Abstract: Authors demonstrate the presence of actin and myosin in pollens from Luffa cylindricaand Zea mays in this report. The molecular weight of the heavy chain of pollen myosinis about 165000 daltons as analyzed by 4–30% SDS gradient polyacrylamide gel electrophoresis. The ATPase activity of pollen myosin is identical with the characteristics of rabbit ske-letal muscle myosin. In 0.5 mol/l KCl, the K+-EDTA activity is the highest and Mg2+ activitythe lowest. The Ca2+ activity is higher than Mg2+ activity and lower than K+-EDTA activity.Pollen actin from Zea mays was prepared by preparative SDS polyacrylamide gel electrophoresis Its molecular weight is 43,000 daltons which is the same as rabbit skeletal muscle actin. The effect of drugs on cytoplasmic streaming of pollen tubes were observed under opticalmicroscope Cytochalasin B (CB), chloropromazine (CPZ) and chlorotetracycline (CTC)inhibit cytoplasmic streaming obviously. But colchicine has no effect on the cytoplasmic streamrog. It is suggested that the motive force of cytoplasmic streaming may be the interaction ofmyosin and actin in the pollen tubes.

Key words: Actin, Myosin, Pollen, Cytoplasmic streaming