The effect of drugs on the cell cycle of Giardia intestinalis

Parasitology. 1989 Dec;99 Pt 3:333-9. doi: 10.1017/s0031182000059047.


Flow cytometric analysis of the binucleated protozoan parasite Giardia intestinalis gave DNA histograms with a broad G1 peak and a definable G2 + M peak with twice the DNA content of G1. Twenty-four hour treatment with metronidazole arrested cell cycle progression of susceptible trophozoites in the G2 + M phase, but had no effect, even at toxic doses, on the DNA histogram of a line selected for resistance to metronidazole. Furazolidone was inhibitory to both stocks, causing an arrest in the S and G2 + M phases. Inhibitors of the mammalian cell cycle were also tested. Hydroxyurea, which blocks mammalian cells in G1/S, and razoxane, which blocks in G2 + M, arrested trophozoites in the G2 + M phase whereas colchicine and gamma-irradiation had little or no effect on the cell cycle of G. intestinalis. These results suggest that the cell cycle of G. intestinalis may be controlled in a different manner from mammalian cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Cycle / drug effects
  • Colchicine / pharmacology
  • DNA / analysis
  • Flow Cytometry
  • Furazolidone / pharmacology*
  • Giardia / drug effects*
  • Hydroxyurea / pharmacology
  • Metronidazole / pharmacology*
  • Razoxane / pharmacology


  • Metronidazole
  • Razoxane
  • Furazolidone
  • DNA
  • Colchicine
  • Hydroxyurea