ELUCIDATION OF THE DNA SYNTHETIC CYCLE OF ENTAMOEBA HISTOLYTICA

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We developed a method to study the DNA synthetic cycles of Entamoeba histolytica and Entamoeba invadens by flow cytometry (FCM) based on a preparative procedure to reduce both high levels of natural fluorescence and non-specific adsorption of flurochromes. We modeled G_1, S,and G_2 phases as a series of overlapping Gaussian curves. Both E.histolytica and E,invadens displayd G_1, S,and G_2 proportions that are consistent with eukaryotic cell populations in exponential of stationary growth phase. Exponetial phase E.histolytica populations contained a hypodiploid subset with a mass of about 20% less than the diploid value which we estimate by FCM to be 24 x 10^<-14>gDNA/cell.Exponential phase E.invadens populations contained a hypodiploid subset with a mass of about 6% less than the diploid value which estimate by FCM to be 30 x 10^<-14>gDNA/cell.We developed also an axnic cultivation system for Entamoeba dispar which was nonpathogenic amoeba, by using newly developed BCSI-S medium in the presence of Crithidia fasciculata. sterilized by treating with 1% hydrogen peroxide for 24 hours at 4ﾟC.DNA polymerase activity of the ameba which was grown in this culture system, was detected and characterized. DNA polymerase activity was high at pH 2 to pH 6, but at pH 8 and 10 the activity was very low in nuclear extracts from both trophozoites of E.histolytica and E.dispar which were grown axnically.