Changes in Organelle Movement in the Nuclear Region during the Cell Cycle of <italic>Adiantum</italic> Protonema

Abstract

Movements of organelles in the nuclear region as the cell cycle progresses in single-celled protonemata of Adiantum capillus-veneris were examined by digital image processing techniques and microscopy of particle movement. Organelles in the nuclear region were not very crowded and moving directionally along the longitudinal axis of the filamentous cell in the G1 and S phases. They began to gather and accumulate in the nuclear region in early G2 phase, after which directional movement changed to undirectional Brownian motion-like movement in late G2 phase. Movement of organelles located on the lateral surface of the nucleus slowed after premitotic positioning of nucleus and lasted until the nucleolus disappeared. Movement of organelles in the cytoplasm surrounding the nucleoplasm resumed just after the nucleolus disappeared, whereas organelles located in the outer regions of the apical and basal surfaces of the nucleus moved rapidly during prophase but did not move during metaphase, movement being resumed after chromosome separation. Thus, organelle movement in the nuclear region showed temporal and spatial change during the cell cycle.