DNA Synthesis and Mitosis in Fused Cells

Abstract

Unlike HeLa homokaryons and HeLa-erythrocyte heterokaryons, heterokaryons made by fusing HeLa cells with Ehrlich ascites cells do not, in general, succeed in synchronizing DNA synthesis or mitosis. Indeed, a form of antisynchrony is observed in which most of the Ehrlich nuclei synthesize DNA and most of the HeLa nuclei do not. This anomalous situation appears to be the consequence of competition between the Ehrlich nuclei and the HeLa nuclei for some factor or factors essential for DNA synthesis. In this competition the Ehrlich nuclei are over-whelmingly successful, so that synthesis of DNA in the HeLa nuclei is largely inhibited. The patterns of DNA synthesis in these heterokaryons are thus essentially determined by the proportions of the two kinds of nuclei in the cell.