Study Of The Nuclear Amitotic Division And Actin Cytoskeleton In Nitellopsis Obtuse

Nitellopsis obtuse is a species of Nitellopsis in Characeae. In other charophytes, it had been reported that nuclear amitotic divisions were extensively exhibited in the internodal cells of Nitellopsis obtuse which were multinuclei. However, many researches focused on the cytoplasmic streaming and organelle motility in charophytes. Little had been known about whether actin effected on nuclear amitosis. Recently, a series of researches showed that microtubules cytoskeleton appeared to have essential function in nuclear amitotic division in Tetrahymena. In charophytes, many physiological activities need the interreaction between actin filaments and microtubules. Therefor, we studied on the processes of nuclear amitosis and its relationship with actin cytoskeleton in Nitellopsis obtuse.In the first chapter, DAPI was used for staining internodal cells, branch cells, bract cells and rhizoid cells. The result showed that nuclear amitosis was the only kind of division in all these cells. In the process of amitosis, there was no chromatin condensing or chromosome. The nuclear membrane didn't disappear either. When division started, the cleaving positions was uncertain and new nuclei were produced in different sizes and shapes. Different dividing Styles were observed, splitting, constricting, and ameboid division. The splitting division and constricting division were dominating.In the second chapter, the rapid growing branchlet internodal cells which were about 2-3cm long were double labelled by Alexa 488-Phalloidin and PI for laser confocal scanning in order to reveal the organization of F-actin and its colocalization with nuclei. Two structures of F-actin cytoskeleton were revealed, the cortical actin filaments which were fine and only a few and the subcortical actin bundles which...