title: Inhibition of encystation of Entamoeba invadens by aphidicolin.
abstract: Effects of aphidicolin, a specific inhibitor of eukaryotic nuclear replicative DNA polymerases, on the growth and encystation of a reptilian parasitic protozoan Entamoeba invadens were evaluated. Aphidicolin blocked the growth of axenic E. invadens strain IP-1 in a dose-dependent manner. Encystation induced by the glucose depletion and osmotic pressure was also inhibited by aphidicolin. The inhibition was almost complete when trophozoites were treated with the drug before being transferred to encystation medium containing the drug. The inhibitory effect of aphidicolin on E. invadens growth was abrogated by removal of the drug, and exposure to 3 microg/ml of the drug for at least 7 days had little effect on the viability. Encystation was also restored by removal of the drug. These results suggest that the trophozoites accumulated at G1/S border by treatment with aphidicolin cannot encyst upon induction of encystation so that they need DNA synthesis before encystation.
authors.affiliation: Department of Tropical Medicine, Jikei University School of Medicine, Tokyo, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Kumagai
authors.forename: A
authors.initials: A
authors.lastname: Makioka
authors.forename: H
authors.initials: H
authors.lastname: Ohtomo
authors.forename: S
authors.initials: S
authors.lastname: Kobayashi
authors.forename: T
authors.initials: T
authors.lastname: Takeuchi
mesh_terms: D000818:Animals; D000981:Antiprotozoal Agents / Q000494:pharmacology*; D016590:Aphidicolin / Q000494:pharmacology*; D004747:Entamoeba / Q000187:drug effects* / Q000254:growth & development; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D019384:Nucleic Acid Synthesis Inhibitors
chemical_list: D000981:Antiprotozoal Agents; D004791:Enzyme Inhibitors; D019384:Nucleic Acid Synthesis Inhibitors; D016590:Aphidicolin