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Reminiscent of their cyanobacterial (A) ancestor, chloroplasts replicate by binary division (B, unicellular alga; C land plant cells). Chloroplast division is performed by the division ring (D) which involves cyanobacterial FtsZ and eukaryotic dynamin (E).

Research

Mitochondria and chloroplasts are energy-converting organelles in eukaryotic cells. Both originated more than one billion years ago when bacterial cells were engulfed by primitive eukaryotic cells. Besides these organelles, there are many examples of endosymbioses which have integrated new functions into host cells. In order to maintain a permanent endosymbiotic relationship, endosymbionts/organelles must be replicated and inherited into each daughter cell during host cell division. We have shown that chloroplasts and mitochondria use similar division systems, both of which are derived from the ancestral bacterial endosymbionts and the eukaryotic host.

The major goal of our study is to understand how two different cells are integrated into a new cell by coordinated proliferation of a host and an endosymbiotic cell. To this end, we are investigating (1) how eukaryotic host cells regulate proliferation of organelles/endosymbionts, (2) how activities of organelles/endosymbionts affect proliferation of the host cells, and (3) how these systems have evolved and contributed to eukaryotic evolution.

The Latest Review (Published in Plant Physiol.)


On-going projects

1. Characterizaiton of the chloroplast division machinery in algae and plants
2. Analyses of the relationship between cell cycle and chloroplast division
3. Characterization of division machinery of endosymbiotic bacteria and eukaryotes in host cells
4. Relationship between metabolic activities of organelles/endosymbionts and host cell cycle.
5. Evolution of division machineries of organelles/endosymbionts

Organisms used in our study

Unicellular algae (Red alage, Green algae, Glaucophyte algae, Cyanobacteria)
Land plants (Arabidopsis, the moss Physcomitrella)
Cellular slime mold
Other protists that possess endosymbiotic bacteria or eukaryotes

©2011 Miyagishima Lab