FIGURE 7.

Schematic representation showing the effect of inhibitors on the host protozoan cell cycle and on symbiont division. Aphidicolin arrested the A. deanei (A) cell cycle in the G1/S phase, and the symbiont underwent DNA replication, generating a bacterium with four nucleoids; however, the cytokinesis was not completed. In S. culicis (B), the same inhibitor blocked the host cell cycle in the S phase and induced symbiont filamentation, indicating different division control of the symbiont in each species. Camptothecin induced host cell cycle arrest in the G2 phase and symbiont filamentation in both species. Oryzalin only showed an effect on the S. culicis cell cycle, which was arrested in the M phase, thus impairing symbiont division.