The cell cycle of Entamoeba invadens during vegetative growth and differentiation

The cell division cycle of Entamoeba invadens was studied during vegetative growth of trophozoites and during their differentiation into cysts. During vegetative growth of trophozoites, it was observed that DNA synthesis typi cally continued after one genome content had been duplicated. During encyst ation, DNA synthesis was arrested after 4n genome content had been synthesi sed. Using multi-parameter Row cytometry. the light scattering properties o f cysts acid trophozoites were studied. The cytoplasmic granularity, reflec ted by the side scatter of light, was proportional to DNA content of tropho zoites, whereas cysts with similar DNA contents showed heterogeneity in the ir cytoplasmic granularity. Dynamic changes in the intracellular calcium po ols were observed during differentiation of trophozoites to cysts. Comparis on of E. invadens and Entamoeba histolytica cell cycles suggest that both o rganisms may have similar regulatory processes during cell division and dif ferentiation. Since E. histolytica cannot be induced to encyst in axenic cu lture, analysis of the E. invadens cell cycle during encystation may be use ful for identifying homologous processes in E.histolytica. (C) 2001 Elsevie r Science B.V. All rights reserved.