Growth of hen erythrocyte nuclei undergoing reactivation in heterokaryons

Abstract

In heterokaryons formed by fusing hen erythrocytes with human HeLa cells, the erythrocyte nuclei undergo a reactivation process. This process is associated with marked alterations in the physicochemical properties of the chromatin and a dramatic increase in nuclear volume and dry mass. The present investigation shows that these changes take place also if the erythrocyte nuclei are rendered incapable of RNA synthesis by UV-irradiation before cell fusion. It is suggested that the nuclear growth is due mainly to a massive influx of human proteins from the cytoplasm of the hybrid cell. The redistribution of protein from the cytoplasm into the erythrocyte nuclei may be linked to the altered properties of the DNP-complex.