[DNA hyperreplication in the nuclei of Amoeba borokensis in the cell cycle]

The relative nuclear DNA contents were determined cytofluorometrically for several groups of synchronized Amoeba borokensis at the early and late interphase. In some groups of these amoebae the nuclear DNA content by the end of the interphase exceeded more than twice that measured 1 h after division, when DNA in amoebic nuclei already being synthesized. This means that the extra DNA was synthesized in the nuclei of amoebae of these particular groups. In other amoebic groups the nuclear DNA content checked at the end of the interphase did not exceed the doubled 1 h level. Thus, in these amoebae the quantity of the synthesized extra DNA was less than that in the former groups, or the extra DNA was not synthesized at all.