DNA synthesis and mitosis in fused cells. II. HeLa-chick erythrocyte heterokaryons.

When chick erythrocyte nuclei are introduced into the cytoplasm of HeLa cells they resume the synthesis of DNA. The reactivated nuclei synthesize DNA in a highly co-ordinated manner and essentially in synchrony with the HeLa nuclei. Asynchronous DNA synthesis is rare. The erythrocyte nuclei in the HeLa cytoplasm respond to the signals which regulate DNA synthesis in the same way as the HeLa nuclei; and they do not, for at least 2 days after cell fusion, interfere in any way with the synthesis of DNA in the HeLa nuclei.