage. Although the disappearance of the nuclear membrane was observed in the presence of antibody, the formation of the mitotic apparatus was more or less disturbed. The formation of daughter nuclei seemed to be scarcely affected by antibody except that the distance between the nuclei was significantly smaller than normal.