Induced division synchrony in Entamoeba histolytica. Effects of hydroxyurea and serum deprivation

Synchronous growth of axenic Entamoeba histolytica was induced by nutritional deprivation and/or hydroxyurea. Axenic amebae maintained in 2% serum culture medium for 17-25 hours and returned to complete TP-S-1 (10% serum) medium showed a single synchronous cycle with a mean division time of 8.8 hours and a synchrony index of 0.47. Exposure to 10 mM hydroxyurea for 20-26 hours induced a single synchronous cycle with a division time of 3.0 hours and a synchrony index of 0.85. Hydroxyurea was toxic to 56% of the cells in the culture. The control generation time in TP-S-1 medium was 14.8 hours. Cells maintained for 44 hours in a nucleotide-deficient medium followed by a 10 mM hydroxyurea treatment exhibited two synchronous cycles. The first cycle had a generation time of 5.0 hours, a division time of 2.2 hours, and a synchrony index of 0.84.