Abstract
The primitive red algae, Cyanidioschyzon, have only a set of organelles, such as nucleus, mitochondrion and chloroplast in the cell. The cell cycle of this organism coordinates with division cycle of chloroplast and mitochondria. However, mechanisms for the regulation of this coordinated cell cycle have not been elucidated. Here, using synchronized cultivation technique, we investigated regulatory mechanisms to initiate organelle replication and that to coordinate organelle cell cycle with that of nucleus.
We identified that replication of chloroplast genome and mitochondrial genome starts before that of nuclear genome by Southern hybridization method. We also identified that a cyclin protein is expressed similar manner with the replication cycle of nuclear genome by Western analysis. These results suggest that the cell cycle of each organelle in Cyanidioschyzon is regulated independently and that as yet known mechanisms might correlate them each other to constitute the coordinated DNA replication and cell division in Cyanidioschyzon.
