The movement between nuclei of an integral protein of the inner nuclear membrane has been studied in rat/mouse and rat/hamster heterokaryons. This protein, p55, was found to equilibrate between nuclei over a period of approximately 6 h in the absence of new protein synthesis. When rat/mouse heterokaryons were constructed using an undifferentiated murine embryonal carcinoma (P19), which lacks la...

The bibenzimidazol derivative 33258 Hoechst can be used to distinguish microfluorometrically between mouse and human nuclei in heterokaryons. This affords a quick and accurate alternative to autoradiography in the analysis of such heterokaryons. The 33258 Hoechst fluorescence patterns can be converted after irradiation to a Giemsa rendition of the differential staining.

Activation of chicken globin gene transcription has been demonstrated in chicken erythrocyte--rat L6 myoblast heterokaryons. The globin mRNA is polyadenylylated and is translated into adult chicken alpha A-, alpha D-, and beta-globin polypeptides. No fetal globin mRNA or globin polypeptides were detected. Heterokaryons between chicken erythrocytes and mouse neuroblastoma cells or hamster BHK ce...