| Budget Amount *help |
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1990: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1989: ¥1,400,000 (Direct Cost: ¥1,400,000)
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| Research Abstract |
Cultured pollen protoplasts of Lilium longiflorum were used to study, with the aid of rhodaminephalloidin staining and immunofluorescence, changes in the organization of actin filaments and microtubules(MTs)during cell-wall regeneration, transition of cell shape from spherical to ellipsoid, growth in cell size and pollen-tube development. In freshly isolated pollen protoplasts, an extensive network of minute actin filaments and disorganized MTs was observed in the central cytoplasm of the vegetative cell. After regeneration of the cell wall cortical actin filaments and MTs gradually became organized but their orientation remained random. At 5-6 d of culture, when the protoplasts changed from a spherical to an ellipsoid shape, the cortical actin filaments were aligned almost in parallel, extending 'bBetween two opposite foci, and in the growing ellipsoidal cell thick actin bundles became oriented transversely to the long axis of the cell. Following the ordering of the cortical actin filaments the cortical MTs also became arranged parallel to the actin filaments. After 8-10 d of culture, when the protoplasts germinated and formed a pollen tube, both actin filaments and MTs entered the tube. Cytochalasin B and colchicine added to the medium from the beginning of the protoplast culture inhibited the organization of the actin and MT cytoskeleton, and addition of the drugs from day 5 of culture destroyed the organization and arrangement of the cytoskeleton. Both drugs blocked pollen germination in the cultured protoplasts. From these observations it is assumed that the arrangement of actin filaments plays a predominant role in pollen germination, but that the arrangement of the MTs is also essential for pollen germination through maintaining cell polarity established by the actin arrangement.
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