Abstract
Mitochondrial and chloroplast division controls number and morphology of the organelles, although how cells regulate the organelles division is unknown. Previous studies have shown the similarity between the mechanisms of mitochondrial and chloroplast division, that FtsZ, Plastid/Mitochondrion Dividing (PD/MD) ring and dynamin are respectively involved in the placement, constriction and severance in the organelles division. Here, we characterized the microtubule organization in association with the organelles division and distribution in a red alga Cyanidioschyzon merolae, and discussed that each step of mitochondrial and chloroplast division is in coordination with cell cycle. When microtubule organization was disrupted, mitochondria and chloroplasts divided once, while inhibition of DNA synthesis resulted in repetitive chloroplast division, restraint of mitochondrial division at the final severance, indicating that each step of these organelles division is regulated at distinct check point. Furthermore, recruitment of dynamin for final mitochondrial severance was shown to be under the cell cycle regulation.
